University of Illinois Library at Urbana-Champaign ACES (W .:* ^mE> /3 f m>A THE FERTILITY IN ILLINOIS SOILS BY CYRIL G. HOPKINS, CHIEF IN AGRONOMY AND CHEMISTRY, AND JAMES H. PETTIT, ASSISTANT CHIEF IN SOIL FERTILITY "Westward the course of empire takes its way," with ruined lands behind. The purpose of the six years' work represented in this bulletin is to furnish definite facts and necessary information to Illinois landowners and farmers that will enable them to plan and adopt systems of farming under which the soils of Illinois will be certain to continue, or improve, in productive power instead of decreasing in fertility as they are doing under the most common present prac- tices. While the bulletin deals primarily with the invoice of plant food in the most important Illinois soils found in a general soil survey of the state, its value is greatly increased and strengthened because of the large amount of definite information concerning the numerous soil types already accumulated in connection with the detail soil survey which is being conducted under the immediate charge of Professor J. G. Mosier with a corps of able assistants ; also by the numerous results already obtained from the soil experiments which are carried on in many parts of the state on representative fields in charge of Superintendent J. E. Readhimer and his assistants. But the absolute basis of these investigations rests upon chem- ical analysis, and especial acknowledgments are made to the fol- lowing chemists upon whose chemical knowledge and analytical skill the accuracy of the work depends : Professor I. O. Schaub, now at the Iowa Station ; Doctor E. M. East, now at the Connecti- cut Station ; Mr. W. F. Pate, now at the Ohio Station ; Mr. An- drew Ystgard, deceased ; Mr. N. E. Bell, now at the Alabama Sta- tion ; and Doctor L. H. Smith, A. W. Gregory, and E. VanAlstine, who continue in the service of Illinois. PLAN OF INVESTIGATION In the investigation of the fertility of the soil in its relation to crop production five general questions must be considered. i. What are the plant food requirements of the crops to be produced ? 187 188 BULLETIN No. 123. [February, 2. What is the total stock of plant food contained in the soil strata which we are able to control? 3. How rapidly by practical methods can this plant food be made available to the growing crops ? 4. When necessary, in order to produce more profitable crop yields, how can we most economically supplement or increase the plant food in the soil? 5. Under what systems will the productive power of the soil be permanently maintained? PLANT FOOD REQUIRED BY CROPS It should be remembered that of the ten different chemical elements required for the growth of agricultural plants, three come directly from air and water in practically unlimited amounts (except in time of drouth), and that these three, carbon, hydrogen, and oxy- gen, constitute, as a rule about 95 percent of the mature crop. Nevertheless each of the seven elements obtained from the soil, though aggregating only 5 percent, is just as necessary to the life and full development of the plant, as are these three. The four elements, sulfur, calcium, iron, and magnesium, are required by crops in such small amounts and are present in nearly all soils in such large amounts that the supply rarely if ever becomes depleted, thus narrowing the problem essentially to three elements, constituting not more than 4 percent of the average crop. The productive capacity of practically all soils in good physical condition is measured by the available supply of the three plant food elements, phosphorus, potassium, and nitrogen, because they are required by all crops in very considerable quantities, while in most soils the supply of one or more of them is limited. If the supply of one of these elements is too limited, it must as a conse- quence, limit the yield of the crop, even though all other factors es- sential to crop production are well provided. It is because of these facts that the three elements, phosphorus, potassium, and nitrogen, in commercial form, have come to have a recgnized money value. A careful study of Table i is sufficient to make the reader familiar with the plant food requirements of the more important Illinois crops. Information is also given regarding the amounts of these valuable elements contained in the different parts of the crop, as grain, stalks, and straw, and in some animal products, in order that it may be known with some degree of accuracy how much of each element is removed from the soil in crops and how much is sold from the farm in different kinds of farm produce. The ideal prac- tice is to return to the soil in farm manures all plant food not sold from the farm. /pa*.] THE FERTILITY IN ILLINOIS SOILS. 189 The data given in Table I are on the basis of pounds per acre for crop yields which are large, but which, when the best conditions are furnished, have been and may be produced with very great profit yields that may well stand as an ideal, desirable and possible to be attained. Of course, approximately proportionate amounts would be re- quired for any other yields. Thus, if it is preferred to plan to make possible yields only one-half as large, then the amounts given may be divided by two. TABLE 1. FERTILITY IN FARM PRODUCE (Approximate maximum amounts removable per acre annually) Produce. Pounds. Market value. Kind. Amount. Nitro- gen. Phos- phorus. Potas- sium. Nitro- gen. Phos- phorus. Potas- sium. Total value. Corn, grain . . . 100 bu. 100 17 19 $15.00 $ 2.04 $ 1.14 $18 18 Corn stover . . . 3T. 48 6 52 7.20 .72 3.12 11.04 Corn crop ...... 148 23 71 22.20 2.76 4.26 29.22 Oats, grain . . . lOObu. 66 11 16 9.90 1.32 .96 12.18 Oat straw 2^T. 31 5 52 4.65 .60 3 12 8.37 Oat crop ...... 97 16 68 14 55 1 92 4 08 20 55 Wheat, grain . SO bu 71 12 13 10.65 1.44 .78 12.87 Wheat straw. . 2^T. 25 4 35 3.75 .48 2.10 6.33 Wheat crop . . . 96 16 48 14.40 1.92 2.88 19.20 Timothy hay. . 3T. 72 9 71 10.80 1.08 4.26 16.14 Clover seed.. . . 4bu. 7 2 3 1.05 .24 .18 .1.47 Clover hay. . . . 4T. 160 20 120 24.00 2.40 7.20 33.60 Cowpea hay. . . Alfalfa hay 3T. 8T. 130 400 14 36 98 192 19.50 60.00 1.68 4.32 5.88 11.52 27.06 75.84 Apples 600 bu. 47 5 57 7.05 .60 3.42 11.07 L/eaves 4T. 59 7 47 8.85 .84 2.82 12.51 Wood growth. 1/50 tree 6 2 . 5 .90 .24 .30 1.44 Total crop 112 14 109 16.80 1.68 6.54 25.02 Potatoes 300 bu. 63 13 90 9.45 1.56 5.40 1641 Sugar beets. . . 20 T. 100 18 157 15.00 2.16 9.42 26.58 Fat cattle 1,000 Ib. 25 7 1 3.75 .84 .06 4.65 Fat hogs 1,000 Ib. 18 3 1 2.70 .36 .06 3.12 Milk lO.OOOlb. 57 7 12 8.55 .84 .72 10.11 Butter 500 Ib. 1 0.2 0.1 .15 .02 0.1 .18 The value of the elements is computed on the basis of the pres- ent market prices for readily available plant food, namely : Nitrogen 15 cents a pound Phosphorus 12 cents a pound Potassium 6 cents a pound 190 BULLETIN No. 123. [February, It may be said that other similar crops resemble somewhat closely those given in Table I as to plant food requirements. Thus rye and barley are not markedly different in requirements from wheat and oats, considering equal yields in pounds of grain and straw. Other root crops may be compared with sugar beets, other grasses with timothy, hay from other annual legumes with cowpea hay, and other biennial and perennial legumes may be compared in a general way with red clover and alfalfa. The figures given in Table i are based upon averages of many analyses, of which some have been made by the Illinois Station and others by various chemists in America and Europe. These aver- ages are believed to be trustworthy for large crops of good quality. Abnormal or special crops may vary considerably from these aver- ages. Thus we have high-protein corn and low-protein corn, one strain requiring nearly twice as much nitrogen and somewhat more phosphorus than the other; and we have shown in Bulletins 76 and 94 that alfalfa and cowpeas are not only much more productive but much richer in nitrogen when grown on Illinois soils with the proper bacteria than without bacteria. TABLE 2. FERTILITY IN MANURE, ROUGH FEEDS, AND FERTILIZERS Name of material. Pounds per ton. Value per ton. Nitro- gen. Phos- phorus. Potas- sium. Nitro- gen. Phos- phorus. Potas- sium. Total value. Fresh farm manure 10 16 12 10 40 43 SO 280 310 400 80 20 2 2 2 2 O 5 4 180 250 250 125 10 10 17 21 14 30 33 24 850 850 200 100 $1.50 2.40 1.80 1.50 6.00 6.45 7.50 42.00 46.50 60.00 12.00 3.00 $ .24 .24 .24 .24 .60 .60 .48 18.00 25.00 10.00 15.00 1.20 $ .60 1.02 1.26 .84 1.80 1.98 1.44 51.00 51.00 12.00 6.00 $2.34 3.66 3.30 2 58 8.40 9.03 9.42 42.00 46.50 60.00 30.00 28.00 10.00 15.00 51.00 51.00 12.00 7.20 Corn stover Oat straw Wheat straw Clover hay Cowpea hay Alfalfa hay Dried blood Sodium nitrate Ammonium sulf ate Raw bone meal Steamed bone meal Raw rock phosphate Acid phosphate Potassium chlorid Potassium sulf ate Kainit Wood ashes* *Wood ashes also contain about 1000 pounds of lime (calcium carbonate) per ton. 1908.] THE FERTILITY IN ILLINOIS SOILS. 191 SOURCES OF PLANT FOOD If the productive capacity of Illinois soils is to be maintained elements of plant food which are present in such small amounts as to limit crop yields even under good systems of farming must be returned to the soil as needed, and information is given in Table 2 to show the average quantities in pounds of the different valuable elements of plant food contained in one ton of average fresh farm manure, rough feeds and bedding, and other fertilizer materials. In computing the value of the plant food in these materials, nitrogen is counted at 15 cents a pound and potassium at 6 cents a pound; while phosphorus is counted at 4 cents a pound in raw rock phosphate, at 10 cents a pound in bone meal, and at 12 cents a pound in acid phosphate, these prices being based upon average market values for the standard fertilizing materials in small lots. In carload lots lower prices may be secured. The information contained in Table i and Table 2 will be found of value in connection with a study of the composition of Illinois soils shown in Table 3, especially in planning systems for the im- provement and permanent maintenance of the different types of soil, containing varying amounts of these plant food elements. Thus, it should be plain to see that to supply the plant food for a four-year rotation consisting of corn for two years, followed by oats with clover seeding the third year, and clover hay and seed crops the fourth year, assuming the yields given in Table I, would require an application of 39 tons of manure to supply the nitrogen, 41 tons to supply the phosphorus, or 33 tons to supply the potas- sium, assuming that the clover secures from the air sufficient nitro- gen for the clover crops removed. In making computations of this sort it is safe to assume that the clover takes at least as much nitro- gen from good soil as remains in the clover roots and stubble. It should also be understood that there will be a very considerable loss of nitrogen in drainage waters, which may easily amount to one-third of the nitrogen applied if the land is much exposed with- out cover crops. It should be kept in mind that it becomes much easier to main- tain the supply of nitrogen if some clover is plowed under and if the rotation is extended to include two or three years of pasture with a mixture of legumes and grasses, as red clover, alsike, alfalfa, timothy, and red top. If the supply of manure is sufficient to fur- nish only 12 tons of manure per 'acre once in four years, it may still be possible to maintain the supply of nitrogen and humus by sup- plementing the manure with legume crops and catch crops grown in the rotation and in pasture, but in such case it is plain to see that 192 BULLETIN No. 123. [February, while the crops remove 82 pounds of phosphorus from an acre the 12 tons of manure return only 24 pounds of that element, leaving a deficiency of 58 pounds, which, however, can be made up by apply- ing with the manure a few hundred pounds of raw rock phosphate, about 50 pounds of phosphate with each load of manure being ample to maintain the phosphorus content of the soil, larger amounts being used if it is desired gradually to increase the supply of phos- phorus in the soil. It will be observed that one ton of rock phos- phate contains more phosphorus than 100 tons of average fresh farm manure. If the soil is exceedingly rich in .potassium, as it will be shown is the case with most Illinois soils, then no further consideration need be given to that element, except to insure its liberation by the action of decaying organic matter, the supply of which will be maintained by following the suggestions for maintaining the sup- ply of nitrogen. On the other hand with soils exceedingly deficient in potassium, as with certain peaty swamp lands whose composi- tion is shown in Table 3, that element may well be supplied in some concentrated potassium salt, such as potassium chlorid (sometimes incorrectly called "muriate of potash"), one ton of which contains as much potassium as 85 tons of average fresh farm manure. If the soil is markedly sour, or acid, of course the acidity should be corrected with an application of some form of lime, ground limestone being the most economical and satisfactory form to use as a rule. In case the total supply of potassium in the soil is very large but the supply of decaying organic matter so small .that applica- tions of soluble potassium salts produce marked increase in crop yields, as shown, for example, on the prairie lands of southern Illi- nois described in the following pages, it should be understood that the effect is produced not entirely by the element potassium but in part at least by the stimulating action of the soluble salt, and that instead of using a high-priced concentrated potassium salt, as would be best to supply potassium for peaty swamp land, it will be les.s expensive and more profitable to use on southern Illinois soil such a low-priced mixture of soluble salts as kainit, which contains nearly 25 percent of potassium sulfate, about 16 percent of magnesium sulfate, 12 percent of magnesium chlorid, and 33 percent of sodium chlorid (common salt), together with about 14 percent of combined water. For more complete discussion of the use of limestone, Illinois readers are referred to Circular no, "Ground Limestone for Acid Soils." THE FERTILITY IN ILLINOIS SOILS. 