I E> R.ARY OF THL UN IVER.5ITY Of ILLINOIS no.433-444- CIRCULATING r URCUL/ UNBOUND Composition of Mature Corn Stover As affected by Variety, Soil Type, and Fertilizer Treatment By D. C. WIMER UNIVERSITY OF ILLINOIS AGRICULTURAL EXPERIMENT STATION Bulletin 437 CONTENTS PAGE INTRODUCTION 175 REVIEW OF LITERATURE 176 PLAN OF ILLINOIS EXPERIMENTS 182 SOIL AND CLIMATIC CONDITIONS REPRESENTED 188 Soil Types Represented 188 Crop Rotations Practiced 191 Soil Treatments Represented 192 Climate 193 VARIETAL DIFFERENCES IN THE COMPOSITION OF MATURE CORN STOVER 196 Different Varieties Grown Under Similar Conditions 197 At Urbana, South Farm 197 At Alhambra 200 At DeKalb 202 At Toledo 203 Composition in Relation to Yields 204 Same Varieties Grown Under Different Conditions 209 At Urbana and Alhambra 209 At Urbana and DeKalb 213 At Urbana, Alhambra and DeKalb 214 EFFECT OF SOIL TYPE AND FERTILIZER TREATMENT ON COMPOSITION OF MATURE CORN STOVER 216 Effect of Different Soil Types Under Same Climatic Conditions 217 Effect of Single Materials in Standard Treatments 220 Residues (R over Check) 220 Limestone (RL over R) 223 Rock Phosphate (RLrP over RL) 226 Potash (RLrPK over RLrP) 229 Combined Effect of Different Materials in Standard Treatments 230 Effect of Phosphorus Carriers With and Without Limestone 236 Rock Phosphate '. 236 Superphosphate 240 Rock Phosphate and Superphosphate Compared 243 Bone, Rock, Slag, and Super Phosphates Compared 246 Effect of Gypsum , 248 Effect of Standard Treatments on Late-Planted Corn 250 SUMMARY AND CONCLUSIONS 252 LITERATURE CITED 257 APPENDIX (Tables 29 to 33) 258 LIST OF TABLES AND CHARTS.. . 271 Urbana, Illinois July, 1937 Publications in the Bulletin series report the results of investigations made by or sponsored by the Experiment Station Composition of Mature Corn Stover As Affected by Variety, Soil Type, and Fertilizer Treatment By D. C. WIMER, Assistant Chief in Soil Physics INTRODUCTION V )f NHE PLOWING DOWN of cornstalks is generally recognized as good farming practice. When it appeared that the European ^ corn borer might make it necessary to burn all cornstalks, re- newed consideration was given to the probable effect that continued burning of cornstalks would have on the productivity of Illinois soils. As an outgrowth of this situation, a study of the fertilizing value of cornstalks on Carrington silt loam" was begun in 1924. A brief resume of this work appears progressively in the annual reports of the Illinois Station. As a supplementary phase of this project, studies on the composition of mature corn stover were started in 1927. The practice of returning cornstalks as residues instead of burning them is common, tho not universal, in the corn belt. Some investiga- tions involving their use in conjunction with straws and green-manure crops extend over a period of more than thirty years. Data from these studies do not show the relative influence of the individual materials on crop yields. Too, the value of cornstalks when used alone is not known, and can be ascertained only by long-continued experimen- tation. Their ultimate effect would be influenced by many factors, of which the composition and amount of stalks applied would be of first importance. Many studies on the composition of the corn plant and its separated parts have been made, some at various periods of growth, others in connection with feeding trials. Results of neither group of studies, however, are satisfactory in showing the composition of mature corn stover grown under different conditions. Studies of the first group usually have not been concerned with the stover of field-grown corn, while those of the second group are generally based on proximate analyses, which furnish little information on fertilizing constituents other than nitrogen. The analyses which have been reported show marked differences in the composition of corn stover. Such variation seems inevitable in view of the wide diversity of conditions represented. But the general lack "The soil for experiment was formerly correlated as Muscatine silt loam. 175 176 BULLETIN No. 437 [July, of definite information as to the source of the samples precludes the possibility of making comparative studies to determine the probable influence of different factors on the composition of corn stover. In consequence, a study of the composition of mature corn stover, representing many varieties grown under similar and different condi- tions, especially with reference to soil type and fertilizer treatment in Illinois, was undertaken. The immediate purpose of this work was to obtain more definite information on the composition of stover and its separated parts. Such information would furnish a more satisfactory basis on which to compute the plant-nutrient balance in soils, or to study the comparative effects on crop yields of different methods of handling the corn stover. REVIEW OF LITERATURE No effort has been made to review the voluminous literature on the composition of plants. Only such contributions as are directly con- cerned with, or closely related to, the present studies on the composition of corn stover will be cited. Studies of the Composition of Corn Stover Based on Proximate Analyses Nutrition Investigations. The earlier, and perhaps more extensive, studies on the composition of corn stover were those made in connec- tion with nutrition investigations. A complete bibliography of those on corn and corn products has been prepared by Keith. 13 * Obviously the analyses which were made incident to such studies indicate the nutritive value of the corn stover rather than show its content of fertilizing constituents. With but few exceptions, the results on the nitrogen and ash contents of stover, which may be obtained from these analyses, have been of little value in this work. Comparative studies could not be made because definite information as to the conditions represented by the respective analyses w^as generally lacking. Fertilizer Investigations. Some of the earliest investigations con- cerned with the use of fertilizers suggested that their effects be meas- ured not merely by yields, but also by the quality of the crop produced. The significance of the latter is reflected in the statement of Hills and associates, 10 " who wrote that "the influence of fertilization, or the lack of such influence upon the composition of a crop, is a matter second only in importance to consideration of yield." Woods 23 * called atten- tion to the source of error involved in the ordinary method of esti- *These numbers refer to literature citations on page 257. 1937] COMPOSITION OF MATURE CORN STOVER 177 mating the effects of fertilizers which assumes uniform content of moisture and nutrients in crops produced. The composition of corn stover as affected by fertilization has been reported by several experiment stations; specific reference, however, will be made only to the work done at Connecticut, Pennsylvania, and Kentucky. Woods 23 * concluded that mineral fertilizers, when used alone or mixed, without nitrogen, increased yields and the total amount of protein, but not the percentage of protein. Nitrogen alone or in combination with mixed minerals produced a slight increase in percent- age of protein over the unfertilized crop, but when compared with the stover from the mixed minerals treatment, the percentage of protein increased with the amount of nitrogen added. These studies also showed that variations in the composition of stover, were due to soil and climatic influences, as well as fertilization of the soil, and were as wide with seed from the same source as from different sources. In a subsequent report Woods and Gibson 24 * concluded that the great variation in the composition of corn stover was no doubt less dependent upon the fertilizers applied than it was upon the difficulty of securing representative stover samples and upon the yield of grain. Analyses reported by Frear 8 * show a greater variation in the com- position of stover (referred to as fodder) than of grain, which is in agreement with other investigations reviewed. The changes in com- position of either grain or stover, due to the use of fertilizers, were not so great as reported by others. Mineral fertilizers alone caused a marked decrease in the introgen content of the stover, yet this treat- ment was the most effective in increasing yields. The use of nitrog- enous fertilizers, especially those containing soluble nitrogen, seemed to increase the nitrogen content of stover. All fertilizers, except mixed minerals when used alone or in combination with sulfate of ammonia, increased the ash content of the stover. Scovell and Peter 17 * found that corn stover was more variable than the grain in nitrogen, P 2 O 5 , and K 2 O content ; however, in the absence of potassium, the variation in the composition of the grain was con- siderable. When applied with either nitrogen or phosphorus or both, potassium produced large increases in yields, but the differences in composition of either grain or stover, due to treatment, were generally less than those caused by soil variation. Composition of the Corn Plant at Various Stages of Growth Studies on the composition of the corn plant at different stages of growth have not been concerned generally with fully matured corn 178 BULLETIN No. 437 (July, stover; neither do they show the content of the different nutrient ele- ments, except nitrogen indirectly. While the analytical results in most cases are not comparable with those obtained in the present studies, reference will be made to certain observations noted and conclusions drawn. Hornberger 11 * found that the percentages of both nitrogen and the mineral elements decreased as the corn plants grew older. The rate of absorption of most elements was reduced after ear formation, and the plants suffered an actual loss in weight of all elements except phos- phorus during the maturing period. It was concluded by Schweitzer 16 * that "the plant takes up nearly all the ash ingredients it needs during the first stages of growth, and subsequent additions are mechanically absorbed with the water imbibed by the roots." Hence, to develop well, the corn plant must have an abundance of readily available mineral nutrients during its early growth. The studies reported by Jones and Huston 12 * are of special interest since they show the total nitrogen, P 2 O 5 , K 2 O, and ash contents of corn grain and stover when the plants reached maturity. Table 1 shows a summary of their results, expressed in percentage on the dry basis, for the later growth periods. All constituents, except potash, continued to increase in the whole plant up to October 8; potash reached its maximum on October 1, when the corn was in the ensilage stage. After August 28, when the first sample to be separated into ears and stalks was taken, the per- centages of nitrogen, phosphoric acid, and potash decreased rather regularly in the vegetative parts of the plant. Differences in the com- TABLE 1. COMPOSITION OF CORN GRAIN AND STOVER AT DIFFERENT STAGES OF DEVELOPMENT, ACCORDING TO STUDIES REPORTED BY PURDUE AGRICULTURAL EXPERIMENT STATION"* (Percentage on dry basis) Stage of development Part N P0 KjO Ash Notes October 8 Ready to shock Stalks* .753 .149 1.584 7.265 Lower blades November 12 Ready for husking Ears'- Stalks 1.519 .744 .685 .143 .481 1.547 1.456 6.896 yellow, upper blades green, husks very dry Corn matured. November 12 Plants left in field Ears Stalks 1.652 .632 .656 .093 .489 1 428 1.487 5.793 Ears and stover in excellent condition Marked reduction BHI 1.512 .682 .483 1.425 in stover due to loss of leaves Include blades and husks. h Grain and cob. 1937] COMPOSITION OK MATURE CORN STOVER 179 position of the shocked and unshocked corn when sampled Novem- ber 12 are regarded as losses due to differences in exposure from October 8 to November 12. Effect of Varying Supply of Nutrients. Duley and Miller 5 * studied the effect of a varying supply of nutrients on the character and com- position of corn. Plants of Reid Yellow Dent corn were grown in sand cultures with Pfeffer's nutrient solution of normal and N/20 concen- trations, referred to as optimum and minimum, which were used in all possible combinations during three 30-day periods. Top growth was increased by the optimum supply of nutrients, while both growth and fibrous development of the roots was favored by the minimum concentration. Ear production was determined largely by the nutrient supply available during the third 30-day period; fair ears were produced with the lower supply of nutrients provided the corn had received the greater supply of nutrients for the previous period. This was said to indicate that the nutrient material had been stored in the stalks and leaves for later use in development of the ears. The second 30-day period was the most important for the vegetative growth of the plants. Potassium was more abundant than nitrogen in stalks and leaves; nitrogen was followed in abundance by calcium, then phosphorus. Variations in calcium with different treatments were much less marked than those with nitrogen, phosphorus, or potassium. When the plants were harvested after 90 days, the percentages of nitrogen and calcium in the leaves were higher than that in the stalks, while in general the reverse was true for phosphorus and potassium, except where the mini- mum concentration of nutrients was used for all three periods. The percentage of nitrogen both in leaves and in stalks decreased with each successive 30-day period, owing apparently to the use of the nitrogen in ear formation. Potassium showed a tendency to decrease in the leaves but to increase in the stalks during the third period. This difference was regarded as due either to translocation of potassium to other parts of the plant or else to loss thru leaching. Where the minimum nutrient solution was used for all periods, relatively large amounts of potassium and calcium but small amounts of nitrogen and phosphorus were absorbed, while the reverse was true with the optimum solution. Since, with a change in concentration of nutrient solution, nitrogen and potassium are more variable, both in percentage and in total amount, than phosphorus and calcium, they were thought to be chiefly responsible for limiting growth when the lower concentration was used. 180 BULLETIN No. 437 [July, Effect of Varying Supply of Moisture. The effects of a varying supply of moisture on the development and composition of corn were studied by Duley and Miller. 6 * Plants of Reid Yellow Dent corn were grown in potometers (24 inches in diameter and 30 inches deep) rilled with a fairly fertile silt loam soil which was maintained at 28 or 13 percent moisture. All possible combinations with these two moisture contents, indicated as optimum and minimum, were used during three 30-day periods. The total production of dry matter was influenced to a greater extent by the moisture supply in the second 30-day period. The effects of drouth during the first period were almost entirely overcome if optimum moisture prevailed for the remainder of the season. Corn plants receiving optimum moisture for the entire season had more leaf area than those receiving minimum moisture ; the approximate differences after 30, 60, and 90 days were 300, 50, and 18 percent. Changes in moisture content affected leaf growth more than other parts of the corn plant. Where such changes were made in the third period, stalk growth was modified only slightly. The average contents of nitrogen and the mineral elements were higher for plants grown with minimum moisture. As the plants grew older, the percentages of these constituents usually decreased, with the more marked reduction taking place where optimum moisture was used. Fertilizing Constituents of Mature Corn Stover Information as to the fertilizing constituents of mature corn stover is rather meager. The analytical results which have been published would indicate that the composition is extremely variable. To call attention to this variation, the data in Tables 2 and 3 have been as- sembled. No attempt has been made, however, to present all available analyses ; neither has any selection been made so as to magnify or to minimize the amount of variation shown. In the preparation of Table 2, several recalculations were necessary in order to have all analyses on a comparable basis. Where such re- calculations have been made, they are noted. The extreme variations in composition are compared with the average composition of corn stover in Table 3. In this table the single elements, rather than oxids of the mineral elements, are given ; also, they are expressed, not in percentages, but in pounds per ton of dry stover. 1937} COMPOSITION OF MATURE CORN STOVER 181 TABLE 2. COMPOSITION OF CORN STOVER AS REPORTED IN DIFFERENT PUBLICATIONS (Percentage on dry basis) N P0i KtO CaO Note* Reference .860 .661 .349 .880 .100 .104 .290 .250 .354 .660 1.379 .588 1.250 1.922 .685 .581 '(a)' '(b)' (c) N. Y. (Geneva) Rpt. (1888) p. 249 Delaware Sta. Rpt. (1890) p. 152 New Jersey Sta. Rpt. (1894) p. 130 U. S. Dept. of Agr. Yearbook (1896) p. 360 Ohio Sta. Bui. 207, p. 44. 1909 .565 1.250 !744 .632 .460 .325 .235 .143 .093 .442 1.934 1.525 2.216 1.547 1.428 .577 .710 !575 (a-c) (a) (c) Hopkins Soil Fertility and Perma- nent Agriculture, p. 603. 1910 Mass. Sta. Rpt. (1911) p. 268 Ohio Sta. Bui. 255, p. 255. 1913 Indiana Sta. Bui. 175, p. 614. 1914 Indiana Sta. Bui. 175, p. 615. 1914 Wis. Sta. Res. Bui. 30, p. 3. 1914 1.'037 1.090 .880 .800 .501 .497 .347 .218 .230 2.067 1.417 1.608 2.062 1.040 .739 '.462 .661 .490 '(c)' (c) (c) (c) Wis. Sta. Res. Bui. 33. p. 118. 1914 Weir Productive Soils, p. 383. 1920 Jour. Agr. Res. 27, p. 850. 1924 Bear Soil Management, 2d ed., p. 18. 1931. Illinois Sta. Soil Rpt. 49, p. 54. 1931 *Recalculations made: (a) computed to dry basis, (b) pounds per ton converted to percent, (c) mineral elements computed to oxids. TABLE 3. FERTILIZING CONSTITUENTS IN A TON OF DRY CORN STOVER Constituent Variation in content Average content* Nitrogen Ibs. 7 to 25 Ibs. 16 Phosphorus 8 to 5.0 2.0 Potassium 9.8 to 36.9 17.3 Calcium 6.6 to 13.7 7.0 As given in 111. Agr. Exp. Sta. Soil Rpts. Elemental Composition Studies The elemental composition of the corn plant and its separated parts has been studied by Latshaw and Miller. 15 * They selected five "mature" Pride of Saline corn plants grown on Summit silt loam a at Manhattan, Kansas, in 1920 for their analytical work. When harvested, the grain was in the late-dough stage, well glazed and dented, while the leaves were still green and all attached to the plants. Full maturity of the plants, therefore, had not been reached; on the other hand, loss thru leaching or actual removal of various plant parts had not occurred. Separate analyses were made of the leaves, includ- ing husks and sheaths, the stems, and the grain, of the individual plants Based on information and samples furnished by Dr. F. L. Duley, Depart- ment of Soils, Kansas State Agricultural College. 182 BULLETIN No. 437 [July, grown under the same conditions, in order to determine the variation in composition. The authors state that "Although the percentage elemental compo- sition is uniform in a like organ of the different plants, the actual amount of a given element expressed in grams varies considerably" since plants "which seem to be uniform in size and general appearance show marked variations in dry weight and in the distribution of this matter in the various organs of the plant." The average amounts of carbon, nitrogen, phosphorus, potassium, and calcium in the corn grain, stover, and the separated parts of the stover are reported in Table 4. The composition of stover has been TABLE 4. ELEMENTAL COMPOSITION* OF CORN GRAIN, STOVER, AND THE SEPARATED PARTS OF THE STOVER (Percentage on dry basis) Part Carbon Nitrogen Phosphorus Potassium Calcium Stover b 42.76 1.09 .153 1.36 .33 Leaves 41.27 1 .30 .207 1.48 .47 Steins 44 51 .84 .089 1.2^ .17 Grain 44.72 2.15 .340 .42 .025 Ten other elements, including hydrogen, oxygen, magnesium, iron, sulfur, silicon, manganese, aluminum, and chlorin, were also determined. b Computed. computed from the data reported by Latshaw and Miller for leaves and stems. Since these parts made up 28.10 and 24.02 percent respectively of the total dry matter of the entire plant, the dry stover consisted of 53.9 percent leaves and 46.1 percent stems. Of the total dry weight of the corn plant, the stover made up 52.12 percent and contained 51.09 percent of the carbon, 38.79 percent of the nitrogen, 39.11 percent of the phosphorus, 77.34 percent of the potassium, and 76.17 percent of the calcium. More fully matured stover, similar to that used in the present studies, would be expected to give much lower values. More of the materials would be trans- located or perhaps lost thru leaching, while a further reduction would result from the loss of leaves and other parts of the plant. PLAN OF ILLINOIS EXPERIMENTS Size of Stover Samples. Samples of mature corn stover for the season of 1928 were used for the analytical work. The samples were taken just after the corn was shucked. Each sample consisted of 10 stalks, including leaves and husks, and was collected by taking one stalk from 10 consecutive hills in which there was a uniform stand of 1937] COMPOSITION OF MATURE CORN STOVER 183 2 plants each. Each 10-stalk sample was secured from a soil area that was uniform in character and representative of an important soil type. The stalks were cut off about 3 inches above the surface of the ground. The size of sample to be taken was decided upon after a statistical study of the total ash and protein contents of individual corn plants reported by Ladd. 14 * It was found that the probable error of the mean of 16 stalks was only slightly less than that of 8 stalks. From this it was concluded that the larger number of stalks would not increase appreciably the accuracy of the work, altho it would add greatly to the problem of collection and preparation of the samples. Information as to the probable variation of the different elements was obtained from the analytical data reported by Latshaw and TABLE 5. VARIATION IN ELEMENTAL COMPOSITION OF CORN LEAVES AND STEMS, BASED ON ANALYSES OF FIVE PLANTS (Percentage on dry basis) Element Leaves Stems Nitrogen 1 30 04 .84 .06 Phosphorus .208 .011 .089 .007 Potassium 1.48 + .04 1.23 .07 Calcium 47 .02 .17 + .01 Carbon 41.27 .17 44.51 .31 Miller, 15 * who determined the elemental composition of the separated parts of five individual corn plants grown under the same field con- ditions. The data in Table 5, prepared from their individual analyses, show that the probable error of the mean in all cases was small. The reliability of sampling for the work reported in this bulletin cannot be determined by means of statistical methods owing to a lack of replication of samples. For the purpose of this work the assumption was made that a sample of 10 stalks was representative of a particular 'set of conditions, where both the soil type and the stand of corn were uniform. General Source of Samples. Stover samples were collected from sixteen Illinois experiment fields. The complete record of all samples, given in Table 29 of the Appendix, indicates the experiment field ; also the plot from which each sample was obtained ; the soil type repre- sented ; the fertilizer treatment used and the variety of corn grown. Definite information concerning some of the important soil and climatic differences on the various experiment fields will be found on pages 188 to 196. 184 BULLETIN No. 437 [July, The following summary shows the varieties, soil types, and treat- ments represented by the stover samples used in this investigation. Varieties Soil types Treatments* Black Hawk Muscatine silt loam Calico Grundy silt loam R Champion White Pearl Grundy silt loam, grayish phase RL Funk 90- Day Grundy clay loam RLrP Funk 176A Drummer clay loam RLsP Golden Glow Elliott silt loam RLbP Krug Putnam silt loam RLslP Minnesota 13 Sidell silt loam RLuP Mohawk Carrington silt loam RLrPK Reid Yellow Dent Carrington silt loam, deep phase RLrPKG Rustler Saybrook silt loam RLrPG Sommer Yellow Dent Saybrook silt loam, deep phase RrP Stanley White Cisne silt loam RsP Western Plowman Cisne silt loam, deep phase RbP Will County Favorite Onarga sandy loam RslP LeL LeL KC1 Symbols used: = no treatment. R = crop residues. LeLsP KC1 L = limestone. rP = rock phosphate. sP = superphosphate. " D im bP = bone phosphate. slP = slag phosphate. uP = underatidu- LeLrr K.L.1 lated phosphate. K = kainit. KC1 = muriate of potash. G = LeLrP K gypsum. Le = legume catch crop. 5-15-5 = mixed fertilizer analysis. 