II B R.AR.Y 
 
 OF THE 
 
 U N I VERS ITY 
 OF ILLINOIS 
 
 G3O.7 
 
 cop 
 
 MRICULTURE 
 
The 
 
 person charging this material is responsible for 
 
 LI61 O-1096 
 
75 M 6-44 28133 
 
SOIL TREATMENTS FOR 
 
 WINTER 
 WHEAT 
 
 A SUMMARY OF FIELD EXPERIMENTS 
 
 v- 
 
 c\\ 
 
 N&/K 
 
 ! YJJ v u 
 
 AGRICULTURAL EXPERIMENT STATKON. 
 
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CONTENTS 
 
 PAGE 
 
 INTRODUCTION 175 
 
 PLAN OF EXPERIMENTS 176 
 
 Fields Where Tests Were Made 176 
 
 Systems of Soil Treatment 177 
 
 Soil Conditions On Test Fields 178 
 
 Cropping Methods Used 179 
 
 WHAT LONG-TIME EXPERIMENTS SHOW 179 
 
 Inherent Differences in Soil Productivity 179 
 
 Effectiveness of Soil Treatment 181 
 
 Part Played by Each Treatment Material 183 
 
 Manure and crop residues 184 
 
 Limestone 185 
 
 Phosphates 185 
 
 Potash 191 
 
 Effect of Long-Continued Treatment 191 
 
 EFFECT OF DIRECT FERTILIZER APPLICATION 194 
 
 Effect of Materials Applied Alone and in Combination 194 
 
 Effect of Nitrogen Fertilizers Top-Dressed 195 
 
 Effect of Different Nitrogen Carriers 197 
 
 Effect of Mixed Fertilizers Applied Directly 197 
 
 Tests Using Experimental Phosphates 199 
 
 Effects of Productivity Levels on Usefulness of Fertilizers 200 
 
 BEST METHODS OF APPLYING FERTILIZERS 202 
 
 RELATION OF SOIL TREATMENTS TO OTHER YIELD FACTORS. .204 
 
 Insect Damage Reduced by Fertilization 204 
 
 Effect on Wheat Lodging and on Clover Stands 205 
 
 Effect of Soil Treatment on Wheat Quality 207 
 
 Fertile Soil Provides Insurance Against Failures 208 
 
 CONCLUSIONS: SUGGESTIONS TO WHEAT GROWERS.. ..209 
 
 Urbana, Illinois July, 1944 
 
 Publications in the Bulletin series report the results of investigations made 
 or sponsored by the Experiment Station 
 
Soil Treatments for Winter Wheat 
 
 A Summary of Field Experiments 
 
 By L. B. MILLER, Assistant Chief in Soil Experiment Fields, 
 and F. C. BAUER, Chief in Soil Experiment Fields 
 
 WHEAT is an important field crop in Illinois. It is seeded on 
 about one-tenth of the cropland and ranks fourth in crop t 
 values. It is easily fitted into crop rotations, is a satisfactory 
 companion crop for legume seedings, and is a reliable cash crop for 
 many farmers. As a cover crop it has considerable value, providing 
 protection against erosion and nutrient losses. Its heaviest require- 
 ments for labor come at a time when other field work is not urgent. 
 For these and other reasons wheat production is well established in 
 the agricultural economy of this state. 
 
 Illinois wheat growers are confronted with wide variation in acre- 
 yields, ranging from failures and near failures to more than 50 bushels 
 an acre. The average yield for the state during the years 1933-1942 
 was only 17.9 bushels. Altho there are a number of reasons for low 
 yields, soil conditions are an important one. 
 
 Compared with other commonly grown nonlegume grains, wheat 
 ranks high in total percentage of certain plant nutrients, especially 
 nitrogen and phosphorus (Table 1). This characteristic makes it some- 
 what sensitive to nutrient deficiencies in the soil and rather responsive 
 to practices that conserve, maintain, and increase the soil's supply of 
 usable nutrients. 
 
 Variations in soil productivity and increasing impoverishment of 
 the soil make it essential for Illinois wheat growers to give more atten- 
 tion to the treatment of their soils. Treatment systems designed to raise 
 productivity levels, direct fertilizer applications at planting time, or a 
 
 TABLE 1. NUTRIENT ELEMENTS IN NONLEGUME GRAINS* 
 
 Crop 
 
 Nitrogen 
 
 Phosphorus 
 
 Potassium 
 
 Calcium 
 
 Magnesium 
 
 Total 
 
 Wheat.. . 
 
 perct. 
 . ... 2 . 20 
 
 perct. 
 .41 
 .36 
 .37 
 .37 
 .27 
 
 Perct. 
 .43 
 .48 
 .49 
 
 .47 
 .34 
 
 perct. 
 .04 
 .08 
 .04 
 .05 
 .02 
 
 perct. 
 .15 
 .12 
 .10 
 .12 
 .13 
 
 perct. 
 3.23 
 3.00 
 2.87 
 2.85 
 2.54 
 
 Oats 
 
 1.96 
 
 Rye 
 
 ... 1.87 
 
 Barley 
 
 1 . 84 
 
 Corn 
 
 1 78 
 
 
 
 Average of analyses from several sources. 
 
 175 
 
176 
 
 BULLETIN No. 503 
 
 combination of these methods is needed. This publication reviews and 
 summarizes the field experiments conducted by the Illinois Agricultural 
 Experiment Station dealing with the effects of these practices on the 
 yields of winter wheat. 
 
 PLAN OF EXPERIMENTS 
 
 Many of the data presented were obtained from twenty Illinois soil 
 experiment fields ( Fig. 1 ) . The other data were obtained in cooperative 
 experiments with farmers. 
 
 Fields Where Tests Were Made 
 
 The Illinois experiment fields that provide information for this 
 study were established twenty-five to thirty years ago. They were 
 designed primarily for the study of the merits of different systems of 
 soil treatment and were located on soils varying widely in productivity. 
 
 Fig. 1. Location of soil experiment 
 fields furnishing data for this publi- 
 cation. The twenty experiment fields 
 on which the long-time studies were 
 made are widely distributed over the 
 state and represent a wide range of 
 soil conditions. 
 
1944~\ SOIL TREATMENTS FOR WINTER WHEAT 177 
 
 Many of the fields had additional space on which supplementary tests 
 could be made with specific fertilizer materials. 
 
 Systems of Soil Treatment 
 
 Nine soil treatments were established on each experiment field 
 four of them illustrating those that would be used in livestock farming 
 and five illustrating those for grain farming. Still being used, these 
 treatments, with the symbols to represent them, are as follows: 
 Plot Treatment symbol Treatment materials 
 
 Manure (Livestock) Systems 
 
 1 None 
 
 2 M Manure 
 
 3 ML Manure, limestone 
 
 4 MLrP Manure, limestone, rock phosphate 
 
 Residues (Grain) Systems 
 
 5 None 
 
 6 R Crop residues 
 
 7 RL Crop residues, limestone 
 
 8 RLrP Crop residues, limestone, rock phosphate 
 
 9 RLrPK Crop residues, limestone, rock phosphate, 
 
 potash 
 
 The field procedures used in handling the treatment materials are 
 as follows: 
 
 None. All top growth of crops was removed. 
 
 Manure. Animal manure, including litter, was applied in proportion 
 to the weight of the crops grown during the previous rotation and was 
 plowed under for the corn crop. 
 
 Crop residues. The residues of crops, including corn stover, grain 
 straws, green sweet clover, and the second crop of legume hays, were 
 plowed under at convenient times. During some years the grain straws were 
 removed. 
 
 Limestone. Crushed limestone was applied initially at the rate of 4 
 tons an acre and thereafter once during each rotation at the annual rate of 
 i/ ton an acre on plowed soil, usually ahead of wheat. After twelve years 
 this procedure was discontinued. No limestone has been applied to the dark- 
 colored soils since, but a 2-ton application was made to the light-colored 
 and sandy soils during the past few years. 
 
 Rock phosphate. Finely ground rock phosphate was applied once 
 during the rotation, usually at wheat seeding time, at the annual acre-rate 
 of 500 pounds. Applications ceased after a total of 4 tons an acre had been 
 applied. Only a small amount of rock phosphate has been applied since 1924. 
 
 Potash. Kainit (containing about 12 percent of K 2 O) was applied 
 once during the rotation at the rate of 200 pounds an acre a year, usually 
 ahead of wheat. Since 1932, muriate of potash (50 percent K 2 O) has been 
 
178 BULLETIN No. 503 [/w/y, 
 
 used at annual rates ranging from 50 to 100 pounds, usually half ahead of 
 wheat and half ahead of corn. 
 
 These systems have involved a step-by-step build-up from no treat- 
 ment to somewhat complex combinations. Long used and modified to 
 some extent by the cropping system employed, they have tended to 
 establish different levels of productivity, the limits of which are de- 
 termined by the nature of the soils. Crop yields reveal the effects of 
 the soil treatments and thus furnish an index to the needs of the 
 various kinds of soil. 
 
 Recent modifications on several of the fields supply data on fer- 
 tilizers and methods of application not used in the original systems 
 of treatment. The various productivity levels established by the original 
 treatments provided a wide range of conditions under which these sup- 
 plementary tests have been made. 
 
 Soil Conditions on Test Fields 
 
 The soils on which the experiment fields are located may be classi- 
 fied in 10 of the 16 Illinois soil groups as follows. 1 The year in which 
 the field was established is indicated in parentheses. 
 
 I. Very dark, moderately heavy soils with moderately permeable sub- 
 soils: Aledo, Mercer county (1910). 
 
 II. Very dark heavy soils with moderately permeable subsoils, car- 
 bonates shallow: Hartsburg, Logan county (1911); Minonk, Woodford 
 county (1910). 
 
 III. Dark soils with moderately permeable subsoils: Kewanee, Henry 
 county (1915). 
 
 IV. Moderately dark soils with moderately permeable subsoils: 
 Dixon, Lee county (1910); Mt. Morris, Ogle county (1910). 
 
 V. Moderately dark soils with grayish cast, slowly permeable sub- 
 soils: Carlinmlle, Macoupin county (1910); Carthage, Hancock county 
 (1911); Clayton, Adams county (1911); Lebanon, St. Clair county (1910). 
 
 VI. Dark soils with slowly permeable subsoils, carbonates shallow: 
 Joliet, Will county (1914). 
 
 VII. Gray, strongly leached soils with very slowly permeable sub- 
 soils: (A) Slick spots infrequent Ewing, Franklin county (1910); Oblong, 
 Crawford county (1912); Toledo, Cumberland county (1913). (B) Slick 
 spots frequent Newton, Jasper county (1912). 
 