193 ILLINOIS SOIL AREAS AND SOIL TYPES According to geological investigation there have been at least three different periods when glaciers, or ice sheets, have covered more or less of the State of Illinois, in consequence of which nearly all of the surface of the state has been covered with drift, or glacial material, which is termed till, or bowlder clay, and is characterized by the presence of more or less coarse material varying in size from pebbles to bowlders, imbedded in clay, the materials having been gathered by the ice sheets as they slowly flowed over the surface of the earth. In the process of transportation much of the drift became finely ground so that when finally deposited the till consisted of material varying in size from clay to bowlders. Where for a long period of time the forward movement of the glacier was practically equalled by the rapidity with which the ice melted, much material was deposited, forming what are termed moraines, or glacial ridges, varying in width from less than a mile to several miles, and extend- ing around the lobe of the glaciated area sometimes for a distance of a hundred miles or more. Generally the glacial till was covered finally by a layer of loess, which is a fine material that was transported by the action of wind or flowing water, probably from deposits of exposed till before it was protected by vegetation (and to some extent from the melting or evaporating glaciers), and deposited over the state to an average depth of three feet or less in some areas (as in the Late Wisconsin glaciation), and to eight or ten feet in others (as in the Upper Illi- noisan and - Pre-Iowan glaciations) ; while in the "Deep Loess" areas covering the bluff lands along some of the large streams the depth of the loessial material may be from twenty to one hun- dred feet. The accompanying general survey soil map shows the areas that have been covered by the different glaciers, also the Unglaciated and Deep Loess areas and the general distribution of the early and late bottom lands and swamp areas, in which the soils vary from heavy clays or clay loams to peat beds on the one hand or to sand plains or drifting dunes on the other. The first glacier may have covered all of Illinois as far south as the Ozark Hills (near the south line of Williamson county) ex- cepting a part of Pike and Calhoun counties and an elevated area in the northwest corner of the state. The area where the drift from this first glacier has not been covered by a subsequent glacier is called the Illinoisan glaciation. For our purpose we divide this Illi- noisan glaciation into three areas because of difference in the agri- cultural values and properties of the most common soils in these 194 BULLETIN No. 123. [Februiry, sections (especially marked between the Lower and Middle Illi- noisan glaciations). These three areas we call the Lower Illinoisan glaciation (No. 3), the Middle Illinoisan glaciation (No. 4), and the Upper Illinoisan glaciation (No. 5), each of which will be more fully described later. The second glacier extended only over three or four tiers of counties from the north line of the state, not including JoDaviess county. On the area where the drift from this second glacier has not been covered by a later glacier we have accepted the two divi- sions *recognized by geologists, one of which (No. 6) we call the Pre-Iowan glaciation, and the other (No. 7) the lowan glaciation. The third and last glacier covered approximately the northeast one-quarter part of the state, and this area is called the Wisconsin glaciation. This is divided into two areas, the early Wisconsin glaciation (Nos. 9 and n) and the late Wisconsin glaciation (Nos. 10 and 12). According to formation we recognize fourteen large soil areas in the state, although some formations are scattered in separated tracts and each of the fourteen areas may contain several or many different types of soil. In studying soil types we consider the time and method of formation; the topography as affecting surface drainage and sur- face washing; the texture, varying from light, loose, or friable to heavy, compact, or plastic; the structure, especially with reference to uniformity or differences of the soil strata at different depths; and we also recognize, of course, the different materials of which soils are composed, as organic matter, clay, silt, sand, gravel, and stone. In naming a soil type we try to indicate ( I ) the great soil area in which it is found (2) the color of the soil, (3) the chief material of which it is composed (as clay, silt, sand, etc.) and some- times (4) the topography. Sometimes the name also indicates the character of the subsoil, especially if it is unusual or abnormal. We use the term clay to designate only true plastic clay, and not as it is so commonly, though incorrectly, used to describe almost any fine-grained soil or subsoil that is deficient in organic matter. True clay is like dough, being sticky or plastic and without individual particles distinguishable by the naked eye. By the term silt is meant a grade of soil particles finer than sand, too fine to feel the individual grains with the fingers, but yet granu- lar to the eye and not sticky or plastic when free from clay. Silt is *These divisions are grouped together for the sake of simplicity, although the terms Pre-Iowan and lowan recognize a greater difference in time of forma- tion ~than the terms Early lowan and Late lowan which have been used ten- tatively. I9o8.] THE FERTILITY IN ILLINOIS SOILS. 195 by far the most common material in our ordinary prairie and timber soils and subsoils, although such soils also contain some smaller percentages of sand and clay. In Table 3 is given the average composition in pounds per acre of the surface soil, approximately 7 inches deep (more exactly 6^3 inches) of the most important soil types in the great soil areas of Illinois. These data are the average results of analyses of many representative samples of soil from each soil type numbered and named in the table. The last two figures in the official number des- ignate the soil type and the preceding figure (or figures) the area in which it is found in accordance with the numbers on the soil map of Illinois, except that No. n may be used for both 9 and n, and No. 10 may be used for both 10 and 12, because the same soil types are not uncommonly found on both moraines and plains. For a more complete outline of the classification of the soils of Illinois, the reader is referred to the appendix. THE MEANING OE SOIL, ANALYSIS In studying the composition of different soils it is well to keep in mind that our most productive soils of normal physical composi- tion contain in the surface seven inches per acre about 8000 pounds of total nitrogen, 2000 pounds of total phosphorus, and above 30,- ooo pounds of total potassium. The total nitrogen varies from about 2000 pounds in the yellow silt loam of the hill lands, or from less than 1500 pounds in the sand soil, to 8900 pounds in the black clay loam prairie of the Late Wisconsin glaciation and even to nearly 35,000 pounds in the peaty swamp soil. The total phosphorus varies from about 800 pounds in the gray silt loam prairie of southern Illinois to about 2000 pounds as an average of the richest areas of black clay loam; while the total potassium varies from 3000 pounds in the peaty swamp soil to 48,- ooo in the Late Wisconsin yellow-gray silt loam. For convenient study and ready comparison the twenty-five soils, comprising the most extensive and important types in the great soil areas, are arranged in the tables in five groups. First, the group of undulating prairie lands, varying in topog- raphy from level to rolling, and including the somewhat peculiar gray silt loam on tight clay of the Lower Illinoisan glaciation in the Illinois wheat belt and the ordinary brown silt loam soils of the corn belt found in the six other glacial areas, and especially exten- sive in the Middle and Upper Illinoisan and in the Early Wisconsin glaciations, constituting by far the most common corn belt soils. 196 BUU.ETIN No. 123. [February, TABI,E 3. FERTILITY IN ILLINOIS Soii,s Average Pounds per Acre in Surface Soil (0-7 inches)* Soil tTpe No. Soil area or glaciation. Soil type. Total nitro- gen. Total phos- phorus. Total potas- sium. Limestone required. Prairie lands, undulating. 330 Lower Illinoisan. Gray silt loam on tight clay 2880 840 24940 2 to 5 tons 426 Middle Illinoisan Brown silt loam 4370 1170 32240 Rarely 526 Upper Illinoisan.. Brown silt loam ...... 4840 1200 32940 Rarely 626 Pre-Iowan . . . Brown silt loam 4290 1190 35340 Yz to 1 ton 726 lowan 4910 1220 32960 ^ to 1 ton 1126 Early Wisconsin. Brown silt loam 5050 1190 36250 Rarely 1026 Late Wisconsin. . Brown silt loam 6750 1410 45020 Rarely Prairie lands, flat. 420 Middle Illinoisan Black clay loam' 5410 1430 31860 None 520 Upper Illinoisan.. Black clay loam 6760 1690 29670 None 1120 Early Wisconsin. Black clay loam 7840 2030 35140 None 1220 Late Wisconsin. . Black clay loam . . 8900 1870 37370 None Timber uplands, rolling or hilly. 135 Un glaciated.. Yellow silt loam 1890 950 31450 2 to 5 tons 335 Lower Illinoisan Yellow silt loam ... . 2150 950 31850 2 to 5 tons 435 Middle Illinoisan Yellow silt loam 1870 820 33470 1 to 2 tons 535 Upper Illinoisan.. Yellow silt loam 2010 840 34860 1 to 2 tons 635 Pre-Iowan Yellow silt loam 2390 850 37180 1 to 2 tons 35 Yellow silt loam 1910 910 35780 1 to 2 tons 1135 Early Wisconsin . Yellow silt loam 1890 870 32720 1 to 2 tons 864 Deep loess Yellow fine sandy loam 2170 960 35640 1 to 2 tons Timber uplands, undulating. 1034 760 Late Wisconsin. . lowan Yellow-gray silt loam Brown sandy loam . . . 2890 3070 810 850 47600 26700 (?) (?) Sand, swamp, and bottom lands. 1331 1451 1481 1401 Old bottom lands. Late bottom lands Sand plains and dunes Deep gray silt loam . . Brown loam 3620 4720 1440 34880 1420 1620 820 1960 36360 39970 30880 2930 1 to 4 tons Rarely (?) Rarely Sand soil Late swamp Deep peat *The numbers given in Table 3 represent the total amounts contained in two million pounds of the surface soil on the dry basis, with the exception of peaty swamp soil, for which the amounts in one million pounds are used, be- cause its specific gravity is only one-half that of ordinary soil, and of sand soil for which 2^2 million pounds are used, because it is about one-fourth heavier than ordinary soil. THE FERTILITY IN ILLINOIS SOILS. 197 Second, the heavy black clay loam soils found in the very flat prairies, usually swampy before being drained, common in the Early Wisconsin and less common in the Middle and Upper Illinoisan and in the Late Wisconsin glaciation. Third, the eroded yellow silt loams on sloping hillsides, the com- monest soil type in the unglaciated area and also found on the bro- ken lands adjoining water courses in most parts of the state; also the yellow fine sandy loam of the deep loess area, especially common on the bluffs adjoining the Mississippi and in places along other large streams. Fourth, the undulating timber uplands of which only the yel- low-gray silt loam of the Late Wisconsin and the brown sandy loam of the lowan glaciation are discussed in this bulletin, these being extensive and consequently of special importance in those areas. Fifth, the sand, swamp, and bottom land areas, which are dis- cussed only with reference to sand soil, peaty soil, and very com- mon bottom lands. In both nitrogen and phosphorus the black clay loam which occupies the very flat prairie land in the northeast quarter part of Illinois is about two and one-half times as rich as the very extensive gray silt loam prairie land of the Lower Illinoisan glaciation. In total potassium all of the soils of Illinois are extremely rich excepting the peaty swamp soil and this is extremely poor in this element containing less than one-tenth as much potassium as is found in normal fertile soils. Even the sand soils are rich in total potassium, showing that much of the material is of granitic origin. While the amount of plant food contained in the soil at depths below seven inches is of interest and will be found reported and dis- cussed in the following pages, it should be kept in mind that the thing of chief concern and importance in systems of permanent profitable agriculture is to have and to maintain a good surface soil, for even a rich subsoil is of but little value if it lies beneath a worn- out surface. We know that we add manure and fertilizers to the plowed soil only and that by thus enriching the surface stratum we are able to increase markedly the crop yields. These well known facts plainly emphasize the importance of maintaining a rich sur- face soil at least 6 or 8 inches deep. The downward movement of mineral plant food is very slight. Even soluble phosphates and potassium salts applied to the surface and harrowed in do not produce nearly so good results as when they are plowed down, thus putting them where the plant roots feed, which is chiefly below the first two or three inches. 198 BULLETIN No. 123. [February, A direct comparison of Table i and Table 3 is instructive and profitable. It will be found, for example, that a hundred-bushel crop of corn removes from the soil 148 pounds of nitrogen, 17 pounds of phos- phorus, and 19 pounds of potassium, assuming that the corn is har- vested and the stalks are burned, which is still the most common practice in the Illinois corn belt. In the commonest corn belt land, the brown silt loams, there are as a general average (excluding the Late Wisconsin glaciation) about 4800 pounds of nitrogen, 1200 pounds of phosphorus, and 34,000 pounds of potassium. These amounts are sufficient to supply the nitrogen for such crops for 32 years, the phosphorus for 70 years, and the potassium for 1790 years. Even the total nitrogen to a depth of 40 inches would extend the possible time limit for such crops to only 95 years for our most common Illinois corn belt land. It will be kept in mind of course that there is an inexhaustible supply of nitrogen in the air which can be drawn upon by means of legume crops with their nitrogen- fixing bacteria, but from Table i it will be seen that a ton of clover contains only 40 pounds of nitrogen, and it may be well to state here, and well for the reader to keep in mind hereafter, that the nitrogen contained in the clover roots will not exceed one-half of the amount contained in the total growth above ground. Thus to return the nitrogen removed by a hundred-bushel crop of corn would require a crop of clover amounting to two and one-half tons of hay together with the corresponding one and one-fourth ton of roots. In addition to this we must face the fact that not all of the nitrogen contained in the clover plant is taken from the air and that the loss of nitrogen by drainage is greater than the amount added in rain.* It is a fact, however, that either by plowing under clover and other green manures and crop residues, or by more or less pastur- ing and by feeding the larger part of the crops grown and saving and returning all manure produced, the supply of nitrogen in the soil can be maintained or even increased. If now we consider the element phosphorus we find that the total amount contained in the plowed soil of the commonest Illinois corn belt land is equivalent to the requirement of a hundred-bushel crop of corn each year for only 70 years if only the grain is harvested, or but 52 years if the grain and stalks were both removed. In the case of phosphorus instead of getting some permanent relief by *Some nitrogen may be supplied by the soil bacteria (azotobacter) that fix atmospheric nitrogen independent of legumes, but no estimate of the amount can be made because of insufficient data. THE FERTILITY IN ILLINOIS SOILS. 199 growing clover we only hasten the depletion, for, as will be seen from Table i, a four-ton crop of clover removes more phosphorus from the soil than is contained in 100 bushels of corn. In Table 2 information is given showing the amounts of phos- phorus contained in various materials that can be applied to the soil. If we consider the element potassium we find that the average amount contained in the surface soil of the corn belt is sufficient to meet the needs of 100 bushels of corn per acre every year for eight- een centuries. Nevertheless the liberation of sufficient potassium and possibly of other elements, as sulfur, calcium, iron, or mag- nesium, even though the relative supply in the soil exceeds that of potassium, may become a very serious problem, and indeed already is a serious problem in soils which are deficient in decaying organic matter, as will be more fully explained in the discussion of specific soil types (see Lower Illinoisan gray silt loam prairie, No 330). It should be kept in mind that while nitrogen is ever present in the air in inexhaustible quantity, the atmosphere does not contain phosphorus or potassium, and the only method of enriching the soil in either of those elements is by direct application to the land either in farm manure or other fertilizers. In Tables 4 and 5 are given the amounts of plant food contained in the subsurface (*7-2O inches) and subsoil (2040 inches) of these most extensive and important Illinois soil types. Except as previ- ously explained the data given in Tables 3, 4, and 5 represent the amounts of plant food contained in two million pounds of surface soil, in four million pounds of subsurface soil, and in six million pounds of subsoil, an acre-inch of our ordinary silt loam and clay loam soils weighing about 300,000 pounds, dry basis. All results are reported on the basis of pounds per acre, because the acre is the unit of measure on the farm. Crops are harvested and reported in yield per acre ; the plant food removed is computed in pounds per acre; manures or fertilizers are applied in tons or pounds per acre; and in harmony with this practical system the composition of Illinois soils is reported and discussed also on the acre basis.t On this basis the stock of plant food in the soil is easily compared directly with the plant food removed in crops and applied in manures or fertilizers, and comparison between soil types or soil strata is also readily made. *More exactly from 6 2 /z to 20 inches. fTo convert the data to the percentage basis divide by 2, 4, 6, according to the stratum, except that i, 2, and 3 should be used for peat, and 2 l / 2 , 5, and 754 for sand, with proper placing of the decimal point in all cases. 200 BULLETIN No. 123. [February, TABLE 4. FERTILITY IN ILLINOIS SOILS Average Pounds per Acre in Subsurface Soil (7-20 inches) Soil type No. Soil area or glaciation. Soil type. Total nitro- gen. Total phos- phorus. Total potas- sium. Prairie lands, undulating. 330 Gray silt loam on tight 3210 1500 53570 426 Middle Illinoisan Brown silt loam. . 5800 1920 62590 526 Upper Illinoisan Brown silt loam 6480 2090 64820 626 Pre-Iowan Brown silt loam 4650 2060 72370 726 lowan Brown silt loam 5140 1940 66220 1126 Brown silt loam 6560 2000 72780 1026 Late Wisconsin . . Brown silt loam. . 