5-15-5 Preparation of Samples. In preparing the stover for analysis, the leaves and husks were separated from the main part of the stalk. The leaf sheaths were included with the stalk portion of the sample, since it was thought that where corn stover was pastured or allowed to stand until spring, the leaves and husks would be removed, while the leaf sheaths would remain with the stalks. In this work the two portions of the stover samples are referred to as "stalks," which include the stalks and leaf sheaths, and "leaves," which include the leaf blades and husks. The stalk and leaf samples were dried at a temperature of approxi- mately 100 F. for a period of two weeks. No attempt was made to secure a water- free condition of the stover, but rather to make possible the drying of all samples to a more or less uniform moisture content,' after which they were weighed and shredded. The shredded material was then ground in a Wiley mill so that the entire sample would pass a 2-mm. sieve. After thoro mixing, a portion of the 2-mm. material was subjected to further grinding until all of it was fine enough to pass a 1-mm. sieve. Methods of Analysis. The moisture content of the samples was determined by drying the material in electric ovens at 100 C. for 24 hours. This temperature was used in preference to 105 C. because it appeared to cause less variation in losses other than moisture. 1937} COMPOSITION OF MATURE CORN STOVER 185 The official methods of analysis of the Association of Official Agri- cultural Chemists were used for the determinations of nitrogen, phos- phorus, and calcium. The Gunning method was used for nitrogen and the magnesium-nitrate method for phosphorus. Ignition of the samples for the calcium determinations was accom- plished by charring the material in a gas muffle at a dull red heat for one hour, after which it was transferred to an electric furnace with a temperature of 650 C. for one-half hour. The resultant ash was weighed and reported as total ash. The cobaltinitrite method of Hibbard and Stout, 9 * with certain modifications suggested by Bray and DeTurk, a was used for the determination of potassium. Carbon was determined by a modification of the method reported by Winters and Smith. 21 * This modified procedure was perfected by Winters 22 * especially to determine the total carbon content of corn stover and similar plant materials. Analytical Results. Determinations of the elements reported were made both for stalks and for leaves, and the composition of the stover was calculated from the composition of the separated parts stalks and leaves. For example, the percentages of nitrogen were .78 and .97 respectively for stalks and leaves in one sample, which consisted of 80 percent stalks and 20 percent leaves. The nitrogen content of the stover was computed to be .82 percent by using the formula: (80 X % N in stalks) + (20 X % N in leaves) % N in stover = JQQ The original plan to analyze the composite sample of stover was abandoned for several reasons. Earlier work had shown a tremendous variation in the composition of stalks and leaves. Then, too, it was realized that where cornstalks are allowed to stand until spring or where they are pastured, the leaves and husks are practically all re- moved. Thus it appeared that the additional information obtained by having the analyses of both stalks and leaves would justify the ad- ditional work involved. The amounts of nitrogen, phosphorus, potassium, calcium, organic carbon, and total ash, as herein reported, represent the averages of duplicate determinations on a water-free basis. 1 ' As an indication of 'Unpublished method used in the division of Soil Fertility, Department of Agronomy, University of Illinois. b Data on organic carbon and total ash have been omitted from the tables thruout the main portion of this bulletin. These values for stover and its sep- arated parts are presented without discussion in the Appendix, Table 33. 186 BULLETIN No. 437 [July, the reliability of the analytical work, the probable error of a single de- termination, calculated by Student's method, 19 * for each element, and for total ash, in stalks and in leaves is given in Table 6. To the errors involved in the respective determinations should be added the errors of sampling. These, as noted previously, cannot be analyzed statistically because of an insufficient number of samples for any specific set of conditions. Reference to the complete record of samples would indicate that while many represent what may appear TABLE 6. PROBABLE ERROR OF A SINGLE DETERMINATION, AND SIGNIFICANT DIFFERENCES IN COMPOSITION (Values in percent) Determination Probable error of a single determination 3.8 X the P.E. of a single determination Significant differences in composition of either stalks or leaves Stalks Leaves Stalks Leaves Nitrogen .006 .004 .021 .009 .295 .064 .008 .004 .020 .011 .281 .129 .023 .015 .080 .034 1.121 .243 .030 .015 .076 .042 1.068 .490 .03 .015 .08 .04 1.25 .50 Phosphorus Potassium Calcium Organic carbon to be similar conditions, the conditions in reality are not identical and hence the samples are not true replicates. Differences in composition, unless greater than .015 percent for phosphorus, .03 percent for nitrogen, .04 percent for calcium, .08 percent for potassium, .50 percent for total ash, and 1.25 percent for organic carbon, are not considered significant but within the limits of experimental error. These values are 3.8 or more times "the probable error of a single determination" given in the preceding table. Further- more, the value designated as a significant difference for each re- spective element, also for total ash, is not only larger than the greatest difference between any duplicates but at least double the difference between the duplicates in 85 percent or more of the determinations. In the tables and discussions which follow, emphasis is placed on the composition of stover as a whole and not of its separated parts. A complete summary, however, of the data on the composition of stalks and of leaves is given in the Appendix, Table 31. In addition to the percentage composition, the pounds of nitrogen, phosphorus, potassium, and calcium contained in the stover, or in its separated parts, per acre are also reported (Appendix, Table 32). The latter expression pounds per acre provides a more convenient way in which to compute 1937] COMPOSITION OF MATURE CORN STOVER 187 the additions where stover is plowed under, or to estimate the losses if the stover is burned or otherwise removed from the land. Computation of Acre-Yields. The material which follows serves to indicate the source of yield values and to call attention to certain relationships shown. The things presented include: (1) the proportion of stalks to leaves in the sample; (2) the computed yield of stover per acre; (3) the yield of grain per acre; and (4) the stover-grain ratio. The proportion of stalks to leaves is based on the dry weights of the separated parts of the stover, and is expressed as a ratio in which the weight of leaves is taken as 1. This value for all samples appears only in the Appendix, Table 29. The yield of stover per acre was com- puted from the weight of the stover sample, which consisted of 10 stalks from 10 consecutive hills having 2 plants each. Thus the sample was collected where a perfect stand obtained, and on this basis represented 1/800 of the total plants per acre. The yield values com- puted in this manner are no doubt too high since a 100-percent stand would be rare. On the other hand, the losses of stover, especially of leaves and tassels, prior to the time samples were collected would tend to lower the true values. But in neither case is there any satis- factory way in which to make allowance for an imperfect stand or to compensate for losses. In the case of certain plots from which stover samples were col- lected, the cornstalks were removed and weighed just after the corn was shucked. This makes possible a limited number of comparisons between the computed and recorded yields of stover. Without excep- tion, the computed yield for each of 15 plots was less than the recorded yield ; the difference in yields varying from .4 to 58.6 percent. These variations were due to many factors, of which moisture was the most important. The recorded yield represents the field weight of moist ma- terial, while the computed yield is based on the weight of material dried at 100 F. for two weeks. Another factor causing considerable varia- tion was the method of thinning practiced. On seven fields, represented by seven of the above comparisons, the number of plants was not uni- formly thinned to 2 per hill. The yield of grain for the plots from which the stover samples were collected are reported in Illinois Agricultural Experiment Bulle- tin 327, except for the corn grown in variety tests or used in corn borer work. For these, the yields were obtained from the field records of the Agronomy Department. The stover-grain ratio should be based on the proportion of stover to grain in the sample, but unfortunately the ears from the sample 188 BULLETIN No. 437 [July, stalks were not weighed separately. The ratio, therefore, instead of being derived from the actual samples, is a comparison of the com- puted yield of stover with the actual yield of grain per acre. These ratios, in which the weight of grain is taken as 1, are reported only in the Appendix, Table 29. SOIL AND CLIMATIC CONDITIONS REPRESENTED The purpose of this section is to set forth in a comparative manner some of the more important conditions under which the stover, used in this work, was grown. As noted previously, samples were obtained from sixteen experiment fields, widely distributed over Illinois. From the material which follows it is evident that the samples used repre- sent a wide diversity in soils and in climate. Soil Types Represented The soil types represented by the stover samples are as follows on the respective fields: Mt. Morris Muscatine silt loam La Moille Muscatine silt loam Kewanee Muscatine silt loam Aledo Grundy silt loam Carthage Grundy silt loam, grayish phase Hartsburg Grundy clay loam c- j 11 I Sidell silt loam { Drummer clay loam Minonk Drummer clay loam Joliet Elliott silt loam DeKalb I Saybrook s '^ loam I Saybrook silt loam, deep phase TT i (Carrington silt loam, deep phase (Davenport plots) [Carrington silt loam and Sidell silt loam (South Farm) Alhambra Putnam silt loam Toledo Cisne silt loam Oblong Cisne silt loam, deep phase Palestine Onarga sandy loam Descriptions of the soil types, except as noted below, are given in Bulletin 273 of this Station (1926), page 313. More recent corre- lation of Illinois soils has necessitated certain changes in the soil-type names as given in this publication. These changes, together with tne experiment fields involved, are here indicated: Tama silt loam, Mt. Morris, changed to Muscatine silt loam. Loessial Clyde clay loam, Minonk and Sidell, changed to Drummer clay loam. Carrington silt loam, light phase, Sidell and Vrbana South Farm, changed to Sidell silt loam. Muscatine silt loam, Davenport plots, Urbana, changed to Carrington silt loam, deep phase. 1937] COMPOSITION OF MATURE CORN STOVER 189 Clarion silt loam and Grundy silt loam, DeKalb, changed to Saybrook silt loam and Saybrook silt loam, deep phase, respectively. Webster silt loam, Joliet, changed to Elliott silt loam. Gray Silt Loam On Tight Clay, Toledo and Oblong, changed to Cisne silt loam and Cisne silt loam, deep phase, respectively. Plainfield sandy loam, Palestine, changed to Onarga sandy loam. Drummer clay loam was developed under somewhat better drainage conditions than the Loessial Clyde clay loam. In consequence the pro- file features of the Drummer clay loam are more comparable to those of the Grundy clay loam, which is described in the reference given. Unpublished analytical data, based on samples taken according to arbitrary depths rather than horizons, indicate a wide variation in the chemical make-up of these soils. This variation is reflected in the differences brought out in Table 7, which shows the acidity, available phosphorus content, and clover growth without limestone. The infor- mation on acidity and clover growth is based primarily on material reported by Bauer, 3 * while that on available phosphorus has been re- ported by Bray. 4 * In both cases unpublished data have been used to supplement those reported. In the case of available phosphorus, the respective soil types at Mt. Morris, Kewanee, Carthage and Sidell, also on the Davenport plots, gave somewhat larger amounts of phosphorus than the other soils which tested "low." On all the fields except Alhambra, DeKalb, Palestine, and Urbana South Farm, sweet clover is seeded in wheat and plowed down as a green-manure crop for corn. Unpublished field notes for 1928 report a good growth of sweet clover on the unlimed plot at Hartsburg and Minonk ; a fair growth at LaMoille and Carth- age; very little growth at Mt. Morris, Aledo, and Sidell; and a very poor growth at Kewanee and on the Davenport plots at Urbana. On both the Toledo and Oblong fields the sweet clover was severely winterkilled, while at Joliet an excellent growth was plowed down for first-year corn in 1927. Many of the differences in the composition of the stover, as well as those in yield of both stover and grain, appear to have a very definite relation to the differences shown in Table 7. Some of these relation- ships are noted in discussions which accompany the data presented. The relative productivity of the untreated soil types on the different fields is shown by Fig. 1. This comparison is based on the average yields of corn, oats, and wheat on Plot 5 (1-W on the Davenport plots) of the particular series from which the stover samples were collected. No satisfactory comparison of the yields of clover or other legumes was possible. Alhambra, DeKalb, and Urbana South Farm have been omitted from the graph since there are no untreated plots on these 190 BULLETIN No. 437 [July, Clover growth without limestone Red, but no sweet clover Sweet clover Red, but no sweet clover Red, but no sweet clover Sweet clover Sweet clover Sweet clover Sweet clover Red, but no sweet clover Red, but no sweet clover Red, but no sweet clover Red, but no sweet clover Red, but no sweet clover 8 3 2 = O B O Z Available phosphorus. Bray test Low Medium to low Low B '%*$ M M SS J 1 II | 1! Medium omber method Bi Strong Slight Medium Slight Medium None Very slight None 2 v 9 o 2 Very slight None ^ X M I m c c 22 5)55 Medium rent horizons, C Aj M E pi EE Ifg Slight Very slight x i II Medium M I M M C C 22 5555 Medium Acidity in diffe Ai ||| 55(7)55 Medium Strong Very slight Medium Slight Medium Medium Medium Medium Medium 8 Very strong Very strong Medium V ih phase. . a y 1 E E E JJJ :B : . M . EE"! E'E JJ B | o E'E II 5 a a it o E'E" 1 >v Muscatine si Muscatine si Muscatine si Grundy silt Grundy silt Grundy clay Drummer els Drummer ch 1 o Saybrook sil Carrington s Carrington s Sidell silt loa Putnam silt Cisne silt loa Cisne silt loa c S o o 1 "a- V B Mt. Morris. . LaMoille Kewanee. . . . Aledo Carthage. . . . Hartsburg. . . c O II * "5 % DeKalb |j ill P 1 X Alhambra. . . Toledo Oblong Palestine 1937} COMPOSITION OF MATURE CORN STOVER 191 fields. Sidell is represented by Sidell silt loam rather than Drummer clay loam. I I I CEREAL CROPS -SOIL UNTREATED FIG. 1. AVERAGE YIELDS OF CORN, OATS, AND WHEAT ON UNTREATED PLOTS OF THIRTEEN ILLINOIS SOIL EXPERIMENT FIELDS FOR THE FIFTEEN YEARS 1914-1928 The fields are arranged in order of increasing corn yields. The Toledo and Urbana fields represent the two extremes for all three cereal crops. Toledo produced 14.7, 7.2, and 5.9 bushels of corn, oats, and wheat respectively an acre; whereas Urbana (Davenport plots) produced 62.3, 65.4, and 34.2 bushels of these crops. Crop Rotations Practiced The crop rotations practiced on the main series of the respective experiment fields are shown in the following outline. This has been prepared from the material contained in Bulletin 273 of this Station, to which the reader is referred if more detailed information on the cropping systems is desired. Unless otherwise specified, "clover" means red clover. On the Hartsburg and Joliet fields alfalfa has been included in the "main series" rotation but had not been grown on the series from which the stover samples were secured. 192 BULLETIN No. 437 [July, Aledo, Hartsburg, La Moille, and Minonk Corn, oats, clover, and wheat" changed in 1923 to corn, corn, oats (Hubam clover), and wheat.* Carthage, Kewanee, and Mt. Morris Corn, oats, clover, and wheat. 8 Urbana (Davenport plots) and Sidell Corn, oats, clover, and wheat 8 with alfalfa for five years. Joliet Corn, oats, clover, wheat, 8 and soybeans changed in 1921 to corn, corn, oats, clover, and wheat. 8 Urbana (South Farm) Corn, oats, clover, and wheat (red-clover green manure) (Southwest rotation). DeKalb Corn, corn, oats, and clover (Saybrook silt loam) Corn, oats, wheat, and clover (Saybrook silt loam, deep phase). Alhambra Corn, oats, mammoth clover, and wheat (sweet-clover green manure). Oblong and Toledo Corn (cowpeas as catch crop prior to 1921), oats, clover, and wheat.* Sweet clover substituted for alsike in 1920 and 1922 respectively. Timothy and clover mixture used in place of sweet clover in 1925 and thereafter. Palestine Corn, soybeans, rye, sweet clover, and wheat 8 changed in 1926 to wheat (Hubam and alsike clover), wheat (sweet clover), corn, soybeans, and alfalfa. ("Seeding of sweet clover on the residues plots) Soil Treatments Represented The stover samples, except those from untreated plots, represent the grain system of farming. In this system "organic matter and nitrogen are applied in the form of plant manures, such as cornstalks; straw from wheat, oats and clover; the second crop of clover; and leguminous green manure crops. ..." While various modifications of the residues system have been made, including the discontinuance of the oat and wheat straw, cornstalks together with a leguminous green-manure crop, usually sweet clover, have always been used. In addition to residues the standard treatments have included lime- stone, rock phosphate, and kainit. The tfeual acre-rates of application for these materials were as follows: limestone 2 tons after the initial application of 4 tons; rock phosphate 1 ton; and kainit 800 pounds every four years or once during a rotation. The phosphate and kainit were applied before, and the limestone after, the clover sod was plowed for wheat. Samples of different varieties on the same field were grown with similar treatment of residues and rock phosphate with or without limestone, depending on the soil type concerned. On 12 of the 16 fields the samples represent various combinations of the standard treat- ments: residues and limestone; and residues, limestone, and rock phos- phate. They also represent residues, limestone, rock phosphate, and 1937] COMPOSITION OF MATURE CORN STOVER 193 kainit ; residues alone ; and no treatment. On five fields various com- parisons with different phosphorus carriers, both with and without limestone, are possible. Other treatments include gypsum used with and without kainit and also a complete fertilizer as a supplement to the standard treatments. The rates at which the various fertilizing materials were applied and the methods of applying them are described in Bulletin 273 of this Station and the yearly supplements.* The total applications of the fertilizing materials are shown in Table 30 in the Appendix. Reference to Table 29 in the Appendix will indicate the field and plot source of the respective samples. Climate While the important effect of climate on growth and yield is recognized, the weather records do not supply adequate specific infor- mation with reference to climatic conditions obtaining at the various experiment fields. This is especially true of such things as light dura- tion and intensity, relative humidity, temperature changes, and wind velocity. The material on climate is therefore limited to two items: (1) the amount and distribution of rainfall, and (2) the length of the growing season, as recorded at the weather stations nearest the respec- tive fields. These data are shown in Fig. 2 and Table 8. For most of the fields the total rainfall for the six months April 1 to September 30, 1928, was practically the same as the fifteen-year average 1914-1928. At Alhambra, DeKalb, and Mt. Morris, the rain- fall was 2.4, 2.6, and 5.2 inches more than average, while at Hartsburg and Minonk it was 4.2 and 5.5 inches less. The rainfall was markedly deficient in the spring of 1928, especially during the month of May. This was particularly true in northern Illinois on the fields at Minonk, Joliet, and DeKalb and to a lesser extent on those at La Moille, Mt. Morris, Kewanee, and Aledo. It is probable, however, that the damage due to drouth early in the season on the northern fields was very much less than on the Palestine and Oblong fields during July and August. In addition to the monthly distribution of rainfall on the experiment fields shown in Fig. 2, the rainless periods of 29 or more days duration and their occurrence during the growing season are given in Table 8. A rainless period was regarded as terminated when a rainfall of .5 inch or more occurred in 24 hours. Not only the number and duration of these rainless periods, but also their occurrence in relation to the development of the plant, is important. All fields except Aledo are Bulletins 280 (1925), 296 (1926), 305 (1927), and 327 (1928). 194 BULLETIN No. 437 [July, inNIVM 3H1IOW VT 3WOINVDAS 91VH3C] MNONIkN HNONItN 13HOP 13HOr VA1VO 33NVM3X NOXIQ OQ3HV VNV8n HOJ OUO33UON) oNOiaoy 3NliS31Vd 3NllS31Vd O tn 6 3 * Qc/5 N1OONH On99iaVH h < 5 oi C S3HDNI 3dVH VI 3OVH1VO O K NVHONIJJ3 OQ3H01 3T1IANVQ 113019 H Z o O NOI1V19 U3H1V3M 1937] COMPOSITION OF MATURE CORN STOVER 195 c o! p (S(N(S CN 000000 oo 00 *.S Q |& aa > >, Sal X.- >> Q.rt s f^ **> S3S TflO>O s 5 SI" Time and duration of rainless periods of 29 or more days, Apr. 1 to Sept. 30, 1928 e 15 to May 1 7, 33 days; May 20 to June 1 7, 29 days 15 to May 17, 33 days; Aug. 5 to Sept. 11, 38 days . 8 to June 16, 70 days . 1 to June 19, 80 days . 16 to June 12, 58 days . 8 to May 18, 41 days; May 20 to June 17. 29 days . 14 to May 14, 31 days; Aug. 6 to Sept. 10, 36 days . 8 to May 10, 33 days . 30 to Sept. 28, 30 days . 14 to May 14, 31 days . 14 to May 15, 32 days; July 23 to Aug. 22, 31 days e 23 to Aug. 23, 62 days; Aug. 30 to Sept. 28, 30 days >. rt T3 55 oo" >, 0) > oaa Z oaa < c. a a < aaa < c 3 <> a < 00 o a H< 2 <5 w j| ^woo sis J> *C W) fSfS(N **"> fNfSCS (N rs N j c : co : cd : "5^: Jj g E-o 'C"5 P i Aledo. . . Mt. Morr Kewanee -*-C $13 Sis a LaMoille Alhambra Sidell . . . Toledo. . Carthage Hartsbun Palestine Oblong l^e ^ |9ri be || S 5 "SS-1 S i 1 ! N^N^NNNrO.N N ) I c OOO'O^^^^'O'OO' ^ \ *r acre o 8 ^S^SSK^KS K 1 f I 2 "ju 1 . (V >^ | *ot^r>i^^oofs*o f^ -ft ^oO^ W^OO^t r* 'O i i 3 4 a U vNrs^.0-rs - < ; " S 15 5 -g, 5 g t M s-a-og-j-js, 3 ' * "o g 3 g 33-s e ^SSSgSS^SS = 2^2 S 5 3 u > *"* ^~ H 4> 1 ^aS&S8S3S5S i: " "5 ~ ^ 5 "3 ! 1 I > I iijiiHii 9 g w c 3 4 j 3 : 4 i ) i 1 j i ! 1 k Champion White Pearl (late Sommer Yellow Dent (medi Reid Yellow Dent (medium Funk 9O-Day (medium-earlj Funk 176A (medium-late). Krug (medium-early) Rustler (early) Minnesota 13 (early) Golden Glow (early) Average of 145 samples > 4 t \ 4 s C) 2 1 j i c --;'- f*> 3 4 j 1 ! rs rs es (N W i j j j j i j d "i 3 d 4 J b 5 ^ 4 | 1 1 '. 1 i k 1 1 Krug (medium-early) Sommer Yellow Dent (medium Reid Yellow Dent (medium-lat Funk 176A (medium-late) .... Black Hawk (late) Mohawk (late) Champion White Pearl (late) . . Average of 145 samples an 4 d 1 I 1 4 1 S&8SS33 1937] COMPOSITION OF MATURE CORN STOVER 199 <= I ^ O-i- r> i^ "5 ! O^ O^^'^ i '^ fSfS(N CM(N(M(N(N r b 2 B k J! 'OOOCOO''N^Ti>O O **5 _] L^ (75 e O O f^* O^ Id u . . . . Z M t O - O O> 6^ (Nf^fOfS fO rt . o-g. c . / A rs 3 g* U ^ u V M ^8S^ S u, u * og ^ e'- O en _ ni ^ c B 2 C _o s - - w S W . 3 1-1 41 I JI E O U a. O^^IO -* xp t>.o *t *O -^ O^ 4P4*4V4 - 4> z E = * ,.