 X. Yellowish gray, strongly leached soils with slowly permeable sub- 
 soils: (A) Slick spots infrequent En field, White county (1912); Raleigh, 
 Saline county (1910). (B) Slick spots frequent Sparta, Randolph county 
 (1916). 
 
 'Classifications prepared by R. S. SMITH, Chief in Soil Physics and Soil 
 Survey. 
 
1944} SOIL TREATMENTS FOR WINTER WHEAT 179 
 
 XIV. Light-brown sands and loamy sand with slight subsoil devel- 
 opment: Oquawka, Henderson county (1915). 
 
 XVI. Yellow soils with slowly to moderately permeable subsoils: 
 Elizabethtown, Hardin county (1917). 
 
 Cropping Methods Used 
 
 Most of the experiment fields were designed for four-year crop 
 rotations. On many of them the crop sequence has been corn, oats, 
 legume hay, and wheat, with a seeding of biennial white sweet clover 
 for use as a green manure. On a few fields other sequences were used, 
 but for most fields a regular biennial or perennial deep-rooted legume 
 occupied the land one year in every four. Each field was so arranged 
 that each crop in the rotation was grown every year, thus providing 
 continuous annual yields of wheat and associated crops. 
 
 WHAT LONG-TIME EXPERIMENTS SHOW 
 
 Inherent Differences in Soil Productivity 
 
 No carefully supervised tests are needed to prove that soils differ 
 inherently in their capacity to produce crops. Those differences have 
 long been observed. Tests are necessary, however, to show the extent 
 of the differences. 
 
 The long-time average yields of wheat from the untreated land in 
 these tests ranged from 1 bushel to nearly 30 bushels an acre. Even 
 tho adapted varieties were used in well-designed systems of cropping, 
 the yields on the light-colored soils averaged less than 6 bushels an 
 acre, ranging from 1 bushel to 8 bushels. Untreated dark-colored soils 
 averaged 22 bushels an acre, the range being from 17 to nearly 30 
 bushels. The untreated land on one sandy field averaged less than 9 
 bushels, but in seasons of favorable moisture almost 20 bushels an 
 acre were obtained (data not shown). 
 
 Thus soils low in productivity often fail to return much more than 
 the equivalent of the seed used, while highly productive soils, even 
 without soil treatment, may return seed 20 to 30 fold when conditions 
 are favorable. 
 
 Altho differences in yields that accompanied differences in soils 
 were narrowed considerably by soil treatment, there were no treat- 
 ments that completely overcame the fundamental soil differences. The 
 highest yields continued to come from those fields that gave the highest 
 yields without any treatment (Fig. 2). 
 
180 
 
 BULLETIN No. 503 
 
 [July, 
 
 
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1944] 
 
 SOIL TREATMENTS FOR WINTER WHEAT 
 
 181 
 
 The continued use of soil treatments, however, has made the 
 naturally low-producing soils of southern Illinois almost as good pro- 
 ducers of wheat as the dark-colored soils of the corn belt (Fig. 3). 
 
 Effectiveness of Soil Treatment 
 
 With few exceptions, the systems of soil treatment used in these 
 experiments raised the yields of wheat on every field (Table 2). The 
 relative effectiveness of the different systems varied greatly, however, 
 with the types of soils to which they were applied. In general the in- 
 creases were largest on the less-productive soils, where the more com- 
 plete treatments were needed. Under treatment, these soils tended to 
 give yields approaching those of the more highly productive untreated 
 dark-colored soils. 
 
 WHEAT YIELDS-LONG TIME 
 
 NET INCREASE FOR TREATMENT 
 NO TREATMENT 
 
 Fig. 2. Long-time wheat yields, showing net increases for most effective 
 treatments. This graph is based on averages ending in 1942. The untreated 
 soils vary widely in their ability to produce wheat. Net response to treat- 
 ment tends to be largest on the less productive soils. 
 
 Both livestock (manure) and grain (residues') systems brought 
 good results. On some fields the livestock systems were most effective ; 
 on others the grain systems had the advantage. On the whole there 
 was little difference in the responses to these two types of systems. 
 
182 
 
 BULLETIN No. 503 
 
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1944] 
 
 SOIL TREATMENTS FOR WINTER WHEAT 
 
 183 
 
 Part Played by Each Treatment Material 
 
 Since the systems of soil treatment used in these experiments in- 
 volve a step-by-step build-up, it is possible to determine the separate 
 effects of each material used. The data -on this point are given in 
 Table 3. 
 
 Most materials, it should be kept in mind, were used in association 
 with other materials. If they had been used alone, larger or smaller 
 effects might have been obtained. When two materials possess over- 
 
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 30 
 
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 WHEAT YIELDS 1939-1942 
 
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 Fig. 3. Wheat yields during last rotation, showing net increases for most 
 effective treatments. Good soil treatment has gradually raised the yields on 
 the light-colored soils of southern Illinois until the best of them have 
 reached almost the level of the dark-colored soils. 
 
 lapping functions, either used alone would tend to have a greater effect 
 than either used with the other. On the other hand, any material used 
 alone would tend to be less effective on a soil deficient in another 
 material than it would be where all plant nutrients were adequately 
 supplied. 
 
 It is evident that the treatment materials used in these experiments 
 increased the wheat yields on most fields. There is, however, consider- 
 able variation in their behavior under different soil conditions. 
 
184 BULLETIN No. 503 
 
 Manure and crop residues. The chief sources of nitrogen and 
 organic matter used in these experiments were animal manure (M) 
 and crop residues (R). Being by-products of the farm, they can be 
 returned to the soil with little or no cash expense. The quantities that 
 can be returned, however, depend on the productiveness of the soil. 
 
 Manure, in general, gave greater increases than crop residues. The 
 manure supplied not only nitrogenous organic matter but also readily 
 usable mineral nutrients and, perhaps, other constituents as well. Crop 
 residues varied a great deal in both quantity and quality. On the less 
 productive soils the legumes usually failed where the land was un- 
 limed; the returned residues consisted chiefly, therefore, of small 
 amounts of stover and straws. On the more productive soils, however, 
 the unlimed land usually produced good stands of legume crops, and 
 their roots and stubble provided considerable quantities of effective 
 residues. 
 
 Altho the manure system gave fairly substantial increases in yield 
 on all experiment fields, it tended to be more effective on the dark- 
 colored soils. The tendency toward smaller increases on the less pro- 
 ductive soils was due in part, no doubt, to the smaller amounts of 
 manure applied. The residues system also was more effective on the 
 dark-colored soils, chiefly because the dark-colored soils produced 
 better stands of legumes and green manure crops and therefore sup- 
 plied more residues to be returned to the soil. The amounts of non- 
 
 Rock phosphate: yield 27 bushels No treatment: yield 16 bushels 
 
 Fig. 4. How wheat responds to rock phosphate. Broadcasted at the rate of 
 1,000 to 1,500 pounds an acre, rock phosphate has substantially increased 
 wheat yields on many soils. The plots shown above are on the University 
 South Farm at Urbana. 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 185 
 
 legume residues returned to the less productive soils were so meager 
 that they had little effect in increasing the yields of wheat. 
 
 Limestone. When applied as a supplement to either manure or 
 crop residues, limestone (L) was the most important aid in increasing 
 the yields of wheat (Table 3). In general the response to limestone 
 increased with declining soil productivity. The tendency, however, was 
 toward better results with the residues systems on the dark-colored 
 soils and with the manure systems on the light-colored soils. Field 
 observations and legume-hay yields (data not shown) suggest that the 
 major influence of limestone was due to the larger accumulation of 
 organic matter which resulted from better stands and better growth of 
 legume crops. Soils capable of growing legumes satisfactorily without 
 limestone gave little or no increase in yields of nonlegume crops as a 
 result of liming. 
 
 Phosphates. In these experiments, rock phosphate (rP) applied 
 as a supplement to the manure-limestone and residues-limestone treat- 
 ments increased the wheat yields on most fields, but the increases were 
 more variable than those which were due to limestone (Table 3). Rock 
 phosphate was, in general, more effective in the residues systems than 
 in the manure systems. Altho there was a tendency toward larger re- 
 sponses on soils of low productivity, some highly productive soils gave 
 rather good increases while some soils of low productivity gave rather 
 poor yield increases (Fig. 4). 
 
 Superphosphate was not used in the original treatment systems, but 
 changes were made in 1923 on a number of experiment fields in order 
 to permit its use. Since it possesses chemical characteristics different 
 from those of rock phosphate, experiments were made to determine 
 whether its effects in the treatment system would be different from 
 the effects of rock phosphate. On some fields superphosphate was 
 broadcasted before wheat seeding at the rate of about 300 pounds an 
 acre while on others it was drilled with the wheat at the rate of around 
 200 pounds. 
 
 Results are now available for periods ranging from 13 to 19 years. 
 Data for this carrier, applied with and without limestone in the resi- 
 dues systems of farming, together with comparable data for rock phos- 
 phate, are shown in Table 4. 
 
 Both carriers tended to give greater increases on soils of declining 
 productivity, but this relationship was not entirely consistent. For 
 example, on the Hartsburg field, located on rather productive soil, both 
 carriers caused greater increases than on some other fields located on 
 less productive soils. At Hartsburg the effects of superphosphate were 
 
186 
 
 BULLETIN No. 503 
 
 [July, 
 
 TABLE 4. AVERAGE ACRE-YIELDS OF WHEAT AND INCREASES FROM ROCK 
 
 PHOSPHATE AND SUPERPHOSPHATE APPLIED WITH AND 
 
 WITHOUT LIMESTONE* 
 
 Without limestone 
 
 With limestone 
 
 Field 
 
 Number 
 of 
 crops 
 
 Yield 
 without 
 phosphate 
 
 Increases from 
 
 Yield 
 without 
 phosphate 
 
 Increases from 
 
 Rock 
 phosphate 
 
 Super- 
 phosphate 
 
 Rock 
 phosphate 
 
 Super- 
 phosphate 
 
 Hartsburg . . . 
 