6870 1960 96420 Prairie lands, flat. 420 Middle Illinoisan 6180 2260 64070 520 Black clay loam 7380 2690 60760 1120 Early Wisconsin Black clay loam 7200 3090 71670 1220 Late Wisconsin . . Black clay loam. . 9100 2860 78840 Timber uplands, rolling or hilly. 135 2030 2120 67320 335 Lower Illinoisan Yellow silt loam 2170 2000 67380 435 Middle Illinoisan Yellow silt loam 1980 1510 65370 535 Upper Illinoisan Yellow silt loam 1900 1610 72570 635 Pre-Iowan Yellow silt loam 2290 1750 76150 735 lowan Yellow silt loam 2120 1960 71180 1135 Early Wisconsin Yellow silt loam 1870 1590 68690 864 Deep loess. . Yellow fine sandy loam. 2610 1600 71760 Timber uplands, undulating. 1034 Yellow-gray silt loam . . . 2710 1390 111100 760 lowan 3920 1590 54300 Sand, swamp, and bottom lands. 1331 Old bottom lands Deep gray silt loam 2250 1830 68090 1451 Late bottom lands Brown loam 6660 2160 77540 1481 Sand plains and dunes . Sand soil 2070 1480 62690 1401 Late swamp. Deep peat 64980 2940 7010 COMPARISON OF DIFFERENT TYPES AND DEPTHS OF SOIL Before passing on to the discussion of the composition and needs of the individual soil types and of results already secured from dif- ferent methods of soil treatment or improvement, let us study briefly the general information given in Tables 3, 4, and 5. THE FERTILITY IN ILLINOIS SOILS. 201 TABLE 5. FERTILITY IN ILLINOIS SOILS Average Pounds per Acre in Subsoil (20-40 inches) Soil type No. Soil area or glaciation. Soil type. Total nitro- gen. Total phos- phorus. Total potas- sium. Prairie lands, undulating-. 330 Lower Illinoisan Gray silt loam on tight clay 3240 2400 84300 426 Middle Illinoisan. Brown silt loam 3440 2680 90040 526 Upper Illinoisan Brown silt loam 3440 2790 98580 626 Pre-Iowan Brown silt loam 3940 3380 102620 726 lowan Brown silt loam 3540 2780 99780 1126 Early Wisconsin Brown silt loam 3420 2620 117880 1026 Late Wisconsin Brown silt loam 3630 2630 160140 Prairie lands, flat. 420 520 1120 1220 Middle Illinoisan. Upper Illinoisan. . Early Wisconsin . Late Wisconsin . . 3020 3140 3490 3180 3030 3640 3630 3930 94900 96220 111280 125370 Timber uplands, rolling or hilly. 135 Unglaciated Yellow silt loam 1970 3280 105430 335 Lower Illinoisan Yellow silt loam 2480 3170 99670 435 Middle Illinoisan Yellow silt loam 2820 2810 99000 535 Upper Illinoisan Yellow silt loam 2280 3270 100950 635 Pre-Iowan Yellow silt loam. 2380 3400 102100 735 lowan Yellow silt loam. 2490 3900 105030 1135 Early Wisconsin Yellow silt loami . 2450 2660 103830 864 Deep loess. . , Yellow fine sandy loam. . 2730 3320 105210 Timber uplands, undulating. 1034 Late Wisconsin Yellow-gray silt loam 3240 2400 156740 760 Brown sandy loam 4160 2440 81180 Sand, swamp, and bottom lands. 1331 Old bottom lands Deep gray silt loam 2280 2620 101610 1451 Late bottom lands Brown loam 4150 2410 119520 1481 Sand plains and dunes. . Sand soil : 3100 2230 94030 1401 Late swamp. . Deep peat. . 97730 3740 11510 The undulating prairie lands are arranged in order of age, the Lower Illinoisan being the oldest glaciation and the Late Wiscon- sin being the most recent. As we pass from the oldest to the new- est soils there is a somewhat regular increase in plant food content. These nearly level or gently undulating prairie soils are less affected mechanically with the passing years than are other soils, such as the rolling hill lands, which lose by surface washing, or the bottom lands, which frequently receive deposits from overflow. 202 BULLETIN No. 123. [February, There are some marked evidences in morainal deposits and in soil composition of considerable differences in time of formation be- tween the Lower Illinoisan, the Middle Illinoisan, the Early Wis- consin, and the Late Wisconsin glaciation and corresponding loes- sial deposits, but less marked evidences of any long periods of time having elapsed between the Middle Illinoisan, Upper Illinoisan, Pre-Iowan, and lowan. Because of this the best comparison is made with the four areas first mentioned. The phosphorus varies in these soils from 840 to 1170, 1190, and 1410, and the potassium from about 25,000 to 32,000, 36,000, and 45,000 pounds per acre in the surface soil. With the black clay loams which occupy some of the flat prairie lands, there are also some such relations indicated, although this type of soil is likely to be modified somewhat because of more or less deposit from overflows. In the case of the yellow silt loams of the hill lands, which are always subject to more or less surface washing, there is no such gradation with the age of formation, because all of these soils were in the recent past unweathered subsoils from which the surface soil has been washed away during recent centuries. Undoubtedly the lower amounts of phosphorus and potassium in the prairie land of the Lower Illinoisan glaciation as compared with the Late Wisconsin glaciation is in large part due to loss by longer weathering and leaching of the older formation during the long period of time that intervened between the earlier and later glaciers. Potassium, being much more subject to loss from weath- ering and leaching, is a better measure of this action than phospho- rus. Even in the f the element that limits the yield of the crop. In Table 6 are given the amounts of annually available plant food as roughly estimated by this method of computation. Of course, these amounts would become smaller and smaller year by year in proportion as the total supply is decreased, and accordingly complete exhaustion is not only impracticable and un- profitable because of the continual reduction in crop yields, but it is mathematically impossible, just as it would be impossible to ex- haust a bank account if only i percent of the remaining deposit could be withdrawn each week. A peaty swamp soil containing 2930 pounds of total potassium per acre in the first seven inches would liberate during the season according to this estimate about 7 pounds of potassium, which would be equivalent to a crop of 10 bushels of corn, which repre- sents roughly about the average yield from such land when not treated with potassium, as is shown in the following pages. The common brown silt loam prairie soil when well farmed will aver- age about 50 bushels of corn per acre, which would require 11^2 pounds of phosphorus and 74 pounds of nitrogen, while 12 and 96 pounds represent i percent of the phosphorus and 2 percent of the nitrogen, respectively, in the surface soil, where phosphorus is the first limiting element. These illustrations are given not to prove that this rough esti- mation is applicable, but rather to show the basis which suggests such a computation. It has some value, chiefly, perhaps, in that it helps one to understand why it is that with phosphorus enough in the surface soil for 50 crops, we obtain only half a crop as an average. On this basis we should try to keep sufficient phosphorus in the surface soil for 100 large crops, of which i percent would then be sufficient for one large crop. This would require about 2300 pounds of phosphorus per acre, or but little more than is actually contained in our most productive corn belt soil, as the Early Wis- consin black clay loam in such counties as McLean, Champaign, Edgar, et al. (see Table 3 and the appendix). 1908.] THE FERTILITY IN ILUNOIS SOILS. 207 TABLE 6. ANNUALLY AVAILABLE FERTILITY IN ILLINOIS SOILS, ROUGHLY ESTIMATED; POUNDS PER ACRE Soil type No. Soil area or glaciation. Soil type. Avail- able nitro- g-en. Avail- able phos- phorus. Avail- able potas- sium Prairie lands, undulating. 330 Lower Illinoisan Gray silt loam on tight clay . . 58 8 62 426 Middle Illinoisan Brown sill loam 87 12 81 526 Upper Illinoisan Brown silt loam 97 12 82 626 Pre-Iowan 86 12 88 726 lowan Brown silt loam 98 12 82 1126 Brown silt loam 101 12 91 1026 Late Wisconsin Brown silt loam 135 14 113 Prairie lands, flat. 420 Middle Illinoisan Black clay loam 108 14 80 520 Upper Illinoisan Black clay loam 135 17 74 1120 Karly Wisconsin. Black clay loam 157 20 88 1220 Late Wisconsin. . Black clay loam. . , 178 19 93 Timber uplands, rolling or hilly. 135 Unglaciated Yellow silt loam 38 10 79 335 Lower Illinoisan Yellow silt loam 43 10 80 435 Middle Illinoisan . . . . Yellow silt loam 37 8 82 535 Upper Illinoisan Yellow silt loam 40 8 87 635 Pre-Iowan Yellow silt loam 48 9 93 735 lowan Yellow silt loam 38 9 89 1135 38 9 82 864 Deep loess Yellow fine sandy loam . . . 43 10 89 Timber uplands, undulating. 1034 Late Wisconsin Yellow-gray silt loam 58 8 119 760 lowan Brown sandy loam 61 9 67 Sand, swamp, and bottom lands. 1331 Old bottom lands .... Deep gray silt loam 72 14 91 1451 Late bottom lands 94 16 100 1481 Sand plains and dunes. 29 8 77 1401 Late swamp. . . Deep peat . . m* 20 7 *The nitrogen in peat is so very slowly available that not even a rough estimate can be made here. Third, we may apply different elements of plant food to the soil and note the effect, if any, in increasing the yield of crops, and thus sometimes discover what element is most deficient in the soil. One might suppose that this would be the best method, but such is 208 BULLETIN No. 123. [February, not the case. This method frequently gives erroneous results which if followed may lead to land ruin, because the substance applied may produce little or no benefit on account of the special plant food element it contains but it may act as a powerful soil stimulant and thus liberate from the soil some other entirely different element in which the soil is already becoming deficient. Thus have many lands been practically ruined by the use of landplaster and salt, by the improper use of lime, and even by the use of clover merely as a soil stimulant. Some good illustrations of this action of soluble salts are shown in the following pages. "In considering the general subject of culture experiments for determining fertilizer needs, emphasis must be laid on the fact that such experiments should never be accepted as the sole guide in de- termining future agricultural practice. If the culture experiments and the ultimate chemical analysis of the soil agree in the deficiency of any plant food element, then the information is conclusive and final; but if these two sources of information disagree, then the culture experiments should be considered as tentative and likely to give way with increasing knowledge and improved methods to the information based on chemical analysis, which is absolute."* PHOSPHORUS In studying the field experiments reported below it is most im- portant to keep in mind the amounts of phosphorus applied to and removed from the soil as well as the cost of the phosphorus applied. For reasons already explained, and completely established by the data and results secured, phosphorus is the only element that must be purchased and returned to our most common soils. Phosphorus is the key to permanent agriculture on these lands. To maintain or increase the amount of phosphorus in the soil makes possible the growth of clover and the consequent addition of nitrogen from the inexhaustible supply in the air; and, with the addition of .decaying organic matter in clover residues and in manure made in large part from clover hay and pasture and from the larger crops of corn which clover helps to produce, comes the possibility of liberating from the immense supply in the soil sufficient potassium, when sup- plemented by that returned in manure and crop residues, for the production of large crops at least for thousands of years ; whereas if the supply of phosphorus in the soil is steadily decreased in the future in accordance with the present most common farm practice, then poverty is the only future for the people who till the common prairie lands of Illinois. And this does not refer to the far distant *Cyclopedia of American Agriculture, Volume i, page 475. /potf.J THE FERTILITY IN ILLINOIS SOILS. 209 future only, for the turning point is already past on many Illinois farms, and lands that have passed their prime with 60 years of cul- tivation will decrease rapidly in productive power and in value during another sixty years of similar exhaustive farm practice. On land deficient in phosphorus the standard rule should be to apply phosphorus equivalent to 25 pounds of the element per acre per annum, remembering that a loo-bushel crop of corn removes 23 pounds of phosphorus. To supply 25 pounds of phosphorus will require 200 pounds of good steamed bone meal, costing about $2.50, or 200 pounds of good raw rock phosphate, costing about 80 cents, or \2. l /2. tons of average fresh farm manure, or the manure that can be made from 200 bushels of corn, costing $70 or $80 as feed. Probably the most practical and profitable method of maintain- ing the supply of phosphorus is by applying 1000 pounds per acre of raw rock phosphate once every five or six years, preferably in connection with all available farm manure, and for the first two or three applications one ton per acre of the phosphate may well be used. It will remain in the soil until removed by crops unless sub- ject to surface washing. If one adopts the rule that when he applies phosphorus it must be at the rate of at least 25 'pounds per acre for each crop in the rotation (not 25 pounds of so-called phosphoric acid, nor 25 pounds of so-called bone phosphate, but 25 pounds of phosphorus), he will then be proof against the misleading and ruinous practice of using ordinary so-called complete commercial fertilizers, for he will at once discover that to buy 25 pounds of phosphorus in such fertilizers will cost from $8.00 to $10.00, and that the amounts he can afford to apply of such fertilizers will not furnish more than J4 to ^ as much phosphorus as is actually removed from the soil in good crops. In the field experiments reported in this bulletin the standard application of phosphorus in steamed bone meal is at the rate of 25 pounds per acre for each year in the rotation. This requires 600 pounds of bone for a three-year rotation, 800 pounds for a four- year rotation, etc. When raw rock phosphate is used, about three times as much is applied, which adds three times as much phospho- rus to the soil but at about the same cost as for the bone. After two or three rotations the amount of rock phosphate to be applied will be reduced to one-third of the present applications. Where farm manure is used the amount applied to any plot is in direct proportion to the total crop yields of the previous rotation. Thus, if the use of phosphorus increases the yield of crops in a ro- tation, it will likewise increase the possible production of manure, and consequently the application of manure is increased for the next rotation on plots where phosphorus and manure are used. Our 210 ' BULLETIN No. 123. [February, present plan is to apply the same number of tons per acre of aver- age fresh manure (25 percent dry matter) as the number of tons of air-dry produce harvested, which requires about two-thirds of the produce to be used for feed and bedding and allows for a loss in practice of 20 percent of the manure produced. INDIVIDUAL TYPES OF ILLINOIS SOIL In the tabular statements (Tables 3, 4, and 5) an absolute in- voice is given concerning the stocks of plant food contained in twenty-five of the principal types of soil in Illinois. In the follow- ing description of the results obtained from pot cultures and field experiments and of systems of soil improvement adapted to these different types, it is necessary in some cases to discuss a single type in a single area, but so far as practicable similar types will be dis- cussed in groups. It is the purpose of this bulletin to make the descriptions of each soil type sufficiently complete so that the read- ing farmer or landowner will recognize the soil of his own farm. Of course, there are minor soil types and abnormal soils which will require the completion of the detail soil survey by counties (a work which is already well advanced), but three- fourths of the farmers of the state should be able to obtain from this bulletin some definite information applying directly to the stock of fertility con- tained in the soil of their own farms and even a larger number can profit by the adoption of suggested systems of soil improvement. GRAY SILT LOAM ON TIGHT CLAY (330) This type of soil is the commonest prairie land in the Lower Illinoisan glaciation. This soil area is marked with the number 3 on the colored general survey soil map of Illinois. It lies chiefly between the Kaskaskia and Wabash rivers and is bounded on the south by the Ozark Hills and on the north by the terminal moraine of the Wisconsin glaciation which passes through Shelby, southern Coles, and Edgar counties. This area includes all of the counties of Fayette, Effmgham, Jasper, Marion, Clay, Richland, Washing- ton, Jefferson, Wayne, Perry, Franklin, and Hamilton, and parts of Montgomery, Shelby, Cumberland, Clark, Crawford, Lawrence, Wabash, Edwards, White, Saline, Williamson, Jackson, Randolph, Monroe, St. Clair, Clinton, and Bond. In most of these counties the gray silt loam prairie soil (330) is the most common type, although it is not the only type in any county and probably not the only type in any township. This type of soil is well known and everywhere recognized by the farmers themselves as "the common hardpan prairie." It con- /po5.] THE FERTILITY IN ILLINOIS SOILS. 