- E : : 2 ta 3 i: 12 TJ Z Q *H ror* r*. V.Q t^ IT) t^. O f* t^ 1 Q '8 a g g 2^ - a S JS 1 1 n * S 1 Sb ! H 1 u < ^ ^ rt 8 S % 2 1 s E u. I 1 " j. | 1 -7 "E "s; = s 3 S5 2 i :rl 2 .ti c N -" * n C ^ U O 1 2 1 I llf 1 1 Y Ill's "* uuS^ a - - a u 3 o o V ^ ^ "a E 6 Z t^oO<>O fO^f^ f 200 BULLETIN No. 437 [July, the other varieties and the proportion of leaves to stalks. Early- maturing varieties are generally characterized by stalks of small diameter with short internodes. The yield of stover was greatest with the one late variety (Cham- pion White Pearl) and decreased progressively as length of growing period decreased. The yield of grain did not follow this order, but was greatest with the two medium-early varieties. Second in grain yields were the medium-late varieties and one early variety (Minnesota 13), while the other two early varieties and the late variety ranked third. Stover yields, however, were more variable than grain yields. For the nine varieties grown at Urbana the amount of potassium ranged from .34 to .62 percent, with both extremes represented by medium-late varieties, which showed comparatively little variation in yield. On the other hand, the stover of three varieties one each for late, medium-late, and medium-early maturity had the same potassium content (.41 percent) but the yields, especially of grain, were markedly different. In contrast with potassium, the calcium content of stover, with a range of only .06 percent among these nine varieties, was the least variable, and in most cases the differences were too small to be significant. Champion White Pearl, the late variety, shows a markedly higher content of both nitrogen and phosphorus than the shorter-season varieties ; which, in view of the high stover yield, means a compara- tively large removal of these elements from the soil that is not offset by a correspondingly high yield of grain. There seems to be no fully consistent relationship between nitrogen and phosphorus contents of the stover and the length of season required for maturity. The medium-late varieties with one exception rank high in both nitrogen and phosphorus, while the medium-early varieties rank low, and one of the early varieties ranks low in phosphorus, but not in nitrogen. That varieties, aside from differing widely in yields, may also differ markedly in composition of the stover, is indicated by the data in Table 10. This is particularly evident when the medium- early or medium-late varieties are compared. The explanation for these differences in composition may lie in differences in the feeding power of the varieties, or in their ability to translocate nutrients to the grain, or in both. In any case, the factors involved appear to be genetic. Varieties Grown at Alhambra Stover yields of all varieties grown at Alhambra were high, varying from 2,919 pounds per acre for Krug, the earliest, to 4,227 pounds for 1937] COMPOSITION OF MATURE CORN STOVER 201 Champion White Pearl, the latest ; while grain yields of all varieties except Champion White Pearl and Reid Yellow Dent were less than the general average of all samples. The length of season required for maturity had a more definite relation to the yield of stover than to the yield of grain. These relationships are in agreement with those noted for the Urbana varieties. The composition of the stover, and the yields of the varieties grown at Alhambra are shown in Table 11. The Alhambra varieties, like those at Urbana, showed that the phosphorus content of stover is more variable than that of nitrogen; potassium, however, is the least instead of the most variable of the three. While most of the differences in the' amount of calcium are probably not significant, the actual percentage of calcium in the stover was somewhat higher for all varieties on this field than" on the Urbana field. This is also true for the percentage of potassium, which varied more widely in the stover of the medium-late varieties than of varieties of different maturing groups. A similar relationship was noted at Urbana. Sommer Yellow Dent and Mohawk stover had the highest nitrogen content. The stover of Funk 176A contained the least amount of nitrogen, yet the grain yield of this variety was 8.7 bushels per acre less than Sommer Yellow Dent, while both stover and grain yields were much lower than those of Mohawk. Champion White Pearl yielded 1,145 pounds of stover and 20.1 bushels of grain per acre more than Funk 176A, and still its stover contained about 25 percent more nitrogen than the stover of Funk 176A. The stover of this variety, however, had the highest percentage of potassium, or an amount nearly 50 percent greater than that in Champion White Pearl, which had the lowest percentage. These data fail to show any definite relation be- tween the nitrogen or potassium content and the yield of stover or the length of growing season; but they do indicate that the utilization of nitrogen and potassium is influenced considerably by variety. The phosphorus content of the stover appeared to be associated more with the yield of grain than with the yield of stover. The highest yielders of grain, Champion White Pearl and Reid Yellow Dent, had the lowest amounts of phosphorus in the stover. The somewhat greater amount of phosphorus in Champion White Pearl stover, in spite of much higher grain and stover yields, would suggest that this variety was better able to assimilate phosphorus. This power, it seems, is especially associated with the late varieties since Black Hawk and Mohawk, which had the highest amounts of phosphorus in the stover, both yielded more grain and stover than either Funk 176A or Krug. 202 BULLETIN No. 437 [July, Varieties Grown at DeKalb The varieties grown at DeKalb, unlike those at Urbana and Alhambra, showed no definite relationship between the length of season and the yield of stover. Stover yields were low for all varieties grown on Saybrook silt loam on this field with the exception of Golden Glow, and for Western Plowman, grown on Saybrook silt loam, deep phase. The data on composition of stover and also on yield for varieties at DeKalb are given in Table 12. The nitrogen content of the stover of the DeKalb varieties varied between wide limits. Four varieties, requiring widely different lengths of season for maturity, had essentially the same nitrogen content but varied greatly in yield. This fact indicates that differences in the ability of these varieties to utilize nitrogen may offer an explanation for the same percentage composition but a much greater removal of nitrogen by some varieties than others. The wide difference in the nitrogen content of Golden Glow stover in comparison with that of Minnesota 13 and Rustler is thought to be an evidence of the effect of soil variation as well as the influence of variety. The significance of soil differences on the composition of stover, shown by comparing the two Western Plowman samples, is discussed on pages 216 to 218. Based on the phosphorus content of their stover, the DeKalb varieties fall into four groups: (1) Reid Yellow Dent and Funk 90- Day; (2) Sommer Yellow Dent, Golden Glow and Western Plowman (on Saybrook silt loam, deep phase) ; (3) Western Plowman and Krug; and (4) Minnesota 13 and Rustler. The differences between Groups 1 and 2, also Groups 2 and 3, are not significant. The early varieties, which yield more grain than the medium-late varieties, con- tained much less phosphorus in their stover, but these differences must be attributed to both soil and varietal influences. It would appear that the stover of Minnesota 13 and Rustler was somewhat depleted of its phosphorus by the much greater grain yields. Of the three medium-early varieties, Funk 90-Day seems to possess greater capacity than either Krug or Western Plowman to utilize phosphorus, for while it yielded 40 percent more grain, the phosphorus content of its stover was 20 percent higher. A comparison of Samples 29 and 34, representing the same variety but different soil types, would indicate that the absorption of phosphorus is undoubtedly affected by the character of the soil. The stover of Western Plowman when grown on the deep phase of Saybrook silt loam contained .012 percent more phosphorus, even tho yields were almost doubled, than that of the same variety on Saybrook silt loam. 1937} COMPOSITION OF MATURE CORN STOVER 203 The stover of Rustler, a variety of early maturity, contained 1.02 percent of potassium. This amount is not only very high in comparison with that of other varieties, but also nearly double the average amount for all samples of stover analyzed. When compared with the other early-maturing varieties, Golden Glow and Minnesota 13, the stover of Rustler had 2 to 2i/ times as much potassium. These early varieties, however, showed wide differences in their capacity to produce, especi- ally grain, but it is doubtful if the differences in yield are sufficient to account entirely for the variation in potassium shown. Exclusive of Rustler, the potassium content of stover at DeKalb was generally much lower than is indicated by the data in Tables 10 and 1 1 for varieties at Urbana and Alhambra. With the exception of one sample each of Western Plowman and Reid Yellow Dent, the calcium content of stover for the varieties grown at DeKalb was almost identical. Western Plowman contained .23 percent and Reid Yellow Dent .37, both values being significantly different from that of the other varieties grown on this field. In gen- eral, the data for calcium are practically the same as those at Urbana, but somewhat lower than those reported for stover grown at Alhambra. Varieties Grown at Toledo Corn in the variety trials on the Toledo field was small and stunted. The character of the soil, Cisne silt loam, together with the compara- tively low content of nitrogen in the stover, would suggest that the low yields might possibly be attributed, at least in part, to a nitrogen defi- ciency quite as well as to "potash starvation," which is commonly mentioned as a cause of low yields on this soil. Potassium fertilizers when used on this soil, however, are very effective in increasing yields. Data for varieties grown at Toledo, given in Table 13, show that the nitrogen content of stover was much more variable than the phos- phorus content. This is a converse relationship to that noted for varieties on three other fields. The nitrogen content of the Stanley White stover was almost double that of Calico, a difference too great to be accounted for by the comparatively small differences in yields, especially of stover. Differences in the phosphorus content of stover for all varieties except Champion White Pearl were too small to be significant. A comparison of the two late-maturing varieties indicates that the amount of phosphorus in the stover had an indirect relation to yield of grain. The range in the amount of potassium for different stover samples was as great as the range shown for varieties at Urbana, while that of calcium was even greater. In most cases the percentage of either ele- 204 BULLETIN No. 437 [July, ment was considerably less than the amount contained in the stover of the Alhambra varieties but only slightly different from that in the stover varieties at DeKalb. The composition of stover for Calico should be noted particularly, since this variety in outyielding the others still maintained a large reserve of nutrients, except nitrogen, in its stover. In having stover with the lowest nitrogen percentage but the highest potassium, together with the greatest yields, Calico stands out as a variety which apparently either lacks the ability to utilize nitrogen or has an unusual capacity to assimilate potassium. A similar situation was noted previously for Funk 176A at Alham- bra, where it was a low yielder. However, in comparison with Calico, the yields of Funk 176A were greater by 14.9 bushels of grain and 619 pounds of stover per acre, yet its stover was richer in nutrients by .25, .022, .15, and .09 percent of nitrogen, phosphorus, potassium, and calcium respectively. In this instance the differences in composition of stover, also in yields, are not merely the influence of variety. This may, in fact, be less important than the effect of soil character in causing the differences reported. Composition in Relation to Yields The comparative yields of grain and stover in relation to the nitrogen, phosphorus, potassium, and calcium content of the mature stover of the varieties grown at Urbana, Alhambra, DeKalb, and Toledo are shown in Figs. 3, 4, 5, and 6 respectively. In these graphs the varieties are arranged according to stover yield rather than in numerical order. On each field the varieties not only fluctuated widely in yields, but also showed tremendous differences in the ratio of stover to grain. Stover yields, in comparison with yields of grain, were appar- ently more variable at Urbana and less variable at DeKalb. At Alham- bra and Toledo this variation in yields was not marked. The amount of nitrogen in mature corn stover exceeded the amount of potassium, and potassium was followed in descending order by cal- cium and phosphorus. It will be noted, however, that the stover of three varieties (Funk 176A at Alhambra, Rustler at DeKalb, and Calico at Toledo) contained more potassium than nitrogen, while the stover of three other varieties (Reid Yellow Dent at DeKalb, also Mohawk and Stanley White at Toledo) contained more calcium than potassium. In the stover samples of the different varieties analyzed, the percentage of phosphorus was generally more variable than that of nitrogen. Both phosphorus and nitrogen ordinarily varied less than did potassium, while calcium showed the least variation of the four elements studied. 79J7] COMPOSITION OF MATURE CORN STOVER 205 The graphs indicate that the nitrogen, phosphorus, and calcium contents of the stover followed the same general trend in the varieties at Urbana and DeKalb but not at Alhambra. The amounts of nitrogen and of potassium in the stover also appeared frequently to bear an inverse relation to each other; this relation, however, being less con- sistent for stover varieties at Urbana than for those on other fields. PERCENT COMPOSITION AND TONS YIELD .- -- W (v* fc. o> M 'a> b w o o o o o o o URB^ tNA / ^^ V^tr TON; > GRAIN ^^ X, \ / \ *v .^^ - ^-^ >x *""""" .**" N * x s>i. "*& \\ *_ 1- ^" ' - TONS STOVEI POTASS'^ / -.-.. ..--^ ^-" ,/"' \ ^ ^^ \-~^ \ ~" _^ CALCIUM ' ~- PHOSPHOt /5 y * 5ly is I 1 is FIG. 3. COMPOSITION OF MATURE CORN STOVER OF DIFFERENT VARIETIES IN RELATION TO STOVER AND GRAIN YIELDS, URBANA, SOUTH FARM (See also Table 10) At DeKalb the composition of stover seemed to bear no definite rela- tion to either stover or grain yields, while at Urbana it appeared to be correlated negatively with yield of grain rather than yield of stover. A similar relationship, except for the nitrogen content, is apparent for the Alhambra varieties. Corn varieties grown under similar conditions exhibit marked differences in their physical make-up. Variations in the size of stalks and the proportion of stalks to leaves are especially important in affecting the yield of stover. Snyder, 18 * in studying the protein con- tent of forage crops, states that "corn stover varies widely in composi- 206 BULLETIN No. 437 (July, tion .... depending upon the density of the stalk and the proportion of leaves present." In other words, the composition of corn stover is variable because of varietal differences ; altho the composition of the same variety may vary when grown under different environments. The differences among varieties in composition of stover can be attributed chiefly to two factors: first, differences in yield and, second, differences in their ability to utilize nutrients. The interrelation of 220 2JOO i 5" > ? ^5 o 3S FIG. 4. COMPOSITION OF MATURE CORN STOVER OF DIFFERENT VARIETIES IN RELATION TO STOVER AND GRAIN YIELDS, ALHAMBRA (See also Table 11) these factors is, however, recognized, for any factor which affects yield influences stover composition. In these studies variation in yield and in composition of the stover of different varieties on the same field must be accounted for primarily by varietal differences. Certain varieties appear to have greater power to assimilate nutrients than others. Varietal differences in the utilization of nutrients would no doubt affect yield, and therefore exert both a direct and an indirect influence on the composition of stover. The larger amount of nutrients in the stover of some varieties than others would indicate either that 7957] COMPOSITION OF MATURE CORN STOVER 207 the intake of nitrogen or phosphorus, for example, was perhaps in excess of what was actually needed for growth, or that the trans- location of nutrient materials from the vegetative parts of the plant in the formation and development of the ear was less complete. Un- less the composition of corn grain is more variable than shown by various investigations, the emphasis must be placed on greater absorp- tion of nutrients. In some cases the yield and composition of stover bear an inverse relation to each other, since high yields of stover are commonly, tho 2.00 FIG. 5. COMPOSITION OF MATURE CORN STOVER OF DIFFERENT VARIETIES IN RELATION TO STOVER AND GRAIN YIELDS, DEKALB (See also Table 12) not always, associated with low percentage composition, and vice versa. It must be remembered in this connection that the yield of stover, as well as its composition, determines the total amount of nutrients extracted from an acre. Thus the total removal of nutrients in the stover is not reflected by merely noting the percentage composition. The wide variations in the percentages of nitrogen, phosphorus, and potassium are in contrast to the rather uniform calcium content of stover for different varieties. As previously noted, variations in the composition of stover are affected greatly by yields ; altho there appears 208 BULLETIN No. 437 [July, to be little or no relation between composition and length of season required for maturity. Based on the analyses of the separated parts of stover given in the Appendix, the nitrogen content of leaves is usually greater than that of stalks for most varieties. The stalks of the Urbana and Alhambra varieties, however, generally contained more phosphorus than did the leaves, altho the actual differences were rather small. This 1.60 l ii FIG. 6. COMPOSITION OF MATURE CORN STOVER OF DIFFERENT VARIETIES IN RELATION TO STOVER AND GRAIN YIELDS, TOLEDO (See also Table 13) difference with reference to the occurrence of nitrogen and phosphorus in the leaves and in the stalks was probably due to the greater trans- location of the phosphorus from the leaves to the developing grain. At DeKalb and Toledo, where grain yields were low, the phosphorus content of leaves was as great as or greater than that of stalks in all cases except two. The soil conditions under which the varieties were grown appeared to exert a strong influence on the relative distribution of calcium and potassium in the separated parts of the stover. For all varieties of stover at Alhambra and Toledo the amount of calcium was higher in the leaves than in the stalks, while the reverse was always true for potassium. But on the younger and more fertile soils at Urbana and DeKalb, to which no limestone had been applied, the calcium content was consistently greater for the stalks than for the leaves, while in 1937} COMPOSITION OF MATURE CORN STOVER 209 most cases the amount of potassium in the leaves exceeded that in the stalks. Only in the stover of Funk 90- Day and Funk 176A at Urbana and Rustler at DeKalb was the percentage of potassium significantly higher in the stalks than in the leaves. Same Varieties Grown Under Different Conditions Comparative data on yields and on the composition of stover for the same varieties grown under different conditions are reported in Tables 14, 15, and 16. To the differences in soil type and treatment, which are shown, should be added differences in climate which are known to exist but have not been measured. Since the relative influ- ence of these various factors is not determinable for this work, the observed differences in yield and composition of stover must neces- sarily be attributed to the composite effect of climatic and soil factors. Same Varieties at Urbana and Alhambra Based on the average analyses of five varieties, the composition of mature corn stover was practically the same, except for potassium, at Urbana and Alhambra (Table 14). A comparison of analyses for an individual variety, however, reveals some important differences in composition which appear to be closely related to yields. The percent- age composition of stover tends to bear a more definite relation to the yield of grain than to the yield of stover. In most cases in these tests the correlation between composition of stover and yield of grain was negative rather than positive since the higher yields of grain were usually associated with a lower percentage of the various nutrients in the stover for each variety. In general, stover yields were greater, but grain yields less, at Alhambra than at Urbana, and as a result the stover-grain ratio was increased for all varieties except Champion White Pearl. Differences in the physical make-up of the stover on the two fields are indicated by the percentage of leaves, which was consistently higher at Alhambra. These fluctuations in yields, due to change in environment, were ac- companied by marked differences in the composition of the stover. When grown at Alhambra, the stover of each variety contained higher percentages of potassium and calcium than did the same variety grown at Urbana, but the percentages of nitrogen and phosphorus were greater for only two or three varieties. When the varieties grown at Alhambra are compared with the same individual varieties grown at Urbana, it is found that those of the medium-late-maturing group exhibit less pronounced differences in yields and in composition of stover than either the medium-early or the 210 BULLETIN No. 437 [July, is-a 2 H o "S ' O>O lO"* 1 *O ^"J lo'oo NCM (S f4 SStS Tf\O 1010 1010 10** ^Tf 1O10 -N OO O OOO SSI O>CN CS 00 CMOO ^"^O O ^ *^ 1O C*lt^ "5 *TI< ^- (so "f * r- I 2 tt Q-O O>00 001O u u;= v OP "g^ ^< '* J **!tJt* 1 ^ _j ^ -H_= g g QQ (d rt ^^55 II ^<: SS c c ^^ ss g p 22 u b '5'S SS S 3 L O U '..>. > > E6 EE ^ ^^ MM rt rt E S2 C C 3 3 *tf *i *i 3 3 I-*- UU e^c/5 a5oS fata WU! E *- -* (N O* f*5 O iO 1937] COMPOSITION OF MATURE CORN STOVER 211 a o - as ri w c/5 > ^ fc w Z O -w O rt < o a So -o o o. H O H o Ovto -*O * t- fOt~ 1 tStS (SIM CS-* 0 u 2 b o a & * 38 XX S3 K?i ^ ** 10 o* *O 00 2 1 ** ?! !5 ?! 