 . . . 18 
 
 bu. 
 28.7 
 28.3 
 27.4 
 26.6 
 23.9 
 9.7 
 7.4 
 5.6 
 
 bu. 
 5.4 
 3.5 
 4.2 
 3.1 
 6.1 
 9.9 
 11.2 
 
 bu. 
 3.5 
 2.5 
 3.4 
 5.9 
 6.7 
 6.7 
 7.7 
 7.0 
 
 bu. 
 26.8 
 34.3 
 32.8 
 31.1 
 27.4 
 20.3 
 15.2 
 24.8 
 
 bu. 
 5.2 
 3.0 
 3.0 
 .7 
 2.5 
 4.6 
 9.6 
 6.8 
 
 bu. 
 8.6 
 2.1 
 3.0 
 3.4 
 4.8 
 5.1 
 10.9 
 8.9 
 
 Aledo 
 
 . . 19 
 
 Dixon 
 
 . . 19 
 
 
 14 
 
 
 . 13 
 
 
 . . 19 
 
 Raleigh 
 
 . . 17 
 
 Ewing b 
 
 . . 14 
 
 
 
 The phosphates were applied to the wheat and corn crops grown in four-year rotations. At the 
 Carthage, Ewing, and Lebanon fields the phosphates were drilled with the wheat and hill-dropped for 
 the corn. The average acre-rates of application on the annual basis were 90 pounds of superphosphate 
 and 140 pounds of rock phosphate. At the other fields broadcast applications were made. The average 
 annual acre-rate was 150 pounds of superphosphate, 300 pounds of rock phosphate without limestone 
 and 400 pounds with limestone. Crop residues were plowed under on all plots. b Potassium deficiencies 
 were corrected. No rock phosphate was used on unlimed land, and on limed land the rock phosphate 
 was residual since 1924. 
 
 especially striking. Recently established experiments on the Minonk 
 field, which belongs to the same soil group, gave similar results. 
 
 The data in Table 4 indicate in general that both rock phosphate 
 and superphosphate increased the yields of wheat on soils of different 
 productivity levels. Without limestone, rock phosphate gave slightly 
 larger increases than superphosphate; with limestone, this relationship 
 was reversed. Usually, however, the highest total yields were obtained 
 on the limed land. 
 
 These experiments show that the usefulness of phosphate may be 
 affected by the presence or absence of other treatment materials. These 
 other materials may add to the phosphorus-supplying power of the 
 soil, or they may overlap the functions of the phosphates. In either 
 event the phosphate would tend to be less effective than if used alone. 
 On the other hand, if another nutrient element, such as potassium, 
 was as deficient as phosphorus, the applied phosphate would be subject 
 to handicaps. 
 
 There is evidence that systems which include manure, crop residues, 
 and limestone do increase the phosphorus-supplying powers of some 
 soils. Chemical analyses (data not shown) of experiment-field soils 
 show that the amount of available phosphorus in the surface soil of a 
 number of fields has increased. This increase may be due (1) to the 
 return of soil-derived phosphorus in applied animal manure; (2) to 
 the use of subsoil phosphorus by deep-rooted legumes and the accumu- 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 187 
 
 lation of this phosphorus in the surface soil when the legumes are 
 plowed under; and (3) to the influence of limestone in maintaining 
 soil phosphorus in more usable forms. Altho these relationships can 
 not all continue indefinitely, they may be of considerable temporary 
 importance. 
 
 Overlapping functions of limestone and phosphate. Limestone and 
 phosphate may also possess overlapping functions. Both contain cal- 
 cium, an important element in plant nutrition. If the calcium in 
 phosphate serves any useful purpose, the total yield increases resulting 
 from separate applications of limestone and phosphate should be 
 greater than the increases from the two when both are applied on the 
 same soil. An experiment established on the Aledo field in 1916 pro- 
 vides data for such comparisons (Table 5). 
 
 TABLE 5. VALUE OF CROP INCREASES" PER ACRE PER YEAR WHEN LIMESTONE AND 
 
 PHOSPHATE WERE APPLIED TO SEPARATE PLOTS AND 
 
 WHEN APPLIED TO THE SAME PLOTS 
 
 (Aledo field, 1916-1940) 
 
 Limestone and phosphate applied to Limestone and 
 
 Phosphorus carriers' 1 and separate plots phosphate ap- Over- 
 amount applied per plied to the lapping 
 
 acre per year Limestone" Phosphate Total same plot effects" 1 
 
 Value of increases during period of phosphate applications, 
 
 1916-1931 
 
 
 Bone (130 pounds) 
 
 $2 . 44 
 
 55.01 
 4.40 
 4.11 
 5.31 
 
 $7.45 
 6.99 
 6.94 
 8.41 
 
 $6.44 
 5.94 
 5.00 
 6.67 
 
 $1.01 
 1.05 
 1.94 
 1.74 
 
 Super (223 pounds) 
 
 2 59 
 
 Rock (467 pounds) . . 
 
 2 83 
 
 Slag (188 pounds) 
 
 3.10 
 
 
 
 Value of increases during period of residual phosphate effect! 
 
 i, 1932-1942 
 
 
 Bone (130 pounds) 
 
 . . $2 . 35 
 
 SI. 82 
 2.86 
 2.71 
 3.26 
 
 34.17 
 6.17 
 6.38 
 6.37 
 
 $4.34 
 4.01 
 5.15 
 4.73 
 
 -$ .17 
 2.16 
 1.23 
 1.64 
 
 Super (223 pounds) 
 
 3.31 
 
 Rock (467 pounds) 
 
 3.67 
 
 Slag (188 pounds) 
 
 3.11 
 
 
 
 With corn at 50 cents a bushel, oats at 30 cents, wheat at $1, hay at $10 a ton. ^Until last 
 pplication in 1931. "Six tons an acre; none applied since 1918. d Difference between Columns 3 and 4. 
 
 Four carriers of phosphorus were applied with and without lime- 
 stone. Limestone was also used with and without the phosphates. The 
 yields show overlapping effects in every instance with the exception 
 of bone phosphate in the last period. Such data may be interpreted as 
 measuring the depressing effects of limestone on phosphates and of 
 phosphates on limestone. It is interesting to note that during the 
 period in which the phosphates were applied, the phosphates alone pro- 
 duced better increases than limestone alone, but in the subsequent 
 period this relationship was reversed. This behavior tends to support 
 the implications discussed above. 
 
188 
 
 BULLETIN No. 503 
 
 Response to phosphate reduced by potash deficiencies. Especially on 
 the less productive soils, a deficiency of potash may prevent phosphate 
 applications from having their full effect on crop yields. If this is 
 true, increases from phosphate should be greater when applied in addi- 
 tion to residues, limestone, and potash (RLK) than when applied with 
 only residues and limestone (RL), as in the original systems of treat- 
 ment. To permit further study of these relationships, some changes 
 were made on the Ewing field in 1929. No new applications of rock 
 phosphate were made, but superphosphate was introduced for compari- 
 son with rock phosphate. The data thru 1942 are recorded in Table 6. 
 
 The residual rock phosphate, on the whole, gave better yield in- 
 creases after the potash deficiency was corrected than before. Super- 
 phosphate applied in addition to potash was less effective than the rock 
 phosphate in the earlier years, but has been more effective during 
 recent years. These results emphasize the need for correcting all defi- 
 ciencies which affect crop yields. 
 
 Another question is raised by a study of these data. Since potash 
 deficiencies affect the usefulness of the phosphates, will not phosphorus 
 
 TABLE 6. INCREASES IN WHEAT YIELDS SHOWING How UNCORRECTED POTASSIUM 
 
 DEFICIENCY REDUCED EFFECTIVENESS OF PHOSPHATIC FERTILIZERS AND 
 
 How UNCORRECTED PHOSPHATE DEFICIENCY REDUCED 
 
 EFFECTIVENESS OF POTASH FERTILIZERS, 1929-1942 
 (Ewing field: data are in terms of four-year mowing averages*) 
 
 Increases from phosphates 1 " 
 
 Increases f 
 
 rom potash 
 
 Year 
 
 Yields from 
 crop 
 residues 
 and 
 limestone 
 (RL) 
 
 Potash 
 
 deficiency 
 
 No potash deficiency 
 
 Phosphate 
 deficiency 
 (RLK/RL) 
 
 No 
 phosphate 
 deficiency 
 (RLrPK/ 
 RLrP) 
 
 Rock 
 phosphate 
 (RLrP/ 
 RL) 
 
 Rock 
 phosphate 
 (RLrPK/ 
 RLK) 
 
 Super- 
 phosphate 
 (RLKsP/ 
 RLK) 
 
 1929 ... . 
 
 bu. 
 . 20 3 
 
 bu. 
 3.4 
 1.2 
 3.0 
 3.3 
 5.3 
 
 7.1 
 6.4 
 7.3 
 5.8 
 
 4.5 
 
 6.3 
 5.7 
 5.0 
 5.3 
 
 5.0 
 
 bu. 
 8.4 
 5.1 
 5.9 
 4.7 
 3.3 
 
 5.1 
 4.5 
 7.8 
 9.9 
 
 8.2 
 
 10.0 
 
 7.7 
 6.5 
 8.1 
 
 6.8 
 
 bu. 
 5.0 
 4.1 
 2.9 
 
 2.4 
 2.1 
 
 6.0 
 7.1 
 11.6 
 15.1 
 11.8 
 
 13.4 
 10.1 
 9.0 
 
 11.4 
 
 8.9 
 
 bu. 
 4.0 
 3.8 
 3.9 
 6.1 
 8.4 
 
 8.3 
 8.2 
 6.0 
 
 4.4 
 5.3 
 
 4.9 
 5.1 
 4.6 
 2.9 
 
 5.3 
 
 bu. 
 9.0 
 7.7 
 6.8 
 7.5 
 6.4 
 
 6.3 
 6.3 
 6.5 
 
 8.5 
 9.0 
 
 8.6 
 7.1 
 6.1 
 5.7 
 
 7.1 
 
 1930 
 
 17.7 
 
 1931 
 
 23.5 
 
 1932 
 
 23 9 
 
 1933 
 
 22.3 
 
 1934... 
 
 24.1 
 
 1935 
 
 17.2 
 
 1936 
 
 14.4 
 
 1937 : 
 
 14.4 
 
 1938 ... 
 
 12 3 
 
 1939... 
 
 15.8 
 
 1940 
 
 20 
 
 1941 
 
 . 23 3 
 
 1942 
 
 23.0 
 
 Average 
 
 19 5 
 
 
 
 Full four-year averages were not attained until 1932. b Rock phosphate was last applied in 
 1924; superphosphate was first applied in 1929, at rates of 200 pounds drilled at wheat seeding and 
 200 pounds at corn planting. "Based on annual acre-yields. 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 189 
 
 deficiencies affect the usefulness of potash? The Ewing experiments 
 throw some light on this point (Table 6). With few exceptions potash 
 gave better increases where the soils did not lack phosphorus. The 
 difficulty of assigning definite values to any one treatment is apparent 
 from these data. 
 