211 sists of a friable gray silt loam which commonly varies in depth from 6 to 12 inches and below which is a light gray or nearly white layer, or stratum, of slightly loamy silt varying from less than one inch to more than 10 inches in thickness, and commonly referred to as the "gray layer." At a depth of 16 to 20 inches the soil is underlain by a tight clay subsoil, frequently termed "hardpan." It should be understood, however, that this subsoil is not true hardpan, which consists of sand or gravel cemented together with clay to form a substance which is practically impervious to water and through which ditches cannot be dug with only a spade. No true hardpan subsoil has yet been found anywhere in Illinois, unless it has been at considerable depths, as in the digging of wells. The subsoil of this gray silt loam prairie is a tight clay, inclined to be gummy. Water passes through it, although quite slowly, and when wet it can be spaded without special difficulty, but when dry it becomes stiff and hard. Where this soil is enriched by proper treatment excellent crops are grown in seasons of normal rainfall, but they are likely to suffer in times of drouth more than would be the case with a better subsoil. As a rule the rainfall in southern Illinois is abundant and well dis- tributed during the growing season and where the top soil is kept fertile severe injury from drouth is not common. From Table 3 it will be seen that the average surface soil of this type contains per acre 2880 pounds of nitrogen, 840 pounds of phosphorus, and 24,940 pounds of potassium, and that it requires an application of 2 to 5 tons of ground limestone. Compared with the requirements for a practical crop rotation this soil is very poor in phosphorus and very deficient in lime. Compared with the com- position of fertile soils it is also deficient in humus as indicated by the total nitrogen. It will be seen from Tables i and 3 that 50 bushels of wheat (grain only) remove from the land, and from the farm if sold, 12 pounds of phosphorus and 13 pounds of potassium; and that the total amounts of these elements in the surface soil of this type are sufficient to supply the phosphorus for 70 years and the potassium for 1900 years, provided they could be liberated as needed; or, if both grain and straw were removed, the phosphorus is equal to 52 such crops and the potassium to 520 crops. It should be understood that the plant food contained in all soils is almost entirely in insoluble form, that growing crops can take up plant food only in soluble form, and that one of the prob- lems always to be considered is how to enable the growing crops to secure sufficient plant food for maximum yields. If by the best systems of crop rotations, with proper use of green manures, and 212 BULLETIN No. 123. [February, in favorable seasons, we can liberate the equivalent of i percent of the phosphorus contained in the surface soil, it would amount to about 8 pounds per acre for the first year for the type of soil under consideration. This would be sufficient for a 25-bushel crop of wheat. If with less perfect systems only half of i percent is lib- erated, it would amount to 4 pounds, or enough for a 12-bushel crop of wheat. On the University soil experiment field near Odin, Marion county, on this ordinary prairie land of the Lower Illinoisan glacia- tion, wheat is grown in a four-year crop rotation with clover, corn, and cowpeas. By having four different series of plots every crop may be grown every year. As an average of the last four years (1904, 1905, 1906, and 1907), wheat grown in this rotation has produced n l /2 bushels per acre with no special soil treatment, all crops having been re- moved. Where one cowpea crop and some catch crops (as cowpeas seeded in the corn) had been plowed under during the rotation, the average yield of wheat was increased to 14 bushels. Where lime or ground limestone had been applied and the cow- peas also plowed under the average yield of wheat has been 18^2 bushels per acre. On this set of plots better cowpea crops and catch crops have been produced and turned under as green manure, be- cause the soil acidity has been corrected by the lime, applied for the special benefit of the legume crops. Where phosphorus has been applied in addition to the use of lime and green manure, the average yield of wheat during the four years has been 27 bushels.; and where potassium also has been in- cluded the average yield has been 29^2 bushels of wheat per acre. These results are quite in harmony with what might be expected from the chemical composition of the soil. If, however, we con- sider the corn crops in the same rotation we have a somewhat dif- ferent set of results. The average yield of corn for the four years on the untreated rotated land has been 38 bushels per acre; with legume treatment (cowpeas turned under) 41 bushels; with legume and lime treat- ment 45 bushels; with legume, lime, and phosphorus 46 bushels; and with legume-lime-phosphorus-potassium treatment the average yield of corn for four years has been 61 bushels per acre. (See Plates i and 2). For more convenient comparison these results are shown in Table 7. THE FERTILITY IN ILLINOIS SOILS. 213 TABLE 7. CROP YIELDS IN SOIL EXPERIMENTS: ODIN FIELD Gray silt loam prairie Lower Illinoisan glaciation. Average of eight tests in four years; two tests each year for each crop, bushels per acre. Soil treatment applied. Wheat. Corn. 11.6 13.8 18.5 27.1 29.5 38.3 40.8 45.3 46.2 61.3 Legume (cowpeas turned under) Legume lime phosphorus Legume, lime, phosphorus, potassium These results are four-year averages. They were made in du- plicate each year. They are representative and trustworthy. They have also been confirmed by results from other experiment fields on the same type of soil. The effects upon corn of the green manure alone and with lime are about the same as upon wheat, but the effects produced by phos- phorus and potassium are very different with the two crops, phos- phorus producing the largest increase in wheat, while potassium is much more effective with corn, although potassium without phos- phorus produces less increase in corn than when applied in addition to phosphorus. A study of Table i will show that a 6 1 -bushel crop of corn re- quires about 50 percent more potassium than a 3O-bushel crop of wheat, which fact may account in part for the greater effect of po- tassium on corn, although about the same relation holds for phos- phorus. A more important difference probably exists in the relative feeding powers of the two crops, influenced ( i ) by the difference in root systems, including the different depths of feeding, (2) by the difference in seasonal conditions and consequent difference in de- cay of humus and decomposition of other soil materials and in ac- tivity of soil organisms during the principal periods of growth, (3) by the solvent action of the carbon dioxid excreted by the bac- teria and from the plant roots, and (4) possibly by different re- quirements as to the forms or combinations in which the plant food elements can be absorbed and assimilated or utilized by corn and wheat. 214 BULLETIN No. 123. [February, PLATE 1. CORN CROP (29.4 bu.) WITH NO SOIL TREATMENT. ODIN SOIL EXPERIMENT FIELD, 1904. THE FERTILITY IN ILLINOIS SOILS. 215 PLATE 2 CORN CROP (64.1 bu.) WITH L,EGUME-L/IME-PHOSPHORUS-POTAS- SITJM TREATMENT. ODIN SOIL EXPERIMENT FIELD, 1904. 216 BULLETIN No. 123. [February, A further very important question is whether more or less of the effect attributed to potassium may not be due to the stimulating action of the soluble potassium salt in liberating other substances from the soil instead of serving directly as plant food; and, if so, would it be advisable and more profitable to substitute some other less expensive material, such as kainit, for the concentrated potas- sium sulfate used in these experiments. Information is accumulating from investigations now in pro- gress which will help to solve these practical problems. It can already be stated that as an average of 28 tests (includ- ing the use of twenty-five different varieties of corn) conducted in- 1907 on the University experiment field near Fairfield in Wayne county, an application of 200 pounds per acre of potassium sulfate, containing 85 pounds of the element potassium and costing $5, in- creased the yield of corn by 7 bushels per acre ; while 600 pounds of kainit containing only 60 pounds of potassium and costing $4, gave i o.i bushels increase. These applications are made but once for a four-year rotation. The kainit with 25 pounds less potassium produced 3 bushels more corn than the sulfate. At 40 cents a bushel for corn the kainit has paid for itself the first year. As previ- ously stated, kainit contains about 25 percent of potassium sulfate together with some magnesium sulfate, magnesium chlorid, and sodium chlorid, all of which are soluble salts ; and the results plainly indicate that the effects produced are due not solely to the element potassium, but in part at least, and probably in large part, to the stimulating action of the soluble salt. In this connection we may well consider results obtained s at the Rothamsted Experiment Station in England where wheat has been grown on the same land every year for 56 years with dif- ferent kinds of soluble salts applied to different parts of the field. As an average of 24 years (from 1852 to 1875) exactly the same increase was produced (5.6 bushels) whether 200* pounds of po- tassium sulfate, 280* pounds of magnesium sulfate, or 366^* pounds of sodium sulfate per acre per annum were applied. These results are not altogether conclusive because considerable potas- sium salts had been used on all three of these plots previous to the beginning of this 24-year test. During a second 24 years the aver- age increases produced were 8.8 bushels by potassium sulfate, 6.6 bushels by magnesium sulfate, and 6.0 bushels by the sodium sul- fate, showing that while the soluble salts of magnesium and so- dium produce a marked effect, the potassium salt is becoming more *Approximately molecular proportions. Excluding water of crystallization the amounts applied were 200 pounds of potassium sulfate, 137 pounds of mag- nesium sulfate, and 162 pounds of sodium sulfate. THE FERTILITY IN ILLINOIS SOILS. 2l7 effective and the difference of 2 or 2.8 bushels may be attributed to the value of the potassium itself as plant food. It may be said that the difference was much greater during the latter part of the second 24-year period and still greater subsequently. In 1906 the increase was 1 8. i bushels by potassium sulfate, 7.8 bushels by magnesium sulfate, and 7 bushels by sodium sulfate, the potassium salt being now more than twice as effective as the other salts. It should be stated that in the experiments reported above both at Fairfield, Illinois, and at Rothamsted, England, the soluble salts were applied in addition to phosphorus and the yields compared with the results obtained where the same amounts of phosphorus were applied without the soluble salts mentioned. Limestone was also provided in all cases. In neither case was farm manure applied and the soils are not well supplied with decaying organic matter, the action of which will largely, or, if provided in abundance, en- tirely take the place of the action of the soluble salts as such. Ad- ditional experiments on the Fairfield field include an equally com- plete test with kainit and potassium sulfate on land to which 8 tons per acre of farm manure had been applied. As an average of 28 tests with each material the 200 pounds of potassium sulfate in- creased the yield of corn by 2.9 bushels, while the 600 pounds pf kainit gave 3.3 bushels increase, as compared with 7 bushels and i o.i bushels increase, respectively, where these soluble salts were applied in the absence of manure, all other conditions being the same. Thus, where farm manure is supplied the soluble salts produce but little effect and are not used with profit. On the other hand, phosphorus produces its greatest effect when used in connection with organic matter. As an average of three years on the Fairfield field rock phosphate and limestone in addition to manure have produced 1 2 bushels more corn per acre than has been produced where manure alone was used, although in the absence of either decaying organic matter or soluble salts the phosphorus produces much less effect, especially on corn. In Table 8 are given the results obtained during the past six ysars on the DuBois experiment field in Washington county. In this field there are two -independent series of ten plots each, and the crop yields reported in the Table are in all cases the average from two plots with like treatment. For convenient comparison the lower part of Table 8 shows the total values of the crops produced during the last four years in this four-year rotation; also the value of the total increase and of the increase above that produced by lime alone. 218 BULLETIN No. 123. [February, TABLE 8. CROP YIELDS IN SOIL EXPERIMENTS: DuBois FIELD Graj silt loam prairie Lower Illinoisan glaciation. Average of two series each year, bushels or tons per acre. Soil treatment applied. Corn, 1902. Oats, 1903. Wheat, 1904. Clover, 1905. Corn, 1906. Oats, 1907. None 4.9 5.0 13.3 16.7 4.8 9.0 1.27 1.67 31.4 34.4 16.0 26.3 Lime Lime, nitrogen 43 10.0 8.3 19.4 26.7 27.4 10.1 26.7 15.5 1.79 2.35 2.19 34.9 34.2 48.2 34.1 37.9 41.8 Lime, phosphorus Lime, potassium Lime, nitrogen, phosphorus 8.7 7.2 13.3 29.4 25.5 27.8 32.0 21.8 29.9 2.37 2.43 2.91 31.4 46.0 52.1 46.3 41.5 47.2 Lime, nitrogen, potassium Lime, phosphorus, potassium Lime, nitrogen , phosphorus, potassium Nitrogen,phosphorus, potassium 10.4 3.4 30.5 29.4 31.9 27.8 2.86 2.69 49.0 45.3 44.4 36.1 Value of Crops per acre in Four Years, 1904, 1905, 1906, 1907. Soil treatment applied. Total value of four crops. Value of increase. None 125 97 Over 34.82 $ 8.85 lime Lime, nitrogen 38.66 12.69 $ 3.84 Lime, phosphorus 54.24 28.27 19.42 Lime, potassium 51.31 25.34 16.49 59.19 33.22 24.37 Lime, nitrogen, potassium 56.32 30.35 21.50 Lime, phosphorus, potassium 68.43 42.46 33.61 Lime,nitrogen,phosphorus,potassium Nitrogen, phosphorus,potassium 67.74 60.49 41.77 34.52 32.92 The values are computed at 35 cents a bushel for corn, 25 cents for oats, 70 cents for wheat, and $6.00 a ton for clover hay. Not only are these prices conservative, but the quality of the crops from the well treated plots is much better than from the untreated land, especially for wheat and clover. With an increase of $42.46 from one acre of land in four years above the total receipts from the untreated land one can well afford to improve the soil. Even with the use of 200 pounds of steamed bone meal at $25 a ton and 100 pounds of potassium sulfate at $50 a ton, making a cost of $5.00 an acre a year, the increase has paid the cost and added 100 percent profit for bone meal and 50 percent profit for the potassium used, besides leaving in the soil more than THE FERTILITY IN ILLINOIS SOILS. 219 half of the phosphorus applied and furnishing clover and other large crops from which to make manure. From all data and information thus far secured, of which only a few average and trustworthy illustrations are mentioned in this bulletin, the following recommendations are made for the improve- ment of the common gray silt loam prairie land of the Lower Illi- noisan glaciation : 1. Correct the acidity of the soil with an application of from two to five tons per acre of ground limestone, best applied after plowing in the summer or fall, and then mixed with the surface soil by disk- ing or harrowing in preparing the seed bed for wheat or timothy where clover is to be seeded the next spring. (See Plates 3 and 4). 