5! too to-* tN (S ri U 6r? f^JW <*5 *"3 fSCS fOCO f*) (N fOCS to to to to B o t*j K^ ^* Ov *^fN O^ ^^H OO^ 1 I/) (N "o c - E Cu ^gs sa ga ss ^2 55 SI X CN O U o;s ss ss as zz ss 00^ oo to oox >. t 1 O^"^ X 55 ""* fOfON fO<^- c i o S 1 ^ I I^NOO <0-tOO -<- d 5 W Or 65 (N^^fS >Or^~* fSWO | H D o U ex < J3 A ^ ^ fa n 2 ^ss ;=S s g * -3 z o a 2 tf O C c U S , fl CU 0U CU 3 b * 9 C CLi hCU - - 1 O S E H 1 55 ^55 p2c< _E tn rj tf U 222 1 -3 S <: i 1 <* a- 95 c "'S5 1 > 1 U3^* .aj;* ^5 11 1 ^~irf?O *^*?O ^^?O 0. U 1 i ^s 7" 7" 7"* j 1 c. ^ I i s 1 1 K f I '. B ^ Q Q "=. ! a . I O > fl s 3 Q >d > i I 1 I residues Id 3 Ai "5, I 6 2 J '"'SS' ^2^ ; 2^ 1937} COMPOSITION OF MATURE CORN STOVER 213 late variety. A comparison of Sommer Yellow Dent and Funk 176A, however, shows that the response of varieties requiring the same length of season for maturity may be quite different when the environment is changed. Reid Yellow Dent, for example, requires 125 days from planting to denting as compared with 135 and 115 days respectively for Champion White Pearl and Krug. The stover of Reid Yellow Dent when grown at Alhambra contained practically the same amounts of nitrogen and calcium, slightly less phosphorus, but considerably more potassium than when grown at Urbana ; while the differences for either Champion White Pearl, a later variety, or Krug, an earlier variety, were much greater not only in yields, but also in the nutrient content of the stover. Same Varieties at Urbana and DeKalb Comparisons of the same varieties grown at Urbana and at DeKalb are given in Table 15. The yield of stover was less at DeKalb for all except the early varieties ; this reduction was marked with the medium- late varieties but only slight with the medium-early varieties. Grain yields were also greatly decreased except for Minnesota 13 and Rustler, which were grown on a more productive soil. All varieties grown at DeKalb showed a lower percentage of leaves and, with the exception of Minnesota 13, a greater stover-grain ratio than when grown at Urbana. On the basis of yields DeKalb seemed more favorable for the early varieties, altho with Golden Glow the greater yield increase in stover was made at the expense of the grain. Differences -between the yields of Funk 90-Day when grown at DeKalb and when grown at Urbana were less marked than those for Krug, but the yield of stover of either medium-early variety was not reduced at DeKalb as much as was that of the medium-late varieties, Sommer Yellow Dent and Reid Yellow Dent. The grain yields of these medium-late varieties however, were lowered more than the grain yield of Funk 90-Day but less than that of Krug. The stover of Sommer Yellow Dent and the early varieties con- tained a lower percentage of nitrogen when grown at DeKalb than when grown at Urbana. The greater decrease in the nitrogen content of Rustler was undoubtedly due to the much larger increase in stover yield. With Reid Yellow Dent, Funk 90-Day and Krug, the greater nitrogen content of stover is out of proportion to the smaller yields. All varieties except Reid Yellow Dent and Funk 90-Day, when grown at DeKalb had a lower phosphorus content of stover than at Urbana ; the reductions in phosphorus content of 40 and 45 percent respectively for the stover of Minnesota 13 and Rustler were relatively greater than the increases in yields, especially of grain, of these two 214 BULLETIN No. 437 [July, varieties. The stover of Funk 90-Day, a medium-early variety which at DeKalb produced 31.2 bushels less grain with no significant difference ] in yield of stover, contained 40 percent more phosphorus. On the other hand, the stover of the medium-late varieties, in spite of their marked reductions in yields, had no higher phosphorus content; in fact the stover of Sommer Yellow Dent had 30 percent less phosphorus at DeKalb than at Urbana. The percentages of potassium and calcium in the stover of most varieties were lower when grown at DeKalb. Differences in the calcium | content are perhaps too small to be significant, except for the stover of Sommer Yellow Dent and Rustler. The variations for potassium i are, however, greater and represent real differences in composition. The response of Rustler to the conditions on the DeKalb field was i exceptional. Despite much greater yields of stover and grain, the potassium content of stover for this variety at DeKalb was almost j treble that at Urbana, even tho the amounts of nitrogen and phos- phorus and also of calcium were markedly lower. Same Varieties at Urbana, Alhambra, and DeKalb Further study of the influence of environment on yields and on the composition of stover can be made from the data given in Table 16. The relative length of season required for maturing these varieties is indicated by the respective number of days 125, 120, and 115 from planting to denting. With all varieties the percentage of leaves, also the yield of stover, was highest at Alhambra and lowest at DeKalb. Grain yields, however, were considerably higher at Urbana than Alhambra, while yields at DeKalb were only about half as great as those at Alhambra. Killing frosts around September 25, while not causing serious damage, no doubt interfered with the further develop- ment of the corn, especially on the DeKalb field, where the corn was planted one week later than at Urbana and 18 days later than at Alhambra. Different varieties on the same field showed practically as much variation in composition of stover as the same variety showed when grown on different fields. This does not mean that differences asso- ciated with variety are greater than differences due to the combined influence of climate, soil type, and treatment; but rather it shows that much of the modification in yield and in composition of stover, with a change in environment, may be due to variety. Forbes and associates, 7 * in discussing the mineral analyses of foods, note that "the inorganic products vary remarkably in accordance with the conditions of growth, especially as relating to soil, rainfall, and 1937] COMPOSITION OF MATURE CORN STOVER 215 sunshine, also rapidity of growth and stage of maturity attained. The variation in organic constituents, however, is very much less than in mineral elements." The Alhambra, DeKalb, and Urbana fields represent widely differ- ent soil and climatic conditions, some of which are noted on pages 188 to 196. Putnam silt loam, which occurs on the Alhambra field, is medium dark in color, strongly acid, and has an impervious subsoil that precludes satisfactory underdrainage. Unless weather conditions, especially with reference to rainfall, are unusually favorable, this soil is less productive, even with treatment, than either Saybrook silt loam at DeKalb or Carrington silt loam at Urbana. The continued use of limestone on the Alhambra field makes possible the use of sweet clover as a green-manure crop. Saybrook and Carrington soils are both dark colored, well drained, and only medium acid in reaction, as they grow red clover without limestone in favorable clover years. Differences in the productive capacity of the soils on the three fields are, no doubt, affected to some degree by climatic conditions. Of the climatic factors the amount and distribution of rainfall, also length of growing season, are known to be important ; other important climatic differences no doubt exist, altho specific information concerning them is not available. Alberts, 1 * in studying the relation of time of planting corn to the time of silking, denting, and senescence, found that the early-maturing varieties develop more readily in cool weather than the late varieties and require a shorter time to reach the silk stage ; moreover the leaves of the early-maturing varieties were found to dry up sooner after denting than those of the late-maturing varieties. The period from silking to denting, however, was approximately the same for all varie- ties even tho they required a variable growth period prior to silking. These observations help to explain differences in the adaptations of different varieties on the same field, also in the response of the same varieties on different fields. The actual length of growing season that is, from planting to the first killing frost in fall at Alhambra was one week longer than at Urbana and nearly three weeks longer than at DeKalb. This repre- sents the approximate differences in corn-planting dates on these fields in 1928. Average temperatures are highest at Alhambra, intermediate at Urbana, and lowest at DeKalb. Late-maturing varieties are best adapted to Alhambra, intermediate to Urbana, and early to DeKalb. The percentage of leaves, the yield of stover, and the proportion of stover to grain of all varieties were generally higher at Alhambra but lower at DeKalb, when compared with the same varieties grown at 216 BULLETIN No. 437 [July, Urbana ; the only exceptions were that the stover-grain ratio for the late variety decreased at Alhambra, while the stover yields of the three early varieties increased at DeKalb. In studying the relation of rainfall to yield of corn, Voorhees 20 * concludes that "effective rainfall is not a function of total rainfall (except when the latter is the limiting factor), but depends entirely upon the condition of the soil and the capacity of the crop for utilizing water." The total and monthly distribution of rainfall from April 1 to September 30 in 1928 is shown in Fig. 2. While the total rainfall was undoubtedly sufficient on all three fields, the distribution at DeKalb was somewhat unfavorable for corn. From April 15 to June 10 there was an actual shortage of rain, and from June 10 to July 5 an excessive amount. Ordinarily corn suffers severely from drouth on Putnam silt loam unless rainfall is generous and well distributed thruout the growing season. In 1928 the rainfall at Alhambra was not only more than average for the season, but nearly 50 percent greater than the average during June, July, and August, and only two rainless periods of more than 10 days duration occurred in those three months. Probably the more serious of these was the one of 24 days which followed 3.5 inches of rain and extended from July 7 to 31. The relative effect of such a period on different corn varieties planted the same date would no doubt be markedly different since they would not likely be in the same stage of development, or at the same critical period, when water was deficient. EFFECT OF SOIL TYPE AND FERTILIZER TREATMENT ON COMPOSITION OF MATURE CORN STOVER It is a matter of common knowledge that soil types vary tre- mendously in productive capacity, and also that an individual type varies within limits in this respect, depending on the system of cropping and treatment as well as on seasonal conditions, which frequently vary considerably within short distances. What relation, if any, these differ- ences in the producing capacity of a given soil type, whatever the cause, bear to the composition of mature corn stover was the chief problem in this phase of the work. While Illinois is characterized by a humid temperate climate, the seasonal conditions prevailing in different parts of the state are rather variable. This fact makes it very difficult to study the effect of soil types thruout the area of their occurrence on the composition of corn stover. Thus, in many cases, comparisons of samples representing different soil types are not justified. On the other hand, widely differ- 1937] COMPOSITION OF MATURE CORN STOVER 217 ent soil types ordinarily do not occur on the same experiment field, where they would likely be under the same seasonal conditions of rainfall, temperature, and other climatic factors. In the few cases where both soil and climatic conditions are similar for two experiment fields, comparable studies on the composition of corn stover could not be made because of the use of different corn varieties or soil treat- ments, or both. Reference to the specific conditions represented by the samples studied will therefore be made in connection with the data reported. Effect of Different Soil Types Under Same Climatic Conditions The effect of soil type on the composition of corn stover is shown by the data in Table 17. Each consecutive pair of samples was col- lected from different soil types on the same field. Since the variety and treatment, as well as the climatic conditions, are the same for each comparison, the differences in composition of stover, also in yields, represent the influence of soil type. The apparent differences between Saybrook silt loam and the deep phase of this type on the DeKalb field are not very pronounced. Ex- cept for variations in depth, the descriptions of these two soils are almost identical. While the yields on the Saybrook silt loam, deep phase were greater by 1,065 pounds of stover and 26 bushels of grain per acre, the composition of the stover was not significantly different, except for calcium, from that grown on the Saybrook silt loam. The data for Samples 29 and 34 would indicate that while the soil type had a marked effect on yields, it had practically none in this case on the composition of stover. It should be noted, however, that the soil types compared are very similar in character. The second comparison in Table 17 is between untreated soils, Drummer clay loam and Sidell silt loam, on the Sidell field. Drummer clay loam is rich in total nutrients, has a high content of available phosphorus, and requires no limestone to grow sweet clover. This soil yielded 1,514 pounds more stover and 20.2 bushels more grain per acre than Sidell silt loam, which is less fertile, lower in available phos- phorus, and more acid in reaction. The stover grown on the Drummer clay loam contained .03 percent less nitrogen but more phosphorus, potassium, and calcium by .033, .48, and .03 percent respectively than the stover grown on the Sidell silt loam. These differences in com- position, except that for calcium, are no doubt significant. Furthermore it appears that both phosphorus and potassium were assimilated in amounts greater than needed, or that growth was limited by the supply of available nitrogen. 218 BULLETIN No. 437 [July, o u u K H J c I 2 9>O> X C 1 *>* C"i 1/3 5S 1/1 =s ^ r o ""> * c E fc '* v a c 0> Q 1 Yellow o "*^ o CO O $$ u-c Qtn ZZ 5 COMPOSITION OF MATURE CORN STOVER 219 tn Q e *o^> * O 3 I 1 _a 'f>ot- sss & M a z "O o z 1 8 o _g ^10 !!! Q Z [if a (N>00 00>0 J U o^ ^ ^ ^ CN <*5 (N J < 1 1 U! _ wmo g; 10000 I^OOO (d o U B < _O 1 <*>* U1O U B (X 6^ ooo tst^ O ^ o U H *J t> c/} *c rt o J= z > Q. o c2 2: ^? r~Oio -= S U o. OS C 1 1 3 E 1 v c o s = o ^ Z 2 2 "55 5 ' e 1 2 1 H V esidues. ti c/i J'*' M -^ sT ill 111 <^2 U z o U) E H d $ a b. >. a a O a g _j g E Ed I I l~ rt~ S U O ^^ * m ^ Z ^J ' ^ * J * at fid m 4>^S ~ 0^- P >i w X X w X B ||| ||| T oo OSO oSo Id 4 | J 1 n I ' >3ooo! KSS H d r 220 BULLETIN No. 437 [July, The soil types included in Table 18 occur on different experiment fields, hence under somewhat different climatic conditions. The differ- ences in composition of stover, also yields, therefore cannot be accounted for merely by soil type but are due to both soil and climatic factors. Since the relative influence of each group of factors is not known, nor determinable for this work, the data in Table 18 are of little or no value in showing the specific effect of soil type on the com- position of stover. They are therefore presented without discussion, excepting to say that the residues, limestone, and rock phosphate treatment not only increased yields but also modified the composition of the stover. Effect of Single Materials in Standard Treatments Residues (R over Check) The so-called standard treatments, as noted previously on pages 192 and 193, are those for the grain system of farming and include: (1) residues; (2) residues and limestone; (3) residues, limestone, and rock phosphate; and (4) residues, limestone, rock phosphate, and kainit. To ascertain the effect of single materials on the composition of stover, samples from the residues-treated plots are compared with those from untreated plots ; samples from the residues and limestone plots are compared with those from the residues plots, and so on. Thus the effect of limestone alone cannot be determined; this is also true for rock phosphate and kainit. In addition to crop residues, such as cornstalks and straw a from wheat, oats, and clover, the residues-treated plots received the second crop of clover. Furthermore a leguminous green-manure crop, usually sweet clover, was seeded in the wheat on these plots to be plowed down for corn. Success with clovers, however, is rather variable, depending on the reaction of the soil type. Table 7 reports the clover growth without limestone on the soil types represented by the stover samples collected from the respective fields. Oblong and Toledo grow neither red nor sweet clover without limestone; Urbana (Davenport plots), Aledo, Joliet, Kewanee, Mt. Morris, and Sidell grow red but no sweet clover; while Carthage, Hartsburg, LaMoille, and Minonk grow sweet clover on the unlimed residues plots. A comparison of the composition of stover, also yields of stover The return of oat and wheat straw was discontinued. On most fields this change was made in 1921 for oat straw and in 1922 for wheat straw except as noted: oat straw at Carthage in 1922, at Urbana (Davenport plots) in 1923, at Oblong and Toledo in 1925; wheat straiu at Aledo, Urbana (Davenport plots), and Toledo in 1923. 1937} COMPOSITION OF MATURE CORN STOVER 221 TABLE 19. EFFECT OF RESIDUES ON COMPOSITION OF MATURE CORN STOVER (Consecutively numbered samples represent same soil type and corn variety) Sample No. Treat- ment* Field Composition of stover Yield per acre N P K Ca Stover Grain 13 14 36 37 56 57 65 66 75 76 80 81 89 90 94 95 99 100 104 105 121 122 126 127 R R R R R R R R R R R R R Urbana (Davenport plots).. Aledo .73 .77 .78 .66 .76 .78 .55 .74 1.03 .86 .83 .59 .62 .78 .52 .64 .68 .67 .74 .58 .86 .90 .58 .50 .72 .71 .070 .074 .076 .167 .077 .065 .105 .062 .079 .055 .059 .041 .083 .077 .074 .061 .062 .061 .074 .058 .082 .075 .122 .091 .080 .074 .53 .56 .58 1.14 .39 .39 .57 .66 .38 .36 .88 .68 .85 .35 .60 .58 .55 .40 .30 .35 .31 .40 .48 .37 .54 .52 .46 .36 .42 .28 .34 .27 .33 .33 .22 .20 .51 .31 .36 .30 .30 .27 .32 .28 .24 .25 .21 .27 .32 .24 .34 .28 Ibs. 2 725 2 994 2 199 2 492 1 706 1 734 1 958 3 144 1 751 1 684 2 192 2 459 2 127 2 639 1 517 2 545 1 882 2 221 1 188 1 621 2 106 2 857 2 231 2 510 1 965 2 408 bu. 49.6 50. & 54.4 68.6 37.8 54.8 43.0 78. O 9.O 7.9 74. 74.6 56.0 60,8 47.3 68.6 35.7 46.4 22.8 23.6 20.6 24.6 21.0 26.0 39.3 48.7 Carthage Hartsburg Joliet Kewanee LaMoille ; M i in in k Oblong Sidell Toledo Average of all = no treatment. R = residues. and grain grown on the check and residues plots, is shown in Table 19. For each consecutively numbered pair of samples the soil type and variety of corn are the same. The average increases in yields for residues over no treatment were 443 pounds of stover and 9.4 bushels of grain per acre; while the average decreases in the amounts of nitrogen, phosphorus, potassium, and calcium in the stover were for residues over no treatment .01, .006, .02, and .06 percent respectively. Of these differences in composition, only that for calcium is significant. The effect of residues on yields, and on the composition of stover is also shown by Fig. 7, in which the differences of "residues" over "check" are plotted as plus or minus values for each field. The yield of grain and stover was increased by residues on all fields except Joliet. The increases, however, in grain at Urbana (Davenport plots ), Kewanee, and Oblong, and in stover at Carthage were too small to be 222 BULLETIN No. 437 [July, STO SOI M IS R DUES ON COMPOSITION (H3IA SNO1 ONV NOU-ISOdtNOO !N30b3d EF FIG. 1937} COMPOSITION OF MATURE CORN STOVER 225 significant. Of the twelve comparisons, six show an increase in the nitrogen content of stover, and six show a decrease, with one in each group differing .02 percent or less. The greatest increases in the nitrogen content of stover for the residues treatment were obtained on those fields where the soil type will grow sweet clover on the residues plot, which has received no limestone. This is true especially for Grundy clay loam at Hartsburg, Drummer clay loam at Minonk, and to a lesser extent for Muscatine silt loam at LaMoille. While the nitrogen increase in stover was greater at LaMoille than Minonk, the increases in yields, both grain and stover, were very much smaller. The decreases in the percentage of nitrogen in the stover, except in that grown at Joliet, were associated with increases in yields, particularly of stover. Ten of the twelve comparisons in Table 19 show a decrease in phosphorus content of stover, ranging from .001 to .043 percent, but these differences are significant in only five comparisons. At Harts- burg, where the yield of grain was increased 35 bushels per acre with residues, the decrease in the phosphorus content of the stover might be expected; but at Joliet, Kewanee, Oblong, and Toledo the differ- ences in grain yields were much too small to account for the variation in phosphorus. These four fields also showed a decrease in the nitrogen content of stover grown on the residues plots. With respect to potassium and calcium, definite changes in the composition of stover were shown in two-thirds of the comparisons between the residues and check samples. Residues, however, resulted in an increase of potassium three times and of calcium but once; the stover sample from late-planted corn at Sidell showing an increase in both potassium and calcium as well as nitrogen. At Aledo the potas- sium and phosphoruS contents of stover from residues were double those from the check plot despite increased yields of stover and grain. Decreases in the amounts of potassium and calcium in the stover at Kewanee, LaMoille, Mt. Morris, Minonk, and Toledo, and of calcium at Aledo, Carthage, and Urbana were invariably associated with increased yields on the residues-treated plots. Limestone (RL over R) The initial application of limestone on all fields was at the rate of 4 tons to the acre, with 2 tons to the acre each rotation thereafter. This material was applied after plowing the clover sod for wheat. The total application of limestone on these fields has varied from 12,000 to 18,000 pounds to the acre, owing chiefly to differences in the length of time 224 BULLETIN No. 437 [July, TABLE 20. EFFECT OF LIMESTONE ON COMPOSITION OF MATURE CORN STOVER (Consecutively numbered samples represent same soil type and corn variety) Sample No. Treat- ment* Field Composition of stover Yield per acre N P K Ca Stover Grain 14 IS 37 38 57 58 66 67 76 77 81 82 90 91 95 96 100 101 105 106 122 123 127 128 R RL R RL R RL R RL R RL R RL R RL R RL R RL R RL R RL R RL R RL Urbana (Davenport plots).. Aledo % .77 .99 .66 .53 .78 .75 .74 .76 .86 .91 .59 .67 .78 .89 .64 .66 .67 .71 .58 .67 .90 1.28 .50 .69 .71 .79 % .074 .063 .167 .196 .065 .063 .062 .060 .055 .091 .041 .047 .077 .101 .061 .063 .061 .071 .058 .073 .075 .101 .091 .078 .074 .084 % .56 .81 1.14 1.01 .39 .38 .66 .66 .36 .32 .68 .65 .35 .51 .58 .60 .40 .47 .35 .44 .40 .60 .37 .32 .52 .56 % .36 .43 .28 .28 .27 .31 .33 .36 .20 .19 .31 .31 .30 .30 .27 .22 .28 .22 .25 .21 .27 .29 .24 .29 .28 .28 Ibs. 2 994 3 821 2 492 2 313 1 734 1 956 3 144 2 590 1 684 1 842 2 459 2 552 2 639 3 057 2 545 2 343 2 221 2 842 1 621 2 464 2 857 3 240 2 510 2 468 2 408 2 624 bu. 50.8 60.0 68.6 74.6 54.8 60.8 78.0 79.4 7.9 15.1 74.6 83.6 60.8 67.3 68.6 70.6 46.4 64.7 23.6 36.2 24.6 32.5 26.0 30.6 48.7 56.3 Carthage Joliet Mt. Morris Oblong Sidell . . Average of all R = residues. RL = residues and limestone. the respective fields have been in operation rather than to differences in soil acidity or the lime needs of the crops grown. a No limestone, however, has been used since 1922 or 1923, when the regular applica- tions of this material were temporarily discontinued until further need of it, as indicated by clover growth, should become apparent. The effect of limestone on the composition of stover, also on grain and stover yields, is shown by Table 20 and Fig. 8. The average increases in yield resulting from limestone are shown in Table 20 to have been 7.6 bushels of grain and 216 pounds of stover per acre. Altho the average composition of the stover grown on the "For information as to the exact amount of limestone or other fertilizing materials applied to the individual plots from which the stover samples were collected, the reader is referred to Table 30 in the Appendix. 1937} COMPOSITION OF MATURE CORN STOVER 225 Q-I3IA SNO1 QNV NOIJ.ISOdkNOO J.N3DW3d 226 BULLETIN No. 437 [July, residues-limestone plots was slightly higher than that from the residues plots, the only significant difference was in the nitrogen content. Yields of grain were increased on all fields ; those of stover on all except four. At Aledo and Toledo the decline in stover yields that was associated with the use of limestone was less pronounced, while the increase in grain yields was more marked than at either Hartsburg or Minonk. The soil types which occur on the Hartsburg and Minonk fields (Grundy clay loam and Drummer clay loam) are naturally well supplied with carbonates, so that the addition of limestone might be expected to have little or no value. Its influence on these two soils was not beneficial so far as yields, especially of stover, were concerned ; while on neither soil was the composition of the stover changed ap- preciably by the limestone. Apparently it did not lessen the availability of the native phosphorus. No explanation can be given for the signifi- cant decrease in the nitrogen and potassium contents of stover at Aledo. Rock Phosphate (RLrP over RL) Rock phosphate has been used at the annual acre-rate of 500 pounds once each rotation before plowing the clover sod for wheat. The total applications of this material were evened up to 4 tons an acre, except on the Davenport plots, where they were equivalent to 13,200 pounds when discontinued. This occurred in 1923 at Hartsburg, LaMoille, Minonk, Mt. Morris, and Sidell; in 1924 at Aledo, Carthage, and Oblong; in 1925 at Urbana (Davenport plots) and Toledo; in 1926 at Joliet, and in 1928 at Kewanee. The soil types occurring on these experiment fields show marked differences in their phosphorus content. The surface 62/3 inches varies in phosphorus content from .035 percent in the Cisne silt loam at Toledo to .098 percent in the Drummer clay loam at Sidell. The varia- tion for other strata is somewhat less. Of greater importance than the total content of phosphorus, however, is the amount of available phos- phorus which, as determined by the Bray test for the untreated soils, is shown in Table 7. Those at Hartsburg and Minonk are ranked "high" in available phosphorus, those at Aledo and LaMoille as "medium," and those at the remaining fields as "low." The tests indicated somewhat smaller amounts of available phosphorus for the soil types at Joliet, Toledo, and Oblong than others in the low group. Rock phosphate increased yields only slightly, 233 pounds of stover and 3.5 bushels of grain per acre, as an average on twelve fields. How- ever, the percentages of both nitrogen and phosphorus in the stover were raised considerably with no marked change in the content of potassium and calcium. These results are shown in Table 21 and Fig. 9. 