 Detailed study of the Ewing wheat yields indicates that there is a 
 need for both phosphate and potash on this field. These materials gave 
 similar increases earlier, but those due to superphosphate are now 
 tending to become somewhat larger than those due to rock phosphate 
 or potash. Similar studies of corn (data not shown) reveal large in- 
 creases that can be credited to potash and comparatively small increases 
 that can be credited to phosphates. 
 
 Special studies with phosphates. Tests to compare the effective- 
 ness of different kinds of phosphates and different rates of application 
 of rock phosphate were begun at the Joliet and Kewanee fields in 1927. 
 The soils were unlimed, slightly acid, and moderately productive for 
 their respective soil groups. 
 
 Wheat and legume hay were grown in a two-year rotation on small 
 replicated plots. Rock phosphate (Table 7) was broadcasted ahead of 
 the wheat drill, half of the total amount being put on in 1927 and the 
 remainder in 1929. Different phosphate carriers were broadcasted before 
 each wheat crop. At the time the experiment was begun, the acre-cost 
 of each treatment was about $3.50. 
 
 TABLE 7. AVERAGE ACRE-YIELDS OF WHEAT WHERE ROCK PHOSPHATE AND 
 
 OTHER PHOSPHATE CARRIERS WERE BROADCASTED 
 
 (Joliet and Kewanee fields, 1928-1939. Rotation: wheat and red 
 
 clover or alfalfa) 
 
 Treatment 
 
 Joliet 
 6 crops 
 
 Kewanee 
 5 crops 
 
 Yields with rock phosphate applied at different rates* 
 
 
 
 No rock phosphate 
 
 bu. 
 . 18.6 
 
 bu. 
 25.9 
 
 500 pounds an acre 
 
 19 4 
 
 28.5 
 
 1 ,000 pounds an acre 
 
 . 23.0 
 
 32.3 
 
 2,000 pounds an acre 
 
 . 24.3 
 
 34.7 
 
 4,000 pounds an acre 
 
 24 9 
 
 34.4 
 
 
 
 
 Yields with different phosphate carriers 1 " 
 
 
 
 No phosphate carrier 
 
 . 16.2 
 
 23.2 
 
 Rock phosphate (400 pounds) 
 
 20 1 
 
 32.3 
 
 Bone meal (110 pounds) 
 
 . 22.1 
 
 32.4 
 
 Superphosphate, 20-percent (250 pounds) 
 
 23 
 
 31.6 
 
 Superphosphate, 45-percent (1 10 pounds) 
 
 . 24.3 
 
 31.9 
 
 
 
 
 Half of the total amount was applied ahead of the 1928 crop and half of the 1930 crop. b Applied 
 for each wheat crop. 
 
190 BULLETIN No. 503 [July, 
 
 The behavior of wheat with rock phosphate was similar at the two 
 fields. The second ton of rock phosphate caused no increase in yield 
 over that of the first ton. The yields were a little larger where a 
 2,000-pound application was made than where a 1,000-pound applica- 
 tion was made. 
 
 At Kewanee the four phosphate carriers gave almost identical 
 results, the wheat increases averaging 8.8 bushels an acre, with a range 
 of only .8 bushel between the lowest and the highest increase. At Joliet 
 rock phosphate and treble superphosphate increased yields 3.9 and 8.1 
 bushels respectively. The effects of the bone meal and of the 20-per- 
 cent superphosphate were midway between these extremes. 
 
 A detailed study of the effect of different phosphates when used 
 with light and with heavy limestone applications has been made at 
 Carlinville. A two-year rotation of corn and wheat, with a sweet-clover 
 green-manure catch crop, was used. The corn was cut before wheat 
 seeding. In this rather exhausting rotation the yields have been low 
 on those plots where sweet clover and the phosphates have been omit- 
 ted (Table 8). On the area receiving only li/2 tons of limestone an 
 acre, the rock phosphate, superphosphate, and concentrated superphos- 
 phate have increased the wheat yields an average of 8.6 bushels an 
 acre, little difference being shown among the three carriers. When 
 used with 5 tons of limestone to the acre, the two superphosphates 
 have given almost equal returns, averaging 10.7 bushels an acre, 
 
 TABLE 8. INCREASES IN WHEAT YIELDS, SHOWING EFFECT OF ROCK PHOSPHATE 
 AND SUPERPHOSPHATE WHEN USED WITH LIGHT AND 
 
 WITH HEAVY LIMESTONE APPLICATIONS 
 (Carlinville field. Rotation: corn, wheat (sweet clover). Phosphates broadcasted) 
 
 Treatment 
 
 Average 
 annual acre 
 rate of 
 application 
 
 Wheat yield 
 
 Increases due to 
 
 8-crop Phosphate 
 average 
 
 Heavy 
 liming 
 
 Sweet-clover 
 catch crop 
 
 
 Light liming (1 
 
 J^ tons an acre) 
 
 
 
 
 
 Ib. 
 
 bu. 
 11.5 
 19.8 
 20.4 
 20.1 
 12.2 
 
 bu. 
 
 S.3 
 8.9 
 8.6 
 
 bu. 
 
 bu. 
 
 - 7 
 
 
 333 
 
 Superphosphate, 20-percent 
 
 167 
 
 
 83 
 
 
 
 
 
 
 Heavy liming 
 
 (5 tons an acre) 
 
 
 
 
 
 
 19.2 
 
 25.5 
 29.0 
 30.7 
 12.7 
 
 '6.3 
 9.8 
 11.5 
 
 7.7 
 5.7 
 8.6 
 10.6 
 
 .5 
 
 6 5 
 
 Rock phosphate 
 
 . 333 
 
 
 167 
 
 
 83 
 
 None Cno sweet clover) . . 
 
 
1944~\ SOIL TREATMENTS FOR WINTER WHEAT 191 
 
 whereas rock phosphate gave only 6.1 bushels. In the four-year rota- 
 tion at Carlinville the long-time average response of wheat to the rock- 
 phosphate treatment in the grain- farming system was only 3.6 bushels 
 an acre (Table 3). This and a number of other experiments indicate 
 that winter wheat is much more responsive to phosphate when grown 
 after a summer crop, such as corn or soybeans, than when grown after 
 a spring grain. The frequency of wheat in the rotation may also be 
 significant in this comparison: wheat in the first mentioned rotation 
 occurs every second year ; in the latter rotation, only every fourth year. 
 
 That organic matter is important in wheat production is again 
 emphasized by the data from the Carlinville experiment (Table 8). On 
 one plot at each limestone level, sweet clover was not seeded. Where 
 the liming was light (li/ tons an acre), this omission caused little 
 change because there was not enough limestone to produce a good 
 growth of sweet clover. On the area which received 5 tons of limestone 
 to the acre, the omission of the sweet-clover catch crop reduced the 
 average wheat yield 6.5 bushels an acre. The average yield of the 
 four plots where sweet-clover was seeded was 8.1 bushels higher on 
 the heavily limed area than on the area receiving only a light liming. 
 
 Potash. On the permanent experiment fields carriers of potas- 
 sium (K) were applied as a supplement to the residues, limestone, rock- 
 phosphate treatment. 
 
 Potassium, thus used, increased the wheat yields on most fields 
 (Table 3). The need for potash increased generally with declining soil 
 productivity. The increases during recent years (data not shown] have 
 become much larger than those of the long-time average. It is also of 
 interest to note that corn and legume crops are much more sensitive to 
 potash deficiencies than is wheat. For a thoro understanding of these 
 data, the disadvantages caused by other nutrient deficiencies should be 
 kept in mind (see page 188). 
 
 Effect of Long-Continued Treatment 
 
 Thruout the thirty-year period the treated land in these tests has 
 yielded substantially more wheat than the untreated land. This is one 
 clear and outstanding fact to be derived from these long-time experi- 
 ments. There are other considerations, however, which are of vital 
 economic importance in the evaluation of soils and systems of soil im- 
 provement. These are the quickness of the response produced and the 
 yield limits attainable. Light on these questions is supplied by Figs. 
 5, 6, and 7, which show yield trends for two systems of treat- 
 
192 
 
 BULLETIN No. 503 
 
 1912 
 
 1916 
 
 1920 
 
 1924 
 
 1932 
 
 1936 
 
 1940 
 
 Fig. 5. Trend of wheat yields on very dark heavy soils, treated and 
 untreated. These soils, with moderately permeable subsoils and shallow 
 carbonates, are represented by the Hartsburg and Minonk fields. Wheat 
 does well on these soils if a good rotation is practiced. The use of minerals, 
 however, is necessary in order to prevent a gradual decline in production. 
 
 1912 
 
 1916 
 
 1920 
 
 1928 
 
 1932 
 
 1936 
 
 1940 
 
 Fig. 6. Trend of wheat yields on moderately dark soils, treated and un- 
 treated. The soils of this group, which have a grayish cast and slowly 
 permeable subsoils, are represented by the Carlinville, Carthage, Clayton, 
 and Lebanon fields. These soils are good producers of wheat. High yields 
 can be maintained with soil treatment and a good rotation. The use of 
 manure and limestone (ML, livestock system) was about as effective as 
 residues, limestone, phosphorus, and potash (RLrPK, grain system). 
 
1944] 
 
 SOIL TREATMENTS FOR WINTER WHEAT 
 
 193 
 
 1916 
 
 1920 
 
 1924 
 
 1932 
 
 1936 
 
 1940 
 
 Fig. 7. Trend of wheat yields on gray, strongly leached soils, treated and 
 untreated. These soils, with slowly permeable subsoils, are represented by 
 the Newton, Oblong, and Toledo fields. Untreated soils of this group are 
 very low in organic matter and are poor producers of wheat. With soil treat- 
 ment, yields increased gradually until 1934, when they reached 36.6 bushels. 
 
 ment (ML and RLrPK) for thirty years on ten experiment fields 
 located on three different groups of soils. 
 
 The highly productive soils in Group II (Fig. 5) show a rapid 
 upward trend in wheat yields during the first four years regardless of 
 treatment a trend probably due to an improved cropping system. 
 For the first twelve years there was little difference between treat- 
 ment and no treatment, but since that time the yields have been 
 declining faster on the untreated land. During recent years differences 
 in yields have been substantially in favor of the treatment systems, but 
 the treatments have not, on the whole, raised yields they have merely 
 prevented declines such as have taken place on the untreated land. 
 
 On the moderately productive soils in Group V (Fig. 6) wheat 
 yields increased gradually during the first eleven years on both the 
 treated and the untreated land. The increases on the treated land dur- 
 ing this time were more rapid than in later years, the yields changing 
 from around 13 bushels to more than 33 bushels an acre. During recent 
 years the yields on the treated soils have been fairly uniform, tending 
 to range between 30 and 35 bushels. Thruout almost the entire time 
 the residues systems have been a little more productive than the 
 manure systems. The yields on the untreated land declined gradually 
 following the first increases but have been slowly rising again. 
 