2. Adopt a good crop rotation in which clover or mixed clover and timothy shall occupy the land from one-third to one-half of the time. 3. Increase the stock of phosphorus in the soil by applying more than would be removed in large crops. An application of 1000 pounds per acre of raw rock phosphate every five or six years will accomplish this. 4. Increase the supply of active humus, or decaying organic matter, by pasturing during part of the rotation and by using for feed and bedding from one-half to two-thirds of the crops har- vested, protecting the manure from exposure and loss by hauling directly from the stall and spreading with the phosphate upon the field preferably upon the new meadows or old pasture land to be plowed under for corn. 5. Where it is impossible at first to apply manure or to turn under liberal amounts of organic matter, an application of 400 to 600 pounds per acre of kainit in connection with the phosphate will help to grow larger crops for a time and thus increase the supply of organic matter to be returned in stable manure and by pasturing, after which the use of kainit may be discontinued. The experiments now being conducted on this type of soil will ultimately furnish more complete information as to the effects of different crop rotations, of the continued use of stable manure, green manures, limestone, phosphorus in different forms, potassium sulfate and kainit; also the effect and practicability of subsoiling and of tile-drainage with the tile laid at different depths and cov- ered with different materials, as with earth alone and also with a few inches of straw or cinders or gravelly sand before filling in with earth. The results of these investigations will be published from time to time in bulletins or circulars which will be sent to all who ask to have their names placed upon the Experiment Station mail- ing list. 220 BULLETIN No. 123. [February, PI.ATE 3. CLOVER (AND CRAB GRASS) WITH PHOSPHORUS ONLY: YIELD 1.05 TONS: EDGEWOOD SOIL EXPERIMENT FIELD, 1905. Bulletin 99, "Soil Treatment for the Lower Illinois Glaciation," and Circular 1 10, "Ground Limestone for Acid Soils," are still available and will be sent to anyone upon request. For more details concerning the chemical composition of this and other types of soil, see the appendix to this bulletin, and for further discussion of soil acidity see under the heading "yellow silt loam" in the following pages. BROWN SILT LOAM PRAIRIE SOILS (26) Brown silt loam constitutes the most common prairie soil in the Middle and Upper Illinoisan, Pre-Iowan, and Early Wisconsin glaciations and is found to some extent also in the lowan and Late Wisconsin. It is called "the ordinary prairie land" by farmers throughout the corn belt, extending from Coles, northern Macoupin, and McDonough counties to the north line of the State. In the name of this soil type, brown silt loam, the term brown is used to designate about the same color as when used to describe a brown horse, as distinguished from a black soil or a black horse. The soil is not reddish brown or chocolate. It is dark colored but I90S.] THE FERTILITY IN ILLINOIS SOILS. 221 PLATE 4. CLOVER WITH LJME AND PHOSPHORUS: YIELD 2:10 TONS: EDGE- WOOD SOIL EXPERIMENT FIELD, 1905. not a genuine black under normal conditions, although when wet the darker phase of the type appears black. All brown silt loams are given the soil type number 26, to which the number of the soil area is prefixed to designate the indi- vidual soil, as 426 for the Middle Illinoisan brown silt loam, 726 for the lowan brown silt loam, etc. Not infrequently the brown silt loam extends over low or broad moraines as well as over the more extensive nearly level or undulating plains between the mo- raines, but only one number is used for the type within a single glaciation, as 1126 for the Early Wisconsin in which the type is more extensive on the intermorainal tracts, and 1026 for the Late Wisconsin, an area consisting largely of broad complex moraines on which more brown silt loam is found than on the smaller areas between the moraines. While the different brown silt loams are similar in many re- spects, they differ somewhat in chemical composition, varying with age or formation of the different areas, and it is noteworthy that in the older soil areas the brown silt loam is either no longer rep- resented (as in the Lower Illinoisan glaciation) or it is replaced to 222 BULLETIN No. 123. [February, some extent by a type of soil intermediate in character and value between brown silt loam and gray silt loam on tight clay. This in- termediate type is well developed in places in the southern part of the Middle Illinoisan glaciation and in the western part of the Up- per Illinoisan, but if is only one of many minor types whose exact location and investigation will be reported in connection with the detail soil survey by counties. The top soil of the brown silt loam consists of a friable dark colored and fairly uniform soil to a depth of 16 to 20 inches with appreciably less organic matter at the lower depth. Below the top soil from 1 6 or 20 inches to 40 inches and more, is the yellow silty subsoil, somewhat less porous or friable than the top soil but not very compact. This soil and subsoil have great capacity to absorb and retain water from heavy rains and later to deliver the moisture to growing crops as needed. In other words, the crops growing on brown silt loam soils are enabled to withstand drouths that would produce very severe damage on such a soil as the Lower Illinoisan gray silt loam on tight clay. Of course even the brown silt loam becomes much less absorbent and less retentive of moisture where the sur- face soil is allowed to become deficient in humus. ; In Table 3 is given the average composition of the surface soil of the brown silt loam in. each area. In nitrogen the brown silt loam of the Middle Illinoisan (426) and of the Pre-Iowan (626) is below the average. The former is the oldest and the latter the most rolling of the six brown silt loam areas, which may account for these lower averages. The phosphorus varies somewhat in har- mony with the variation in nitrogen, except in the Early Wisconsin area. The Late Wisconsin brown silt loam (1026) is the most recent and also the richest in nitrogen, phosphorus, and potassium. In the Pre-Iowan and lowan glaciations the brown silt loam is commonly somewhat sour, the acidity being more marked in the subsurface and subsoil than in the surface, as is usually the case with strongly acid soils (see appendix for details). The principal type of upland soil in the lowan glaciation is a sandy loam (760), further described in the following' pages. The fact that the Pre- Iowan and lowan brown silt loams contain more fine sand than is found in this type in other glaciations suggests that the higher acidity in these two areas may be due to an original deficiency in lime, the loessial deposit having been modified by the sandy ma- terial which is so commonly exposed and which must have contrib- uted more or less to the glacial drift from which the loess was probably derived as already explained. ipo8.] THE FERTILITY IN ILLINOIS SOILS. 223 As a general average (the Late Wisconsin being disregarded) the brown silt loams contain in the surface soil of an acre about 4800 pounds of nitrogen, 1200 pounds of phosphorus, and 34,000 pounds of potassium, amounts which, if they could be drawn upon at will, would furnish the nitrogen for 100 bushels of corn (grain only) every year for 48 years, the phosphorus for 70 years, or the potassium for 1790 years. For four -tons per acre of clover hay each year, the nitrogen, if drawn only from the surface soil, would be sufficient for 30 years, the phosphorus for 60 years, and the potassium for 280 years. These data are for very large crops, and take into account only the plant food in the surface soil to a depth of seven inches but these crops are not too large to try to raise and the fertility of the surface soil must be maintained if we are to maintain a permanent profitable agriculture. We may reduce the crop yields to the low- est limit of profit on land valued at $150 to $200 an acre, but still the absolute limit in years is short for the nitrogen and phosphorus in this most common Illinois prairie soil ; and, if such crops of corn and clover as are mentioned above had been removed from this land from the time Columbus discovered America until now, every pound of phosphorus contained in the soil to a depth of four feet would have been required for the crops grown. Nitrogen can, of course, be secured from the air by means of clover and other legumes, but on any land capable of producing 40 or 50' bushels of corn per acre the soil will furnish as much nitrogen to the clover crop as will remain in the roots and stubble after the hay and seed crops are removed. In other words, to enrich such soil in nitrogen the clover crop must be returned to the land, either directly or in manure. The amount of clover necessary to be plowed under in order to furnish sufficient nitrogen to meet the needs of the grain or grass crops to be grown in the rotation can easily be computed from Table i, and every farmer should make such computation for his rotation. On the ordinary Early Wisconsin brown silt loam on the Uni- versity soil experiment field at Urbana, a three-year rotation of corn, oats, and clover is practiced on three fields so that every crop is grown every year. As an average of the last three years, includ- ing three crops of corn, three of oats, and three of clover, the yields per acre have been 72 bushels of corn, 59 bushels of oats, and .89 ton of air-dry clover hay where no phosphorus has been applied; but where phosphorus has been applied on similar land in the same fields the average yields have been 90 bushels of corn, 71 bushels of oats, and 1.78 tons of air-dry hay. (See Plates 5 and 6). 224 BULLETIN No. 123. [February, PLATE 5. CLOVER AFTER OATS WITH L,IME TREATMENT: YIELD .87 TON: URBANA SOIL EXPERIMENT FIELD, 1905. At 35 cents a bushel for corn, 25 cents for oats, and $6.00 a ton for hay, the value of the increase produced by the phosphorus is twice the cost of the phosphorus applied in the form of steamed bone meal, a form in which phosphorus costs nearly three times as much as in raw rock phosphate (see Table 2). Furthermore, the land to which no phosphorus was applied has lost 30 pounds of phosphorus per acre in the crops removed, while, the bone meal ap- plied contained 35 pounds more phosphorus than was removed in the three larger crops. Where both bone meal and manure have been applied the aver- age yield of corn was 93 bushels, and where potassium also has been applied in addition to the manure and phosphorus, the yield has been 96 bushels of corn, as a three-year average. As a rule potassium is of little benefit on the brown silt loams, and not infrequently it reduces the crop yields. With two tests each year on each crop potassium produced an average increase of 3 bushels of corn and .16 ton of hay, but decreased the yield of oats by 2 bushels. Table 9 gives results obtained during the past six years from the Sibley soil experiment field, located in Ford county on typical brown silt loam prairie of the Illinois corn belt. 1908.] THE FERTILITY IN ILLINOIS SOILS. PLATE 6. CLOVER AFTER OATS WITH L/IME AND PHOSPHORUS TREATMENT: YIELD 1:83 TONS: URBAN A SOIL EXPERIMENT FIELD, 1905. Table 9 is so easily understood that it is not necessary to take space here for a complete discussion of the data. Previous to 1902 this land had been cropped with corn and oats for many years under a system of tenant farming and the soil had become somewhat deficient in active humus. While phosphorus was the limiting element of plant food, the supply of nitrogen becoming available annually was but little in excess of the phosphorus, as is well shown by the corn yields for 1903 when phosphorus produced an increase of 8 bushels, nitrogen without phosphorus produced no increase, but nitrogen and phosphorus increased the yield by 15 bushels. After six years of additional cropping, however, nitrogen ap- pears to have become the most limiting element, the increase in 1907 being 9 bushels from nitrogen and only 5 bushels from phos- phorus, while both together produced an increase of 33 bushels of corn. By comparing the corn yields for the four years, 1902, 1903, 1906, and 1907, it will be seen that the untreated land has appar- ently grown less productive, whereas on land receiving both phos- phorus and nitrogen the yield has appreciably increased, so that in 1907 when the untreated rotated land produced only 34 bushels of corn per acre, a yield of 72 bushels, or more than twice as much, was produced where lime, nitrogen, and phosphorus had been ap- 226 BULLETIN No. 123. [February, plied, although these two plots produced exactly the same yield (57 bushels) in 1902. While the actual yields might be quite different under different seasonal conditions, the relative and increasing dif- ferences between the plots must be considered as representative and due to the difference in soil treatment. TABLE 9. CROP YIELDS IN Sou, EXPERIMENTS: SIBLEY FIELD Brown silt loam prairie Early Wisconsin glaciation. Corn, 1902. Corn, Oats, 1903. 1904. Wheat, 1905. Corn, 1906. Corn, 1907. Plot. Soil treatment applied. Bushels per acre. 101 102 None 57.3 50.4 60.0 54.0 74.4 74.7 29.5 31.7 36.7 39.2 33.9 38.9 Lame 103 104 105 Lime, nitrogen 60.0 61.3 56.0 54.3 62.3 49.9 77.5 92.5 74.4 32.8 36.3 30.2 41.7 44.8 37.5 48.1 43.5 34.9. Lime, phosphorus Lime, potassium 106 107 108 Lime, nitrogen, phosphorus . . . Lime, nitrogen, potassium Lime, phosphorus, potassium. . 57.3 53.3 58.7 69.1 51.4 60.9 88.4 75.9 80.0 45.2 37.7 39.8 68.5 39.7 41.5 72.3 51.1 39.8 109 110 Lime, nitrogen, phosphorus, potassium 58.7 60.0 65.9 60.1 82.5 85.0 48.0 48.5 69.5 63.3 80.1 72.3 Nitrogen, phosphorus, potassium Value of Crops per acre in Six Years. Plot. Soil treatment applied. Total value of six crops. Value of increase. 101 None $101 . 66 Over 102 Lime 108.11 $6.45 lime. 103 Lime, nitrogen 113.78 12.12 $5.67 104 Lime, phosphorus 122.71 21.05 14.60 105 Lime, potassium 102.15 .49 -5.92 106 107 108 Lime, nitrogen, phosphorus . . . Lime, nitrogen, potassium Lime, phosphorus, potassium. . 147.26 113.80 118.18 45.64 12.14 16.56 39.19 5.69 10.11 109 Lime, nitrogen, phosphorus, potassium 150.20 48.58 42.13 110 Nitrogen, phosphorus, potassium. 144.70 43.08 In the lower part of Table 9 are shown the total values per acre of the six crops from each of the ten different plots, the amounts varying from $101.62 to $150.20; also the value of the increase produced ; first, above the untreated land ; and, second, above the treatment with lime alone, corn being valued at 35 cents a bushel, oats at 25 cents, and wheat at 70 cents. /po tons per acre for the six-year rotation and this application is to be repeated for the second, and possibly for the third and fourth, rotations, after which 1000 pounds of rock phosphate are to be applied every six years. At $8.00 for the 12^ percent rock phosphate in carload lots, the 1 l / 2 tons cost $12.00 and added to the soil 375 pounds of the element phosphorus, of \vhich the six crops on treated land removed about 68 pounds, leaving the soil richer in phosphorus by 307 pounds than at the beginning. At this rate this system will increase the phosphorus content of the plowed soil from 1160 pounds (the average of the Galesburg field in 1904) to nearly 1500 pounds in 1910, and to 1800 pounds (an increase of 50 percent) in 1916, and, if continued, to 2100 pounds per acre in 1922, and to 2400 pounds (double the original content) in 1928. On the other hand it should be kept in mind that the six crops harvested from the untreated land left .the soil poorer in phosphorus by 56 pounds per acre, which is 5 percent of the phosphorus present in the surface soil. While it is to be taken for granted that some part of this came from the subsurface and subsoil, the fact still re- mains that phosphorus is already so deficient in this soil as to limit the crop yields, and we may well ask ourselves the question \vhether we shall continue to reduce the productive power of the soil toward /pa?.] THE FERTILITY IN ILLINOIS SOILS. 