1937] COMPOSITION OF MATURE CORN STOVER 227 TABLE 21. EFFECT OF ROCK PHOSPHATE, WHEN USED WITH LIMESTONE, ON COMPOSITION OF MATURE CORN STOVER (Consecutively numbered samples represent same soil type and corn variety) Sample No. Treat- ment* Field Composition of stover Yield per acre N P K Ca Stover Grain 15 16 38 39 58 59 67 68 77 78 82 83 91 92 96 97 1101 102 106 107 123 124 128 129 RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP RL RLrP Urbana (Davenport plots).. Aledo % .99 1.11 .53 .57 .75 .71 .76 .90 .91 .78 .67 .91 .89 .96 .66 .75 .71 .91 .67 .71 1.28 1.12 .69 .71 .79 .85 % .063 .131 .196 .108 .063 .064 .060 .064 .091 .081 .047 .080 .101 .125 .063 .070 .071 .116 .073 .119 .101 .119 .078 .161 .084 .103 % .81 .88 1.01 .67 .38 .33 .66 .62 .32 .30 .65 .65 .51 .58 .60 .40 .47 .45 .44 .34 .60 .79 .32 .32 .56 .53 % .43 .52 .28 .28 .31 .26 .36 " .37 .19 .21 .31 .36 .30 .36 .22 .26 .22 .22 .21 .22 .29 .27 .29 .33 .28 .31 Ibs. 3 821 4 204 2 313 2 092 1 956 2 184 2 590 3 344 1 842 2 144 2 552 3 122 3 057 3 002 2 343 2 311 2 842 2 768 2 464 2 963 3 240 3 440 2 468 2 715 2 624 2 857 bu. 60.0 73.6 74.6 73.4 60.8 61.7 79.4 82.0 15.1 22.3 83.6 86.2 67.3 69.1 70.6 72.0 64.7 70.0 36.2 40.6 32.5 36.0 30.6 31.6 56.3 59.8 Carthage Hartsburg Joliet LaMoille Minonk Mt. Morris Oblong Sidell Toledo Average of all Average of all RL = residues and limestone. RLrP = residues, limestone, and rock phosphate. Reference to Fig. 9 shows that only on a few fields did the rock phosphate exert a negative influence on yield and composition. Of the five decreases in yield, four were for stover and of these only one represents a significant difference. On three fields, Carthage, Joliet, and Sidell, the percentage of nitrogen in the stover was decreased with the use of rock phosphate ; in two cases, Joliet and Sidell, stover from late-planted corn was utilized for analysis. Substantial increases in yields of both grain and stover on these fields, however, were obtained with the phosphate treatment. Only in the stover from the Aledo field was there an actual decrease in phosphorus content, and this was associated with decreased yields. While the untreated soil, Grundy silt loam, is ranked as medium in available phosphorus, the amount of phosphorus rendered available by 228 BULLETIN No. 437 (July, CH3IA SNOX QNV NOIllSOdlNOO J.N3D3d 1937] COMPOSITION OF MATURE CORN STOVER 229 the residues and limestone treatment is undoubtedly very much greater, so that the application of rock phosphate proved ineffective in changing either yields or the phosphorus content of the stover. Where rock phosphate had been used in addition to residues and limestone, relatively few pronounced changes in the potassium and cal- cium contents of the stover resulted, altho some significant decreases, as well as increases in the amount of each element, were shown by the stover samples from the phosphated plots on several fields. These changes, however, in the composition of stover, resulting apparently from the rock-phosphate treatment, appear to bear no definite rela- tionship to yields either of grain or of stover. Potash (RLrPK over RLrP) Potash has been applied on the Illinois soil experiment fields chiefly in the form of kainit, except on the Davenport plots, where K 2 SO 4 was used, and during the war period, when K 2 CO 3 was substituted. The kainit was applied once per rotation before plowing the clover sod for wheat, at the annual acre-rate of 200 pounds or an equivalent amount of its substitute. Owing to differences in length of time the experiment fields have been in operation, the total applications of kainit have varied from 3,200 to 4,400 pounds per acre ; the exact amount for the respec- tive fields is given in Table 30 in the Appendix. The effect of potash on stover composition and on yields is shown by the data in Table 22 and by Fig. 10. No comparisons are given for Carthage, since the potassium-treated plot, unlike the plots for the other standard treatments, on Series 200 of that field is represented by a different soil type. Potash, in 11 comparisons from as many fields, increased yields by an average of 150 pounds of stover and 4.9 bushels of grain per acre. The greatest increases were on the light-colored soils at Toledo and Oblong; while the only significant decreases were on the heavy, dark-colored soils, Grundy clay loam at Hartsburg and Drummer clay loam at Minonk. Both of the latter soil types are either neutral or very slightly acid in the surface. If, as suggested by Bauer 3 * (page 469 of work cited), large amounts of limestone tend "to prevent the formation of readily available potassium," it would appear that kainit should exert a beneficial rather than a detrimental effect on these soils. The percentages of nitrogen and phosphorus in the stover were decreased by the potash treatment ; while the calcium content was either decreased or unchanged. With increased yields, such changes in composition might be expected, as shown especially at Joliet, Mt. Morris, and Toledo. But on the clay loam soils, yields were reduced, 230 BULLETIN No. 437 [July, TABLE 22. EFFECT OF POTASH (CHIEFLY KAINIT) ON COMPOSITION OF MATURE CORN STOVER (Consecutively numbered samples represent same soil type and corn variety) Sample No. Treat- ment* Field Composition of stover Yield per acre N P K Ca Stover Grain 16 17 39 40 68 69 78 79 83 84 92 93 97 98 102 103 107 108 124 125 129 130 RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK RLrP RLrPK Urbana (Davenport plots).. Aledo % 1.11 1.21 .57 .55 .90 .73 .78 .70 .91 .69 .96 1.04 .75 .66 .91 .81 .71 .81 1.12 1.15 .71 .62 .86 .82 % .131 .127 .108 .115 .064 .046 .081 .066 .080 .056 .125 .109 .070 .053 .116 .093 .119 .118 .119 .119 .161 .102 .107 .091 % .88 1.12 .67 .80 .62 .75 .30 .34 .65 .97 .58 .75 .40 .57 .45 .69 .34 .57 .79 .95 .32 .83 .55 .76 % .52 .43 .28 .29 .37 .32 .21 .23 .36 .32 .36 .36 .26 .26 .22 .24 .22 .21 .27 .27 .33 .31 .31 .29 Ibs. 4 204 4 248 2 092 2 200 3 344 3 220 2 144 2 379 3 122 2 921 3 002 2 909 2 311 2 222 2 768 2 893 2 963 3 505 3 440 3 615 2 715 3 653 2 919 3 069 bu. 73.6 81.2 73.4 77.6 82.0 68.8 22.3 28.1 86.2 90.4 69.1 69.8 72.0 66.7 70.0 71.1 40.6 66.4 36.0 43.0 31.6 47.0 59.7 64.6 Joliet . . LaMoille Minonk Mt. Morris Oblong Sidell Toledo Average of all Average of all RLrP = residues, limestone, and rock phosphate. RLrPK phate, and potash. residues, limestone, rock phos- and the amounts of nitrogen and phosphorus in the stover were lowered by the use of potash. On'the other hand, the potash treatment increased the potassium content of stover in all cases, percentage of increase varying from 13 at Joliet to 160 at Toledo. At the same time yields also were increased except at Hartsburg and Minonk. Combined Effect of Different Materials in Standard Treatments The combined effect of the fertilizing materials on the composition of stover and on yields is ascertained by comparing the respective treatments with the checks. These comparisons are shown by a series of graphs (Figs. 11, 12, and 13) which are presented without a repeti- tion of the data on which they are constructed. With a few minor exceptions, the combined treatments (1) resi- dues and limestone; (2) residues, limestone, and rock phosphate; (3) 1937] COMPOSITION OF MATURE CORN STOVER 231 i j. 013IA SNOJ. ONV NOIllSOdWOO !N3D3d . u X > fi E W G) I 232 BULLETIN No. 437 [July, C/5 u 2 O f- U 2 a g 5 u - - . W QH3IA SNO1 ONV NOIllSOdlNOD lN3D3d 1937] COMPOSITION OF MATURE CORN STOVER 233 p I S 1 I i- X 35 W 2 u t/) * x ii; o c g 8 g t/5 > Jc/5 M ,. QH3IA 9NO1 OMV NOIll9OdkNOO !N303d I W 234 BULLETIN No. 437 8 I I QH3IA SNO1 QNV NOUISOdlNODlN30a3d R EFFECT FIG. 1937] COMPOSITION OF MATURE CORN STOVER 235 residues, limestone, rock phosphate, and kainit increased yields of both grain and stover over the untreated checks. This was true in spite of the fact that the single materials in many cases exerted a negative influence on yields. Limestone, for instance, caused a reduction in the yield of stover at Aledo, Hartsburg, Minonk, and Toledo ; rock phos- phate depressed stover yields chiefly at Aledo ; while kainit decreased the yields of both grain and stover at Hartsburg and Minonk. The most pronounced change in the composition of stover, due to the combined treatments, was in the nitrogen content. This was fol- lowed in turn by potassium, phosphorus, and calcium. Of 35 compari- sons for each nutrient, significant changes in the nitrogen, potassium, phosphorus, and calcium contents of the stover were shown in 34, 27, 23, and 19 comparisons respectively. These changes represent increased amounts of nitrogen in approximately two-thirds of the comparisons, increased amounts of phosphorus in three-fourths, potassium in three- fifths, and calcium in only one-fourth of the comparisons. In only seven instances did the changes in composition occur in the same direc- tion with all nutrients; these were in the percentage increases caused by all treatments at Sidell and by the RLrP treatment on the Davenport plots, and in the decreases caused by the RL treatments at Carthage and Kewanee and the RLrP treatment at Carthage. Examination of Figs. 11, 12, and 13 shows that decreases occurred in the nitrogen content of the stover at .Aledo and Joliet under all the combined treatments; at Kewanee and Oblong under the RL treat- ments ; at Carthage and Oblong under RLrP ; and at Kewanee under RLrPK. It will be noted that these reductions in the nitrogen content of the stover were associated generally with marked increases in yield, both of grain and stover. The only exceptions to this apparent relation- ship had to do with the stover yields obtained at Aledo under all treatments and at Joliet under the RL treatment. The phosphorus content of stover was reduced by all the combined treatments at Hartsburg; by RL and RLrPK at Toledo; and by RLrPK at Minonk. Grain yields for these treatments, however, were increased 36.4, 39.0, and 25.8 bushels per acre at Hartsburg; 9.6 and 26 bushels at Toledo, and 19.4 bushels at Minonk ; stover yields also were increased in amounts varying from 237 to 1,422 pounds per acre. Even where the decreases in the percentage of phosphorus under the combined treatments were relatively small, large increases in yields were obtained. The amount of potassium in the stover was decreased by all the combined treatments at LaMoille ; by RL and RLrP at Kewanee, Mt. Morris, and Toledo ; and by RLrP at Joliet and Minonk. On the other 236 BULLETIN No. 437 [July, hand, all combined treatments at Aledo, Kewanee, Minonk, and Mt. Morris caused reductions in the amount of calcium in the stover; as did also RL at LaMoille and RLrP at Carthage. These reductions in the potassium and calcium contents of the stover were obviously due in large part to the effect of the yield increases that resulted from the different treatments. Except for the yields of stover obtained under the RLrP and RLrPK treatments at Aledo, yields were increased by all combined treatments on all fields. Effect of Phosphorus Carriers With and Without Limestone Rock Phosphate The effect of rock phosphate when used with residues and limestone on the composition of mature corn stover has been shown by the data in Table 21 and also by Fig. 9. This section, including the data in Table 23, is concerned with a study of the effect of rock phosphate when used with and without limestone, on yields and on the composi- tion of stover, particularly the phosphorus content. Information con- cerning the soil types involved in these comparisons is given on pages 188 to 191. The wide variations in the reaction of these types and the marked differences in their content of available phosphorus, should be noted especially. After the total application of rock phosphate had reached 8,000 pounds per acre, the plots on the main series of the Aledo, Hartsburg, and Toledo fields, represented by Grundy silt loam, Grundy clay loam, and Cisne silt loam respectively, were divided in 1924 in order to make possible further phosphorus studies. On one half of all plots in each series it was indicated that the "original soil treatment was continued." The application of limestone and rock phosphate, however, and the return of all residues except cornstalks, had previously been discon- tinued. The supplementary phosphorus studies were begun on the other half of the plots. Thus Samples 39, 68, and 129 represent plots on which the appli- cations of rock phosphate had reached 8,000 pounds per acre and were then discontinued; while Samples 44, 73, and 135 represent the other half of these respective plots, where the phosphate applications were continued. The additional 3,000 pounds per acre of rock phosphate was applied as follows: 1,000 pounds in the spring of 1924, 500 pounds before oats in the spring and 1,000 pounds before wheat in the fall of 1926, and 500 pounds in the spring of 1928. The same distribution of the phosphate was made on the RrP plots represented by Samples 42, 71, and 133. COMPOSITION OF MATURE CORN STOVER 237 sl 1 ~* "O>O O>O i ~* *> ao" *> oe 55 vO>OX3-0.O> - g ss 00 X 00 O es r* o SooS ^o-^ T >A c ""- ** "C U 1 O V > s ^ g^ Slf v 92 c ~t C^c IU 3 hambra Putnam sili Cham pi edo (minor a Grundy sill Will Co "^ < 0. %J 0, SSS S , 238 BULLETIN No. 437 [July, The data reported in the first part of Table 23 show that rock phosphate without limestone failed, in most cases, to change either the grain or stover yields significantly. The stover yield on Grundy silt loam, however, was decreased 557 pounds an acre by the phosphate treatment, whereas the grain yield on Grundy clay loam was increased by 7.0 bushels an acre. Where rock phosphate had been used with limestone prior to 1924, it increased the yields, especially of stover, at Hartsburg and Toledo, but decreased them at Aledo. The recent rock phosphate applications on the heavily limed plots have, however, increased the yields both of grain and of stover in all cases except the yield of stover at Toledo. Altho wide variations in the nitrogen, potassium, and calcium con- tents of stover under various treatments are shown by the data in Table 23, this discussion will be limited primarily to the phosphorus differences. When used without limestone, rock phosphate produced no significant change in the phosphorus content of the stover grown at Hartsburg. This was also true where rock phosphate had been used with limestone prior to 1924; but where recent applications of rock phosphate had been made to a plot limed prior to 1924, the phosphorus content of the stover was raised from .064 percent to .086 percent. Rock phosphate, when used either with or without limestone, caused a great decrease in the phosphorus content of the stover at Aledo but produced a marked increase in the stover at Toledo. The continued use of rock phosphate at Aledo failed to increase the percentage of phosphorus in the stover, but at Toledo it resulted in a further significant increase. The Grundy clay loam, Grundy silt loam, and Cisne silt loam of these fields are "high," "medium," and "low," respectively, in available phosphorus. In reaction these soil types are very slightly, medium, and very strongly acid. Altho these soil differences undoubtedly would influence the utilization of the applied phosphate, the differences in the phosphorus content of the corn stover under corresponding phosphate treatments on the Grundy silt loam and Grundy clay loam are not so great as might be expected. Evidence of the greater utilization of rock phosphate on the Cisne silt loam is provided by the increase of more than 40 percent in the phosphorus content of the stover when phos- phorus was used alone and the doubling of its phosphorus content when phosphorus was used with limestone. The lighter applications of limestone at Toledo, together with a lower amount of available phos- phorus prior to treatment, were no doubt important factors affecting the availability of the applied phosphate and the phosphorus content of the stover produced. 1937] COMPOSITION OF MATURE CORN STOVER 239 Comparison of the data for the RLrP and RL treatments indicates that limestone suppressed the availability of the applied phosphate on Grundy silt loam at Aledo (Series 300). However, the phosphorus content of the stover from the RLrP plots averaged 42 percent greater than that from the RrP plot. Equally heavy applications of limestone on the Grundy clay loam at Hartsburg, a nonacid soil high in available phosphorus, failed to decrease either yields or the phosphorus content of the stover. It is difficult to offer a satisfactory explanation for this difference in the influence of limestone on the availability of rock phosphate when used on the Grundy silt loam and when used on the Grundy clay loam. These results are not in agreement with the tentative conclusions of Bauer 3 * (page 463 of work cited), who has attributed the lack of response to rock phosphate, particularly on the latter soil, to the retard- ing influence of limestone on the availability of the rock phosphate. Since this soil type is naturally well supplied with both total and avail- able phosphorus and contains sufficient lime to grow sw r eet clover satis- factorily as a green-manure crop, little or no response from either limestone or rock phosphate, when used alone or together, could be expected. Additional data to show the influence of rock phosphate on the composition of mature stover are reported in the second part of Table 23. While the Putnam silt loam is strongly acid and low in available phosphorus, it is more productive, either with or without treatment, than the Cisne silt loam. Not only were the yields for corresponding treatments greater on the former soil, but the nutrient content of the mature stover was higher, except for the amounts of phosphorus and potassium where rock phosphate was used with and without limestone respectively. Rock phosphate without limestone at Alhambra increased yields and also the percentages of nitrogen and phosphorus in the mature stover; but when it was used with limestone, the stover yield was further increased and the yield of grain decreased. This reduction in grain yield appears to have been due to a phosphorus deficiency, since the nitrogen content of stover was 25 percent greater and that of phosphorus 30 percent less. These results would indicate that the lime- stone had caused the phosphorus to become less available. The differ- ent effect of limestone on the availability of rock phosphate at Alham- bra and Toledo seems to bear a definite relation not only to the char- acter of the soils but also to the proportion of rock phosphate and lime- stone applied. The Putnam silt loam received 16,000 pounds of limestone per acre and 6,000 pounds of rock phosphate ; whereas the 240 BULLETIN No. 437 [July, Cisne silt loam received 13,000 pounds of limestone and 8,000 or 11,000 pounds of rock phosphate. The soil type and basal treatments are similar on both Series 300 and the minor series at Aledo. The system of cropping and the total applications of limestone and of rock phosphate, however, have been very different. Samples 46, 49, 52, and 53 from the minor series are not, therefore, duplicates of the samples for corresponding treatments on Series 300. A comparison of the yields on the two series reveals no striking differences. The same is true with reference to the compo- sition of stover, so far as nitrogen and calcium are concerned. The phosphorus content of the stover, however, shows wide variation not only between different treatments on the same series, but also for the same treatment on the two series. With potassium, the percentage was uniform for the stover on the minor series but quite variable for that on Series 300. The amount of phosphorus in the mature stover grown on the R and RL plots of Series 300 was three and one-half to four times as great as that for the corresponding treatments on the minor series. While this variation is thought to have been due primarily to soil differ- ences, there is no direct evidence to offer in support of this assumption. Unfortunately no specific information concerning the reaction or phos- phorus content of the soil on the individual plots of the two series is available, or obtainable, at present. Rock phosphate, when applied alone or with limestone on the minor series, increased both the yields and the phosphorus content of the stover. These effects are just the opposite of those reported for the corn grown on Series 300 at Aledo. Almost three times as much rock phosphate was used for the RrP treatment on the minor series as on Series 300; and while the amounts of phosphate are comparable for the RLrP treatment on the two series, the applications of limestone were 4,000 pounds per acre less on the minor series. Here again the amount of limestone used in relation to the total application of rock phosphate appears to have been an important factor in the utilization of phosphorus. Superphosphate The effect of superphosphate, when used with and without lime- stone, on the composition of mature corn stover is shown in Table 24. The data for corresponding treatments on the Aledo, Hartsburg, and Toledo fields, reported in the first part of Table 24, appear to be directly comparable. The comparison of different treatments on the same field may be questionable in view of the treatment prior to the COMPOSITION OF MATURE CORN STOVF.R 241 1 : i 1 1 J : i o S s '. s 1 i "5 .s ) ex *- 2 CD V *^ i I = i - a c - 5 V 1 p ' u (1) O > 4 1 i s : 5 6 i o ! M -fS -OfO *G\O> _g ^'*5 rt^ir>. lOOO'C Ovfno OO ^^ tt~-O> ^Ol- OioSoO TO"5fO U-. C "!". -H B ti cd IX t^OOt^ (NtNO'* f^OOfS OOW51-O ^SoSS SoSS S S O O *8SS?3 S3SS SSSr: ")i>-oo iy-.u-.Cu-. o "C U - > C 0) 'C o > e fc EQ g,ll Jl g^ .2i s- ^.2 g'EU O w g *5i S su B ^s 05 o u |o "Su J6 "3 e x= in ^2 V o> < a H < o - &4 CU a. & cuj =2 ^j.2 ^^^ & j.2 o p ^"*5 ^" NOl^OI^* CNf)P l ***S OO' !/-. .<. 242 BULLETIN No. 437 [July, phosphate application ; also because of the manner in which the super- phosphate and limestone have been used. The superphosphate, where applied on unlimed soils, was used with "residues" on a plot which prior to 1924 was an untreated check; whereas the superphosphate with limestone has been applied to a residues-limestone plot. "Residues," therefore, had been used only five years in the former case, as compared with fifteen to eighteen years in the latter. While it is not clear just what significance should be attached to this difference, obviously it should not be ignored when comparisons are made. Superphosphate and limestone were not applied during the same period on the RLsP plots ; the superphosphate has been used on plots which already had received 13,000 to 16,000 pounds of limestone per acre up to 1920. These amounts of limestone represent excessive lim- ing, which, however, extended over several rotations whereas the limited superphosphate applications were made over a five-year period. In each case, superphosphate has been used since 1924 at the annual acre-rate of 200 pounds applied twice in the rotation ahead of wheat and first-year corn. The total application of superphosphate prior to the time when the stover samples were collected was 1,200 pounds per acre on each field. In spite of the similarity in soil type and in the basal treatments on Series 300 and the minor series at Aledo, the data from these two series are not to be regarded as duplications. Alfalfa was grown on the minor series from 1910 to 1915, with no residues returned until 1919. Also, the total applications of superphosphate have been two and one-half times as great on the minor series as on Series 300, whereas the amount of limestone has been only three-fourths as much. This situation is similar to that noted previously in connection with the study of the effect of rock phosphate on the composition of the stover grown on the two series. Superphosphate without limestone depressed the yields of both grain and stover at Toledo and on Series 300 at Aledo ; but when used on Grundy clay loam at Hartsburg and on the minor series at Aledo, which is also on Grundy silt loam, yields, except for the stover at Hartsburg, were increased. Increased yields were accompanied by marked increases in the phosphorus content of the stover, while the decreased yields on Series 300 at Aledo were associated with very large reductions in all nutrients except calcium. At Toledo, where the soil is very strongly acid, the use of superphosphate produced no significant changes in the composition of the stover except in regard to phos- phorus. Altho the phosphorus content of the stover was nearly doubled, 1937} COMPOSITION OF MATURE CORN STOVER 243 the yields of stover and grain declined more than one- fourth and one-third respectively. When used on heavily limed plots, superphosphate increased stover and grain yields on all plots except on Series 300 at Aledo. The com- position of the stover, except for the phosphorus or potassium in each sample, was, however, but slightly modified. The amount of phos- phorus in the stover grown on Cisne silt loam was raised from .078 percent to .142 percent. The change in phosphorus content was even greater for the stover grown on the minor series at Aledo ; in fact the percentage of phosphorus was trebled. In the other cases no significant change in the phosphorus content of the mature stover was produced by the superphosphate-limestone treatment. Rock Phosphate and Superphosphate Compared The data in Table 25, showing comparative effects of rock phos- phate and superphosphate when used with and without limestone, on the composition of mature corn stover, are for the most part a repeti- tion of those given in Tables 23 and 24. The conditions under which these comparisons were made have already been discussed and will not be repeated. At Oblong the limestone was applied in 1925, while the phosphates were used in the fall of 1926 and the spring of 1928. This comparison for the deep phase of Cisne silt loam could be objected to because of the dissimilar treatment of the soil prior to the time the phosphates were applied. On the Muscatine silt loam at Kewanee lime- stone was applied at the rate of 8,000 pounds per acre in 1915 and 1919, while the use of phosphorus carriers was not begun until 1921. On the basis of yields, rock phosphate has generally been superior to superphosphate when these materials have been used without lime- stone ; the chief exceptions were for stover on the Grundy silt loam at Aledo. The increases for rock phosphate were considerably greater on the Cisne silt loam, a very strongly acid soil low in available phos- phorus than on the Grundy clay loam, which is nonacid and high in phosphorus, both total and available. In general the phosphorus content of the stover grown on soils treated with rock phosphate was somewhat less than that of the stover grown on the plots treated with superphosphate. The differences were .029 percent at Hartsburg, .043 percent at Toledo, and .024 percent at Aledo on the minor series. The differences at Kewanee and on Series 300 at Aledo were too small to be significant. These lower amounts of phosphorus in the stover grown where rock phosphate was used do not necessarily indicate less available phosphorus, but should be 244 BULLETIN No. 437 [July, lion per acre Limestone _g ii oo 22 <*)fO fS(S TfTt o 8 1 a a 4) 1 a 8 .8888 < CSOtNO -o 8888 fMOflO 8888 (NOfSO O'J'O'* O'OO'O 11 1111 1 c **o oo rs OO-*^f csooo w fSfi OMO OOO i/5O~ u 8 O O *J"O ") *f> ro f*5 r^ t> ^ oa5 -^ r^ ^ OOf r^iot^fs O'N'*-* O~Oitif> CS f*5t5W5 U 1 o M Q POfJiOOO g; T> in t>. to O>O 0)^f if) OOO W (N1OO fO>OT^ T(mn O O-* aovo^ OOvOOO> "o c "" jmpositic cu O 10 t^ tr> ^SSS2 W i/i ir) oo oooo mo csO t~<*5 1>O p3 O>O>O -ioot^a ^nO-"O IOI^ 00") 00>O^>O ssss U ^5 mmmm 00 1** t* O^ ^Tjir-oo miomio 1T)IO vomoooo 2< E son iype Corn variety Aledo (Series 300) Grundy silt loam Will County Favorite Hartsburg Grundy clay loam Reid Yellow Dent Toledo Cisne silt loam Champion White Pearl Aledo (minor series) Grundy silt loam Will County Favorite Oblong Cisne silt loam, deep phase Mohawk Kewanee Muscatine silt loam Krug j II Cud. ^25 &&&& 0,0. ^%^J MMHff O.CU %%^i K0I33 a. a. - - ^ ^ 01 UMM p^aia:oi . O.O. 3.J 05 { 0,0, CLO.