194 BULLETIN No. 503 
 
 The wheat yields on the light-colored soils of Group VII were low 
 when these experiments were begun (Fig. 7). Crop rotation without 
 soil treatment had little effect in bettering them. With treatment, how- 
 ever, there was a fairly consistent upward trend until the drouth 
 period beginning in 1935, when yields declined sharply. During recent 
 years recovery is in evidence. Yields have risen as high as 35 bushels 
 an acre on the treated land, being somewhat higher in the residues 
 systems than in the manure systems. There was no evidence that the 
 highest levels had been obtained during the predrouth period, but 
 whether yields will continue upward following recovery from the 
 drouth remains to be seen. 
 
 EFFECT OF DIRECT FERTILIZER APPLICATION 
 
 The cumulative effects of long-continued treatments have just been 
 described. The treatment materials were used with crop rotation, and 
 their influences on wheat yields seem to be due largely to their effect 
 on organic matter replenishment and the general productivity level of 
 the soil. 
 
 Fertilizer materials applied directly for winter wheat also have been 
 studied in many tests. The relative importance of certain nutrient ele- 
 ments nitrogen, phosphorus, and potassium and the most appropriate 
 time, method, and amount of their application have been considered. 
 Several different commercial carriers of nitrogen and phosphorus have 
 been compared, and also a number of experimental phosphates. 
 
 Effect of Materials Applied Alone and in Combination 
 
 Tests were made during the years 1931-1939 to compare certain 
 individual fertilizer materials ammonium sulfate (N), muriate of 
 potash (K), rock phosphate (rP), and superphosphate (sP) broad- 
 casted for winter wheat. Each material was used alone, and the phos- 
 phates were used also in combination with nitrogen and potassium. 
 The tests were made cooperatively on farmers' fields which had been 
 limed. Average results from 13 trials on seven dark-colored soils 
 and 6 trials on three light-colored soils are reported (Table 9). The 
 nitrogen (N) applications were broadcasted in the spring, ammonium 
 sulfate being used at the rate of 100 pounds an acre in most tests. Just 
 before wheat seeding, the other fertilizers were broadcasted on the 
 prepared seedbed. Potassium was supplied in muriate of potash applied 
 at the rate of 100 pounds an acre. Rock phosphate was applied at rates 
 
1944] 
 
 SOIL TREATMENTS FOR WINTER WHEAT 
 
 195 
 
 TABLE 9. INCREASES IN WHEAT YIELDS RESULTING FROM USE OF AMMONIUM 
 
 SULFATE (N), POTASSIUM CHLORIDE (K), ROCK PHOSPHATE (rP), AND 
 
 SUPERPHOSPHATE (sP) ON DARK-COLORED AND LIGHT-COLORED SOILS 
 
 (Broadcasted on limed land, 1931-1939) 
 
 Fertilizer 
 
 Dark-colored 
 soils, average 
 of 1 3 crops on 
 7 fields 
 
 Light-colored 
 soils, average 
 of 6 crops on 
 3 fields 
 
 Dark-colored 
 Fertilizer soils, average 
 of 13 crops on 
 7 fields 
 
 Light-colored 
 soils, average 
 of 6 crops on 
 3 fields 
 
 N... 
 
 bu. 
 . . . 5.6 
 
 bu. 
 .8 
 3.9 
 
 
 6.4 
 3.9 
 
 2.5 
 
 .3 
 3.4 
 
 
 6.5 
 4.4 
 
 2.4 
 
 rP 
 
 bu. 
 3.4 
 2.2 
 4.7 
 3.3 
 
 3.4 
 
 5.5 
 6.2 
 6.2 
 6.0 
 
 6.0 
 25.6 
 
 bu. 
 4.4 
 .2 
 .8 
 3.3 
 
 2.2 
 
 9.5 
 7.5 
 8.5 
 8.5 
 
 8.5 
 18.1 
 
 N over K 
 
 . 4 4 
 
 
 N over rP 
 
 . . . 5.4 
 
 rP over K 
 
 
 6 3 
 
 rP over NK 
 
 N over rPK 
 
 3 
 
 Average increase 
 
 N over sPK 
 
 ... 4.2 
 
 Average increase 
 from N 
 
 . . . 4.8 
 
 sP 
 
 K... 
 
 . . . 2.6 
 
 
 sP over K 
 
 K over N 
 
 . . . 2.4 
 
 sP over NK 
 
 K over P 
 
 3 9 
 
 Average increase 
 
 K over sP 
 
 ... 3.3 
 
 K over rPN 
 
 . . . 1.5 
 
 . Average yield with- 
 out fertilizer . . . 
 
 K over sPN 
 
 . . . 1.2 
 
 Average increase 
 from K 
 
 . . . 2.5 
 
 
 
 varying from 400 to 800 pounds an acre ; superphosphate rates varied 
 from 200 to 350 pounds an acre. 
 
 Previous liming and the use of legumes had made the soils moder- 
 ately productive. Where no fertilizers were applied, the average wheat 
 yields on the dark-colored and the light-colored soils were 25.6 and 
 18.1 bushels respectively. 
 
 Superphosphate was the most effective of these fertilizers, giving 
 an average acre-return of 6 bushels on the dark-colored soils and 8.5 
 bushels on the light-colored soils. Potash used in addition to nitrogen 
 and phosphate was quite effective on the light-colored soils. Nitrogen 
 applied in the spring consistently increased yields on the dark-colored 
 soils, the increases averaging 4.8 bushels an acre. On the light-colored 
 soils, it caused an average increase of 4.7 bushels an acre when used 
 with potash but failed to give consistent increases when potash was 
 omitted. 
 
 Effect of Nitrogen Fertilizers Top-Dressed 
 
 Nitrogen deficiencies affect winter wheat in spring more than at 
 any other time. When severe, the plants become pale green or yellow. 
 
 Most of the nitrogen for Illinois crops is supplied by the use of 
 legumes in crop rotations and by the return of animal manure to the 
 soil, but under some conditions the use of additional nitrogen from 
 commercial sources has been found practical. 
 
196 BULLETIN No. 503 [July, 
 
 TABLE 10. WHEAT INCREASES DUE TO TOP DRESSINGS OF AMMONIUM SULFATE AT 
 
 DIFFERENT DATES AND FOLLOWING DIFFERENT CROPS 
 
 (Grundy silty clay loam, Greene county, 1931. Ammonium sulfate applied at rate of 
 100 pounds an acre to land previously limed and phosphated) 
 
 Time of application 
 
 Wheat after wheat 
 
 Wheat after oats 
 
 Wheat after four 
 corn crops 
 
 Average 
 increase 
 
 Total 
 yield 
 
 Increase 
 
 Total 
 yield 
 
 Increase 
 
 Total 
 yield 
 
 Increase 
 
 
 bu. 
 37 
 
 bu. 
 
 2.0 
 4.1 
 1.5 
 
 2.5 
 
 bu. 
 34.0 
 38.0 
 41.3 
 37.4 
 
 bu. 
 
 i'.b 
 
 7.3 
 3.4 
 
 4.9 
 
 bu. 
 25.4 
 35.0 
 42.0 
 28.1 
 
 bu. 
 
 9\6 
 16.6 
 
 2.7 
 
 9.6 
 
 bu. 
 
 S'.2 
 9.3 
 2.5 
 
 Late fall (October 29) .... 
 Early spring (March 18) . . 
 Late spring (April 22) .... 
 
 . 39.0 
 . 41.1 
 . 38.5 
 
 
 
 
 
 The efficiency of nitrogen-carrying fertilizers for winter wheat de- 
 pends principally on (1) the productivity of the soil, (2) previous 
 crops, (3) time of application, and (4) weather conditions in April 
 and May. Tests with ammonium sulfate on productive dark-colored 
 soil in Greene county (Table 10) have supplied information regarding 
 the effect of the first three of these conditions, and numerous other 
 field experiments show similar results. Wheat following four consecu- 
 tive corn crops made considerably larger responses to this nitrogen 
 fertilizer than were made by wheat after wheat or wheat after oats. 
 Without ammonium sulfate, however, the wheat after corn produced 
 considerably less than wheat after grain; and the early spring appli- 
 cation brought yields up to approximately the same level on each of the 
 three rotations. Best returns' from ammonium sulfate have usually 
 been obtained from applications made about the time spring growth 
 becomes active. In the Greene county test, applications made March 18 
 were considerably more effective than those of either April 22 or 
 October 29. 
 
 In seasons favorable to wheat growth nitrogen applications have 
 frequently failed to give crop increases on soils of moderate or high 
 productivity. Instead they have sometimes caused lodging (see page 
 205), which has resulted not only in reduced yield but also in a 
 lower quality of grain. Damage to the clover seeded in the wheat may 
 also result from lodging. 
 
 On the more productive soils clover stands have sometimes been 
 greatly reduced by nitrate applications even where wheat growth was 
 not excessive. Poor inoculation on high nitrate soils suggests that an 
 excessive supply of nitrates may interfere with normal activity of the 
 nodule bacteria. 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 197 
 
 TABLE 11. INCREASES IN WHEAT YIELDS DUE TO DIFFERENT CARRIERS OF 
 
 NITROGEN TOP-DRESSED ON WHEAT ON PREVIOUSLY 
 
 UNTREATED SOILS Low IN NITRATES 
 
 County, soil type, and date of application 
 
 Nitrogen carrier and amount 
 applied per acre 
 
 1934 
 
 1939 
 
 Crawford : 
 O'Neill sandy 
 loam, 
 March 20 
 
 'Crawford: 
 O'Neill sandy 
 loam, 
 April 25 
 
 Montgomery: 
 Harrison silt 
 loam, 
 May 2 
 
 Washington: 
 Cisne silt 
 loam. 
 May 2 
 
 Increases due to treatment 
 
 Ammonium sulfate (100 pounds) . 
 Calcium cyanamide (100 pounds) 
 Sodium nitrate (135 pounds) .... 
 
 bu. 
 ... 5.4 
 . . . 8.8 
 . . . 9.5 
 
 bu. 
 -1.0 
 2.7 
 5.8 
 
 bu. 
 2.4 
 5.9 
 11.4 
 
 bu. 
 6.0 
 
 7.7 
 
 
 
 Yields without treatment 
 
 No treatment 16.0 16.0 13.1 11.0 
 
 Effect of Different Nitrogen Carriers 
 
 Tests of different carriers of nitrogen applied in the spring have 
 shown sodium nitrate to be slightly more effective than either 
 ammonium sulfate or calcium cyanamide. 
 