231 ultimate land ruin, and thus become the curse of our own grand- children or their children, or whether we shall adopt a system which assures even greater profits to ourselves and a richer soil as a heritage to our children, and greater future prosperity to the commonwealth of Illinois. The Myrtle soil experiment field in Ogle county is located on the Pre-Iowan brown silt loam (626). Apparently phosphorus and nitrogen are about equally deficient. The experiments have been in progress for four years. Where rock phosphate was applied at the rate of I ton per acre for the initial application, with no adequate supply of decaying organic matter in the soil, but little effect has appeared in the grain crops, the average increase being 2.5 bushels per acre of corn and 1.6 bushels of oats. With the clover crop, however, which it should be remembered need not be limited in yield because of any deficiency of soil nitro- gen, having power to secure from the air nitrogen to supplement so far as necessary the soil's available supply, the effect of phosphorus has already been marked, the increase of air-dry clover hay as an average of four tests each year being .22 ton for 1906 and .63 ton for 1907. With the increased amount of clover residues and with the increased amount of manure to be made from the larger yield of clover hay and with the help of this decaying organic matter to liberate more phosphorus from the rock phosphate applied, in- creased crops of corn and other grains must follow on this field as they have on others. No soil experiment fields have yet been established on the lowan brown silt loam (726) nor on the Late Wisconsin brown silt loam (1026). Results similar to those reported for this type in other areas are to be expected in those areas, except that they will prob- ably be less marked in the Late Wisconsin, especially on the better phase of the type, because of the higher percentages of both phos- phorus and nitrogen in the brown silt loam of that area. Additional soil experiment fields are greatly needed, and will be established as soon as sufficient funds are provided, not only on these most important soil types but also on several other more local and less extensive types, and not only for purposes of investigation but also to serve for demonstration and definite object lessons where farmers and landowners may see for themselves the results produced by the best and most profitable practice in soil improve- ment looking toward permanent systems of agriculture for the state, and conducted on soil types which they will be able to recog- nize on their own farms. 232 BULLETIN No. 123. [February, RECOMMENDATIONS FOR BROWN SILT LOAM PRAIRIE SOILS The information thus far secured is too meager to justify rec- ommendations concerning many important problems relating to methods and systems of farming on the brown silt loam prairie soils, but two principles are already well established. First, we must maintain or increase the supply of decaying or- ganic matter in the soil, by means of crop rotations and the use of animal manures and green manures. A six-year rotation (similar to that on the Galesburg field) in which grain crops are grown for three or four years followed by mixed clover and timothy for two or three years in meadow and pasture, with about two-thirds of the total crops fed on the farm and all manure carefully saved and re- turned to the land, will certainly be approaching toward a perma- nent system for maintaining a sufficient supply of humus in the soil, as compared with the present most common soil-exhausting practice of growing from two to five crops of corn in succession, burning the stalks each year, and then substituting oats for one year, possibly with some clover seeded in the oats to be plowed un- der either the same fall or the next spring with a feeling that the land has been fertilized enough for three or four more corn crops. Second, we must return to the soil in some form at least as much phosphorus as we remove in crops, and the weight of evidence thus far secured from properly conducted investigations is clearly in favor of using liberal amounts of fine-ground raw rock phos- phate, with the full understanding that abundance of decaying or- ganic matter is to be provided to assist in 'making the phosphorus soluble and available for growing crops. To provide for as large crop yields as we ought to try to produce will require an application of 25 pounds of phosphorus per acre for each year in the rotation, preferably spread on the field at one time and plowed under with manure or other organic matter. The phosphorus content of the manure applied may of course be consid- ered a part of the required amount. To increase the total amount of phosphorus in the surface soil to 2000 pounds per acre would require heavier applications for a few years. Three tons of rock phosphate containing 12^2 percent of the element would add 750 pounds of phosphorus, and would cost at present prices from $25 to $30. This would raise the phosphorus content of the soil from 1200 pounds, the present average, to 1950 pounds. To determine whether it will be profitable to increase still further the total stock of phosphorus in the surface soil requires further investigation. The THE FERTILITY IN ILLINOIS SOILS. 233 750 pounds suggested above would equal the phosphorus required for 100 bushels of corn (grain only) every year for 44 years, or for 44 bushels (about the present average yield for the Illinois corn belt) every year for 100 years. In other words the man who in- creases the phosphorus content of his soil by 750 pounds provides the only element that need be purchased sufficient to meet the needs of the present average yields for another one hundred years, and at present prices for corn and rock phosphate the expense for such an application is no more than the value of one 7o-bushel crop of corn. It is very evident from the information already secured that we can thus not only increase the phosphorus content of the surface soil by more than one-half of our present stock, but also that the increase in crop yields in a proper system of farming will pay for such applications in a few years. Further data are required, and are accumulating, concerning the effect of lime on the brown silt loams. As mentioned above the composition of this type in the Pre-Iowan and lowan glaciations indicates that the use of limestone may be advisable and profitable in those areas. In the Middle and Upper Illinoisan and Early Wis- consin glaciations the supply of limestone in the brown silt loam is frequently already exhausted and on some fields very appreciable effects have followed its application. For a more complete discussion of the effect of crop rotations, the value, and methods of increasing the value, of farm manure, and for additional data relating to soil improvement and the com- parative value of different forms of phosphorus, Illinois readers are referred to Circular 96, "Soil Improvement for the Illinois Corn Belt," and to Circular 108, "Illinois Soils in Relation to Systems of Permanent Agriculture," which will be furnished free of charge upon request. BLACK CLAY LOAM PRAIRIE SOILS (20) The commonest type of soil on the very flat prairie lands of the corn belt is black clay loam. As indicated by the name, it is black in color, clayey, or sticky and plastic, in texture, and rich in organic matter. It is commonly known as the heavy black prairie soil, and is sometimes called black gumbo land. It is most abundant in the broad intermorainal tracts in the Early Wisconsin glaciation where it represents the richest Illinois prairie land existing in large area, containing as an average in two million pounds of surface soil about 7800 pounds of nitrogen, 2000 pounds of phosphorus, and 35,000 pounds of potassium. 234 BULLETIN No. 123. [February, Iii the Middle and Upper Illinoisan glaciations, which are older formations and have the natural drainage systems better developed, there are some smaller areas of black clay loam but in those areas this type of soil is not so rich in plant food. In the Late Wisconsin the extent of this type is quite limited. Traces of acidity are sometimes found in the black clay loam, but it is never strongly developed, and usually the subsoil contains large amounts of limestone. (See appendix for details.) The first problem with the black clay loam areas has always been to secure adequate drainage, but in most places this difficulty has been largely overcome by making large open dredge ditches and the laying of drain tile. Most of this land has been brought under profitable cultivation within the past 20 years and it has contributed much toward maintaining the average crop yields of the corn belt during recent years when the yields on the long-cultivated lands have been decreasing. Where properly drained this black clay loam will continue to produce large yields for many years, provided sufficient rotation of crops is practiced to avoid too great development of injurious in- sects. It is probable however that even on this soil the best results will be obtained by adopting systems of farming and soil treatment that will maintain the present high content of phosphorus and pre- vent too great depletion of humus and nitrogen. Investigations should be started at once to secure definite infor- mation concerning these points. As yet no soil experiment fields have been established on black clay loam because of the much greater present need for experiments on soils that are not so rich. This type of soil is sometimes called red clay hill land, and we have in a previous bulletin (115) called it red silt loam, but yellow better describes the prevalent color. It is found in all glaciations and much more abundantly (relatively) in the unglaciated areas. Like most of the soils of the state, it consists of a loessial deposit. It occupies much of the sloping lands or hill sides, not only in the original hilly sections of the state (the unglaciated, or driftless, areas), but also in the broken land regions along most of the interior streams. Under ordinary methods of cultivation these lands are subject to serious loss from surface washing, and even when not under cultivation there is and has been more or less rapid erosion taking place. Where this soil has been under ordinary cultivation for several years it is invariably poor in humus and nitrogen and /po ( 395 Ib ) { Potassium | \ chlorid, 400 Ib. f None Kainit, 600 Ib I Kainit, 600 Ib. J \ Acidulated ( bone, 350 Ib. ) j Potassium } | chlorid, 200 Ib. j j Sodium ) ( chlorid, 700 Ib. \ ( Sodium ) 1 chlorid, 700 Ib. f Kainit, 600 Ib Kainit, 1200 Ib Kainit, 600 Ib Kainit, 300 Ib Kainit, 300 Ib None None : ^Estimated from 1903; no yield was taken in 1902 because of misunder- standing'. The use of 700 pounds of sodium chlorid (common salt) pro- duced no appreciable increase over the best untreated plots, indicat- ing that where potassium is itself actually deficient, salts of other elements cannot take its place. Applications of two tons per acre of ground limestone produced no increase in the corn crops, neither when applied alone nor in combination with kainit, neither the first year nor the second. Reducing the application of kainit from 600 to 300 pounds, for each two-year period, reduced the yield of corn from. 164.5 to I2 5-9 bushels. The two applications of 300 pounds of kainit furnished 60 pounds of potassium for the four years, or sufficient for 84 bush- els of corn (grain and stalks). The difference between this and the 125.9 bushels obtained is 42 bushels, about what was obtained from the poorest untreated plot. The underdrainage provided for this experiment field was not sufficient for the best results, probably because of insufficient nitri- fication. In other experiments on peaty soil with imperfect drain- age the addition of $15 worth of nitrogen with potassium produced .about 15 bushels more corn than where potassium alone was used. iyoS.] THE FERTILITY IN ILUNOIS SOILS. 253 OTHER PEATY AND ALKALI SOILS , Aside from deep peat, there are many other types of peaty soil, as will be seen from the classification of Illinois soil types given in the appendix. Thus we find shallow peat and medium peat, under- lain with clay, sand, rock, etc., and also sandy peat and peaty loam; and in some instances peaty soils also contain alkali, consisting chiefly of harmless calcium carbonate (limestone) with smaller amounts of injurious magnesium carbonate. In some cases these peaty soils actually contain a good percent- age of total potassium, more commonly in the subsurface or subsoil, but sometimes in the surface soil also, and yet the untreated soil is unproductive while the addition of potassium salts produces large and very profitable increases in the yield of corn, oats, etc. In pot culture experiments we have even been able by the addi- tion of potassium sulfate to correct to a considerable extent the in- jurious property of magnesium carbonate that has been purposely applied to ordinary brown silt loam prairie soil which is known to contain abundance of available potassium. These facts are mentioned here because we recommend, tenta- tively, the application of potassium salt to all classes of peaty and alkali soils that are unproductive after being well drained, when- ever the supply of farm manure is insufficient. It should be under- stood that plenty of farm manure, preferably quick-acting, or read- ily decomposable, manure, such as horse manure, will supply potas- sium and thus accomplish everything that potassium salts can ac- complish, and on some swamp soils manure produces good results where potassium is without effect. In pot culture experiments soils containing injurious amounts of magnesium carbonate have been treated with calcium sttlfats (landplaster) which brings about a double decomposition, or intet- change, forming the harmless insoluble calcium carbonate (lime- stone) and the very soluble magnesium sulfate, which is subse- quently leached out, leaving the soil productive. The new Manito experiment field, located three miles east of Manito in Tazewell county on the Mason county line, is on alkali soil consisting of peaty, clayey sand with some gravel, and contain- ing sufficient total potassium for normal crop yields. In Table 15 are recorded the treatment applied and results ob- tained in 1907 on the new Manito field. 254 BULLETIN No. 123. [February, TABLE 15. CORN YIELDS IN SOIL EXPERIMENTS: NEW MANITO FIELD, PEATY ALKALI SOIL Plot No. Treatment applied for 1907. Corn , bu. per acre. 201 None 8.8 202 W Manure, 6 tons 43.5 202 E Manure, 12 tons 64.9 203 Potassium sulf ate, 400 pounds 73.0 204 Calcium sulfate, 2 to 16 tons 4.9 205 None 5.4 Plot 204 is divided into four equal parts and the calcium sulfate applied at the rate of 2 tons, 4 tons, 8 tons, and 16 tons, per acre, at a cost of $6.00 per ton. It produced no benefit in 1907. Whether it will assist in the removal of the magnesium carbonate by double decomposition and leaching and thus improve the soil in time, time alone will tell. The 400 pounds of potassium sulfate are applied for a three-year rotation at an initial cost of $10.00. The increase of 66 bushels of corn produced the first year, at 35 cents a bushel, amounts to more than twice the total cost of the potassium. The manure also gave very excellent results. In Table 16 are given all results obtained during six years' ex- periments on part of the Momence soil experiment field, located three miles south of Momence, Kankakee county, on peaty swamp land which contains much decaying peat and coarse sand in the surface and in the subsurface, with a clayey sand subsoil resting on impure limestone, while the surface, subsurface, and subsoil con- tain more than half of the normal amounts of total potassium (19,- ooo, 47,000, and 73,000 pounds, respectively, per acre). The soil contains but little alkali. After 1902 (when the corn was damaged by water) the land was tile-drained sufficiently well for ordinary years, but in the ex- tremely wet season of 1907 the corn was planted very late and with the continued wet weather resulted in almost a complete failure. Potassium was not applied to plot 102 for 1902 and 1903 and was not applied to plot no for 1904. The untreated check plot 101 is naturally somewhat more pro- ductive than the other plots. /po n rH ^t vo o ri vo x n rH -*t rH Tf VO t- -* rH Tl- 2 . Y -^ Uc J3 O VO 00 O vo X O VO rH O VO rH O VO O o vo x VO 2 H S H ^ rH rH n n n rH n ft ^ 43 b s CO S, * c "* *7 /^ J} g o o O O O O So o o o o O O O o o o i M tfl B tf Q n *^h n n x n * x o vo XXX H ^ w w ^ o li ro 1> * VO rH VO rO X O ro X * rH 1> t^ ro * O rO Oi t> M ^2 ^ O^ VO r< | H a o X o t-H f 2 Phos- horus. vo t^ VO v-H 88S VO rH rH rH ri O O O n n n VO rH ri rH ri o o 1>- ro vH IS| OOQ ri n o t- rO t> rH ri 888 1 ^ S a 4 (OUT 0-' BOUT 21 3 S a , o .H H & > SO O X X rH n Ol vo M VO n vo i> n vo x ^f rO O n ro ^- rO 38 rH X vo * n vo o o VO X rO X o o o x * * VC n rH H C W ,4 3 2 . 1 tfi 0) 3 Jj a o 00 x o ^ ** o o o sSS O O O VO vo X VO vo vo O t^ VO X ro 8? 1 M |H rH M rH ri rH rH rH rH rO H O A 55 o O tf o CO n P CO 3 2 a ft *^ 4) -a * ro n ro ro * rO ri ro ro n ro ro rH VO rH O o ri ro Tf X n n n O O O VO X * I> 00 VO n n n ^j ^J to 3 & p o co % 3 o Jn 4 o o o ri ,0 a O O O X O O 9553 rO X O ro n ro g ro -3 3 o M : 5 O i * (0 ft < G X ch fc M q p 55 o 4 M VO P S 1 H o. O O x vo o ^VO rH rO g M ro O rH n * I>- O - O rH VO VO o o o n x ri rH O VO rH^VO 2 3 55 V V V V O 0) C C c a . ^ ^/i O 55 P ft o n >y coun O 'C a .2 3 S o fe 1 C 1 E 5 ft 9 1 X w o H w rO 6 55 W to M S3 S a S S S % ^ M p C/3 ft ft ft ft ft ft ft n *H -1-1 ^ ^a -o a -T3 -d H p ci rH u i- rj i co o o & w "^ro -ro ro oT r w ro H ; to O a t* 3 w&J ^^4 r^f4 ro'f4 rH T ^^ ri^: M ' 2 tf5 01 3 '~ | rH CO'rH -to fc r5 rH *_i 3 o d n r - r r r P4 r "t. r r W r p 55 ri " >5 " r4 t^ f-\ r/l rt ^5 * t^ r/) t^ r/) \9* V. p pEj pr] j^ (Jj J** ^ **^ ^H to 3 W K O & N ^ C1 ri -VO w S5 10 H rf0 2 t J ^ CD CO ^ CO _r I-H % CO g CO ti CO co 1908.