^^ H*4*"1 KMMM < 1 b -fM'^"*' O- (N'O'tIO OJS W5 gr OnoOt^ j i - N *"" - 1937} COMPOSITION OF MATURE CORN STOVER 245 attributed at least in part to the increases in yields produced by this treatment. When used with limestone, rock phosphate produced the greater yields at Aledo and Oblong, but superphosphate was first at Toledo and Kewanee. At Hartsburg the grain yield was favored by super- phosphate and the stover yield by rock phosphate. The relation of these differences in the phosphate response of corn, to the composition of the stover, particularly to the phosphorus con- tent, is important in indicating the influence of limestone on the rela- tive availability of rock phosphate and superphosphate. On the Grundy silt loam at Aledo (in both Series 300 and the minor series), the phosphorus content of the stover from the RLsP plot was higher than that from the RLrP plot. The differences of .102 and .074 percent of phosphorus in favor of the superphosphate are too great to be ac- counted for merely by the slightly smaller yields obtained with super- phosphate than with rock phosphate. A comparison of the data show- ing the composition of the stover grown on both the limed and the unlimed phosphate plots, indicates clearly that limestone increased the availability of both rock and superphosphate when used on this soil. If. however, the limed plots were compared, one might conclude erroneously that the availability of rock phosphate was suppressed by limestone. At Oblong the stover grown on the RLsP plot contained .185 per- cent of phosphorus and the stover grown on the RLrP plot .137 percent. The difference of .048 percent is relatively small in comparison with the differences in yields, which were greater by 535 pounds of stover and 13.8 bushels of grain for the RLrP treatment. In this case no comparison can be made with unlimed plots to determine whether limestone increased or suppressed the relative availability of either form of phosphate. When both yields and the composition of the stover are considered, rock phosphate appears to have been utilized better than superphosphate. The deep phase of Cisne silt loam at Oblong is a strongly acid soil and has received only 4,000 pounds of limestone per acre, so that the soil conditions there were probably more favorable for the utilization of rock phosphate. While the phosphorus content of the stover was higher for the RLrP than for the RLsP treatment on Grundy clay loam and on Cisne silt loam, the differences of .035 and .058 percent are perhaps negligible in view of the differences in yields, especially of grain. On the Grundy clay loam at Hartsburg the increase in grain obtained with superphosphate and limestone was accompanied by a marked decrease 246 BULLETIN No. 437 [July, in the phosphorus content of the stover ; however, a decrease in grain under rock phosphate used with limestone resulted in a significant increase in the phosphorus content of the stover. The situation at Toledo on Cisne silt loam was essentially the same as at Hartsburg on Grundy clay loam with respect to the effect of superphosphate used with limestone, in that with increased yields the amount of phosphorus in the stover declined. When the RLrP and RrP treatments are compared, yields for the former are seen to have been less by 180 pounds of stover, but more by 9.8 bushels of grain, while the phosphorus content of the mature stover was raised from .130 percent to .200 percent. These data certainly do not furnish any evidence that heavy liming has exerted a retarding influence on the availability of rock phosphate. Bone, Rock, Slag, and Super Phosphates Compared The effect of some less common phosphates, in comparison with rock and superphosphate, on the composition of corn stover and on yields is shown in Table 26. On the Aledo field, in the first part of this table, these phosphorus carriers are compared when used with limestone and without it, and here they may be studied under more comparable conditions than those reported in Tables 23, 24, and 25 and the second part of Table 26, since the soil, prior to the use of phosphates, was uniformly cropped and treated, and differences in the amounts of the various phosphates applied have been less pronounced. The phosphates were originally applied for wheat. In 1923 they were used for first-year corn ; and since 1927 they have been applied twice in the rotation, ahead of wheat and first-year corn. With the last change the annual acre-rates of bone phosphate were reduced from 200 to 100 pounds; superphosphate from 3331/3 to 200 pounds; and rock phos- phate from 6662/3" to 500 pounds. The rate for slag phosphate was maintained at 250 pounds. Total applications of these phosphates prior to the time stover samples were collected are shown in Table 26. The soil type on which these phosphates were compared, Grundy silt loam, is medium acid in reaction and "medium" in available phosphorus. Limestone increased yields but slightly, but both the nitrogen and phosphorus contents of the mature stover were increased significantly by it. All phosphorus carriers when used without lime- stone increased yields, with the exception that slag phosphate did not increase grain yields, and the amount of phosphorus in the stover from the phosphorus plots varied from two to nearly four times as much as that contained in the stover from the residues plot. The yields for the various phosphates were somewhat greater with lime- 1937] COMPOSITION OF MATURE CORN STOVER 247 u o C 55 n o O H i i 6 5) O o J O U o 1 "a a CO 3 losphate H & a. 55 i 00 W S V u a c 1 H b P O O TJ X .it V ,?* ^* ;> 53 Q a ^ U c ^* p O I | w u U s > 3 i/r H W 5 < 2 "o s S a! 3) a _o S s" i t S 0, _c 08 H o U X 0* ^* ~ t^^ = 5 a 2 Z O o" 1 Aledo tie uf 8 OJ w o CQ c I O 1 1 H H S 0- U u j IQ 03 $? - ! 1 1 ! ! !!1 8Q OO ^^ OO O *O O *$ ^* i/) i/l o * CS(N **1^ 0000 ^^ -< 00 OOWOO'* tt^fN -^00 **> *f ^**O O*-* 01^ \no x ~* (N CS 3 u^ w HHH^a S3 SS S3 ^ 82^22 248 BULLETIN No. 437 [July, stone than without it, with the exception that superphosphate with limestone failed to show an increase in yield of stover. Where bone and rock phosphates were used, the phosphorus con- tent of stover was no greater with limestone than without it. Super- phosphate used with limestone raised the amount of phosphorus in the stover to .170 percent as compared with .113 percent for the phosphate alone. However, the yield increases for superphosphate were slightly less than those for either bone or rock phosphate. When compared with the R and RL treatments, slag phosphate, either with or without limestone, increased stover yields but not grain yields. Both treat- ments were effective in increasing the phosphorus content of the stover. The availability of the slag phosphate, however, was no doubt increased by the limestone, since the yields as well as the phosphorus content of the stover were greater when this phosphate was used with limestone than without it. The comparisons reported in the second part of Table 26, showing the effect on the composition of mature stover and on yields of grain and stover, of different phosphates applied to the deep phase of Cisne silt loam, are presented without discussion. Differences in previous soil treatment and variations in the amounts of phosphate and lime- stone applied preclude satisfactory comparisons. Effect of Gypsum Gypsum Used With Rock Phosphate at Same Rate The effect of gypsum on the composition of mature corn stover is shown by the data in Table 27. On Grundy silt loam, grayish phase, at Carthage, gypsum has been used with rock phosphate. These materials, used in three different amounts representing 100, 200, and 400 pounds per acre per year, were plowed down with sweet clover for corn. The soil had received 8,000 pounds of limestone per acre in 1912 and had grown alfalfa from then until 1920. Stover samples used for analyses were collected from the plots receiving the lowest and the highest amounts of gypsum and rock phosphate. The results from the Carthage field would indicate that this soil responds to rock phosphate. The use of this material not only increased the yields of stover and grain, but raised the phosphorus content of the stover considerably. Sample 63 represents a phosphate application four times as great as Sample 61 ; however, the phosphorus content of Sample 63 was raised only 30 percent. This increase, moreover, was associated with decreased yields. The gypsum, when applied with rock phosphate at the same rate, 1937] COMPOSITION OF MATURE CORN STOVER 249 TABLE 27. EFFECT OF GYPSUM ON COMPOSITION OF MATURE CORN STOVER Sample No. Treatment 1 Composition of stover Yield per acre N P K Ca Stover Grain Carthage field: Grundy silt loam, grayish phase, KruR 60 RL % .58 % 053 % 43 % 30 Ibs. 1 558 bu 42 4 61 RLrP ; .69 .093 .37 30 1 902 50 4 62 RLrPG 58 069 50 29 1 865 45 6 63 RLrP .53 .120 49 31 1 720 46 64 RLrPG . 60 108 41 29 1 635 45 2 Hartsburg field: Grundy clay loam, Reid Yellow Dent 69 74 RLrPK .73 .99 .046 .111 .75 .78 .32 .35 3 220 3 546 68.8 80.0 Rl.rPKG Toledo field: Cisne silt loam. Champion White Pearl 130 136 RLrPK .62 .34 .102 .142 .83 .94 .31 .28 3 653 4 020 47.0 58.4 RLrPKG Samples 60 to 64 (Carthage field) were from plots receiving 8,000 pounds each of limestone per acre, with the following additional treatments: Sample 61, 1 ,000 pounds rock phosphate. Sample 62, 1,000 pounds each of rock phosphate and gypsum. Sample 63, 4,000 pounds rock phosphate. Sample 64, 4,000 pounds each of rock phosphate and gypsum. Samples 69 and 74 (Hartsburg field) were from plots receiving 16,000 pounds of limestone per acre, with 8,000 pounds rock phosphate, 3,600 pounds kainit, 1,400 pounds gypsum. Samples 130 and 136 (Toledo field) were from plots receiving 13,000 pounds of limestone per acre, plus the same additional treatments as Samples 69 and 74. resulted in no increase in yield, and it caused a marked reduction in the phosphorus content of the stover. The differences in grain yields, and also in the phosphorus content of the stover, between samples from the gypsum and no-gypsum plots were greater where the smaller amounts were applied. While gypsum apparently limited the intake of phosphorus, the deleterious effect exerted was more noticeable with the lighter application, where a phosphorus deficiency no doubt existed. Where rock phosphate was used without gypsum, the absorption of phosphorus was perhaps in excess of the amount needed for growth, w r ith the result that a greater accumulation of phosphorus occurred in the stover. Gypsum Used With Full Treatment After Rock Phosphate Was Discontinued On both the Hartsburg and Toledo fields, as shown in Table 27, gypsum was applied to plots treated with residues, limestone, rock phosphate, and kainit after the phosphate applications had reached 8,000 pounds per acre and were discontinued (1924). The gypsum used at the annual acre-rate of 200 pounds was applied twice per rotation before wheat and first-year corn. The total application of 250 BULLETIN No. 437 [July, gypsum on each field was at the rate of 1,400 pounds per acre. The Grundy clay loam at Hartsburg, a nonacid soil high in available phos- phorus, had received 16,000 pounds of limestone per acre, whereas the Cisne silt loam at Toledo, a very acid soil low in available phosphorus, had received only 13,000 pounds. Data in Table 21 show that the Hartsburg soil was more responsive than the Toledo soil to the phosphate treatment when both the stover and grain yields were considered. The change in the phosphorus con- tent of stover, however, was more pronounced on the Cisne silt loam than on the Grundy clay loam. The reverse was true for nitrogen, which perhaps is associated with differences in the response to lime shown by the two soils. Liming stimulated sweet-clover growth on the Cisne silt loam, and it appears to have increased very greatly the avail- ability of the phosphorus. It is likely that this action represents both a direct and an indirect effect of the limestone, especially on the applied phosphate. The addition of gypsum to the RLrPK plots after the application of rock phosphate had been discontinued increased stover and grain yields markedly. Grain yields were increased more than those of stover ; also, the increase at Toledo was greater than that at Hartsburg. Gypsum also affected the composition of the stover, the nitrogen and phosphorus contents being modified more than the amount of potassium or calcium. Both nitrogen and phosphorus in the stover were increased at Harts- burg, but only the phosphorus at Toledo, where the nitrogen content of the stover was reduced almost one-half. The increase for phos- phorus where gypsum had been used with rock phosphate was nearly four times as great for stover on the Grundy clay loam as on the Cisne silt loam. However, the actual phosphorus content of stover grown on the latter soil was 28 percent higher. As noted previously, the use of kainit appeared to reduce the phos- phorus content of the stover on both soils from .064 percent to .046 percent on Grundy clay loam and from .161 percent to .102 percent on Cisne silt loam. Yields, however, were decreased on the former soil, but increased on the latter. The use of gypsum not only increased yields, but raised the phosphorus content of the stover. The gain in phosphorus was more than enough to offset the reduction in phosphorus produced by the kainit on Grundy clay loam but not on Cisne silt loam. Effect of Standard Treatments on Late-Planted Corn Stover samples from both the Joliet and Sidell fields represent late- planted corn used in corn borer studies. The standard treatments, 1937} COMPOSITION OF MATURE CORN STOVER 251 except for residues on Saybrook silt loam at Joliet, were effective in increasing both grain and stover yields. Gains in grain yields were considerably greater than those for stover, as indicated by the data in Table 28. These increases in yields on the Joliet field were accompanied by marked reductions in the nitrogen and phosphorus contents of the stover but with no significant change in the amount of either potassium or calcium. The deleterious effect of residues on yields, also on the composition of the stover, would suggest a deficiency of both nitrogen and phosphorus. Such deficiencies, however, should no doubt be attributed to soil variation in this particular case rather than merely to treatment. On the Sidell field the standard treatments caused a substantial increase in the nitrogen and potassium contents of the stover, while all treatments except residues increased the content of phosphorus. The increases in calcium for different treatments when compared with the check varied only from .06 to .08 percent. The combined treatment of residues and limestone was the most effective in raising the nitrogen content of the stover, while the RLrP and RLrPK treatments were equally effective in increasing the amount of phosphorus. And, as TABLE 28. EFFECT OF TREATMENT IN CHANGING THE COMPOSITION OF STOVER FROM LATE- PLANTED CORN Sample No. Treatment* Composition of stover Yield per acre N P K Ca Stover Grain Joliet field: Saybrook silt loam, Western Plowman 75 0. . % 1.03 % .079 % .38 % .22 Ibs. 1 751 bu. 9.0 76 R... .86 .055 .36 .20 1 684 7.9 77 RL ... .91 .091 .32 .19 1 842 15.1 78 RLrP .78 .081 .30 .21 2 144 22.3 79 RLrPK .70 .066 .34 .23 2 379 28.1 Sidell field: Sidell silt loam. Reid Yellow Dent 121 0. . .86 .082 .31 .21 2 106 20.6 141 5-15-5 b .78 .086 .34 .29 2 662 33.1 122 R .90 .075 .40 .27 2 857 24.6 142 R and 5-15-5 b . . . .85 .078 .46 .26 3 066 33.5 123 RL .28 .101 .60 .29 3 240 32.5 143 RLand 5-15-5>> .12 .094 .75 .32 3 192 40.5 124 RLrP .12 .119 .79 .27 3 440 36.0 144 125 RLrP and 5-15-5 b RLrPK .14 .15 .135 .119 .65 .95 .33 .27 3 987 3 615 40.9 43.0 145 RLrPK and 5-15-5 b .12 .127 .79 .34 3 422 44.9 The plots on the Joliet field from which samples were taken received 16,000 pounds of limestone, 8,000 pounds of rock phosphate, 3,200 pounds of kainit per acre, where these materials were applied. The plots on the Sidell field from which samples were taken received 18,000 pounds of limestone, 8,000 pounds of rock phosphate, and 3.600 pounds of kainit, where these materials were applied. b For the 1928 corn crop 200 pounds per acre of 5-15-5 fertilizer was hill-dropped on the plots from which these samples were taken. 252 BULLETIN No. 437 [July, might be expected, the highest percentage of potassium in the stover was obtained where kainit was part of the treatment. Unlike the results obtained on Saybrook silt loam at Joliet, those on Sidell silt loam at Sidell show that full treatment of residues, limestone, rock phosphate, and kainit not only increased yields of both stover and grain, but raised the nitrogen, phosphorus, potassium, and calcium contents of the stover appreciably. On half of the check plot and on the standard treated plots at Sidell, a 5-15-5 fertilizer, hill-dropped at the rate of 200 pounds per acre, was used for the 1928 corn crop. The use of this fertilizer pro- duced marked increases in yield on nearly all plots; the chief exception was on the RLrPK plot. These increases in yield, however, were made at the expense of the nitrogen content of the stover on all plots except the one treated with RLrP, where the difference is probably not significant. The only significant change in the phosphorus content of the stover, that was due to the complete fertilizer, was where com- plete fertilizer was used as a supplement to the RLrP treatment. Even tho yields were increased by 4.9 bushels of grain and 547 pounds of stover per acre, the phosphorus content of the stover was raised from .119 percent to .135 percent. Where the additional fertilization was made on the RLrP and RLrPK plots, the potassium content of the stover was significantly decreased, but when used on the check and the RLrP and RLrPK plots, the calcium content was significantly raised. Only on the RL plot did the 5-15-5 fertilizer produce a signifi- cant increase in the amount of potassium in the stover. SUMMARY AND CONCLUSIONS Mature corn stover from 15 varieties of corn grown on 15 soil types under 21 soil treatments was collected from 16 Illinois experi- ment fields in 1928 and used for the studies herein reported. The varieties ranged from early maturing to late maturing and the soils from very low to high in productivity. The soil treatments varied from nothing to full treatment with residues, limestone, rock phosphate, and kainit, supplemented with a complete fertilizer. Each sample, consisting of 10 stalks with their leaves and husks, was obtained from an area where both the soil type and the stand of corn were uniform. The sample was later separated for analysis into two portions, "stalks" and "leaves," the former including the stalks and leaf sheaths, and the latter the leaf blades and husks. The composition of each of the stover samples reported here is based on the 1937} COMPOSITION OF MATURE CORN STOVER 253 separate analyses of stalks and leaves and the proportion that each part was of the whole sample. Four elements nitrogen, phosphorus, potassium, and calcium were given primary consideration in this study of the composition of stover. Altho organic carbon and total ash were also determined, no analytical results for either are reported except in Table 33 in the Appendix. Except in the determinations for potassium and organic carbon, the analytical methods used were those of the Association of Official Agricultural Chemists. Varietal Differences. Studies to determine the relationship of variety of corn to the composition of mature corn stover were con- cerned first with different varieties grown under similar conditions, and second with the same varieties grown on different fields in order to determine the influence of environment in changing the composition of stover. Where varieties are grown under similar conditions, variations in the composition of stover and in yields must be accounted for primarily by varietal differences. The nature and extent of the modifications in composition and yield with changes in environment appear to vary greatly with the variety, tho the response of different varieties requiring the same length of season in which to mature may be decidedly different. Besides differing in yield, varieties may differ markedly in compo- sition of mature stover owing to differences in their feeding power, or in their ability to translocate nutrients to grain, or both. Certain varieties appear to have greater power to assimilate nutrients than others, tho there seems to be no completely consistent relationship between this power and the length of season required for maturity. In these tests, with a few exceptions, the amount of nitrogen in mature corn stover of different varieties exceeded the amount of potassium, which was followed in descending order by calcium and phosphorus. The marked differences in the percentages of nitrogen, phosphorus, and potassium were in contrast with the rather uniform calcium content of stover. The composition of stover was affected greatly by yields ; but there appeared to be little or no relation between the composition of the stover from the different varieties and the relative length of season required to mature them. The total amount per acre of the various nutrients contained in the stover was more definitely reflected by the stover and grain yields than by merely the composition of the stover. The nitrogen content of leaves was usually greater than that of 254 BULLETIN No. 437 [July, stalks. The stalks, however, generally contained more phosphorus, except where grain yields were low, in which case the leaves were less depleted of their phosphorus. In the stover of all the varieties grown at Alhambra and at Toledo the amount of calcium was higher in the leaves than in the stalks, while the reverse was always true for potassium. But on the younger and more fertile soils at Urbana and at DeKalb, to which no limestone has been applied, the calcium content was considerably greater for stalks than for leaves, and in most cases the amount of potassium in the leaves exceeded that in the stalks. Influence of Soil Type. Soil type, in the two comparisons that were possible, had practically no direct effect on the composition of mature corn stover altho it exerted a marked influence on yields. Except for calcium, the differences in the composition of stover of the same variety grown on two different soil types at DeKalb were not significant, but at Sidell all differences except that for calcium were significant. On each field the yields of stover and grain were greater on the more- fertile and less-acid soil, which is higher in available phosphorus. The wide variations in climate in different parts of Illinois have made it very difficult to study the effect of soil types, thruout the area of their occurrence, on the composition of corn stover. Widely differ- ent soil types ordinarily do not occur on the same experiment field therefore seldom under the same seasonal conditions of rainfall, tem- perature, and other climatic factors. Because of these and other limi- tations, comparisons that will show the effect of soil type on the composition of stover' are indeed rare. Influence of Soil Treatment. The stover samples used to study the effect of soil treatment on the composition of stover were taken from plots on which the basal treatment was crop residues and green manures rather than animal manures. The effects of different phosphorus carriers, of gypsum, and of a 5-15-5 fertilizer used in addition to the standard treatments all in the grain system of farming on the Illinois experiment fields were studied. On all fields except Joliet residues increased the yields of grain and stover. These greater yields on the residues plots were usually accom- panied by definite reductions in the phosphorus content of the stover. This was generally true also for nitrogen, except on fields where the soil will grow sweet clover on the unlimed residues plot, in which case the nitrogen content was raised significantly. With potassium and calcium, definite changes in composition of the stover were shown in two-thirds of the comparisons between residues and check samples. 