 Crop increases resulting from several different soil conditions are 
 reported in Table 11. Application rates were adjusted so that each 
 carrier supplied 20 pounds of the element nitrogen per acre. 
 
 The chemical nature of sodium nitrate makes it* more quickly 
 effective than either ammonium sulfate or calcium cyanamide, and 
 the sharp reduction in response that followed delayed applications of 
 these latter materials suggests that they should be applied somewhat 
 earlier than the most effective top-dressing date for sodium nitrate. 
 
 A series of tests using ammonium sulfate or sodium nitrate to 
 supply 20 pounds of nitrogen an acre on limed land in the spring was 
 made during the seasons 1931 to 1938. The tests included 22 wheat 
 crops grown on 10 different farms having a wide range of soil types. 
 All the soils were in a fairly high state of productivity. Wheat yields 
 were increased an average of 4 bushels an acre by the use of these 
 nitrogen carriers. 
 
 Effect of Mixed Fertilizers Applied Directly 
 
 Mixed fertilizers are prepared by combining available plant nutri- 
 ents in simple mixtures. Compounds of any two or all three of the 
 nutrient elements nitrogen, phosphorus, and potassium may be included. 
 
198 
 
 BULLETIN No. 503 
 
 C/u/y, 
 
 The proportion of each ingredient is designated by a numerical sys- 
 tem. Nitrogen is reported directly as percent of nitrogen, phosphorus 
 as percent of phosphorus pentoxide (P 2 O 5 ), commonly called phos- 
 phoric acid, and potassium as percent of potash (K 2 O). The portions 
 of the three ingredients are reported in the order just mentioned. Thus 
 a 2-12-6 fertilizer mixture contains 2 percent of nitrogen, 12 percent of 
 phosphoric acid, and 6 percent of potash. 
 
 The relative effectiveness of the three different ingredients in fer- 
 tilizer mixtures when drilled with wheat was studied in field tests made 
 during the seasons 1935 to 1937. Each year three previously untreated 
 fields were selected. The fertilizers were especially mixed, the amount 
 of one ingredient being progressively increased without changing the 
 percentages of the other two (Table 12). 
 
 The single-element carriers were also included in most of the tests. 
 All materials and mixtures were drilled with the seed wheat at the acre 
 rate of 200 pounds. 
 
 Superphosphate, whether used alone or in any combination, gave 
 good results in all these tests. Apparently the amount of phosphorus 
 supplied by a 200-pound application of 2-12-6 was enough when drilled 
 with the seed to remove the deficiency for the wheat crop (Fig. 8). 
 
 In these and many other tests the use of nitrogen in fertilizers has 
 increased yields only slightly. Ordinarily under Illinois conditions 
 this nutrient is best supplied by the use of inoculated legumes in the 
 
 TABLE 12. YIELDS OF WINTER WHEAT WHERE FERTILIZER MIXTURES WERE 
 DRILLED WITH THE SEED 
 
 Fertilizer drilled at 
 rate of 200 pounds 
 an acre 
 
 Average by years* 
 
 Average on different soils 
 
 1935 
 
 1936 
 
 1937 
 
 Light-colored 
 soils 
 
 Moderately 
 dark soils 
 
 Dark 
 soils 
 
 
 bu. 
 . 14.1 
 
 bu. 
 16.6 
 26.3 
 31.6 
 29.3 
 34.9 
 34.2 
 21.4 
 
 17.2 
 20.3 
 31.5 
 31.6 
 30.2 
 30.9 
 27.6 
 
 17.2 
 30.8 
 31.6 
 33.9 
 36.9 
 27.1 
 25.0 
 
 bu. 
 27.2 
 39.2 
 37.5 
 39.0 
 39.0 
 36.2 
 29.3 
 
 26.3 
 29.2 
 39.4 
 38.7 
 36.4 
 37.1 
 36.5 
 
 22.1 
 34.1 
 37.2 
 36.1 
 37.0 
 33.5 
 23.3 
 
 bu. 
 13.6 
 21.6 
 24.5 
 24.7 
 23.3 
 
 15.1 
 16.9 
 32.1 
 24.6 
 23.0 
 
 13.7 
 25.5 
 23.0 
 27.6 
 29.0 
 
 bu. 
 17.8 
 35.0 
 30.2 
 30.0 
 32.0 
 29.2 
 22.2 
 
 18.1 
 21.8 
 30.3 
 32.6 
 30.9 
 32.7 
 30.2 
 
 15.7 
 28.4 
 31.8 
 32.0 
 33.0 
 30.7 
 22.3 
 
 bu. 
 26.4 
 33.1 
 38.6 
 37.1 
 38.3 
 
 25.1 
 27.0 
 33.3 
 39.2 
 37.8 
 
 38.7 
 
 27.1 
 33.2 
 35.3 
 39.1 
 41.1 
 
 0-12-6 
 
 . 24.2 
 
 2-12-6 
 
 . 24.2 
 
 4-12-6 
 
 . 23.4 
 
 8-12-6 
 
 . 19.6 
 
 8-12-0 
 
 
 12-0-0 
 
 
 None 
 
 . 14.8 
 
 2-0-6 
 
 . 16.1 
 
 2-6-6 .... 
 
 25 
 
 2-12-6 
 
 . 26.0 
 
 2-18-6 . 
 
 25 
 
 0-24-6 
 
 
 0-24-0 
 
 
 None 
 
 17.3 
 
 2-12-0 
 
 . 22.3 
 
 2-12-6 
 
 21.3 
 
 2-12-12 
 
 . 28.7 
 
 2-12-18 
 
 29 2 
 
 0-6-24 
 
 
 0-0-24 . 
 
 
 
 
 "Tests each year were made on three previously unfertilized fields. 
 
1944] 
 
 SOIL TREATMENTS FOR WINTER WHEAT 
 
 199 
 
 rotation. Commercial nitrogen, if used for winter wheat, is usually 
 most effective when applied as a top-dressing in the spring (see 
 page 197). 
 
 Most of the gray-colored soils of southern Illinois are sufficiently 
 low in available potassium to justify including it in fertilizer mixtures 
 for wheat because of its effect on succeeding crops as well as its effect 
 on the wheat. 
 
 Fig. 8. Mixed fertilizers and superphosphate are usually most effective 
 when drilled with the seed. The plot at the left shows the effect of a 2-12-6 
 fertilizer drilled for wheat. The plot at the right had superphosphate. Taken 
 near Savoy in Champaign county, this picture shows typical spring-growth 
 response to phosphate fertilizers on phosphorus-deficient soils. 
 
 Tests Using Experimental Phosphates 
 
 During recent years the U. S. Department of Agriculture has done 
 considerable research in the preparation of phosphate fertilizers, some 
 of which have been used in field tests with winter wheat. Altho the 
 new materials are not on the market at present, the results of the tests 
 are of interest. 
 
 TABLE 13. AVERAGE ACRE-YIELDS OF WHEAT ON PLOTS FERTILIZED WITH 
 
 COMMERCIAL SUPERPHOSPHATE AND ON PLOTS FERTILIZED WITH 
 
 EXPERIMENTAL PHOSPHATES 
 
 Available 
 Treatment phosphoric 
 acid 
 (PiOs) 
 
 Approxi- 
 mate 
 acre-rate 
 drilled 
 
 Average acre-yields each year 
 
 Average for four 
 years 
 
 1937 
 5 trials 
 
 1938 
 2 trials 
 
 1939 
 
 5 trials 
 
 
 5 trials 
 
 Yield 
 
 Increase 
 
 None 
 
 perct. 
 
 Ib. 
 
 iso 
 
 125 
 75 
 60 
 
 bu. 
 17.3 
 28.2 
 26.9 
 29.8 
 29.5 
 
 bu. 
 34.4 
 40.6 
 40.7 
 38.4 
 44.2 
 
 bu. 
 27.6 
 30.8 
 32.5 
 3K6 
 33.6 
 
 bu. 
 24.1 
 36.4 
 33.4 
 35.8 
 35.4 
 
 bu. 
 25.9 
 34.0 
 33.4 
 33.9 
 35.7 
 
 bu. 
 
 8.1 
 7.5 
 8.0 
 9.8 
 
 Superphosphate 
 
 20 
 26 
 51 
 63 
 
 Fused rock phosphate. . . 
 Monocalcium phosphate. . 
 Metacalcium phosphate. . 
 
200 
 
 BULLETIN No. 503 
 
 {.July, 
 
 Comparisons show these phosphates to be about as effective as 20- 
 percent superphosphate when drilled for wheat in amounts which 
 supply equal quantities of available phosphorus (Table 13). The con- 
 centrated materials, however, have the advantage of being more con- 
 veniently sacked and shipped, and it now seems that their place in 
 commercial use will be determined largely by their cost and by the 
 supply of equipment with which to apply them satisfactorily. 
 
 Effects of Productivity Levels on Usefulness of Fertilizers 
 
 There are different opinions as to the place of readily available 
 fertilizers in a soil-improvement program. Should such fertilizers be 
 used at the beginning of such a program, or should they be used as the 
 last step after the cropping system, well balanced with deep-rooted 
 legumes, has been established ? The soil-experiment fields provide excel- 
 lent opportunities for answering questions of this kind because, as a 
 result of various treatments, a wide range of productivity levels has 
 been developed. Plots on several of the fields are now being utilized for 
 this purpose. Results with wheat on dark-colored soils of medium pro- 
 
 40 
 
 35 
 
 30 
 
 J25 
 
 10 
 
 WHEAT - CARTHAGE 
 
 ORIGINAL TREATMENT 1 
 + ROCK PHOSPHATE 
 
 + SUPERPHOSPHATE Q 
 -f MIXED FERTILIZER 
 
 M ML MLrP 
 
 RL RLrP RLrPK 
 
 Fig. 9. Wheat yields on the Carthage field, with original and with supple- 
 mentary treatments, 1930-1942. On the untreated plots (0) of this moder- 
 ately productive land, wheat has responded markedly to phosphates and 
 mixed fertilizers drilled at seeding time. The effect of such supplementary 
 treatments has been much reduced, however, wherever any of the basal 
 systems of treatment have been used. 
 
1944] 
 
 SOIL TREATMENTS FOR WINTER WHEAT 
 
 201 
 
 ductivity at Carthage and on light-colored soils of low productivity at 
 Ewing are of interest. 
 