} 1 1 y "Si THE FERTILITY IN ILLINOIS SOILS. 263 VOVOO VOVOO VOVOO I>VOO VOCOO t>-*O l^OOO t^VOO rH * rH - ovovo oi^vo o vo c\ o i> * o i> o o t- oo 1-HrHrHrHrHCMCMcM O OOO OOO CM VO 00 00 CM CM CX rH rH ^f rH t- O O * CM OC co O O Q OOO CM CM O * * CM I> VO rH VO O VO OOO CM CM CM t^ CO CM rH CM O 00 * 5 S a o .H ooo * CM CM -* rH CO CM vo 00 OOO * * co * rH * 1> 00 CM VOI> CO CM vo vo ' . I 00 CM vo 00 00 CM VO CO vo VO CO CO CO CM vo O^ O O * oo 00 rj- So o 00 VO 2 d S 2 S _ ." % -* -* 10 VO rH CO CM CM f>l O 00 * O rH fM 10 rH rH IO O O O 00 "* n rH ^ fN SO O vo oo 00 CO v%X S-ee M-H V ill &S9 in rt'Cg St| 121 1-1 %% co- co co v v ri .*3 Sti S PJ VH (fl HH S O h to = c^-^ CO J Wi CO co u rt.'S "H O n M a ill c?-^ CO vo O t^voo 1> vo O I-N. 00 O t^ 00 O l^ 00 Cl TH TH TH o o o \> \J rj- t^ t^ TH rO 00 iO O Q O oo o n IO iH >O So o O O c\ n t- vo vo O\ SO O t- QO t- o vo 888 So o VO 00 t> TH VO COO^T^ n TJ- oo 80 o o o o __ CO ( O O O cN co CO CC g^'-g 42^| H * a 5"^ 03 S88 oo n co ON VO ro C-l rn * 2 o 03 s i O - li rt o Si cc O I> Cl O 00 00 00 CO O l^ O o o 5 S 00 VO VO *O * fM 00 VO 00 O 8 CO rH ' CO rH 000 VO ^O ^? 00 't rH rHCO VO CO VO 00 COVOOO OOO Q ' vo vo oo O< i oo oo I rH CO g 8 ooo ooo CO 00 O CO 00 O 66 rH OOCOrH O^ 00 ** CO * vo CO "t VO CO * CO C-l co co vo Tf VO * o ooo o 00 Cl "* VO co ^ O VO t^ rH CO C-l vo 00 CO iO o o o vo oo vo oo co oo vo c-i vo v O rt'E O CO CO to *5 s "" "3 co co-co CO CO t) Ss y.s^ CO VO VO 1> 00 O rH I CO CO CO CO * ^ - VO vo vo vo vo vo i x/) i/J u U o rt bo c rt co bo rt CO CM CO tn PH' is* COrH PH' CO r w r CO 266 BULLETIN No. 123. [February, w u 6 < ' S t^ 00 O J> 00 O rH -* t^ vo O rH ) t^ 00 O rH *J- t^ 00 O rH Tf 6 +J 1< X O l^ O O l> M Ot> 00 O I> O OI> O VH H rt M rH M CM W J i ' ^ C - W ^ l] |i OO'O 8S? O O O O O O -t "* CO o o i O ^ o co ^5 fNJ ^^ ^* ON O vo r-i vo GO oo 10 *^ *3 ^H "* 00 VO 1> 00 vo 00 00 ON O\ I> I> co 5? w Q rH fM rH (SS rH rj rH CO rH CO 1 12 g S o o o vc rt -i- 80 o 00 VO O O O 00 * vo SO O o n O O 00 O vo o Ji A O oo * oo 00 * fN< w ^ ^H ii a a < 21 3 Ij 5 a 3 .S i, A 111 S S S? t^ co ao n vo o\ CO vo 00 o o o IO ON f-1 t> co M CO J> rH co t>- O rH 0. o VO O rH CO VO * 00 rH 1 "rt -M i J vo vo 000 Q O O O fNI C-l 000 r j * o O O O Cl vo Q 3 5 o . a o rH rH M r^f^^ CO IO rH rH CM CO C\ oo IS rH C^ rH CO 1 ^^ 3 S a g 000 C<1 00 ^1- ogo 000 \ *r o .< j V - bo - S rH * CN -* ri co CO * CO CO * co M w JH Q t~ "f 3 i d a 2 11 CM Q fN| CM O * O O O oo vo oo O !> vo 1> CO t^ VO Ov CO O O O co iO CO o oo r-i rH VO O 8-! Tj- * CO " o 3 o *ii M ^ P3 S 55 5< 3tt P." O __, pq o 5 II il o o o C-1 00 vo rH SO VO 00 rH rH rH O O O * Cl 00 rH rH gg rH rH CO OT kJ 3 PQ O* g w D *<< "* 04 S 1 B w 8 * V Sli 8- O c w o rt rn H O 5 cfl "^ O *-c b 42^ S rt ;~* O *** a_8 a ^ Q tf) B 3 "*3 3 w 3 3 ^* 3 """s 3 _o"3 g g CO^CO CO'gCO CO^CO CO 3CO LOyCO CO CO CO CO CO 1/1 ^ fe 1 S I o ^ O rH rH rl M 00 00 00 CO CO *! 00 00 00 oo oo c> 00 00 00 t^ 00 0\ CO CO co O rH M * * * ON O^ OA M P4 ^ 1-4 3*3 c C fl C ^ O !=< K o C O O w 3 o >-J nJ <-. ti .2 g 6 6 g fc O rt bu B 3> n bo * o c rt CO 'C u i CO c rt CO rt CO 55 < ' HI to * d U '^ ^ ^ - _ ,_; J "* 5 w JH ^ w ^ .9 PH PH PH' PH' PH a! fc "rt TJ T3 to" TJ T* ^ TJ l- UJ HH o ^ CO o'co N CO ^ CO iH M o 4) (O rH t >< w ? H g * 14 L a 01 r^ w r ^ ^^ W *^ w;^ (1 O D 1 g^J COt- t* tO _ |j! i a vi S5 .. r ^ r ^" ^ r ^ < M w" N M co ^T- co ^co ^ J3 ^ . Z *' H r r^ 3 w r & w r ^ ^ HH CO *z\ CO Z ^5 1908.] THE FERTILITY IN ILLINOIS SOILS. 267 o S u & S co S * w S u 2 ^ i M <^ H r H o Z> fc g <_ Q J3 j 5 o P 2 co to (H S w O u < < d. W a o O o^ S! sfi S3 S5 O Q O e> 55 -M 0^ J3 fd C O H rt , A 2 a 551 - - .H n JS- jS a O I> M O t- vo OI> O O t^ O I> O O M ' OI> i o O ' S * M rO M 88 QQ 00 Ot- 00 oo vo 00 N N O t>- o * vo t^ O O O O O O d M VO * vo * rH rH ON 00 r<5 I> C"l VO VO 1/5 rO VO rO VO ON CO !> c5 CJ (S VO -* LO rO vo O 1/5 1/5 1/5 t^ CO rO rO M TJ- r-" * t- rr> vo ON rO vo O\ vo ^t* vo c5 ( rH C^l rO rH : :8 S ,! ,0 000 1 * vo oo ri i O rH M 00 M rH (M C-J i/> OOQ O O O O i M * O * VO VO 00 i Oi N M 00 f3 rO i/5 i O O OO O VO M 1/5 00 * rO rf rO * m rO O O O n * oo *** 00 O rO ,00 O i vo f^l VO i/5 Q ON * VO O C5 O\ O r5 ro W i/5 VO to VO 00 * i/5 rH ON * ' VO ON r<0 VO i I M S i vo ci vo S88 u 3^3 T- 3 ^3 a en S a w 3 - 3.0 H 3 CO CO CO _g 3 3J S pCO CO*gCO CO CO OrHM rO-*l/5 ONOrH 000000 000000 00 ON ON t> t> t** * t^ t> ON O rH ON O rH 1/5 VO VO f*5 ^ Tf O O O rH rH rH rH rH rH rH rH rH D-. W JB S ^ PH' PH" J= J5 PH PH PH CO . W CO W s PH' a 5 ' H w CO W CO- 2 " 268 BULLETIN No. 123. [February, tn o . , , i^ oo o !> 00 O t^ oo o i^ oo o 1-, vo O t~- vo O o w g 'O in rH ^- rH Tj- rH ^J- rH Tj- rH T- rH T- ^ t-- 3 I I I 1 1 1 l I I 1 I t I I 1 I I I o (- * i < 1> P I 0>> N O l^ O OI> O Ot> 00 rH Ol^ 00 rH PH g '- H c/} n t/) t/ M U & SJ i 1} a 1 l ;! 8|| O C 25 ri SO Q VO g 111 III 5 fe rH CO rH CO rH CO rH fM rH M rH Cl 9 , 3 i torus. O O n n oo rH CO 1C III 111 O O O f^l vo * SO O f>l ^J- rH t>. r J O O O M vo n O IT) rH 03 to *it p H ft ss M M r/. Q 1 3 s o -S H slum. O O O VO Cl * 00 t^ O -* O rH rH O O O 00 CM rf rH ON CO CO t> O in ~ 2 CO !> O VO vo vo vo if) 00 CO t^ O rH . & 3 S. 3 | o ^a H P 00 rH rH M O O O OO vo O rH fM CO M r-i ri CO ON T)- rH rH CO M CO vo rH M CO rH CO CO B 1 g ri 3 fi o ."S B S g i 000 ^h 00 ^" CO * CO 111 SOO 00 M 111 * * CO i? i d 5? 11 VC O 'C O O O * * ri O O ^ S83 00 * * O O rH CO O O O O ** vo vo 00 ON ON Q "i 1 i '! ON * O covo CO U5 Jo N rH VO rH VO -*l^ *f Tf rH ^ ^ O c o i ^ *^** t/) D . a g i A L" K u -I |s Q r5 "^ H o t- * ^ O ti c* II il 111 80 O VO 00 rH !>. CO 8S8 rH Cl IO III O O O * o * vo oo n ri vo ^ S H r3a c- rH rH rH rH M rH rH tz o !3 g o V V V V U W ^ S ,-j Q y "* W " o rt -* y {j TO iW cat: v w_ cj " rtt: ||| - O ri fc CO 9 o ^ 'o CO i-* c4 c 111 t4_i 1-1 C/) is 3 *9 3 M 3 CO "StO J- tn u, 3.O 3 " 3 co-co <-C "- 1 VI ^ 3 J3 3 m 3 co *2 co +-i i- 1 ^ 3 J3 3 3 co-co CO CO CO CO CO CO ^ !< w ^ , ^ g s rf) 55 ' ON ON ON M CO * ON ON ON * Tf- <} ON ON ON 00 ONO Tf Tfr tO ON ON ON O rH fN M f<> CM C-1 C>1 CN ON O rH ON ON ON 1-J _ O ^ tn uu , &. 8 O C C O < ^ bo O bo N W O t* JD c C V ^0 | PH a a V 9 V "o Q "bO 1 J o o \ " S a, V Cu u _c * i M * in to U ^ o ^ 1 l jg g g g g ^ .2 PH" PH' PH' PH' PH' PH' 2 "rt -5 J3 ,g JO 0--S w u K 23 "^ 2 ^ - Tt^ ^ (M 5- Tt* W y *7 C " *^ s2 *"* ^1 I_i W ft ^ .J -^ , * g PH rH CO to co ^ . oo o O t- O l^ VO rH *! O t^ 00 TH l> VO O TH -t O 1> 00 TH X 1 II o o o CN X 00 CO 00 * l^ vo I> TH CM O O CO CM O VO CO vo TH CM O O O CM C>1 CM CO I> 00 1> vo O> rH d O * CM oo oo oo 00 rH CM 2 i , VC M Tf- O^ vo VO 000 * VO TH VO TH rH rH CM O * O\ iH rH M oog CM VO 00 rH rH rH 3 s a , o 2 c* & O O O 000 n * * Tj- Tj- TH TH CM Q CO VO O rH 000 CO VO O TH O O O rH CM VO co vo a\ < 1 Ul rt S v O b a O O vo oo 01 TH 00 TH O O O rt- CO VO M 00 <* l goo co O vo ^ ft a *"* 3 * o ** w ^H J3 111 000 1> J> 00 oo o\ o^ o\ CO 't vo C-l M CN vo r- oo CM CM r) By county. Winnebago Whiteside Whiteside Location. By land survey. P-l C 00 fr_3 frl ^} CO t>~ >-> ^ o CO ^ W CO P-I 5? P-l to" 73 270 BULLETIN No. 123. [February, o H fe 3 o P r PH PH 3 W S fc < ^ S5 w o & I ^ M PH in g 85s r? 3 O 525 a -a "^ vo CO VO vo 00 vo VO t^ rj- VO I> CO VO vo CM VO 00 Th VO 00 TJ- I X $ 1 ! 1 i i i i i i . i T 1 || OVON O VO CM =8 O VO O\ rH O VO 00 rH OVOO OVOO flj cS C o o o * CM O O O VO "^ O 00 fM 000 00 Tf vo O O O O O O vo GO vo rO fM VO O O O 00 vo vo ON iO 00 O O CM * fM rH * LO rH fM rH CO rH fM VO * vo rH fM 00 00 VO rH CO l> vo 00 1> -5j- VO rH fM CO *^ x 2 S 11 O O O fM * TJ- rH VO VO O O O VO vo CM O *O tO 000 00 vo TJ- III ill O O O <* n ON ^ ON a 3 a , o .2 i 5 8 O O O CO fM fM t" cO vo VO rH IO CO1> rH O O O ^ c^ ^~ CO vo O rH O O * fM Cl CO 00 CM CO VO O rH O O * >* CM O\ vo t* CO t^ fM CO vo O rH O O Tt O 00 CO CM O rH tO ON tO CO VO rH rH n * oo rh ON "O CO vo O rH i rH rH rH CO rH rH fM O OA O rH rH CM rH l> 00 rH rH rH rH fM rH CM fM CM t^~ t rH rH CM 3 2 a O O O o o o fM CM O 000 8 8 000 gog O O rh fM t"i fl CO ON CO tO VO CO * t^ CO t VO CO to to ON * vo CO * vo co ^^9 rH ^J- l^ to vo co "rt 'S O "o rt - g 11 SO O * * O 1> 00 l> CO fM O O O rj- CM CM t^ to O VO O\ -t 000 000 fM CO CM rH CO 00 iO 1> fM tOl> CM O * o o CM 00 CO I>1> CO iO 00 CO O O vc M ^00 i ' . a c 2 s {Js HHM ^^ ** iH S i "O O O O VO CO vo o o o oo rH 98 CO CM VO rH ss OO O * 00 VO OO * * vo 1 1 V ^ -I- U V m ^H S rt **"* O rst: o *C o cd **"* O r3 "^ O c3 *** O r3 **' O cc g -M cfl CO 3 CO v-i h co oo ON rH CO * * g3 ON O rH iO VO VO ON O rH rH CM 01 05 H be . bfi C bo g) C bo a 43 rt 3 ca a 3 3 A u Q, o. a Q, S S g g G e H 3 rt 03 3 m 6 JS U U U u 6 u d o PH' 1 PH' jj PH' PH' PH' "S g -TJ CO li d 13 TJ o 1-t oo co T^ rH 1-1 CO rH oo M 00 OO rH S ^ W 7"ff1 frl f TrT Trl w r w w rw **frl frl P4 W d co 05 c/i * co m co' ^ CO ^ c/i CO * i l r ' */ * / r^* y_r . -r ' ^-^ ^ ^ 5J > w W w^ W ^ S ^i s Z,~ ^ ^S J2iS ^S W t4 fyl N g jj N THE FERTILITY IN ILLINOIS SOILS. 271 , , Vfi l>. + vo t- * VO rH CO vo ** oo VC l>- M VO O VO 00 rH t> 00 CM VO 00 H ' l y (fl rH TJ- rH ^ - M * ci * rH Tt CM rH ^- TT rH CM 'T * a J i I I I i I i i i i i i i i i I I I ' 1 I 1 1 1 -4-J ^. r< O VO o vo o O VO rH o vo * O VO 00 o vo vo * i> O t^l> N * J3 | M CM rH f -~ S rH ^-r"*^ ^--v^- C-l M [/I to . . j h 000 888 000 888 ogo o o CM CM s ^> o f! rH M rH M rH CO 00 t^ VO rH CO CO CO rH oo i> oo rH CM <* l> oo oo rH s rH rl f d i 3 O O Q n o o o o 00 CM O O O SO O VO vo O O O 00 -t * 8 R o CM 8 5? o VO vo 00 CM TJ- rH 1> rH rH VO t- O rH rH 10 vo a 3 8 a o || ||S CO I> CM rH VC ^ 00 to ON ON CO VO O rH O Q O CM VO CM CM rH CO VO CM to CO I> rH rH O O O oo * oo i> ON oo CO VO rH rH COO O rH o^ to rH VO CO VO 1 to ^ CO VO rH i -r. 3 2 o ja o O O VO VO |S| O Q O O VO C\ CO CO 1> 000 CM oo vo S 8 CO VO VO 1 H o. -S a rH rH M rH rH CM rH rH rH rHCMCM rHCMCM rH rH CO rH rH fM 3 % a O O O 00 VO VO O O O r-l oo -* ogo Q VO O 000 * o o O O * ^f O 8 3 O o ON rH l> o o oo ^O Cl rH rH ~1" 00 00 CO CO 00 ON CO 00 C*1 t"* 53 co I> M * 1> co vot-co * "* cM VOVOCO vo vo CM vo vo CM rt 'S O If! ^ U OO -t- cc ri O rH CO VO 00 rH * vo oo -^- rH CO VO CM rH * 00 CO 000 o** vo t^* o oo n O O O ^J* VO vo VO co vo VO CM 00 * VO CM QQO O O 00 1> 00 CM 8 | CM 5 !> yS 1 t5 oo CM i u i Q Q o o ^p rS O i g rH vo vo rH rH rH |PI <* oo vo 00 CM VO rH ss rH 000 CM TJ- 00 rH rH O O oo oo 'o cc stratum. Surface ubsurface Subsoil O V <->^, <4-H t- 1 V) 3 w 3 Surface ubsurface Subsoil Surface ubsurface Subsoil Surface ubsurface Subsoil Surface ubsurface Subsoil Surface ubsurface 'o n " to CO to CO to CO to CO N vo VO VO O rH CM CM co * VO I> 00 O\ O rH rH M M CM CO CM fM VO to <* n CM co to vo VO vo vo VO be bo s> 3 3 *o o C C Q g d a. tfl 1 a rt O u P3 S rt 1 u 3 u $ n U U * * ^ S3 O PH" PH' PH' PH' PH' P-! PH' 4-1 tt* ..T3 *O *T3 TJ p TJ 00 u u l_ Vi O ^ CO CO rH CO CO co CO CO CO o b. u 3 Jgd co'W rH . 3JW 2"w to rM . r/S 0> ^ ^ J ^ fj] - * CQ * 1 1 d c t^' . . W r tJ * CO r ^ " w . ^3 t-. ^^ ^^ >o r wS5 w;z; 'A j | ^^ *^ W' w TN i* Q o e\j r^ CQ {ZS w & * ^ w r > co co w r ^ * 5? 55 CO a g 55 272 BULLETIN No. 123. [February, d TJ 111 -M CL, ,C v- 5 53 rn >-H Cfi i/l -_- i> oo o O t> O CM b- 00 O TH if O t- O TH Tt- OI> O ON CM VO 00 ON C-l rH CO VO VO I' 5 ON CM CO 88 $: OO VB . i 1 O O OOO ' T)- 00 * 00 * > * CM ON * O rH CM rH CM O O 00 OOO -* * cM M CM 00 TH ri CM a SO OOO VO 00 O NO : C^l CO VO VO O 1 i Cl rH VO rH ON i 1> rH CO !> ON OOO Q Q O 00 CM O O O * co t rH t> M ON vo 00 CC VO CM -t- CO VO CN CO l^ O O O 00 CM VO rH r^- 1^ CO I> OOO OOO VO VO OO O CM VO rH rH 00 rH ON ^t" rH CM C>) rH rH CM VO VO 00 VO O OOO _ _ i CM 00 ^l" VO CM co 66 rH 00 ON rH M * rHCMCM rHrHrH rHfMCM OO -to co vo rH CM OO * O CM CM * VO 00 CM * VO VO TJ- vo rH iO CO Q t J vO 'O O 8 O ^ !S S: VO M OOO OOO oo n oo vo M c rH O rH O v (j TO .--. I 4) O t r^ (j < r^ _. *L/ ' -H O | 4) u ; ~ S. 3 3 in' CO (/) 3 ( c^ i/l 3 - CO CO CO ON O rH CM CO * OO ON ON ON ON ON M CM CM CM CM C-l VO N ON CM ri CM . _ rHCMcO ^"VOVO 1>OOON ON ON ON OCO OOO o o vT COCOCO COCOCO cOcOcO PL, PH J O CO PH PH PH r ^* ^ N cOfr. co ^ CO co co )8.] THE FERTILITY IN ILLINOIS SOILS. 273 BIT-; ^r 1> 00 O i> oo o t> 00 O t> 00 O l> 00 O I> GO O t^ 00 O t-OOO ^ * r . . i i i i 1 1 1 1 1 1 1 1 1 1 1 1 *H Tj- 1 1 1 -*- p t r^ O t> O O I>- O Ot> O O t>- O o t^ o Ol> O O t^ O O t>- O So M M CM M M M c^ S 3 & 1 ll O ft ft ft co 00 VO * ft CO 00 ft I> M ft M to OOO ft M to VO CM CM OM> ft ft CO 000 ^ft co 000 00 M M oo vc oo ft M ooo CM O 00 CO O\ ft M VO 2 ^ < II 111 8,, M to a Sc^ Cl 10 O OOO O> iO I> o o VO O o o o ^^M 000 O M * tO CO VO 00 VO vo ft 1> ft P< ft ft T"1 Ol rH CM CM fi <~H cM fft sa og 00 So o CM Tf 80 o VO VO 000 CM VO 00 O O O OOO 00 * 00 000 2 rt S t* oo l> co ft t^ CO co >O M ft CO 00 to vo ^t* ft oo O rH r ' *"* o o .2 CO VO CO VO VO O * 00 vo CO M ft * CA VO 5 00 to co O t^ CO 1>O CM t^ M ro VO O CO t^ O $ oot^ T-I ft ft ft ft ft ft -. , in a to a 9 S G ogo 000 OOO o o goo goo ooo r) x C? 000 o .3 o O C^ rH CM 00 co ^t VO ft OA CO rH O -- vo CO to t^ o M ^t" C^ CM CO 00 O co O VO co O^ CO ft H S * tn co VO VO co t^ to CO tOJ>cO t^ CO * to co VO 1> M to t> CO - .SJ ri 888 000 ooo * CM 00 OOO CM * 00 O O O 01 vo * O O O 000 ggo "*~* rt f^ &\ ^ vo CO O VO OM> ft M Th O M CT\ vo ^\ il CTv "1" ~~*~ r *~. Q\ ^^ t^* & S VO M t^ tO VO M <* ft M 00 00 M to O\t^ 00 10 M CO l> 00 VO 00 M CO co M I> 00 CO to *+ vo to to M C^ rH CO SSc^ o> O O g 88 O O CO O p c S ^ ^^ to O O to CO O .S O S3 to to CO ft M Ml^ .? tc P* VO O CO ft O M ft M ft is 4! OOO * 00 M ft O O M * o o M * -. 99 ooo ft vo S o M Soil stratum. Surface ubsurface Subsoil Surface ubsurface Subsoil U o o o rt^ r3*H ?: *-* - 9 S3| ^-w Surface ubsurface Subsoil Surface ubsurface Subsoil Surface ubsurface Subsoil Surface ubsurface Subsoil Surface ubsurface Subsoil CO CO CO CO CO CO CO CO f< O ft M ft ft ft O ft M co * to M M r-i O\ O r-t to VO VO ft M CO i?" 1^* t>* to vo i> C^ O *"H ef> ^ -4- vo t^ oo ft ft ft O -, rrj ^Ci co CO CO VO vo vo VO vo vo O vo vo ** ^ ** *t <* ^j- VO VO O >W ^W N W >^ o a TH - ^ . ^JTH CO -* f4 to r K . r-* W r co r ^ ^^ ,^f J2J ...' sf^ j^f^; ^ M ZN Ss S W co' M CO co ro "^ f ao r r w r r CO r ^ ^ W z ^ ^ r yZ ^ ^ ^i CO CO ^ ^ CO 274 to " * tn - w 898 W ^ .. g ~ 8 PH s ? H s d * S 'C 3 ^ to c ^ ri ti 2 3 S , o 2 H o, 5 w 2 2 5 s 8 S I! 51 o ^ cc BULLETIN No. 123. i O l^ vo O l> vO O I ^ rH ^f rH *! [February . ve O t>voO I^VOO 1>VOO O VO 00 O t> 00 O l> 00 O 1> 00 O t^ 00 O t^ Ol>00 M CO VO 00 00 rH rH CO i fN 00 I CO rH 111 rH VO VO rH CM tO ?: CN T- rj rH rH CJ O * i vo * i SO oo * OO t-- CO t- rH 00 M O VO O\ l * rH rj- O ! ' K 4) 4) O __ to -1/1 to i-. 3,0 3 tn 3 tn 3 w 3 to-^to to CO vo r> oo if) if) 10 fN fN fM oo rt PH 3 Q w PH -a (M PH T3 ? rW PH O -co PH o ^ to PH o to - co w" oi OOO * c-i ri O\ VO O\ OOO * fN * rH CO VO t> l> M o rt ^3 t- 3^2 3 3 < 3 to-gto to fM CO - vo O rH ^1" 3 JH 4> 1 1 i I I I O t^ 00 O !> 00 (ti rj O HMD rH rH fi n iS C/3 to ! - .2 3 1 88- 000 CM n oo * "8 * rH 00 rH rH CN rH CM t i * E fit O O O CO CO CO l oo o n rH rH M A g 4 d 111 o o rH O o -g s 1> CM rH rH rH CO 00 co rH - , to O O O OO fl 5 C 43 00 M M fN S * *. rH rH CJ rHfM fN 3 a Q O Q O CO O US o s c^ a t^)l>M I> 1> CO .5 n _ o o o oo oo vo O Q O * O * CO fM VO IP bo u t^ w rt CO CO 00 i 8 S S 2 ti 00 CO 2 " K " S rH rH If s| VO M rH O 00 VO i t- t^ 02 fl S V 0) o u K eq a H-l 2 d .2 PH "ri rft -"S O &"> Cvt CO t* ffj o g TH ^ S > ^"^ ri^ ** 553 r^j C/3 a 276 BULLETIN No. 123. [February, I i 7 5 |1 S 3 W b- X < rH ' OI> t* 00 O 1> O O I> X O I> X O 1> X O I> X O rHTj- C1 "* rH rf rH Tf rH ^ rH ^ O 1> O O l> M O 1> O O I> O O 1> O O l> O II 'OO OOO OOO iOrH rOrOrH rOO>t> IdrO rHdrO rHrHfM OOO rt ri o VO Ol rH OOO M X O ro O t>- 2 I X fM rO ' 000 ro O vo o o i rH VO S w *- -w 1> - ri rt C O I O ^ i o a c c o O O O MD C-l 00 I> TH ooo O ro O O ro O OO' ro O < rO O i ro X O * * M l rH M rO XXX XXX 88 O rH d X O^ O t^ X ON rHrHrH fNfMrO rHrHrH OOO OOO XXX be c rt CO in CO PL! p I p . CO* U, gf IH PH' c/ t- .^00 COt- CO" 5 CO^ w CO w z CO w CO 1908.] THE FERTILITY IN ILLINOIS SOILS. 277 H M U /V VI W Q W S S 1 O PH pi 5 3 f T . (^ u u s g o fc o o PH 13 e i 7 I> O O 1^0 Cl * l^ ci i- ^35 l^ 3 ^J p t t r] o r- r> O i^ ri O i"** O Ol^ O Ol^ ttf rt O b 9 5 fN fN N a! & S S38 000 goo ogo 80 o M VO 3 o 2 5 fN t^ fN l> * IO rH fN co oo oo &\ 00 t>- rH fN rH vo CO fN CO vo rH VO "O VO fN O rH CO VO * t^ rH 2 AS 000 O O O t- n oo O O O oc cc -t SO o c-i 000 rH fN CO rH fN fN rH fN CO rH fN CO JJ i 5 H P, M SO O o r) CO O vo oo oo >o O O O fN n oo rH O\ 00 rH VO Tf CO VO O rH rH fN 00 CO VO <3\ rH rH Tt 00 I> fN iO Oi O O O * M O t> <7l rH fN vo O~N i 01 n! in 3 i! o t- ogo goo goo 000 ogo ,3 O rHfN^- TIM'* rHfNCO rH fN CO rH fN CO 3 a o o o O O O oo * -* O O O fN vo O O O O rt- 00 fN 5SR o *-* ^ vo vo co VO 00 VO O\ 00 rH fN vo t^ H 'a * 1> VO fN VO I> CO vo vo CO VO1> CO - a O O O 00 tj- VO O Q OO 000 fN 00 M 000 ^3 S n rH fN VO !