1937] COMPOSITION OF MATURE CORN STOVER 255 The general tendency of limestone was to raise the nitrogen, phos- phorus, potassium, and calcium contents of the stover and to increase the stover and grain yields. The chief exceptions were in the stover yields on soils naturally well supplied with carbonates, where the addition of limestone might be expected to have little or no effect. Rock phosphate, when used in addition to residues and limestone, increased yields only slightly. The percentages of nitrogen and phos- phorus in the stover were, however, raised considerably, but there were relatively few pronounced differences in the contents of potassium and calcium. The changes in the composition of stover that were due appar- ently to the rock-phosphate treatment appeared to bear no definite relationship to yields. Potash, chiefly as kainit, increased yields on all fields except those with heavy, dark-colored soils at Hartsburg and Minonk, and raised the potassium content of stover in all cases, the increase varying from 13 to 160 percent. The percentages of both nitrogen and phosphorus in the stover were reduced by the potash treatment, while the calcium content was either decreased or unchanged. With a few minor exceptions, all soil treatments RL, RLrP, and RLrPK increased both stover and grain yields above those obtained with no treatment. The most pronounced changes in the composition of the stover, that were due to the combined treatments, were in the nitrogen content, followed in turn by potassium, phosphorus, and calcium. Of 35 comparisons for each nutrient, significant differences in the nitrogen, potassium, phosphorus, and calcium contents of stover were shown in 34, 27, 23, and 19 comparisons respectively. These differences represent increased amounts in approximately two-thirds of the nitrogen comparisons, three-fourths of the phosphorus, three- fifths of the potassium, and only one-fourth of the calcium comparisons. The form of phosphorus used on the treated plots had a marked effect on the phosphorus content of the stover. On soils treated with rock phosphate the phosphorus content of the stover was usually much less than it was where superphosphate was used. In increasing yields, however, rock phosphate was generally the more effective. The use of limestone was no doubt less favorable for the utilization of rock phos- phate than of superphosphate. Heavy liming, however, appeared in most cases to exert little or no retarding influence on the availability of the rock phosphate, even on Grundy clay loam, a soil naturally well supplied with lime. The possibility of such action appears to bear a definite relation not only to the character of the soil but also to the proportions of rock phosphate and limestone applied. 256 BULLETIN No. 437 [July, Where four different phosphates were used on Grundy silt loam at Aledo, yields were increased by all forms except slag, whether the phos- phates were used with limestone or without it. The phosphorus content of the stover from these plots was from two to four times as great as that of the stover grown without phosphate. When the super and slag phosphates were used with limestone, the percentage of phosphorus in the stover was much greater than when these phosphates were used without limestone ; with the bone and rock phosphates, the differences were not significant. Gypsum, when used with residues, limestone, and rock phosphate, and applied at the same rate as the phosphate, caused no increase in yield but did cause a marked reduction in the phosphorus content of the stover. The deleterious effect of gypsum was more pronounced with light applications of gypsum and rock phosphate than with heavy applications. Where the lighter applications 'were made, a phosphorus deficiency appeared to exist. The addition of gypsum to the RLrPK plots after the application of rock phosphate had reached 8,000 pounds and been discontinued, increased the phosphorus content of the stover, also yields, especially of grain, on both the Grundy clay loam at Hartsburg and the Cisne silt. loam at Toledo. Altho the amounts of potassium and calcium in the stover were modified only slightly by the gypsum treatment, the nitrogen content was raised one-third in the stover at Hartsburg and reduced one-half in that at Toledo. The use of a 5-15-5 fertiliser as a supplement to the standard treatments usually increased yields but resulted in marked reductions in the nitrogen content of the stover. The only significant change in the percentage of phosphorus in the stover, that was due to the complete fertilizer, was where it was applied on the RLrP plot. The calcium content of stover was generally higher where the soil had received the additional fertilization than where it had not, but the additional treatment was effective in raising the amount of potassium only when it was used to supplement the RL treatments. 1937] COMPOSITION OF MATURE CORN STOVER 257 LITERATURE CITED 1. ALBERTS, H. W. Relation of time of planting corn to the time of silking, denting, and senescence. Jour. Amer. Soc. Agron. 18, 375-380. 1926. 2. BAUER, F. C, SMITH, R. S., and SMITH, L. H. The Illinois soil experiment fields. 111. Agr. Exp. Sta. Bui. 273. 1926. 3. - - Response of soils to systems of soil treatment. 111. Agr. Exp. 4. BRAY, R. H. A field test for available phosphorus in soils. 111. Agr. Exp. Sta. Bui. 337. 1929. 5. DULEY, F. L., and MILLER, M. F. The effect of a varying supply of nutrients upon the character and composition of the maize plant at different periods of growth. Missouri Agr. Exp. Sta. Res. Bui. 42. 1921. 6. - - The effect of a varying moisture supply upon the development and composition of the maize plant at different periods of growth. Missouri Agr. Exp. Sta. Res. Bui. 76. 1925. 7. FORBES, E. B., BEEGLE, F. M., and MENSCHING, J. E. Mineral and organic analyses of foods. Ohio Agr. Exp. Sta. Bui. 255. 1913. 8. FREAR, WM. The composition of corn receiving different fertilizers. Pa. State Col. Rpt. 1887; Part II, Agr. Exp. Sta., pp. 42-50. 1888. 9. HIBBARD, P. L., and STOUT, P. R. Estimation of potassium by titration of the cobaltinitrite with potassium permanganate. Jour. Assoc. Off. Agr. Chem. 16, 137-140. 1933. 10. HILLS, J. L., WHITE, B. O., and JONES, C. H. Effect of fertilization upon the composition of crops. Vt. Agr. Exp. Sta. Ann. Rpt. 11, pp. 146-150. 1898. 11. HORNBERGER, R. Chemische Untersuchugen Uber das Wachsthum der Mais- pflanze. Landwirthschaftliche Jahrbikher Bd. 11, 359-523. 1882. (Cited from Missouri Agr. Exp. Sta. Res. Bui. 42, p. 4. 1921.) 12. JONES, W. J. JR., and HUSTON, H. A. Composition of maize at various stages of its growth. Purdue Univ. Agr. Exp. Sta. Bui. 175. 1914. 13. KEITH, HELEN M. A bibliography of researches bearing on the composition and nutritive value of corn and corn products. 111. Agr. Exp. Sta. Bui. 257. 1925. 14. LADD, E. F. Analysis of individual stalks of corn. N. Dak. Agr. Exp. Sta. Ann. Rpt. 14, pp. 39-40. 1904. 15. LATSHAW, W. L., and MILLER, E. C. Elemental composition of the corn plant. Jour. Agr. Res. 27, 845-860. 1924. 16. SCHWEITZER, P. Study of the life history of corn at its different periods of growth. Missouri Agr. Exp. Sta. Bui. 9. 1889. 17. SCOVELL, M. A., and PETER, A. M. Experiments with corn. Ky. Agr. Exp. Sta. Bui. 26. 1890. 18. SNYDER, HARRY. Forage crops of high, medium, and low protein content. Minn. Agr. Exp. Sta. Bui. 101. 1907. 19. STUDENT. The probable error of a mean. Biometrika 6, 1-25. 1908. 20. VOORHEES, J. F. A further study of effective rainfall. U. S. Mo. Weather Rev. 54, 332-336. 1926. 21. WINTERS, ERIC JR., and SMITH, R. S. Determination of total carbon in soils. Jour. Indus. Engin. Chem. (Anal. ed. 1, 202). 1929. 22. - and WIMER, D. C. A total carbon procedure. Jour. Amer. Soc. Agron. 23, 280-285. 1931. 23. WOODS, C. D. Effect of different fertilizers upon the composition of corn. Conn. (Storrs) Agr. Exp. Sta. Ann. Rpt. 2, pp. 127-178. 1890. 24. and GIBSON, H. B. Proximate composition of corn and stover of New England grown maize. Conn. (Storrs) Agr. Exp. Sta. Ann. Rpt. 3, pp. 112-119. 1891. 258 BULLETIN No. 437: APPENDIX [July, APPENDIX In the following tables will be found a complete summary of the data on all samples with reference to: Field and plot sources. Variety of corn, soil type, and treatment represented. Stover and grain yields. Ratios of stalks to leaves, and stover to grain. Percentage composition of stover and its separated parts. The amounts of nitrogen, phosphorus, potassium, and calcium contained per acre in the stover and in its separated parts. 1937] COMPOSITION OF MATURE CORN STOVER 259 TABLE 29. SOURCES OF STOVER SAMPLES AND YIELDS OF STOVER AND GRAIN; ALSO RATIO OF STALKS TO LEAVES AND STOVER TO GRAIN: 16 ILLINOIS EXPERIMENT FIELDS, 15 SOIL TYPES, 15 CORN VARIETIES, 21 SOIL TREATMENTS (Each sample consisted of 10 stalks with leaves and husks) Sample No. Variety Plot Treatment Ratio of stalks to leaves (1) Yield per acre Stover Grain Ratio of stover to grain ( 1) Urbana, S. Farm, Carrington tilt loam 1 Champion White Pearl... 165-6W RrP 2 Sommer Yellow Dent.... 165-6W RrP 3 Reid Yellow Dent 165-6W RrP 4 Funk 90 Day 165-6W RrP 5 Funkl76A 165-6W RrP 6 Krug 165-6W RrP 7 Rustler 165-6W RrP 8 Minnesota 13 165-6W RrP 9 Golden Glow 165-6W RrP I'rbana, S. Farm, Sidell tilt loam 10 Reid Yellow Dent 165-6E* RLrP 1 1 Reid Yellow Dent 1 62-3E* RLrP 12 Reid Yellow Dent 167-8E* RLrP I'rbana, Davenport plott, Carrington tilt loam, deep phase 13 Reid Yellow Dent 501 W 14 Reid Yellow Dent 502 W R 15 Reid Yellow Dent 504W RL 16 Reid Yellow Dent 506W RLrP 17 Reid Yellow Dent 508W RLrPK Mhambra, Putnam tilt loam 18 Krug 232S RLrP 19 Sommer Yellow Dent.... 233N RLrP 20 Reid Yellow Dent 234N RLrP 21 Funkl76A 234S RLrP 22 Black Hawk 237N RLrP 23 Mohawk 237S RLrP 24 Champion White Pearl... 231S RLrP 25 Champion White Pearl... 229N R 26 Champion White Pearl... 230N RrP DeKalb, Saybrook tilt loam 27 Reid Yellow Dent 304-5-6S RrP 28 Sommer Yellow Dent.... 304-5-6S RrP 29 Western Plowman 304-5-6S RrP 30 Funk 90 Day 304-5-6S RrP 31 Krug 304-5-6S RrP 32 Golden Glow 304-5-6S RrP DeKalb, Saybrook tilt loam, deep phase 33 Minnesota 13 324^-68 RrP 34 Western Plowman 324-5-6S RrP 35 Rustler 324-5-6S RrP Alfdo, Grand]/ tilt loam 36 Will County Favorite. 305W 37 Will County Favorite. 306W R 38 Will County Favorite. 307W RL 39 Will County Favorite. 308W RLrP 40 Will County Favorite. 309W RLrPK 41 Will County Favorite. 305E RsP 42 Will County Favorite. 306E RrP 43 Will County Favorite. 307E RLsP 44 Will County Favorite. 308E RLrP 45 Will County Favorite. 309E RLrPK 46 Will County Favorite. 501 R 47 Will County Favorite. 502 RbP 48 Will County Favorite. 503 RLbP 49 Will County Favorite. 504 RL 50 Will County Favorite. 602 RsP 51 Will County Favorite. 603 RLsP 52 Will County Favorite. 702 RrP 53 Will County Favorite. 703 RLrP 54 Will County Favorite. 802 R slag P 55 Will County Favorite. 803 RL slag P 3.01 2.89 2.72 2.88 3.08 3.27 2.56 2.10 2.65 2.94 3.72 2.11 2.01 2.51 2.13 2.17 2.50 2.38 2.77 2.45 2.94 2.66 2.89 2.22 2.06 2.19 3.48 3.26 3.12 4.15 4.00 2.83 2.75 3.12 3.22 1.64 2.48 3.90 3.06 3.20 2.64 2.51 3.08 3.05 3.29 2.68 3.44 3.59 2.76 2.88 3.13 2.75 3.27 3.18 2.79 Ibt. 3 143 3 044 3 006 2 147 2 872 2 611 1 018 1 432 1 705 3 193 3 103 3 263 2 725 2 994 3 821 4 204 4 248 2 919 3 043 3 170 3 082 3 133 3 581 4 227 3 306 3 976 2 295 1 995 1 690 2 069 2 381 2 618 1 762 2 755 1 900 2 199 2 492 2 313 2 092 2 200 2 030 1 935 2 335 2 575 2 852 1 909 2 059 2 319 2 066 2 361 2 233 2 105 2 212 2 260 2 502 fru. 42.0 54.8 56.6 71.6 56.9 75.1 39.3 55.6 38.9 62.5 91.5 38.4 49.6 50.8 60.0 73.6 81.2 43.3 50.6 54.9 41.9 49.5 48.8 62.0 48.7 67.5 26.4 26.1 28.9 40.4 29.2 32.1 69.1 54.9 46.3 54.4 68.6 74.6 73.4 77.6 64.4 70.6 72.8 77.2 80.2 69.8 71.7 78.3 72.0 73.2 74.9 74.3 76.5 69.3 71.0 1.50 1.11 1.06 .60 1.01 .70 .52 .52 .87 1.02 .68 1.70 1.10 1.18 1.27 1.14 1.07 1.35 1.20 1.15 1.47 1.26 1.47 1.36 1.35 1.18 1.74 1.53 1.17 1.02 1 63 1.63 .51 1.00 .81 .73 .62 .57 .57 .63 .55 .64 .67 .71 .55 .57 .59 .57 .64 .60 .57 .58 .65 .70 *These three samples were from plantings of different dates: Sample 10, May 21; Sample 11, May 1; Sample 12, June 13. 260 BULLETIN No. 437: APPENDIX TABLE 29. Continued [July, Sample No. Ratio of yield per acre R* 1 ' of Variety Plot Treatment stalks to 5- _ r- stover to leaves (1) btover Graln grain (1) Carthage, Grundy silt loam, grayish phase 56 Krug 205 57 Krug 206 R 58 Krug 207 RL 59 Krug 208N RLrP 60 Krug 701E RL 61 Krug 702E RLrP 62 Krug..... 703E RLrPG 63 Krug 706E RLrP 64 Krug 707E RLrPG Hartsburg, Grundy clay loam 65 Reid Yellow Dent 305W 66 Reid Yellow Dent 306 W R 67 Reid Yellow Dent 307 W RL 68 Reid Yellow Dent 308 W RLrP 69 Reid Yellow Dent 309 W RLrPK 70 Reid Yellow Dent 305E RsP 71 Reid Yellow Dent 306E RrP 72 Reid Yellow Dent 307E RLsP 73 Reid Yellow Dent 308E RLrP 74 Reid Yellow Dent 309E RLrPKG Joliet, Elliott silt loam 75 Western Plowman 305 W 76 Western Plowman 306 W R 77 Western Plowman 307 W RL 78 Western Plowman 308 W RLrP 79 Western Plowman 309W RLrPK Kewanee, Muscatine silt loam 80 Krug 205W 81 Krug 206W R 82 Krug 207W RL 83 Krug 208W RLrP 84 Krug 209W RLrPK 85 Krug 601W RrP 86 Krug 602W RsP 87 Krug 603W RLrP 88 Krug 604W RLsP LaMoille, Muscatine silt loam 89 Will County Favorite.... 305N 90 Will County Favorite.... 306N R 91 Will County Favorite. ... 307N RL 92 Will County Favorite.... 308N RLrP 93 Will County Favorite.... 309N RLrPK Minonk, Drummer clay loam 94 Will County Favorite .... 305 95 Will County Favorite .... 306 96 Will County Favorite .... 307 97 Will County Favorite .... 308 98 Will County Favorite .... 309 Ml. Morris, Muscatine silt loam 99 Will County Favorite.... 205E 100 Will County Favorite 206 101 Will County Favorite .... 207 102 Will County Favorite .... 208 103 Will County Favorite .... 209 Oblong, Cisne silt loam, deep phase 104 Mohawk 205S 105 Mohawk 206S 106 Mohawk 207S 107 Mohawk 208S 108 Mohawk 209S 109 Mohawk 201N 110 Mohawk 205N 111 Mohawk 206N 112 Mohawk 207N 113 Mohawk 208N 114 Mohawk .. . 209N R RL RLrP RLrPK R RL RLrP RLrPK R RL RLrP RLrPK RLsP RLuP RLrP RLhP RLrP RLrPK 2.05 2.40 2.97 3.01 2.56 2.47 2.25 3.01 2.73 2.37 3.50 3.59 3.41 4.00 3.41 2.88 3.97 3.24 3.18 3.72 4.68 4.62 3.18 3.78 1.52 2.88 2.53 2.55 2.62 3.13 2.27 2.15 2.16 2.32 2.72 2.62 2.94 2.92 2.60 3.06 2.97 2.79 4.05 1.94 3.06 2.89 2.73 2.65 1.26 2.21 2.00 2.06 2.36 2.14 2.02 2.34 1.98 2.04 2 79 Ibs. 1 706 1 734 1 956 2 184 1 558 1 902 1 865 1 720 1 635 1 958 3 144 2 590 3 344 3 220 3 150 3 269 2 770 3 660 3 546 1 751 1 684 1 842 2 144 2 379 2 192 2 459 2 552 3 122 2 921 3 025 2 907 3 542 3 447 2 127 2 639 3 057 3 002 2 909 1 517 2 545 2 343 2 311 2 222 1 882 2 221 2 842 2 768 2 893 1 188 1 621 2 464 2 963 3 505 1 879 2 073 2 414 2 759 2 888 3 549 bu. 37.8 54.8 60.8 61.7 42.4 50.4 45.6 46.0 45.2 43.0 78.0 79.4 82.0 68.8 82.0 85.0 88.4 83.4 80.0 9.0 7.9 15.1 22.3 28.1 74.0 74.6 83.6 86.2 90.4 88.0 85.5 96.1 104.1 56.0 60.8 67.3 69.1 47.3 68.6 70.6 72.0 66.7 35.7 46.4 64.7 70.0 71.1 22.8 23.6 36.2 40.6 66.4 22.0 21.0 35.8 40.8 38.4 60 4 .90 .03 .04 .71 .73 .75 .82 .75 .72 3.89 4.26 2.44 1.92 1.69 .59 .66 .61 .49 .65 .74 .66 .76 .87 .91 .87 .83 .64 .74 .67 1.05 .79 .81 .04 .37 .36 .46 .05 .71 .97 .35 .35 .50 1.17 1937] COMPOSITION OF MATURE CORN STOVER TABLE 29. Concluded 261 Sample Variety Plot Ratio of Yield per acre Ratio of leaves (1) Stover Grain stover to grain (1) Palestine, Onarga sandy loam Ibt. 6u. 115 Mohawk 305 LeL 1.46 2 798 26.4 2.12 116 Mohawk 306 LeL, KC1 1.79 2 764 26.8 2.06 117 Mohawk 307 LeLsP, KC1 1.66 3 147 25.8 2 44 118 Mohawk 308 LeLrP, KC1 1.91 2 602 27.2 1.91 119 Mohawk 309 LeLrP, Kainit 1.58 3 184 26.4 2.41 Sidill, Drummer day loam 120 Reid Yellow Dent 101N 3.57 3 620 40.8 1.77 Sidill, Sidell silt loam 121 Reid Yellow Dent 105N 2.92 2 106 20.6 2.04 122 Reid Yellow Dent 106N R 3.03 2 857 24.6 2.32 123 Reid Yellow Dent 107N RL 4.43 3 240 32.5 1.99 124 Reid Yellow Dent 108N RLrP 3.12 3 440 36.0 1.91 125 Reid Yellow Dent 109N RLrPK 3.08 3 615 43.0 1.68 Toledo, Cisne silt loam 1 26 Champion White Pearl . . 205S 1.91 2 231 21.0 2.12 127 Champion White Pearl.., 206S R 2.89 2 510 26.0 1.93 1 28 Champion White Pearl . . 207S RL 1.92 2 468 30.6 1.61 129 Champion White Pearl . . 208S RLrP 1.84 2 715 31.6 1.72 130 Champion White Pearl . . 209S RLrPK 2.55 3 653 47.0 1.55 131 Champion White Pearl . . 201 N RL 2.46 2 602 37.4 1.39 132 Champion WTiite Pearl . . 205N RsP 2.64 1 813 16.2 2.24 133 Champion White Pearl.. 206N RrP 2.57 2 357 24.0 1.96 134 Champion White Pearl . . 207N RLsP 2.12 3 113 37.8 1.65 135 Champion White Pearl . . , 208N RLrP 2.12 2 177 33.8 1.29 136 Champion White Pearl . . , 209N RLrPKG 2.76 4 020 58.4 1.38 137 Champion White Pearl.. 801S RLrP 2.70 2 140 18.1 2.36 138 Calico 801 N RLrP 2.32 2 463 27.0 1.82 139 Mohawk 802N RLrP 2.05 1 727 25.0 1.38 140 Stanley White 803N RLrP 2.27 2 354 21.7 2.17 SidtU, SidtU tilt loam 141 Reid Yellow Dent , 105N | Fertilized 3.88 2 662 33.1 1.61 142 Reid Yellow Dent , , 106N R with 5-15-5 2.79 3 066 33.5 1.83 143 Reid Yellow Dent 107N RL > hill-dropped 3.33 3 192 40.5 1.57 144 Reid Yellow Dent , 108N RLrP 200 Ibs. 2.80 3 987 40.9 1.95 145 Reid Yellow Dent , 109N RLrPKJ per acre 3.16 3 422 44.9 1.52 262 BULLETIN No. 437: APPENDIX {.July, TABLE 30. TOTAL APPLICATION OF FERTILIZING MATERIALS ON PLOTS FROM WHICH STOVER SAMPLES WERE TAKEN (Pounds per acre) Sample No. Limestone* Phosphate b Kainit Gypsum Sample No. Limestone* Phosphate h Kainit Gypsum 1-9 10-12 15 16 17 18-24 26 27-35 38 39 40 41 42 43 44 45 47 48 49 50 51 52 53 54 55 58 59 60 61 62 63 64 67 68 69 70 71 72 73 74 77 78 79 82 83 Ibt. 1 000 6 000 16 600x 16 600x 16 600x 16 000 Ibt. Ibt. Ibt. 14000 14 000 84 85 86 87 88 91 92 93 96 97 98 101 102 103 106 107 108 109 110 111 112 U3 114 115 116 117 118 119 123 124 125 128 129 130 131 132 133 134 135 136 137-140 141-1 142^ 143-1 144-1 145< lb,. 12 000 ft, 8 000 3 600 1 400s 3 600 1 400s Ibt. 3 200 Ibi. 16 000 16 000 15 000 15 000 15 000 16 000 16 000 16 000 14 000 14 000 14 000 15 000 15 000 15 000 4 000 4 000 4 000 15 000 15 000 15 000 8 000 8 000 8 000 8 000 8 000 18 000 18 000 18 000 13 000 13 000 13 000 4 000 13 000 13 000 13 000 18 000 13 200 13 200 3 000(KiSOO 6 000 6000 12000 s'666 8 000 3 600 1 200s 3 000 1 200s 11 000 11 000 3 600 2 400b 2 400b 3' 0668 3 066s 8 344 8 344 3 250sl 3 250sl 8 666 '.'.'.'.'. '.'.'.'.'. i 606 1 000 1 000 4 000 4 000 4 000 s'666 8 000 3 600 1 200s 3 000 1 200s 11 000 8 000 3 600 1 400 tin 8 000 3 200 s'666 '.'.'.'.'. '.'.'.'.'. 8 000 8 000 3 400 8 000 8 000 s'eoo 16 000 16 000 16 000 8 000 8 000 4'4'66 ie 666 16 000 16 000 8000 8 000 800s 800u 1 600 800b 8 000 8 000 4'666 4' ooo 12 000 12 000 12 000 i2 666 12 000 15 000 15 000 8 000 8 000 8 000 8 000 8 000 16 000 16 000 16 000 ie 666 16 000 16 000 16 000 16 000 16 000 12 000 12 000 "360s 3 900 3 900 250 (KCI) 250 (KC1) 250 (KCI) 2 700 8 000 8 000 3' 600 8 000 8 000 s'eoo 1 200s 3 000 1 200s 11 000 8 000 4 000 3 600 1 400 is 606 18 000 18 000 8 000 8 000 3 600 x also 651 pounds of slaked lime. ''Rock phosphate was used except where otherwise noted: s = super, b = bone, si = slag, u = underacidulated. i )in;ih:i salt (KiCOj) was substituted for kainit during the World War period. d ln 1928, 200 pounds of 5-15-5 fertilizer was applied for corn. 193T\ COMPOSITION OF MATURE CORN STOVER 263 TABLE 31. PERCENTAGES OF NITROGEN, PHOSPHORUS, POTASSIUM, AND CALCIUM IN SAMPLES OF MATURE CORN STOVER AND ITS SEPARATED PARTS Sample No. Nitrogen Phosphorus Potassium Calcium Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover 1 1.30 1.10 1.25 .225 .199 .219 .40 .44 .41 .32 .32 .32 2 .92 1.19 .99 .165 .170 .166 .31 .42 .34 .34 .28 .32 3 .84 .95 .87 .131 .116 .127 .42 .37 .41 .36 .28 .34 4 .69 .82 .72 .093 .085 .091 .53 .41 .50 .29 .26 .28 5 .99 1.05 1.00 .172 .137 .163 .65 .54 .62 .32 .25 .30 6 .73 .98 .79 .119 .126 .121 .40 .43 .41 .33 .26 .31 7 .99 1.16 1.04 .142 .138 .141 .33 .40 .35 .31 .33 .32 8 .86 .90 .87 .119 .103 .114 .42 .53 .46 .31 .32 .31 9 .89 .90 .89 .138 .123 .134 .49 .44 .48 .32 .28 .31 10 .82 .90 .84 .130 .117 .127 .60 .53 .58 .36 .27 .34 11 .87 .68 .83 .192 .096 .172 .68 .41 .62 .40 .29 .38 12 .95 .103 .98 .139 .133 .137 .48 .52 .49 .40 .28 .36 13 .46 1.27 .73 .059 .091 .070 .64 .30 .53 .35 .69 .46 14 .63 1.13 .77 .072 .080 .074 .63 .39 .56 .36 .37 .36 15 .87 1.25 .99 .054 .082 .063 .99 .44 .81 .42 .45 .43 16 .96 1.44 1.11 .125 .143 .131 1.05 .50 .88 .48 .62 .52 17 1.04 1.65 1.21 .123 .137 .127 1.33 .58 1.12 .42 .46 .43 18 1.01 .92 .98 .207 .146 .189 .69 .51 .64 .34 .38 .35 19 1.00 1.43 1.11 .177 .155 .171 .59 .42 .54 .37 .39 .38 20 .57 1.59 .87 .111 .116 .112 .67 .46 .61 .33 .43 .36 21 .74 .83 .76 .191 .134 .177 .90 .52 .80 .38 .40 .39 22 .79 .90 .82 .271 .197 .251 .62 .37 .55 .29 .51 .35 23 1 06 1.27 1.11 .225 .204 .220 .68 .51 .64 .37 .56 .42 24 .97 1.10 1.01 .139 .150 .142 .59 .41 .53 .32 .50 .38 25 .57 1.00 .71 .114 .131 .120 .57 .48 .54 .27 .34 .29 26 .75 .90 .80 .215 .192 .208 .59 .33 .51 .28 .39 .31 27 .94 1.11 .98 .126 .135 .128 .30 .38 .32 .39 .31 .37 28 .79 1.02 .84 .121 .108 .118 .27 .34 .29 .29 .26 .28 29 .77 1.04 .84 .096 .127 .104 .38 .45 .40 .31 .31 .31 30 .86 1.23 .93 .119 .165 .128 .26 .43 .29 .29 .22 .28 31 .78 .97 .82 .102 .125 .107 .31 .33 .31 .31 .25 .30 32 .80 .98 .85 .108 .133 .115 .36 .47 .39 .33 .18 .29 33 .65 .88 .71 .060 .094 .069 .49 .48 .49 .32 .29 .31 34 .80 .89 .82 .116 .118 .116 .40 .36 .39 .25 .17 .23 35 .63 .80 .67 .076 .078 .076 1.17 .53 1.02 .29 .23 .28 36 .56 1.14 .78 .051 .117 .076 .58 .59 .58 .34 .55 .42 37 .59 .83 .66 .174 .150 .167 1.41 .46 1.14 .29 .27 .28 38 .52 .58 .53 .212 .136 .196 1.15 .45 1.01 .28 .27 .28 39 .57 .59 .57 .114 .091 .108 .78 .32 .67 .28 .29 .28 40 .53 .63 .55 .117 .108 .115 .92 .42 .80 .29 .27 .29 41 .47 .59 .50 .068 .098 .076 .48 .29 .43 .40 .27 .36 42 .54 .68 .58 .064 .101 .075 .57 .42 .53 .41 .25 .36 43 .49 .65 .53 .230 .136 .207 .87 .40 .75 .34 .26 .32 44 .51 .54 .52 .106 .103 .105 .40 .30 .38 .33 .25 .31 45 .51 .58 .53 .147 .121 .141 .73 .42 .66 .31 .27 .30 46 .48 .59 .51 .029 .062 .038 .64 .32 .55 .30 .24 .28 47 .47 .56 .49 .141 .101 .132 .70 .37 .63 .34 .29 .33 48 .52 .50 .52 .140 .092 .130 .52 .32 .48 .35 .29 .34 49 .72 .54 .67 .055 .052 .054 .68 .27 .57 .30 .23 .28 50 .50 .61 .53 .119 .096 .113 .75 .34 .64 .26 .31 .27 51 .57 .60 .58 .189 .110 .170 .68 .31 .59 .31 .29 .31 52 .49 .64 .53 .091 .082 .089 .61 .40 .55 .28 .27 .28 53 .52 .74 .57 .093 .106 .096 .57 .37 .52 .30 .31 .30 54 .50 .61 .53 .150 .107 .140 .56 .27 .49 .35 30 .34 55 .50 .52 .51 .225 .125 .199 .49 .29 .44 .34 .20 .33 56 .62 1.05 .76 .062 .108 .077 .40 .36 .39 .28 .46 .34 57 .71 .96 .78 .056 .088 .065 .42 .32 .39 .26 .29 .27 58 .69 .91 .75 .056 .083 .063 .40 .34 .38 .29 .37 .31 59 .72 .66 .71 .052 .100 .064 .33 .34 .33 .24 .32 .26 60 .48 .82 .58 .045 .075 .053 .44 .40 .43 .29 .33 .30 61 .64 .80 .69 .092 .095 .093 .36 .39 .37 .29 .33 .30 62 .49 .78 .58 .059 .092 .069 .54 .41 .50 .28 .32 .29 63 .48 .70 .53 .124 .109 .120 .56 .28 .49 .29 .37 .31 64 .52 .81 .60 .098 .134 .108 .46 .29 .41 .27 .34 .29 264 BULLETIN No. 437: APPENDIX [/M/V, TABLE 31. Continued Sample No. Nitrogen Phosphorus Potassium Calcium Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover 65 .41 .87 .55 .096 .127 .105 .59 .52 .57 .24 .55 .33 66 .67 .97 .74 .054 .088 .062 .71 .47 .66 .33 .33 .33 67 .72 .89 .76 .057 .070 .060 .70 .52 .66 .34 .44 .36 68 .90 .89 .90 .063 .068 .064 .68 .41 .62 .36 .40 .37 69 .68 .91 .73 .041 .064 .046 .82 .46 .75 .33 .30 .32 70 .80 .92 .83 .076 .103 .082 .53 .39 .50 .34 .41 .36 71 .69 .93 .75 .039 .094 .053 .60 .43 .56 .34 .43 .36 72 .72 .82 .74 .043 .084 .051 .90 .48 .82 .33 .41 .35 73 .97 .93 .96 .083 .095 .086 .70 .43 .64 .37 .52 .41 74 .94 1.13 .99 .104 .135 .111 .85 .56 .78 .35 .36 .35 75 .98 1.22 1.03 .064 .133 .079 .38 .40 .38 .23 .17 .22 76 .82 1.07 .86 .049 .085 .055 .34 .43 .36 .22 .11 .20 77 .87 1.10 .91 .082 .130 .091 .30 .42 .32 .20 .15 .19 78 .75 .89 .78 .075 .100 .081 .27 .40 .30 .23 .14 .21 79 .65 .87 .70 .061 .084 .066 .34 .36 .34 .25 .16 .23 80 .49 1.35 .83 .026 .110 .059 .98 .73 .88 .35 .76 .51 81 .50 .85 .59 .029 .075 .041 .77 .41 .68 .30 .33 .31 82 .60 .83 .67 .044 .053 .047 .74 .42 .65 .31 .31 .31 83 .90 .95 .91 .069 .107 .080 .71 .50 .65 .35 .40 .36 84 .60 .94 .69 .045 .085 .056 1.19 .40 .97 .29 .40 .32 85 .47 .76 .54 .059 .083 .065 1.14 .39 .96 .28 .43 .32 86 .54 .88 .64 .060 .085 .068 1.37 .47 1.09 .34 .39 .36 87 .67 1.14 .82 .048 .104 .066 1.11 .54 .93 .31 .45 .35 88 .66 1.16 .82 .062 .108 .077 1.06 .44 .86 .33 .44 .36 89 .54 .79 .62 .069 .117 .083 .90 .74 .85 .35 .39 .36 90 .66 1.09 .78 .065 .111 .077 .36 .33 .35 .29 .31 .30 91 .82 1.06 .89 .095 .116 .101 .55 .39 .51 .27 39 .30 92 .91 1.09 .96 .122 .134 .125 .61 .48 .58 .33 .43 .36 93 .97 1.23 1 04 .106 .116 .109 .85 .46 .75 .35 .40 .36 94 .50 .58 .52 .077 .067 .074 .62 .55 .60 .29 .32 .30 95 .63 .68 .64 .061 .060 .061 .64 .40 .58 .28 .25 .27 96 .64 .71 .66 .063 .062 .063 .63 .52 .60 .20 .26 .22 97 .75 .74 .75 .076 .054 .070 .41 .38 .40 .27 .25 .26 98 .66 .66 .66 .053 .052 .053 .60 .47 .57 .27 .23 .26 99 .54 .96 .68 .049 .088 .062 .56 .52 .55 .30 .37 .32 100 .63 .80 .67 .059 .069 .061 .41 .37 .40 .29 .23 .28 101 .70 .73 .71 .072 .069 .071 .49 .40 .47 .23 .21 .22 102 .91 .91 .91 .115 .119 .116 .47 .41 .45 .21 .26 .22 103 .79 .86 .81 .088 .107 .093 .79 .43 .69 .25 .20 .24 104 .63 .88 .74 .068 .082 .074 .32 .27 .30 .21 .28 .24 105 .48 .80 .58 .051 .075 .058 .40 .25 .35 .22 .31 .25 106 .58 .84 .67 .069 .080 .073 .47 .39 .44 .18 .28 .21 107 .67 .79 .71 .122 .114 .119 .38 .26 .34 .19 .29 .22 108 .78 .87 .81 .116 .124 .118 .63 .42 .57 .20 .24 .21 109 .44 .75 .54 .202 .148 .185 .33 .23 .30 .25 .29 .26 110 .50 .79 .60 .130 .133 .131 .40 .31 .37 .20 .23 .21 111 .50 .70 .56 .148 .111 .137 .48 .25 .41 .18 .25 .20 112 .67 .93 .76 .156 .169 .160 .34 .33 .34 .23 .32 .26 113 .74 1.02 .83 .174 .192 .180 .35' .36 .35 .27 .34 .29 114 .71 .92 .77 .126 .127 .126 .57 .37 .52 .22 .26 .23 115 .74 1.32 .98 .132 .216 .166 .78 .86 .81 .46 .80 .60 116 .88 .98 .92 .110 .160 .128 .46 .50 .47 .39 .52 .44 117 .93 1.37 1.10 .145 .219 .173 .86 .82 .84 .49 .91 .65 118 .78 1.20 .92 .138 .234 .171 .52 .68 .58 .42 .71 .52 119 .80 1.19 .95 .094 .186 .130 .92 1.02 96 .36 .67 .48 120 .78 1.03 .83 .109 .135 .115 .87 .52 .79 .24 .24 .24 121 .79 1.08 .86 .075 .102 .082 .30 .34 .31 .21 .22 .21 122 .80 1.20 .90 .068 .096 .075 .43 .32 .40 .28 .22 .27 123 1.28 1.27 1.28 .094 .132 .101 .64 .44 .60 .30 .25 .29 124 1.07 1.27 1.12 .108 .155 .119 .85 .61 .79 .27 .27 .27 125 1.11 1.28 1.15 .111 .145 .119 1.06 .60 .95 .28 .25 .27 1937] COMPOSITION OF MATURE CORN STOVER TABLE 31. Concluded 265 Sample Nitrogen I 'hosphoru s 1 'otassiui \ Calcium No. Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover 126 .46 .80 .58 .114 .138 .122 .49 .46 .48 .27 .42 .32 127 .43 .70 .50 .090 .092 .091 .39 .31 .37 .23 .26 .24 128 .57 .91 .69 .068 .096 .078 .35 .27 .32 .25 .37 .29 129 .62 .88 .71 .166 .153 .161 .36 .26 .32 .31 .37 .33 130 .53 .86 .62 .094 .122 .102 1.00 .40 .83 .30 .34 .31 131 .47 .66 .52 .056 .084 .064 .48 .37 .45 .24 .30 .26 132 .41 .69 .49 .181 .153 .173 .43 .26 .38 .23 .30 .25 133 .34 .64 .42 .132 .125 .130 .69 .43 .62 .24 .29 .25 134 .64 .85 .71 .135 .157 .142 .36 .32 .35 .26 .34 .29 135 .72 .96 .80 .200 .201 .200 .33 .24 .30 .32 .39 .34 136 .13 .93 .34 .140 .146 .142 1.11 .47 .94 .26 .34 .28 137 .62 .90 .70 .168 .176 .170 .38 .29 .36 .25 .33 .27 138 .43 .70 .51 .163 .138 .155 .79 .34 .65 .29 .32 .30 139 .59 .03 .73 .144 .154 .147 .38 .27 .34 .34 .39 .36 140 .91 .12 .97 .145 .177 .155 .26 .26 .26 .27 .33 .29 141 .70 .08 .78 .085 .091 .086 .33 .40 .34 .29 .29 .29 142 .72 .20 .85 .075 .086 .078 .48 .42 .46 .26 .25 .26 143 1.05 .35 1.12 .092 .100 .094 .80 .57 .75 .33 .28 .32 144 1.10 .27 1.14 .132 .142 .135 .67 .59 .65 .34 .29 .33 145 1.04 .36 1.12 .124 .136 .127 .86 .55 .79 .35 .29 .34 266 BULLETIN No. 437: APPENDIX [.July, TABLE 32. AMOUNTS OF NITROGEN, PHOSPHORUS, POTASSIUM, AND CALCIUM IN MATURE CORN STOVER AND ITS SEPARATED PARTS (Pounds per acre) Sample Nitrogen Phosphorus Potassium Calcium Calculated yield No. Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover H>. Ibt. Ibt. Ibi. Ibt. Ibt. Ibt. Ibt. Ibt. Ibt. Ibt. Ibi. Ibi. Ibt. Ibi. 1 30.7 8.6 39.3 5.31 1.56 6.87 9.4 3.5 12.9 7.6 2.5 10.1 2 360 783 3 143 2 20 8 93 30 1 3 73 1 33 5 06 70 33 10 3 77 22 99 2 261 783 3 044 3 18.5 7.7 26.2 2.88 .94 3.82 9.2 3.0 12.2 7.9 2.3 10.2 2 198 808 3 006 4 11.0 4.5 15.5 1.48 .47 1.95 8.4 2.3 10.7 4.6 1.4 6.0 1 593 554 2 147 5 21.5 7.4 28.9 3.73 .96 4.69 14.1 3.8 17.9 6.9 1.8 8.7 2 168 704 2 872 6 14.6 6.0 20.6 2.38 .77 3.15 8.0 2.6 10.6 6.6 1.6 8.2 1 999 612 2 611 7 7.3 3.3 10.6 1.04 .39 1.43 2.4 1.1 3.5 2.3 0.9 3.2 732 286 1 018 8 83 42 12 5 1 15 48 1 63 41 25 66 3.0 15 45 970 462 1 432 9 11.0 42 15.2 1.71 .58 2.29 6.1 2.1 8.2 4.0 1.3 5.3 1 237 468 1 705 10 19.5 7.3 26.8 3.10 .95 4.05 14.3 4.3 18.6 8.6 2.2 10.8 2 383 810 3 193 11 21.3 4.5 25.8 4.69 .63 5.32 16.6 2.7 19.3 9.8 1.9 11.7 2 445 658 3 103 12 21.0 10.8 31.8 3.07 1.40 4.47 10.6 5.5 16.1 8.9 2.9 11.8 2 212 1 051 3 263 13 8.4 11.5 19.9 1.07 .82 1.89 11.7 2.7 14.4 6.4 6.2 12.6 1 820 905 2 725 14 13.5 9.6 23.1 1.54 .68 2.22 13.5 3.3 16.8 7.7 3.2 10.9 2 142 852 2 994 15 22.6 15.2 37.8 1.41 1.00 2.41 25.8 5.4 31.2 10.9 5.5 16.4 2 602 1 219 3 821 16 27.7 19.1 46.8 3.60 1.89 5.49 30.3 6.6 36.9 13.8 8.2 22.0 2 881 1 323 4 204 17 31.6 20.0 51.6 3.73 1.66 5.39 40.4 7.0 47.4 12.7 5.6 18.3 3 034 1 214 4 248 18 20.8 8.0 28.8 4.25 1.26 5.51 14.2 4.4 18.6 7.0 3.3 10.3 2 055 864 2 919 19 22.4 11.5 33.9 3.96 1.25 5.21 13.2 3.4 16.6 8.3 3.1 11.4 2 237 806 3 043 20 12.8 14.6 27.4 2.50 1.07 3.57 15.1 4.2 19.3 7.4 4.0 11.4 2 249 921 3 170 21 17.0 6.5 23.5 4.39 1.05 5.44 20.7 4.1 24.8 8.7 3.1 11.8 2 299 783 3 082 22 18.0 7.7 25.7 6.18 1.68 7.86 14.1 3.2 17.3 6.6 4.4 11.0 2 279 854 3 133 23 28.2 11.7 39.9 5.99 1.88 7.87 18.1 4.7 22.8 9.8 5.2 15.0 2 660 921 3 581 24 28.2 14.5 42.7 4.05 1.97 6.02 17.2 5.4 22.6 9.3 6.6 15.9 2 911 1 316 4 227 25 12.7 10.8 23.5 2.54 1.41 3.95 12.7 5.2 17.9 6.0 3.7 9.7 2 226 1 080 3 306 26 20.5 11.2 31.7 5.87 2.39 8.26 16.1 4.1 20.2 7.7 4.9 12.6 2 732 1 244 3 976 27 16.8 5.7 22.5 2.25 .69 2.94 5.4 2.0 7.4 7.0 1.6 8.6 783 512 2 295 28 12.1 4.8 16.9 1.85 .51 2.36 4.1 1.6 5.7 4.4 .2 5.6 526 469 1 995 29 99 43 14 2 1.23 .52 1.75 49 19 68 4.0 353 279 411 1 690 30 14.3 4.9 19.2 1.98 .66 2.64 4.3 1.7 6.0 4.8 .9 5.7 667 402 2 069 31 14.9 4.6 19.5 1.94 .60 2.54 5.9 1.6 7.5 5.9 .2 7.1 905 476 2 381 32 15.5 6.7 22.2 2.09 .91 3.00 7.0 3.2 10.2 6.4 .2 7.6 1 935 683 2 618 33 8.4 4.1 12.5 .77 .44 1.21 6.3 2.3 8.6 4.1 .4 5.5 1 291 471 1 762 34 16.7 6.0 22.7 2.42 .79 3.21 8.3 2.4 10.7 5.2 .1 6.3 2 085 670 2 755 35 9.1 3.6 12.7 1.10 .35 1.45 17.0 2.4 19.4 4.2 .0 5.2 1 450 450 1 900 36 76 95 17 1 .70 98 1 68 79 49 12 8 46 6 92 1 365 834 2 199 37 10.5 5.9 16.4 3.09 1.07 4.16 25.0 3.3 28.3 5.2 .9 7.1 1 776 716 2 492 38 9.6 2.7 12.3 3.90 .64 4.54 21.2 2.1 23.3 5.2 .3 6.5 1 840 473 2 313 39 9.0 3.0 12.0 1.80 .47 2.27 12.3 1.7 14.0 4.4 .5 5.9 1 577 515 2 092 40 8.9 3.3 12.2 1.96 .57 2.53 15.4 2.2 17.6 4.9 .4 6.3 1 676 524 2 200 41 6.9 33 10 2 1.00 .55 1 55 7.1 1.6 8 7 5.9 5 7.4 1 473 557 2 030 42 75 38 11 3 89 .56 1 45 79 23 10 3 57 4 71 383 552 1 935 43 8.6 3.7 12.3 4.05 .78 4.83 15.3 2.3 17.6 6.0 .5 7.5 762 573 2 335 44 9.9 34 13 3 2.06 .65 2.71 7.8 1.9 9 7 6.4 .6 8.0 940 635 2 575 45 11.2 3.9 15.1 3.22 .80 4.02 16.0 2.8 18.8 6.8 .8 8.6 189 663 2 852 46 6.7 3.1 9.8 .40 .32 .72 8.9 1.7 10.6 4.2 .3 5.5 390 519 1 909 47 7.5 2.6 10.1 2.25 .47 2.72 11.2 1.7 12.9 5.4 .4 6.8 595 464 2 059 48 9.4 2.5 11.9 2.54 .47 3.01 9.4 1.6 11.0 6.4 .5 7.9 813 506 2 319 49 10.9 3.0 13.9 .83 .29 1.12 10.3 1.5 11.8 4.6 .3 5.9 517 549 2 066 50 8.8 3.7 12.5 2.08 .58 2.66 13.1 2.1 15.2 4.6 .9 6.5 752 609 2 361 51 9.7 3.2 12.9 3.20 .59 3.79 11.5 1.7 13.2 5.3 .6 6.9 693 540 2 233 52 7.6 3.6 11.2 1.40 .46 1.86 9.4 2.3 11.7 4.3 .5 5.8 542 563 2 105 53 8.8 3.8 12.6 1.57 .55 2.12 9.7 1.9 11.6 5.1 .6 6.7 693 519 2 212 54 8.6 3.3 11.9 2.58 .58 3.16 9.6 1.5 11.1 6.0 .6 7.6 720 540 2 260 55 9.2 3.4 12.6 4.14 .83 4.97 9.0 1.9 10.9 6.3 .9 8.2 842 660 2 502 56 7.1 5.9 13.0 .71 .60 1.31 4.6 2.0 6.6 3.2 .6 5.8 147 559 706 57 8.7 4.9 13.6 .69 .45 1.14 5.1 1.6 6.7 3.2 .5 4.7 224 510 734 58 10.1 4.5 14.6 .82 .41 1.23 5.9 1.7 7.6 4.3 .8 6.1 464 492 956 59 11.8 3.6 15.4 .85 .54 1.39 5.4 1.9 7.3 3.9 .7 5.6 641 543 184 60 5.4 3.6 9.0 .50 .33 .83 4.9 1.8 6.7 3.3 .4 4.7 120 438 558 61 8.7 4.4 13.1 1.24 .52 1.76 4.9 2.1 7.0 3.9 .8 5.7 353 549 902 62 6.3 4.5 10.8 .76 .53 1.29 7.0 2.4 9.4 3.6 .8 5.4 290 575 865 63 6.2 3.0 9.2 1.60 .47 2.07 7.2 1.2 8.4 3.7 .6 5.3 1 291 429 720 64 0.2 3.5 9.7 1.17 .59 1.76 5.5 1.3 6.8 3.2 .5 4.7 1 198 437 635 COMPOSITION OF MATURE CORN STOVER 267 TABLE 32. Continued Sample Nitrogen Phosphorus Potassium Calcium Calculated yield No. Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover Ibt. Ibi. lb. Ibi. Ibt. Ibt. Ibt. Ibt. Ibt. Ibt. Ibt. Ibt. lb,. Ibt. Ibt. 65 5.6 5.1 10.7 .32 .74 2.06 8.1 3.0 11.1 3.3 3.2 6.5 1 376 582 1 958 66 16.4 6.8 23.2 .32 .62 1.94 17.4 3.3 20.7 8.1 2.3 10.4 2 445 699 3 144 67 14.6 5.0 19.6 .15 .40 1.55 14.2 2.9 17.1 6.9 2.5 9.4 2 025 565 2 590 68 23.3 6.8 30.1 .63 .52 2.15 17.6 3.1 20.7 9.3 3.0 12.3 2 584 760 3 344 69 17.6 5.7 23.3 .06 .40 1.46 21.2 2.9 24.1 8.6 1.9 10.5 2 590 630 3 220 70 19.5 6.6 26.1 .85 .74 2.59 12.9 2.8 15.7 8.3 2.9 11.2 2 434 716 3 150 71 16.7 7.8 24.5 .95 .79 1.74 14.6 3.6 18.2 8.3 3.6 11.9 2 426 843 3 269 72 15.9 4.6 20.5 .95 .47 1.42 19.9 2.7 22.6 7.3 2.3 9.6 2 214 556 2 770 73 27.1 8.0 35.1 2.32 .82 3.14 19.6 3.7 23.3 10.4 4.5 14.9 2 796 864 3 660 74 25.4 9.6 35.0 2. 81 '1.14 3.95 22.9 4.7 27.6 9.5 3.1 12.6 2 699 847 3 546 75 13.5 4.5 18.0 .88 .49 1.37 5.3 1.5 6.8 3.2 0.6 3.8 1 381 370 1 751 76 11.4 3.2 14.6 .68 .25 .93 4.7 1.3 6.0 3.1 3 3.4 1 388 296 1 684 77 13.2 3.6 16.8 1.24 .43 1.67 4.5 1.4 5.9 3.0 0.5 3.5 1 514 328 1 842 78 12.2 4.6 16.8 1.22 .51 1.73 4.4 2.1 6.5 38 07 45 1 632 512 2 144 79 12.2 4.3 16.5 1.15 .42 1.57 6.4 1.8 8.2 4.7 0.8 5.5 1 882 497 2 379 80 6.5 11.8 18.3 .34 .96 1.30 12.9 6.4 19.3 4.6 6.6 11.2 1 321 871 2 192 81 9.1 5.4 145 .53 .48 1.01 14.0 2.6 16.6 5.5 2.1 7.6 1 824 635 2 459 82 11.0 6.0 17.0 .80 .38 1.18 13.5 3.0 16.5 5.7 2.2 7.9 1 829 723 2 552 83 20.2 8.4 28.6 1.55 .94 2.49 15.9 4.4 20.3 7.9 3.5 11.4 2 242 880 3 122 84 12.7 7.6 20.3 .95 .69 1.64 25.2 3.2 28.4 6.1 3.2 9.3 2 115 806 2 921 85 10.8 5.6 16.4 1.35 .61 1.96 26.1 2.9 29.0 6.4 3.2 9.6 2 293 732 3 025 86 10.9 7.8 18.7 1.21 .76 1.97 27.6 4.2 31.8 6.9 3.5 10.4 2 018 889 2 907 87 16.2 12.8 29.0 1.16 1.17 2.33 26.9 6.1 33.0 7.5 5.1 12.6 2 420 1 122 3 542 88 15.6 12.6 28.2 1.46 1.18 2.64 25.0 4.8 29.8 7.8 4.8 12.6 2 357 1 090 3 447 89 8.0 5.1 13.1 1.03 .75 1.78 13.4 4.7 18.1 5.2 2.5 7.7 1 487 640 2 127 90 12 7 77 20 4 1 25 79 2 04 7.0 2.3 9.3 56 22 78 1 930 709 2 639 91 18.1 9.0 27.1 2.10 .98 3.08 12.2 3.3 15.5 6.0 3.3 9.3 2 212 845 3 057 92 20.4 8.3 28.7 2.73 1.02 3.75 13.7 3.7 17.4 7.4 3.3 10.7 2 240 762 3 002 93 21.0 9.1 30.1 2.30 .86 3.16 18.4 3.4 21.8 7.6 3.0 10.6 2 168 741 2 909 94 5.5 2.5 8.0 .84 .28 .12 6.8 2.3 9.1 3.2 1.4 4.6 1 095 422 1 517 95 12.1 4.3 16.4 1.17 .38 .55 12.3 2.5 14.8 5.4 1.6 7.0 1 919 626 2 545 96 11.2 4.2 15.4 1.10 .37 .47 11.0 3.1 14.1 3.5 1.5 5.0 1 752 591 2 343 97 12.8 4.5 17.3 1.29 .33 .62 7.0 2.3 9.3 4.6 1.5 6.1 1 701 610 2 311 98 11.8 2.9 14.7 .94 .23 .17 10.7 2.1 12.8 4.8 1.0 5.8 1 783 439 2 222 99 6.7 6 1 12.8 61 56 17 7 3.3 10.3 37 24 61 1 242 640 1 882 100 10.6 4.4 15.0 .99 .38 .37 6.9 2.0 8.9 4.9 1.3 6.2 1 676 545 2 221 101 14.8 5.3 20.1 1.52 .50 2.02 10.4 2.9 13.3 4.9 1.5 6.4 2 112 730 2 842 102 18.4 6.8 25.2 2.33 .88 3.21 9.5 3.1 12.6 4.3 1.9 6.2 2 025 743 2 768 103 16.6 6.8 23.4 1.85 .85 2.70 16.6 3.4 20.0 5.3 1.6 6.9 2 099 794 2 893 104 4.2 4.6 8.8 .45 .43 .88 2.1 1.4 3.6 1.4 1.5 2.9 662 526 1 188 105 5.4 4.1 9.5 .57 .38 .95 4.5 1.3 5.8 2.5 1.6 4.1 115 506 1 621 106 9.5 6.9 16 4 1 13 66 1 79 7 7 3.2 10.9 30 23 53 644 820 2 464 107 13.4 7.7 21.1 2.43 1.11 3.54 7.6 2.5 10.1 3.8 2.8 6.6 993 970 2 963 108 19.2 9.1 28.3 2.85 1.29 4.14 15.5 4.4 19.9 4.9 2.5 7.4 461 1 044 3 505 109 56 45 10 1 2 59 89 3 48 4.2 1.4 5.6 32 17 49 281 598 1 879 110 6.9 5.4 12.3 1.80 .91 2.71 5.6 2.1 7.7 2.8 1.6 4.4 387 686 2 073 111 8.5 5.1 13.6 2.50 .80 3.30 8.1 1.8 9.9 3.1 1.8 4.9 692 722 2 414 112 12.3 8.6 20.9 2.86 1.56 4.42 6.2 3.1 9.3 4.2 3.0 7.2 833 926 2 759 113 14.3 9.7 24.0 3.37 1.83 5.20 6.8 3.4 10.2 5.2 3.2 8.4 937 951 2 888 114 18.5 8.6 27.1 3.29 1.19 4.48 14.9 3.5 18.4 5.7 2.4 8.1 611 938 3 549 115 12.3 15.0 27.3 2.19 2.45 4.64 13.0 9.8 22.8 7.7 9.1 16.8 662 1 136 2 798 no 15.6 9.7 25.3 1.95 1.59 3.54 8.2 5.0 13.2 6.9 5.2 12.1 773 991 2 764 117 18.3 162 34.5 2.85 2.59 5 44 169 9.7 26.6 9.6 10.8 20.4 965 1 182 3 147 118 13.3 10.7 24.0 2.36 2.09 4.45 8.9 6.1 15.0 7.2 6.3 13.5 708 894 2 602 119 15.6 14.7 30.3 1.84 2.29 4.13 18.0 12.6 30.6 7.0 8.3 15.3 1 953 1 231 3 184 120 22.0 8.2 30.2 3.08 1.07 4.15 24.6 4.1 28.7 6.8 1.9 8.7 2 826 794 3 620 121 12.4 58 18.2 1.18 .55 1.73 4.7 1.8 6.5 3.3 1.2 4.5 1 568 538 2 106 122 17.2 8.5 25.7 1.46 .68 2 14 9.3 2.3 11.6 6.0 1.6 7.6 2 150 707 2 857 123 33.8 7.6 41.4 2.49 .79 3 28 16.9 2.6 195 7.9 1.5 9.4 2 644 596 3 240 124 27.9 10.6 38 5 2.81 130 4.11 22.1 5.1 27.2 7.0 2.3 9.3 2 604 836 3 440 125 30.3 11.3 41.6 3.03 1.28 4.31 28.9 5.3 34.2 7.6 2.2 9.8 2 729 886 3 615 268 BULLETIN No. 437: APPENDIX TABLE 32. Concluded SampU Nitrogen Phosphorus Potassium Calcium Calculated yield No. Stalks Leaves Stover Stalks Leaves Stover Stalks Leaves Stover St.-ilks Leaves Stover Stalks Leaves Stover 126 Ibi. Ibs. Ibi. 67 61 12 8 Ibt. lb>. Ibt. 1 67 1 06 2 73 lb,. Ibt. lb>. 72 35 10 7 Ibt. Ibt. Ibt. 40 32 72 Ibt. lb,. Ibt. 464 767 2 231 127 128 120 130 131 132 133 134 135 8.0 4.5 12.5 9.3 7.7 17.0 10.9 8.4 19.3 13.9 8.8 22.7 8.7 5.0 13.7 5.4 3.4 8.8 5.8 4.2 10.0 13.5 8.5 22.0 10 6 67 17 3 1.68 .59 2.27 1.10 .81 1.91 2.92 1.46 4.38 2.47 1.25 3.72 1.04 .63 1.67 2.38 .76 3.14 2.24 .83 3.07 2.85 1.57 4.42 2.96 1.40 4.36 7.3 2.0 9.3 5.7 2.3 8.0 6.3 2.5 8.8 26.2 4.1 30.3 8.9 2.8 11.7 5.7 1.3 7.0 11.7 2.8 14.5 7.6 3.2 10.8 4.9 1.7 6 6 4.3 1.7 6.0 4.1 3.1 7.2 5.5 3.5 9.0 7.9 3.5 11.4 4.4 2.3 6.7 3.0 1.5 4.5 4.1 1.9 6.0 5.5 3.4 8.9 4.7 '2.7 74 866 644 2 510 623 845 2 468 759 956 2 715 625 1 028 3 653 849 753 2 602 314 499 1 813 1 697 660 2 357 2 113 1 000 3 113 1 478 699 2 177 136 137 138 139 140 3.8 10.0 13.8 9.8 5.2 15.0 7.4 5.2 12.6 6.9 5.8 12.7 14 9 81 23 4.13 1.56 5.69 2.62 1.02 3.64 2.81 1.02 3.83 1.67 .87 2.54 2 37 1 27 3 64 32.7 5.0 37.7 5.9 1.7 7.6 13.6 2.5 16.1 4.4 1.5 5.9 43 19 6.2 7.7 3.6 11.3 3.9 1.9 5.8 5.0 2.4 7.4 3.9 2.2 6.1 44 24 6.8 2 949 1 071 4 020 1 561 579 2 140 1 722 741 2 463 1 161 566 1 727 1 634 720 2 354 141 14 8 59 20 7 1 80 50 2 30 70 22 92 61 16 77 2 115 547 2 662 142 143 144 145 16.3 9.7 26.0 25.8 9.9 35.7 32.3 13.3 45.6 27.1 11.1 38.2 1.69 .69 2.38 2.26 .74 3.00 3.88 1.49 5.37 3.23 1.12 4.35 10.8 3.4 14.2 19.6 4.2 23.8 19.7 6.2 25.9 22.4 4.5 26.9 5.9 2.0 7.9 8.1 2.1 10.2 10.0 3.0 13.0 9.1 2.4 11.5 2 258 808 3 066 2 456 736 3 192 2 937 1 050 3 987 2 602 820 3 422 COMPOSITION OF MATURE CORN STOVER 269 TABLE 33. TOTAL ASH AND ORGANIC CARBON IN SAMPLES OF MATURE CORN STOVER AND ITS SEPARATED PARTS Sample No. Total ash Organic carbon SUlks Leaves Stover Stalks Leaves Stover ' % % % c* 70 % % I 4.78 5.20 4.88 46 17 43.97 45 62 2 3.85 653 4.54 45.99 43.35 45 31 3 4.17 6.72 4.86 45.09 42.94 44 51 4 3.64 5.62 4.15 44.94 42.87 44.41 5 4.07 6.21 4.59 45.39 43.26 44.87 6 3.54 5.18 3.92 45.72 43.70 45.25 7 4 33 8.68 5.55 46.05 42.24 44.98 8 3.81 8.21 5.23 46.22 42.13 44.90 9 4.37 6.72 5.01 46.23 42.59 45.23 10 3.41 4.98 3.81 46.37 44.31 45.85 11 4.1.7 5.50 4.45 45 55 42.73 44.95 12 3.92 6.27 4.68 45.22 43.46 44.65 13 6.04 13.72 8.59 45.17 40.90 43.75 14 5.59 8.47 6.41 44.87 42.58 44.22 15 5.78 8.97 6.80 44.82 42.53 44.09 10 5.45 9.56 6.74 44.10 42.61 43.63 17 5.83 8.69 6.65 45.18 43.97 44.83 18 4.99 7.53 5.74 45.99 42.91 45.08 10 5.03 6.90 5.53 45.24 43.36 44.74 20 5.00 8.87 6.12 44.82 42.31 44.09 21 5.65 7.11 6.02 44.04 43.04 43.79 22 5.11 8.65 6.08 45.10 42.39 44.36 23 5.87 11.81 7.40 45.13 42.16 44.37 24 4.59 7.93 5.63 45.02 43.02 44.40 25 4.47 7.78 5.55 46.10 42.76 45.01 26 4.89 7.82 5.81 45.12 43.11 44.49 27 4.27 7.05 4.89 45.95 43.96 45.51 28 3.59 7.01 4.39 47.14 43.75 46.34 29 4.33 6.84 4.94 46.92 43.96 46.20 30 3.82 6.98 4.43 46.51 43.78 45.98 31 4.01 5.40 4.29 47.35 44.01 46.68 32 3.17 4.23 3.45 47.09 44.67 46.46 33 4.06 7.97 5.10 44.59 43.23 44.23 34 3.80 5.34 4.15 45.43 44.18 45.13 35 5.20 6.54 5.52 45.19 42.69 44.60 36 5.93 1053 7.67 44.08 41.27 43.01 37 6.62 9.81 7.54 45.26 40.92 44.01 38 6.32 7.34 6.53 45.12 42.33 44.55 39 5.25 8.63 6.08 45.40 41.64 44.48 40 6.04 10.79 7.17 44.90 41.08 43.99 41 5.20 6.90 5.73 44.31 42.38 43.78 42 5.33 6.95 5.79 44.51 42.25 43.87 43 6.18 7.65 6.54 44.78 42.31 44.17 44 5.03 7.49 5.64 43.66 41.79 43.20 45 5.39 8.69 6.16 43.78 42.01 43.37 46 5.32 6.34 5.60 44.57 42.01 43.87 47 5.68 7.29 6.04 43.88 41.74 43.40 48 5.43 6.90 5.75 43.94 42.10 43.54 49 5.54 5.46 5.52 43 58 42.61 43.32 50 6.44 8.39 6.94 42.92 41.61 42.58 51 6.55 7.85 6.86 44.23 42.63 43.84 52 5.13 7.02 5.63 44.11 43.22 43.87 53 6.15 8.49 6.70 44.49 43.22 44.19 54 5.77 7.80 6.25 44.39 43.08 44.08 55 6.06 7.25 6.37 43.80 43.18 43.64 56 6.13 9.97 7.39 43.67 41.91 43.09 57 4.96 8.81 6.09 45.27 42.69 44.51 58 4.14 10.14 5.65 44.53 41 69 43.81 59 3.71 7.19 4.58 45.24 42.39 44.53 60 6.45 11.90 7.98 43.38 40.70 42.63 61 5.51 12.64 7.56 45.06 40.61 43.78 62 6.23 14.80 8.87 44.83 40.51 43.50 63 5.95 14.78 8.15 44.20 40.32 43.23 64 5.71 14.60 8.09 44.48 40.08 43.30 270 BULLETIN No. 437: APPENDIX TABLE 33. Continued Sample No. Total aab Organic carbon Stalks Leaves Stover Stalks Leaves Stover 65 5.41 11.62 7.25 44.34 41.85 43.60 66 4.57 7.27 5.17 45.38 43.49 44.96 67 5.64 8.69 6.30 44.45 42.21 43.96 68 4.90 7.32 5.45 44.46 44.09 44.38 69 5.13 7.86 5.68 43.90 42.04 43.53 70 4.57 7.14 5.15 44.90 42.23 44.29 71 4.45 8.07 5.38 44.19 43.88 44.11 72 4.71 6.77 5.12 45.20 43.93 44.94 73 5.06 7.40 5.61 44.06 43.28 43.88 74 5.36 7.67 5.91 44.02 43.28 43.84 75 3.27 4.43 3.52 45.61 42.16 44.88 76 3.17 4.47 3.40 45.51 42.08 44.91 77 3.48 3.94 3.56 45.23 42.32 44.71 78 3.25 6.23 3.96 44.40 43.24 44.12 79 3.77 6.17 4.27 44.46 42.72 44.10 80 5.60 12.21 8.22 43.56 42.25 43.04 81 5.15 7.32 5.71 44.14 43.72 44.03 82 5.24 6.95 5.72 44.46 42 96 44.04 83 5.00 7.66 5.75 44.79 42.54 44.16 84 5.65 9.29 6.65 43.85 42.62 43.51 85 5.01 9.09 6.00 44.28 42.50 43.85 86 6.25 9.65 7.29 45.06 42.65 44.32 87 5.35 10.04 6.84 44.86 42.54 44.12 88 4.89 9.45 6.33 44.93 42.97 44.31 89 6.14 7.44 6.53 43.56 43.49 43.54 90 4.39 6.28 4.90 44.12 43.23 43.88 91 4.47 8.81 5.67 45.06 43.86 44.73 92 5.47 8.25 6.18 44.30 43.85 44.19 93 5.34 8.76 6.21 44.75 44.35 44.65 94 4.71 5.74 5.00 45.16 43.55 44.71 95 3.81 5.13 4.13 45.44 44.11 45.11 96 3.72 5.79 4.24 45.49 44.38 45.21 97 3.38 5.04 3.82- 46.12 44.12 45.59 98 4.00 5.11 4.22 45.21 43.75 44.92 99 5.35 10.60 7.14 44.49 41.93 43.62 100 4.08 5.26 4.37 44.67 43.75 44.44 101 3.61 4.36 3.80 45.36 45.96 45.51 102 3.80 5.12 4.15 45.14 45.20 45.16 103 3.87 4.34 4.00 43.67 45.05 44.05 104 7.26 9.11 8.08 43.21 43.56 43.37 105 5.55 10.30 7.03 43.59 42.13 43.13 106 5.58 7.97 6.38 43.63 43.18 43.48 107 4.18 7.31 5.20 43.55 44.79 43.95 108 4.23 6.53 4.92 43.59 43.97 44.70 ' 109 4.88 8.15 5.92 43.93 42.51 43.48 110 4.75 7.38 5.62 44.53 43.36 44.14 111 5.21 7.31 5.84 43.88 43.34 43.72 112 4.75 8.23 5.92 44.69 43.09 44.15 113 4.33 8.26 5.62 44.41 42.54 43.79 114 3.89 7.25 4.78 44.53 43.25 44.18 115 4.34 7.87 5.77 44.85 43.71 44.39 116 3.27 5.03 3.90 45.79 43.98 45.14 117 4.10 7.52 5.39 45.29 43.81 44.73 118 3.68 6.53 4.66 44.89 43.96 . 44.57 119 3.81 7.45 5.22 45.95 43.47 44.99 120 4.62 5.54 4.82 45.25 43.47 . 44.86 121 3.71 5.20 4.09 44.52 43.28 44.20 122 4.25 5.29 4.51 45.66 45.34 45.58 123 4.08 5.32 4.31 45.85 45.10 45.71 124 4.37 5.76 4.71 45.76 45.33 45.66 125 4.81 5.15 4.89 45.77 45.36 45.67 1937] COMPOSITION OF MATURE CORN STOVER 271 TABLE 33. Concluded Sample No. Total ash Organic carbon Stalks Leaves Stover Stalks Leaves Stover 126 5 55 9.46 6.90 44.79 42.13 43.87 127 4.65 7.78 5.45 45.41 43.68 44.97 128 5.30 7.85 6.17 45 14 43.93 44.73 129 4.92 7.20 5.72 45.29 43.94 44.81 130 4.99 7.33 5.65 45.96 43.70 45.32 131 4.85 7.50 5.82 45.28 43.06 44.64 132 5.43 10.67 6.87 44 53 41.35 43.66 133 5.14 8.56 6.10 45.35 42.24 44.48 134 4.51 7.69 5.53 45.39 42.76 44 54 135 5.10 8.28 6.12 44.87 42.44 44.09 136 4.98 8.17 5.83 45.74 43.18 45.06 137 5.44 8.92 6.38 44.04 43.51 43.90 138 4.88 7 89 5.79 45.32 44.05 44.94 139 5.40 9 94 6.89 45.09 43.12 44.44 140 4.55 8.69 5.82 45.59 42.91 44.77 141 4.43 6.11 4.77 46.42 43.52 45.83 142 4.50 6.41 5.00 45.66 43.20 45.01 143 4.56 6.30 4.96 45.40 43.34 44.92 144 4.41 5.86 4.79 45.65 44.69 45.40 145 4.58 6 12 4.95 45.88 44.83 45.63 LIST OF TABLES AND CHARTS TABLES PAGE 1. Composition of corn grain and stover at different stages of development, according to Purdue studies 178 2. Composition of corn stover as reported in different publications 181 3. Fertilizing constituents in a ton of dry corn stover 181 4. Elemental composition of corn grain, stover, and separated parts of the stover 182 5. Variation in elemental composition of corn leaves and stems 183 6. Probable error of a single determination, and significant differences in composition 186 7. Acidity, available-phosphorus content, and clover growth, different soil types 190 8. Weather data and length of growing season at 14 Illinois weather sta- tions, 1928 195 9. Time required to mature corn, 4 experiment fields 197 10. Composition of mature corn stover, Urbana, South Farm, Carrington silt loam 198 11. Same, Alhambra, Putnam silt loam 198 12. Same, DeKalb, Saybrook silt loam 199 13. Same, Toledo, Cisne silt loam 199 14. Comparison of five varieties of corn, grown at Urbana and at Alhambra with respect to composition of mature stover 210 15. Same, seven varieties, Urbana and DeKalb 211 16. Same, three varieties, Urbana, Alhambra, and DeKalb 212 17. Influence of soil type on composition of mature corn stover, DeKalb and Sidell fields.. . 218 272 BULLETIN No. 437: APPENDIX TABLES (continued) PAGE 18. Same, Aledo, La Moille, and Minonk fields 219 19. Effect of residues on composition of mature corn stover 221 20. Same, limestone 224 21. Same, rock phosphate, when used with limestone 227 22. Same, potash (chiefly kainit) 230 23. Same, rock phosphate, used with and without limestone 237 24. Same, superphosphate, used with and without limestone 241 25. Comparison of superphosphate and rock phosphate, used with and with- out limestone, on composition of mature corn stover 244 26. Same, bone, rock, slag, and super phosphates, used with and without limestone 247 27. Effect of gypsum on composition of mature corn stover 249 28. Effect of treatment in changing th,e composition of stover from late- planted corn 251 29. Sources of stover samples and yields of stover and grain ; also ratio of stalks to leaves and stover to grain 259 30. Total application of fertilizing materials on plots from which stover samples were taken 262 31. Percentages of nitrogen, phosphorus, potassium, and calcium in mature corn stover 263 32. Amounts of nitrogen, phosphorus, potassium, and calcium in corn stover 266 33. Total ash and organic carbon in corn stover 269 FIGS. PAGE 1. Average yields of corn, oats, and wheat on untreated plots, 13 experi- ment fields, 1914-1928 191 2. .Rainfall during growing season, 1928, 16 experiment fields 194 3. Composition of mature corn stover of different varieties in relation to stover and grain yields, Urbana, South Farm 205 4. Same, Alhambra 206 5. Same, DeKalb 207 6. Same, Toledo 208 7. Effect of residues on composition of mature corn stover and on yields of stover and grain: 12 Illinois soil experiment fields 222 8. Same, limestone, 12 experiment fields 225 9. Same, rock phosphate, 12 experiment fields 228 10. Same, potash, chiefly kainit, 11 experiment fields 231 11. Same, residues and limestone, 12 experiment fields 232 12. Same, residues, limestone, and rock phosphate, 12 experiment fields 233 13. Same, limestone, rock phosphate, and potash, 11 experiment fields 234 7.37 405012124 "iVERSITYOFILLINOIS-URBANA