 The use of supplementary fertilizers was begun in 1929, about 
 twenty years after the original treatments were established. At both 
 fields the plots were subdivided in order to maintain on some plots the 
 original treatments and on others to allow for drilling fertilizers with 
 wheat and corn at planting time as a supplement to each of the original 
 treatments. At Carthage 400 pounds of rock phosphate, 200 pounds of 
 20-percent superphosphate, and 200 pounds of 2-12-6 were drilled with 
 the wheat at seeding time. At Ewing the supplementary treatments 
 consisted of 100 pounds of muriate of potash and the same quantity 
 of potash combined with 200 pounds of 20-percent superphosphate. 
 At Ewing during recent years these fertilizers have been drilled into 
 the soil a few days ahead of wheat seeding to avoid delaying germina- 
 tion. The effects of these practices are shown graphically in Figs. 
 9 and 10. 
 
 Both the original and the supplementary treatments increased wheat 
 yields on the two fields. 
 
 At Carthage the effect of the supplementary treatments was rather 
 
 40 
 35 
 30 
 
 10 
 
 WHEAT-EWING 
 
 ORIGINAL TREATMENT 
 
 + POTASH 
 
 + POTASH AND sP 
 
 O M ML MLrP O RL RLrP RLrPK 
 
 Fig. 10. Wheat yields on the Ewing field, with original and with supple- 
 mentary treatments, 1929-1942. This field is representative of the gray soils 
 of southern Illinois which, without the help of lime and legumes, are too 
 low in organic matter and nitrogen to produce satisfactory wheat yields 
 or satisfactory yields of any other crops. Fertilizers used at seeding time 
 cannot overcome the basic deficiencies of these soils. 
 
202 BULLETIN No. 503 [July, 
 
 large on the untreated land but decreased with the increasing pro- 
 ductivity which was brought about by the long-continued basal treat- 
 ments. The supplementary treatments brought yields to almost as high 
 a level on the previously untreated plots as they were on the plots 
 which had received treatment for many years. The thirteen-year 
 average shows superphosphate to have been slightly more effective than 
 rock phosphate and less effective than the 2-12-6 fertilizer. In recent 
 years, however, the effects of rock phosphate (data not shown) have 
 approached those of superphosphate and with some treatments have 
 surpassed them. 
 
 Supplementary treatment on unlimed land at Ewing approximately 
 doubled the yield of wheat, but even with this increase the yield was 
 still too low for efficient production. On limed land where long con- 
 tinued treatment had supplied the necessary phosphorus and potassium, 
 the supplementary treatment had little effect; but where either phos- 
 phorus or potassium was lacking, the treatments gave large increases. 
 
 Thus where productivity levels are not too low, fertilizers applied 
 directly for wheat may be helpful in attaining satisfactory yields. But 
 on soils which are as depleted of nutrients as those of the untreated 
 plots at Ewing and which have other conditions as unfavorable, such 
 fertilizers are of little value until organic matter has been replenished 
 by the use of manure, crop residues, and limestone. 
 
 BEST METHODS OF APPLYING FERTILIZERS 
 
 From the many experiments which have been made to compare the 
 efficiency of different methods of fertilizing wheat, a number of 
 guiding principles have been fairly well established. 
 
 1. Nitrogen-carrying fertilizers are most effective when broad- 
 casted in the early spring. 
 
 2. Rock phosphate should be thoroly mixed with the surface 
 soil, and is most effective when used with legumes in a good rotation. 
 Acre-applications of 1,000 to 1,500 pounds made at intervals of eight 
 to twelve years have been satisfactory and on phosphorus-deficient 
 soils have been followed by good wheat responses. Excessive liming 
 should be avoided if rock phosphate is used, because a slightly acid 
 soil reaction is necessary for greatest returns from rock phosphate. 
 Numerous tests using small amounts of rock phosphate drilled for 
 wheat have shown drilling to be somewhat less effective than broad- 
 casting the larger amounts mentioned above. 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 203 
 
 3. Superphosphate in small amounts drilled near the seed will 
 satisfy the needs of a single crop since most of the phosphorus in 
 superphosphate is quickly available to wheat plants. The phosphorus 
 requirements of other crops in the rotation, however, must be satis- 
 fied, and this often can be most conveniently done by a single larger 
 treatment at wheat-seeding time. As larger applications are made, the 
 need for drilling becomes less imperative ; in fact where large amounts 
 of superphosphate are used, drilling sometimes causes delays in ger- 
 mination, but this method does have the advantage of timeliness, con- 
 venience, and uniformity of distribution. Since winter-wheat plants 
 seem to require an abundance of phosphorus during their early growth, 
 drilling superphosphate near the seed is the best method of applying 
 it. When applied in the spring, superphosphate treatments for winter 
 wheat on phosphorus-deficient soils show only slight increases. 
 
 4. Potassium, where needed for winter wheat, is most beneficial 
 when applied at seeding time. It may be broadcasted on the prepared 
 seedbed or included in a fertilizer mixture. Drilling potash with the 
 seed, either alone or in large quantities in a mixture, is likely to inter- 
 fere with germination, especially if the seedbed is dry. Altho acre- 
 applications as large as 150 to 200 pounds of 0-20-20 have been drilled 
 without damaging effect, larger amounts are likely to reduce stands. 
 
 Most of the potassium tests reported in the preceding pages were 
 made with muriate of potash, this being the carrier most commonly 
 used now in Illinois. 
 
 5. Mixed fertilizers have given greatest returns when applied 
 with a fertilizer attachment on a wheat drill, as suggested for super- 
 phosphate. There are now on the market granular fertilizers which 
 can be drilled successfully from the wheat hopper of an ordinary grain 
 drill if a fertilizer attachment is not available. This is a makeshift 
 method which requires a second trip over the field, but it gives good 
 results. Finely powdered fertilizers, however, cannot be applied satis- 
 factorily from the wheat hopper. 
 
204 BULLETIN No. 503 [July, 
 
 RELATION OF SOIL TREATMENTS TO 
 OTHER YIELD FACTORS 
 
 Insect Damage Reduced by Fertilization 
 
 Fertilization of soil offers some protection against at least two of 
 the major insect enemies of wheat the chinch bug and the Hessian 
 fly. It is well known that chinch bugs prefer thin wheat. If they can 
 find feeding places elsewhere, they will avoid the rank growth of 
 fertile wheat fields. Hessian fly injury is prevented to a large extent 
 by delaying seeding until after the relatively "fly-free date." Occasion- 
 ally, even if this precaution is taken, weather conditions are such that 
 damage by the spring brood of Hessian fly may be quite serious. In 
 such seasons losses on soils well supplied with phosphorus have 
 been low. 
 
 TABLE 14. RESPONSE OF WHEAT INFESTED WITH HESSIAN FLY TO DIFFERENT 
 
 FERTILIZERS, 1939 
 
 Fertilizer 
 
 Acre-rate 
 drilled 
 
 Acre 
 yield 
 
 Test 
 weight 
 
 Fallen' 
 straw 
 
 Hay 
 yield b 
 
 None 
 
 Ib. 
 
 bit. 
 21 3 
 
 Ib. 
 54.5 
 
 perct. 
 18.0 
 
 Ions 
 1.69 
 
 Rock phosphate (broadcasted) 
 
 1 ,000 
 
 32.3 
 
 57.5 
 
 5.7 
 
 2.47 
 
 Superphosphate, 20 percent 
 
 ISO 
 
 39 4 
 
 57 5 
 
 .3 
 
 2.17 
 
 None 
 
 
 23.4 
 
 56.0 
 
 8.3 
 
 1.34 
 
 0-20-20 
 
 150 
 
 46 2 
 
 57 
 
 1 3 
 
 2.14 
 
 Calcined phosphate 
 
 125 
 
 47 
 
 56 5 
 
 .7 
 
 2.63 
 
 None 
 
 
 27.7 
 
 56.0 
 
 9.0 
 
 1.57 
 
 Fused phosphate . . 
 
 125 
 
 48 5 
 
 57 5 
 
 .3 
 
 2.46 
 
 Metaphosphate 
 
 60 
 
 47 4 
 
 57.0 
 
 2.3 
 
 2.10 
 
 None 
 
 
 26.1 
 
 55.0 
 
 17.7 
 
 1.69 
 
 Average of untreated plots . . 
 
 
 24 6 
 
 55.4 
 
 13.2 
 
 1.57 
 
 Average of treated plots 
 
 
 43.5 
 
 57.2 
 
 1.8 
 
 2.33 
 
 
 
 
 
 
 
 Courtesy of J. H. Bigger, Illinois State Natural History Survey. b Clover-timothy mixture. 
 
 The response of wheat to phosphate fertilization on phosphorus- 
 deficient soils is usually good and is quite certain to be large during 
 Hessian fly seasons. In such seasons yields are usually low as well as 
 of poor quality unless the soil is well supplied with available phos- 
 phorus. The results given in Table 14 and the contrast shown in Fig. 1 1 
 illustrate this point. The plots were located on Catlin silt loam in 
 Champaign county. The fertilizers were drilled with the wheat in the 
 fall of 1938. The average yields on the treated plots were almost 
 double those on the untreated plots: 43.5 bushels compared with 24.6 
 bushels. The high percentage of fallen straw on the untreated plots is 
 a common symptom of Hessian fly injury. 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 205 
 
 :^ \,*l 
 
 Fig. 11. Well-nourished wheat (right) is less susceptible to Hessian fly 
 injury. This pest of wheat is usually well controlled by delaying seeding 
 until the recommended date. Sometimes, however, weather conditions en- 
 courage serious infestation by the spring brood even tho the seeding rule is 
 followed. Phosphate fertilization has greatly reduced losses from this cause. 
 (Data for above plots are given in Table 14.) 
 
 Effect on Wheat Lodging and on Clover Stands 
 
 Wheat often makes rapid and heavy growth on fertile soils, some- 
 times becoming so rank that it falls to the ground before maturing. 
 This condition, commonly called lodging, makes harvesting difficult 
 and frequently reduces the yield and quality of the grain. 
 
 Lodging is usually associated with high nitrate supplies in the soil. 
 Therefore, to prevent it, efforts have been made to balance these high 
 nitrate supplies by adding phosphate and potash fertilizers. Most of 
 these efforts, however, have been unsuccessful, and it seems best to 
 combat wheat lodging by using varieties that have stiff straw 1 and by 
 so placing wheat in the rotation that it will come at a time when soil 
 nitrates are not excessively high. 
 
 Ordinarily a legume or hay mixture seeded in wheat will be bene- 
 fited by the residual effect of phosphate and mixed fertilizers used 
 for wheat (Table 14). However, the heavy growth which results from 
 the use of fertilizers sometimes causes severe shading and other 
 injury to the clover seeding and may possibly be the direct cause of 
 failure. Losses of this kind occur only on soils of relatively high 
 fertility. Where wheat lodging and excessive growth of straw are a 
 
 'For latest recommendations see Circular 563 of this Station, "Winter 
 Wheat Varieties in Illinois," 1943. 
 
206 
 
 BULLETIN No. 503 
 
 - 
 
 O C 
 
 *> O 
 
 .2 s 
 
 y O 
 <u o 
 
 o rt 
 
 i- C 
 O OJ "~ 
 
 ** C 
 
 ? :3 o 
 
 8H 
 
 * c 
 
 .0 o 
 
 J3 
 
 J3 > < 
 
 35^ 
 
 JJ -MO 
 
 S o OT 
 
 <u 
 
 ^ *^S 
 
 . 
 
1944} 
 
 SOIL TREATMENTS FOR WINTER WHEAT 
 
 207 
 
 perennial problem, it may be best to change the present crop rotation 
 or to pasture or clip spring growth. 
 
 Effect of Soil Treatment on Wheat Quality 
 
 Test weight per bushel is the most commonly used measure of 
 quality for market wheat. During seasons of extreme damage from 
 plant diseases, drouth, or insects the test weight is usually increased 
 by soil treatment. The effect of soil treatment in reducing Hessian 
 fly damage is illustrated in Table 14. In 1937 central Illinois wheat 
 suffered an epidemic of stem rust which made some fields of grain 
 almost worthless. On other fields fertilization greatly reduced the 
 damage and improved the yield and quality, apparently because the 
 treatments hastened maturity by making the plants less susceptible to 
 infection when the disease' struck. 
 
 In any season when there is danger of disease, drouth, or insect 
 damage, early maturity is of considerable advantage (Figs. 12 and 13). 
 
 No treatment: yield 20.8 bushels, 
 test weight 47 pounds 
 
 )-20-10: yield 43 bushels, 
 test weight 56.5 pounds 
 
 Fig. 13. Fertilized wheat is usually less damaged by disease. The earlier 
 ripening of fertilized wheat is often a reason for its escaping disease injury. 
 The wheat stems of Fulhio shown here were grown in Pike county in 1941. 
 
208 
 
 BULLETIN No. 503 
 
 [July, 
 
 Fertile Soil Provides Insurance Against Failures 
 
 Under Illinois conditions soil fertility helps to stabilize wheat yields 
 from year to year. Mention of the protection which soil treatment gives 
 against insect damage was made on page 204. 
 
 The value of a fertile soil in protecting the wheat crop against the 
 combined effect of all hazards over a fifteen-year period on four fields 
 Aledo, Carlinville, Mt. Morris, and Oblong varying widely in their 
 productive capacity, is shown in Fig. 14. In this graph the frequency 
 
 45 
 40 
 35 
 30 
 
 Q- 15 
 
 10 
 
 OBLONG 
 
 "*-ALEDO 
 
 -CARLINVILLE 
 
 MLrP O R RL 
 
 SOIL TREATMENT 
 
 RLrP RLrPK 
 
 Fig. 14. Extent to which wheat yields have deviated from the average 
 under different soil treatments, fifteen-year average for four fields. Syste- 
 matic soil treatment has tended to stabilize wheat yields. The smallest 
 variations have occurred where treatments were most complete. The four 
 fields selected for this analysis have varied widely in their productive 
 capacity (Table 2). 
 
 with which crop failures have occurred is indicated by the extent to 
 which yearly yields deviated from the average yield for the period, 
 wide variation indicating frequent failures. At Aledo, for example, 
 where the untreated soil is relatively fertile, the average yearly devia- 
 tion was low and was not greatly affected by soil treatment. At Oblong, 
 where the untreated soil is rather unproductive, yielding only about 9 
 bushels an acre during the fifteen-year period, yearly variations from 
 the average were very wide, averaging 46.1 percent. But land that had 
 been built up with crop residues, limestone, phosphate, and potash 
 showed an average yearly deviation of only 22.7 percent from the 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 209 
 
 average yield for the period, thus demonstrating the "insurance" value 
 of soil treatment. 
 
 The frequency of low yields during the fifteen-year period is re- 
 ported in Table 15 for each fertility level on these same fields, Aledo, 
 
 TABLE 15. FREQUENCY OF Low WHEAT YIELDS ON DIFFERENTLY 
 TREATED PLOTS ON FOUR EXPERIMENT FIELDS, 1921-1935 
 
 Number of times during 15 years that low 
 
 yields (less than 60 percent of 
 Soil treatment average) were secured 
 
 
 Aledo 
 
 Carlinville 
 
 Mt. Morris 
 
 Oblong 
 
 o 
 
 1 
 
 3 
 
 3 
 
 5 
 
 M 
 
 
 
 1 
 
 2 
 
 3 
 
 ML 
 
 1 
 
 1 
 
 1 
 
 3 
 
 MLrP 
 
 1 
 
 1 
 
 1 
 
 2 
 
 . 
 
 . 
 
 2 
 
 4 
 
 5 
 
 R 
 
 
 
 2 
 
 4 
 
 3 
 
 RL 
 
 
 
 
 
 2 
 
 1 
 
 RLrP 
 
 2 
 
 
 
 1 
 
 1 
 
 RLrPK 
 
 1 
 
 
 
 1 
 
 1 
 
 
 
 
 
 
 Carlinville, Mt. Morris, and Oblong. Altho there is a definite tendency 
 for the better soils to have fewer failures or near failures, it is also to 
 be observed that the number of failures on the poorer soils was greatly 
 reduced by appropriate soil treatments. 
 
 CONCLUSIONS: SUGGESTIONS TO 
 WHEAT GROWERS 
 
 Satisfactory yields of winter wheat can be produced on most of 
 the cropland of Illinois if adapted varieties 1 are grown and if suitable 
 soil treatments are used. The following soil-management practices are 
 of major importance in producing wheat efficiently. 
 
 Rotations are needed that will provide a moderate supply of 
 nitrates and organic matter in the soil at seeding time. On soils of 
 moderate or low productivity, wheat can be grown successfully after 
 legume or sod crops; but on fertile soils it is better to have it follow 
 a small grain crop. During favorable seasons, wheat may be seeded 
 after soybeans or corn. Under most conditions, it is a satisfactory 
 companion crop for legume seedings. 
 
 Liming of acid soil is necessary in order to get a good growth of 
 
 'See Bulletin 460 of this Station, "Winter Wheat Varieties for Illinois," 
 1939 ; and Circular 563, "Winter Wheat Varieties in Illinois," 1943. 
 
210 BULLETIN No. 503 [July, 
 
 soil-building legumes, without which the nonlegume crops, including 
 wheat, cannot be produced efficiently. 1 
 
 Phosphating of phosphorus-deficient soils is essential. The appli- 
 cation of 1,000 to 1,500 pounds of rock phosphate an acre every eight 
 to twelve years is recommended. If superphosphate or other carriers 
 of this nutrient are used, they give best results when applied in small 
 amounts for each responsive crop in the rotation. Best utilization of 
 phosphorus from applied fertilizers or from minerals in the soil re- 
 quires the regular growing of legumes and the maintenance of a good 
 supply of organic matter. 2 
 
 Drilling fertilizers that contain phosphorus or phosphorus and 
 potash is effective where soils have low supplies of these nutrients. 
 Standard grades, such as 20-percent superphosphate and 0-20-10, may 
 be drilled at the rate of 100 to 150 pounds an acre at seeding time. 
 If broadcasted, the rate should be increased to 200 to 250 pounds, and 
 the fertilizer should be applied before seeding and mixed with the 
 surface soil. 
 
 Potassium, where needed, may be supplied by broadcasting 100 to 
 250 pounds of muriate of potash per acre at seeding time ; the best rate 
 will depend on the degree of deficiency and the methods used to 
 fertilize other crops in the rotation. Winter wheat will tolerate a greater 
 potassium deficiency than will corn or legumes, but it is especially 
 sensitive to a shortage of phosphorus during the early stages of its 
 growth. If wheat is seeded after a late-maturing crop, such as soybeans, 
 a temporary phosphorus deficiency may develop and justify drilling 
 superphosphate or mixed fertilizers even on soils which are otherwise 
 well supplied with available phosphorus. 
 
 Top-dressing wheat with a nitrogen-supplying fertilizer gives 
 variable results, depending largely on weather conditions and the pro- 
 ductivity of the soil. Early spring applications of 100 to 125 pounds 
 of ammonium sulfate an acre, or the nitrogen equivalent supplied by 
 other carriers, have given good returns on nitrogen-deficient soils. On 
 fertile land, top-dressing with nitrate fertilizers is usually ineffective 
 and may cause lodging. Under most Illinois conditions, however, nitro- 
 gen is best supplied by the systematic use of legumes in the rotation. 
 
 Phosphates and mixed fertilizers applied as top-dressings in the 
 
 detailed discussion of this problem will be found in Bulletin 405 of this 
 Station, "Response of Illinois Soils to Limestone," issued in 1934. 
 
 2 The phosphate problem is discussed in detail in Bulletin 484 of this Station, 
 "The Problem of Phosphate Fertilizers," issued in 1942. 
 
1944] SOIL TREATMENTS FOR WINTER WHEAT 211 
 
 spring are much less effective than when drilled at seeding time and 
 are not advised unless needed for succeeding crops. 
 
 Wheat lodging often occurs on soils high in nitrates. The use of 
 phosphorus and potash to balance this condition frequently causes 
 greater lodging and seldom reduces it. Where lodging is a serious 
 problem, stiff-strawed varieties should be grown. In extreme cases a 
 change in the crop rotation or the use of spring pasturing or clipping 
 may be practical. 
 
 Failures and near failures of winter wheat are less frequent 
 when it is grown on fertile land. Under Illinois conditions the hazards 
 from winterkilling and drouth and from insect and disease injury are 
 materially reduced by good soil management. 
 
WINTER WHEAT IS A RELIABLE 
 widely-adapted cash crop for Illinois 
 farmers. It fits easily into rotations, helps to 
 distribute the farm labor load, reduces soil 
 erosion, and provides a satisfactory companion 
 crop for legume seedings. 
 
 Except for phosphorus, the nutrient require- 
 ments of winter wheat are only moderate. 
 Where there is too little available phosphorus, 
 yields are likely to be low and quality poor, 
 and in unfavorable seasons complete failure of 
 the crop is almost certain. 
 
 A good time to apply fertilizers is when the 
 seedbed is being prepared or the seed being 
 drilled. Any plan of treatment should recognize 
 the needs of the other crops in the rotation. 
 
 Of all our common crops winter wheat is 
 one of the most responsive to phosphate 
 fertilizers. 
 
 12,0507-4428188 
 
SRSITYOF.LLINUIS-URBANA