> CN! ^ *O ^H *O VO 't CO ^ fN CO fH wf rt ^ O O CO vo vo O> CT\ fN S fN ^ oo i^ 00 O vo rH VO M O 1> CO Tf CO 00 00 i _ o 800 OO O O 3 5 v ^4 *o rH fN VO 1> 00 vo si** * rH rH fN rH fN rH rH CO i "S OO 00 2* 1 ** O 4) l cO * fN fN Cl vo VO t^ fN fN M vo I> CO fN M r>l 000 O\ O rH sss M CO "! CO co co 000 * co CO co CO co CO CO CO co M JS X! bo bo bo m* JJ j 3 a ^ X O o O o O c c C o C o o jj w Q p p PQ y o u S s 2j d .2 PH' g PH' PH' PH' "rt J3 ^ J5 rG s-s o ^ ^ . ^ -* of ^ ^ o g m ^f CO , r ^ I TW rW -^ ^^ f T ^ I r-J CQ .. > HH *^ a e ^ " CO r 5 ^ CO N ^ 5 ^ S5 ^J" fi? wj ^ >. tf W (M r^ ^ i> M iH ^ T "' W ,fl to ^ ^~ CO __ CO co > w r ^ ffl W ^: 55 c/i ^/5 S? ^i 278 BULLETIN No. 123. [February, 4 UJ Z< S w r- 1 3 2 ri >, 5 -} O K. S ' S 7 l^ O O CM ft r j ft VO vo O rH ft i^ oo o t^ vo 00 rH rH C l^ 00 O rH ft ^rHf? 3 , :; D i i i i i i i l l 1 1 1 III 1 l l i 1 1 1 -M O I> ft O t^ 00 O vo 00 o t^ o O l> J> O t> O Ot^O rt 3 O CM CM rH d d CM IH 4-> 3 53 ^v- f CO ^ d II o o o t^ vo ft C-l vo ft 00 ft uo SSI ON ON ON ooo ri ft oo rH 00 VO ON ON 00 00 00 ON ON o -t g. O ft 00 K ft VO "o - rH rN rH CM rH C-J rH C^ rH CJ rH C-l rH CM 'u t, Si rH (M rO OOO ON ft VO rH M rO OOO 80 o VO CM 1> CO 00 00 vo rH CM o ri X CM o o VO CM CM CM 000 (M O 00 CM ft ft rt 'S 5 a S .2 a w OOO ro I> O OOO 00 Cl ft t> I^N ^^ rO rH t rO I> O rH ro vo rH rH VO CM 00 VO O 00 to t~ O rH 1 g O T-l rH ooo 00 ft M rH ft ON O Mt^ ro vo ON SS8 83S ro vo O rH "itf , 1 CO en 3 O t" a o rH 1C 8O O c-i oo 88 OOO t^ ft ON ON rH O X OOO vo vo n ft ro ft OOO H ft a rH rO ro CM ro ft rH CO rH CN M rH CO rO CM ro CO CM ft f? 13 *- g OOO O Q O 000 CS CM M O O 00 vo O -t- OOO ft ft VO ooo x c-i oo o . -i QJ T^ VO t** I^ 1 * *O *-O ^5 v/) 00 CM rH 00 CM rH VO ft O t> rH ON ro *j d VO vo <0 1> VO ro 00 t^ CM 00 VO CM ri 00 X CM ON 00 ft rt J S 3 O o o OOO OOO X vo 00 88 1 1 o OOO 88 g LO rH VO CM CM ft (M 00 l> O rH rH M 00 rH rH K uo vo ft ft CO H 5 v I>t>CM 00 l> CM O ON CJ rH ONI> CM 00 t^ ro 00 00 CM ON ON iC S = 2~ ISI OOO O rO O iC ro O OO CO O rO O 1 rO CO 00 rO >o OOO CO O O oo o o VO vo O *** ^ *" < ~ rH t~* *O ro vo ON rH CM rH VO 00 I-H !>. to ON 00 ON vo rH rj- rH rH rH CO rH O t- CO rO rO rH CM t> rH CM rH i i *a .| S| S 38 H a o- Q 4) O o V 'rH a 3 o crj rs c2t! o (> <_> rt . V <-> _ o rt r3 cy cj >+S 'S cu o cj rt rt **^ 'o ^ rt rz3 00 ON rOftiC co ft U) VO1> 00 CM ro ft XXX rH rH rH rH rH CO fa vo vO vo VO vo vO ON ON ON rO ro rO CO CO ro rO ro rO rH rH d 3 8 *& U 'v (U .1 rt 0. u .Is C rt CD C rt rt u N rt N rt s PH rJ M H H 1 o JH o u a ^ g ^ ^ ^ ^ d .2 PH' PH' PH' CU PH' PH' PH' -4-> TJ -o o -o T3 -*O O 00 u 5? ^w ** tb"" i-T 00 -co CO CO J_J E w !> >^>- 00 Cd 1-1 Cii rH .: sTtJ oo" 3 "1^ r^ J^ niW ^^ ^1^1 [^ rH tj*4 0! W* . X ^ T ^ _. W" m i * c W' \n a f^ ^^ CO . t rM ^ t a SH r J" ? ^'Z tOjJ 1 co' r -!z r CO r M rig ^ CM [4o Ns (ifo Nw WN CO CO "z* CO CO w r ^ W w w ^ 4 to ^i 10 CO co ^i THE FERTILITY IN ILLINOIS SOILS. 279 I^OOO l^OOO l^OOO Ol> O Ol> O ,8, O O O O O Q TH O t- O O > O\ OS rH W) Tf- CO TH CO TH CO IO O O rh 00 ;8. II CO VO O CO I> Q\ ro vo 3 a a> 3 o 5 2 *o ^ O * QQ O O o o o o o o 000 CO O\ i i VO 00 CO IO rh 00 I> 00 CO 80 *O ' o i co CM s a * y O O O O o g 3 " t 1 O "3 'S o 2 i t2 ** u Tt * OO vo ^t" oo VO fM O CM vo 00 00 Tf CM N " o u rH < ^ OI>-O 3 5 Oo H p |||g VO O VO O rH O M < < j J v_/ t 1 8*1! OO O PQ en - V* *^ Tj- Tj- VO - s S s< | w w . 4) 4J H W t D H 4) <-> _^ < u o ^ ^ (j rt rt **^ O J 5 CO < & Q rX ^ I- 343 t-> 3 .^ 3 g a w 1 g to 3 C/i-C/5 3 OT 3 to ftt (H C/) t/5 ^* ?\ ii W S S 8 3 1 ^ 00 00 00 00 W O rH rH CM OQ D ** r o i3 55 * ^ H O i. a rt 1 >> 1 3 a S PM C t J -J U rH Q .. S '* M 3 P a t> | t S3 " 5 ? a ^ ^d w K .9 PM PM ^ U 55 '4-1 T3 *O - (H * r-l w ^ " E a S > a N o t>* o M i- ?3 S H pu, tL a 00 ^01 N- >4 W H n i3 H 8 t/i r ^ r c) ^j5 5 ^ t> O <^ X tJ 00 W*o ^ o tt c/i "* o 5 >4 [February, THE FERTILITY IN ILLINOIS SOILS. 281 i i 1 "H s | CO S VO VO X VO rf X CN * CM rt- Ovovo Ovovo O !> O Ot^O O I> O O t> O O I> O 01 C-l C-l N tN vo vo CO vo r-t f n , 5 i 3 o i. a o Pi a a o 5 pop pp. N t> vo co vo cO O O CO t> CM o o o * CM 00 * ON vO * ON O CO VO rH O O O X O * OS ON ON CO vo * * rj o CO I> rH It 3 J o >-> O J O 3 2 a O >-> rH rH CO 8O O 01 * CO CO I> rt a o o 5. H w rt ^ o u i "2 i S o OO O O vo * X X vo t- f>l CO 1> O ON O\ TT 01 OOO OOO VO O vo (S X X M 1> XX MO fN O I 3 )* CO CO ) O g 3 ^"3 CO 3 at ) CO 3 w 3 3 CO-CO CO CO A O PH C O in C J3 O C O in 'o C o tn C O w s PH' O CO w ~C3> PH' w -o -co coco W CO co PH' PH t-i s w . "Cu frl co . 282 BULLETIN No. 123. [February, en o . , . I> 00 O i^ oo o t~~ 00 O i^ oo o Q W S "^ M rH Tt rH ^~ rH rJ- 2 t_ S ^ 4> 1 I I i i i 1 I 1 I I I O H OH g ^ a x p c o fi 1 J ^ CJ o t^ o O l^ O ^8 CC M C- < ^ 4 s 000 o o o o o o o 2 ^ 1 i fNj O ^t" oo x o O Cl t- ci g 8 c3 3 o 5 *o ^ ^o * ci rH Cl rt ro * rH Cl 00 ^D w S a > ? goo 8O Q * o 8|8 ogo 3 M '* o ^ 00 C*l 1> IO Tj- 1^ Tt 00 ^ *^ rt T^ C^ rH Cl rH M d ro c/) tO 0. 5 O "M 1 rJ 3 S 000 Tf Tt O 000 ^O VO Cl O O O oo o ci O Q O o o ci 10 o oo 00 w w 5 al rH %%% oo ci F- ^ ^j- ^> ro t^ O rH K 02 i U> rt ce 3 -*-* O ^* JJ III 11 o o o Cl Cl O rH rH d ill i J 3 ^ d O *" U t~i a rH C4 rH o o o oo o *o i> o\ oo rH rH rH d d rH o o o rH d d H <* rt '3 O |S8 O O O C) C O O O co o oo 00 00 rH O O O Cl 5 GO g Si * O IO rH I> C5 O O\ rH rH ^ S S rH r^ rH d rH rH rH rH o U PH S U i * ' n n .% *^ rH O U " S i i o M o m i *d OO O Cl *O ^^ rH rO rH O O O 000 000 00 O * O rO ro rH S C* ro d d rH J J3 J3 w t> 4) 1) E cj rt -T3 8 cans o o o rt rS o ^3 f$ *H *O III 4 J -M 0} *H Ui M 3 oo 3 CO -2 CO 4H I- 00 3 oo 3 VM I- oo u, 3ja 3 oo 3 CO-CO IH 3 43 3_g 3 CO-gCO - W CO CO CO CO < S co w < 3 1 d ro * ro ro ro iO VO 1> rO ro ro x x oo ro ro ro Tj- lO 1O 00 00 00 ro ro ro 5 Q C/J V3 W Q < K u to o a < O PH 3 C C C C S S fc O O O U) O (/) fc o o p^ C C n * ) fi. >H M J2 f- J O .O .0 o T-H r-3 ^O a g 3 g ^ *5 5 Pk Pk PH' Pi O j^j " N Q "rt o ^ OO* l_ CM CO ." V-. -CO - u W 55 55 o * O co 1-1 < 3 fifW rtjj "Iw -W F-H W * 8 co "* fy^ y Tf W IM j O 'en' c r co^ CO r ^' " o ^ S JJ .^fco r co^ .CO CO CO K o m Wg ^S (4s J2 PH i I rH ^ *"* t-^ co O ^ ^ ^4 fe ^; IjJ . r 3 r* r*_ W ^ I I ^ 'Z, CO co 1908.} THE FERTILITY IN ILLINOIS SOILS. 283 55 u > < 6 (/) W a o * I Q PL, < K -1 O K 3 - 5 5 d CO O (2 o t-J C3 P *!>(-< M S n H a s '<> a II o tJ S" H S " Jw CC J>cMO t> CJ O I> VO O I> VO O t^VOO t^VOO O l> 00 O I> CO O I> 00 O l> 00 80 o o o o ( CM 00 O C-l CM i O VO ** 00 1>- ' rH rH CM rH i :8 i * rH rH CM O o 00 (M CM CM _ N tM rH ;OO OOO CM 00 CM * * CO O O VO 00 t> ^O rH !> ^> tN co i d oo 10 ON O o CO a- i- 3.Q 3 co 3 3 co 3 3 co 3 C 3^5 3 co 3 l> X ON oo oo oo 00 ON O M CO * rH rH rH ON ON ON CM tN CM rO CO co CM CM CM "O O PQ U n j ^^ TJ TJ ^T " - "- 1 N CO ^ CO "W ^W ^ n . rH CO r S? r PH' ty W c/i OOO vo vo oo * rH ON o o 00 VO _ - * ro 1> CO VO ON S 80 o o o * oo * oo o 00 ID o oo vo co ri n CO O 1C CM rH t-- \f) Tj- t- VO CO CO > t) CJ * -~-^ ' '^ TH i+4 u tn +H I-" co 3 to 3 3 cg^ i v 5< ^ cy *^ ^ ?3 o cs rs o cars U co PH' 284 BULLETIN No. 123. Z w i CJ d 'd ^ t** t^> o t^ VC rH Th b- vo O I> O rH Tl- > < 3 " fl5 i i t 1 1 1 i i i 1 1 1 6 s ta ** ^ rH rH O t> X rH O t- X rH W 00 *" ~ a < P tC 08 tl CO C/J i Q O O O O O O O O O O Q H fc, QJ ^ *- Tt Tj- VO 'COO P 2 o 5 * rH X IO IO rH ^ fN rO C> C) rH (/I CO Q rH Cl rH CO rH rO '^ r^ To Id A P f o S o o o foo o 000 80 * o . o vo c^ c^ vo vo t 1 "* C 1 ! *O l> C^ rH Q PH < S rH C^ rH CO rH C^l rH f>l 55 o. J O S a ,0-53 r* 5. m 000 CO iO 00 000 X M M tO rH f>l 1/3 O * rO I> O rH O O O ON O ^ rO X f-1 CO VO rH Q O O rH S H * rt to 3 S o 1-1 o a o 1S1 || O O ~f ri 5 X CO 1> C^gg I> M M o 2 H o. -9 rH C^ rH CO rH CM rH M *jr a. <-> * /-N *-I / "^ GO J t S S 3 o o o 000 O O O oog W S * 5 o * a> H '3 * rH rH CM S2 X rH rH rH f\) CO 28^ if 5~ - .H c M n O O O O 000 oog oog o *; 1 II I> VO O c^^*^ n x * rH X O S c5 x rJ <=> " O O rH rH C^ C4 rH rH C4 rH M rH rH C) H H N jJ P N i o i "1 ~I|g O N ""' ** 3 w o d >" co o -S t-> "^ O O O * xo OO NOM O O O VO X VO 000 n N * O^ rH oo . t 'Ji S tH Q 1 ^ i_ i-i jr 55 S CC ^< O> O rH M ro rO XXX 111 X O\O rH rH rH rH 3 * 3 ~ 2 S K ij EH * a n C o 8 2 U 1 1 g rt 1 g ft Q 8 Jw bo bo ra bo > 55 M c C C 55 < ) j rt rt rt .. w ^ fS CO CO CO *" W " s a ^ - a d < .2 p-i PH' PH' * a js '"S a IM "S OO~ VH "8 W PH o * -CO CO rH CO rTco O H g 2 01 ^ 1^ &:* w;^ J P H HOP O a CO r ^"l ^* ^^ CO ^ rt -^ ^Iz; w'*^ w ^ > pq Wo f4 !z "^ ^ "* g < - CO 1 " 1 co"" 1 r | w !" w r ^ p6 tS ss CO XH '/. 1908.] THE FERTILITY IN ILLINOIS SOILS. 285 W ' Csi "* to (fl fc S rn OQ r^ i/i - w ? s 3 g n o o w tO g w to o g s .. < 6 to > 55 1 S g > PH < . , , ^rH I> VO O t^ vo O t"* ^t" ^5 8 "g A rH tf rH - vo O l> 00 O I> 00 O t> vo S S g rH rH rH rH S S j i 500 O O O oo n <* 000 SO O vo oo 3 o I 10 ri r^ GO rH VO iO CO CM ^- 10 oo CM ON co rH Ol rH CO ^ rH CO rH CO "C MS 5 - 000 000 CO CM CM 00 ON rH GO ** X O Q O oo o ri t> * rH < Pk a rH CN rH CO rH 01 rH CO o. _, , o o O O O O O O O O O rt S S 5 ^ coS S vo 8 >^ So oo o^ , o 5 fen P< 10 CO I> O rH iO CO 00 co l> OS CO I> O rH c^go^ . i 01 rt to 3 c goo 000 000 000 o ,2 o VO 5 O O 00 CO ON vo ** t^ *O Ol H a -a rH CO rH rH CO rH CO rH CO ^ *" a 3 2 g 000 g\ s O O O GO VO CM O O O CM VO CM C^ fl rHrHrl CM CM CM CM rH CM ._, a) C O I | O O 00 j* rH 00 ON 000 'O co ON ON O O C-l rH O 80 o 00 Tf CM O r-l * rH CO " l-5'oo O-" i - i i |2-5 O O O 00 <* M CI CM rH O O O 00 ?^ O 00 vo o o Cl 'O O GO O O rH * CO H * o 1 rH V GO ON O O O rH CM rH rH rH ON O rH rH CM CM to ^ i>l>t> rH rH rH rH rH rH r^ rH rH fl o tfl X o X O O o c<3 c c t. *O .2 P^ s ; PH' PH' "rt .c . -5 O S-, * *n & oo" ^ti ^ N W a "00 r? T CO r to''!. .2 tOc/i r^ r ^< . ^ T-l M'O ^ Jl, J3 S | 8 t> vo O rH ^> Ol> X rH t- VO O O t^ X rH rH rj- O t^ X rH .2 31 P-< X oop ^t- n o vo vo vo rH M r-i n n cot^ VO vo 1> rH r-l O O O VO VO vo ro rH X VO VO X rH d 'I si Jj J3 O p.* X VO rH rH rO O O vo r-i vo I> vo CO rH CO poo O r-i r-i rH rO 3s J I 5 P 1 O< to VO M O rH VO * x vo * CO t> O O O O vo vo r-i VO 1> CO rH O O O ri vo X VO VO rH rH i M w V 5 ^ * a O O O r-i x r-i X VO rH rH CO O O O x vo r-i rH rO opo X O Tf X O X n ro 3 | g 5 'S & O O O x r-i M rH CO VO r ro ON Soil stratum. 3 oo 3 Surface Subsurface Subsoil Surface Subsurface Subsoil 1 r? r-i r-i M X O\ O r-l r-i n rH rH rH r-i r-i r-i O u M Winnebago Winnebago O c '1 Location. By land survey. ^ in N to if c/i w w co .Jj rd . ^ to w to o < tO B5 5; a rfl rf O D w >^ 55 g 55 M 55 I - jj 3 7 4-> Q, .c S 1 s l_jjl t^ vo O rH rf O I> 00 rH rH rr O t^ X rH 1 II O O O ** "t CO O X rH ri O O O VO vo O rH CO J( 1 * i fc M Cl 8 V\ t*+ fO rH rO oop VO vo O, rH ro 3 8 .2 H ex, to O O O x >* n vo 8 ro ro t^ O rH O O O x r-i TJ- r-i ro t^ vo r-i vp rO I> O rH 111 11 O O O n ri x Xl> O i S t^ S3 rH rH r-l 000 -.Ho Ctf C O g a? O O O X X vo * o oo X (S O poo ro X ro rH I> rO M rH rH ~ i i .|||i i "3 o o o * vo X ro X O O O r-i * r-i VO O rH 'o 3 O u rt~ t*H 1- W] ^ SJ3 3 oo 3 CO Surface Subsurface Subsoil rH . '-- vo vo I s - X C^ J/3 rH ri ri ri ci r-i n By county. Winnebago Winnebago Location. Ky land survey. PH' (M u P-i |M frl CjJ W ^.J co THE FERTILITY IN ILLINOIS SOILS. 287 ^ co 00 ti. H O 00 STJ oj * S T-H ^ rd rj vo O rH Tf Ol> X rH l> VO O rH Tf O J> X rH t> vo O rH Tf rH rH Tf rH t> Tf O rH Tf O t> vo rH rH Tf O I> vo rH oo Q P^ 2 O PH cj S S 1 !l O O O CM Tf vo vo ON rH CO O Q CO Tf Tf co ON rH C* O O O vo Tf x rH CM 1/5 rH CO O O O X vo O O rH 1> VO VO CM rH CO rH X I> IO CO CM rH CO Q jz; 2; o ^ 1 *3 2 i ^ i O O O VO vo CM 1> CO X rH CM O Q O rH CM rH rH l^. CO t- rH CM X M O O O ON VO O\ rH rH S "** H M 3 s a 1 1 1 " P4 W rH VO X co vo ON O O O VO ON vo CO VO O rH 00 O CM Tf Tf O J>- CO CO VO rH rH O O O -f X Tf X X ON CO rH rH COI> O rH X (M vo rH ON X vo O l> co t> ON CO ON CM CO VO O rH ? 3 w 3 u W u K i i r- , CO 2 2 o ,3o O O O X Tf X I> Tf rH rH CO ^ rH CM rH rH VO Tf l> ON rH CM O O O rH CM VO CM M rH CM ^ PH I ~ H a ' o o Hi X CM VO l> ON Tf rH rH CM O O ON vo rH rH fN Q CM O O rH Tf CM CM CM O O O M CM CM X rH X rH M (M O O O (M X Tf X vo co rH rH M O O Tf Tf O fM rH M < H D r-l ID o -. .H a rt c O ft u O O O O vo Tf O CM vo CM t^ vo ON ON Tf ON 111 CI rH ON CM LO X CM VO rH rH O O CM O Tf H **< o * o o co -J "> o w SUBSOIL iU CB O 3 1 ^ [< ?H J2 55" ^ O 00 i 41 -d 8 -22| ^ g, O O VO O Tf CM M IO rH OO CM Tf VO rH O VO X CM rH O OO M X X O 00 CM VO O rH M OO vo r-l vo ON O Tf VO fa H O Soo Q 2 t> a .^H S cs r3 V U fd HH CS'+H O V O O ( cj rt -^^ V t> o _ W ei u u >2'o c o^ O c8 " < Z. E> O o X * 2 O co 2 03 3 oo 3 CO ^ 3Xi 3 oo 3 CO 3 oq 3 CO-CO CO 3 oo 3 co-co CO 3 oo 3 co-gco CO co-|co CO 55 2 <0 ? 5 CO ^ rH CM CO CM CM Ol X ON t^l>- X Tf xo vo XXX Tf Tf Tf rH CM CO rH rH rH CO Tf vo Cl CM CM CM CM cM vo vo vo 00 5 rH rH T-t ^ N J INCHES), AND By county. McLean Uc rt bo S o W Tazewell Tazewell Tazewell CO [ ^H *^ rH PH II W > PH t_, 3 * CO W 2 O 13 i i (M t- H O U U H 00 Location. By land survey. PH' co co 7 N a PH' o~ c /^ ^H frl ^/^ CO M< rH co a PH' TtT" d H ! L tH w . a . l-H O H W S < CO ^ co LO ^ S S fe OT III > fc PH PL, rH rH ^ ^ .. H U ^* H PH t- rl i 1^ Tj- O t^I^ O 1^ vo O l^ vo O l~- vo O 1> t^ O l^ l^ O i: S S , . i . . , 1 1 , i i i , . . i i . , 1 1 -M Li ^ O t~- >O O I> O or- oo o t^ oo O !> 00 O t^ l^ O t^ t^ a o rH rH rH 4- 1 GO /) C- < s o o 888 000 OOO 000 OOO 000 2 O - G"\ ^ 1>- VO 00 O ^O !> 00 to oo vo I>* QC rO rH fsj I/) *O O GO 1O ^ C-l */} fH ^ *-O d 00 i^ cr\ <* 'O *O C^-l !> t" 1 * M o rH tO rH fsl rH CN rH O rH tO r-t tO "S S 000 O vo O VO rH t^ o o oo oo !> VO to OOO GO X * III OOO 00 00 rh 000 O 00 rH OOO * * oo 00 Tj- O ^ PH .C rH M rH tO rH rH rH rH tO rH rH 3 S fi o .2 ^ 05 OOO * 00 M tO O rH VO O\ fO to vo a. VO M 00 * o oo tO I>" C^ iH OOO to 10 * tO VO O rH to t^ a\ OOO VO vo O r^. IT) -4- tOl> O rH O O Q O -4- O rH VO 00 i> to a\ fO t^ O rH fO VO tO <* Oi to to vo O rH rt , i f S 2 o 000 CTi tO O 000 OOO rH VO rH OOO Cl * Q C-i vo O G\ TJ- O OOO rH ON rr 000 f| a rH tO rH Tj- rH rH tO rH CO rH O rH rH tO rH rH M 3 ts . i fl - j ^ 3 OOO I> i/3 VO 1> O VO 111 OOO Cl O O\ rH O 00 OOO O -3- VO CO O 1> TJ- to VO SO O VO vo O CT\ tO oo to * 5 rH O rH rH O * rH tO O rH to to n i 1 O o -4-J to o rU * S 28 rH VO rH sl AS * 00 O OOO * oo oo O M OOO GO vo * OOO o oo oo OOO O 00 VO **> * tn ^ to rH IO * oo O CO to M o- "* * co i-H 4) CD t to to to tO fO fO oo o\ o tO to * O ro ^f ON O rH O to *1- uo vo t^ ^ l^- 1> t>- t^ l^ I> r~ i-- t>. 1^ t>- 1- t^ I> l^ county. D u, 'c3 u 'rt U tf> B a gomery gomery gomery (>, M t/5 CO co < o c o . g a ^ ^ g jg J3 PH PH PH PH P-i PH PH ri -j-0 o a .43 -T3 d a 5* fO CO CO CO w co o ^ r . N . fe ' 1-1 . 1C ^^ w^ fS ^ ^ ^^ W^ tj CO 01 co S oo CO 00 ^ (M c^ "* co * J r " r r " rco ^ " r r z H CO ^ CO ^ Sw CO ^ ^ ^! oo CO ^ o co ^ ^ f5 ^ ^ W jj; CO CO 53 J5 ^ CO CO IQOt d fc i s m Z -l H o g i Pi a" < r3 > Q 55 < CO w z M UH 1 vJ W >^ < M W 3 & M Q T* CO 00 6 & s 5 Ai > H S CO (0 5 S5 3 ( i Stratum sampled. (Inches.) Ot^ O THE FE l> 00 O rH Tt O t> O S" O O Tt 01 o OOO oo oo oo rH rH CM . rH rH rH O Q O d O VO 00 M Tt rH rH Ills M*! 3s g, O O O O O VO rH Tt O-N rH VO O 00 VO M Tt rH rO Soil stratum. o ca rzj IM H 3 oo 3 Surface Subsurface Subsoil ii Tt IO VO Tt Tt Tt t^- 00 ON Tt Tt Tt By county. c3 C/)' Location. By land survey. to" i- co fc PH' S3 THE FERTILITY IN ILLINOIS SOILS. 289 oo b S t> fJ oo Q w 2; P< O d ^ ^ - 3 g s a Q * S r ? I H S 5 Tf S N < H H O & P J S S 1/1 J ti s^ a iS" > < &. SS ?J| 2 S ^ H S5 ^ < !D O S J q < PH J o S M > -i ^ " Q E < > ^ ^ - W oo H S H H O ffi 3J.1 Q. O Tt HH (M s s - * fc o 55 ft 5 W OT s < (2 S M Q < p. fc H 5 O O ^ W S D 2 < co o 15 3 O vo 00 O t> 00 O O O M Tt 00 e c l o . +_, li to L|_| l-c 00 1-, 343 I-, 343 3 uo 3 a oo a co-gco CO I> 00 O\ O^ ON CT* VO VO O VOI> 00 1> I> l^ vo tO 10 a r-l PH PH N CO N CO 3 43 3 oo 3 O O O vo vo Tt vo 10 vo rH N OO OOO OOO Oci cSTtc^ OvoTt Tt 00 00 00 Tt VOIOVO rOMM MMrO droro OOO OOQ OOO Tt M M VOOO VOOOCO O\ rH !> 00 Tt rH O GO l^- IO O rH O 00 ^ O t* rO rOMM rOCJM rOrOfO O df O 343 oo 3 to PH PH r W rW iS cOl c/ BULLETIN No. 123. [February, in o Q Oi | \ to Stratum sampled. (Inches.) l> vo vo TH CO Ot> VO TH O l^ 00 00 TH TH O I> 00 tH o i^ oo TH I> vo O TH Th o t^ oo tH c3 2 | a 1 ^ ^ O vo TH tH CO TH TH vo CO CM TH CM "* tH TH tH CM vo CM Sj oo * ri * tH 00 tH TH 3 ON co 00 l>- ON CM vo O\ * HT 00 VO CM co tH CO TH CM * VO CM vo 00 Q P-t M , 1C rt w S Saw o js o OOO * vo CM ON vo CM OOO VO 00 * VO CM t^ TH TH OOO 00 VO <* VO tH 1> TH TH OOO CM CM 00 TH CO CO TH CM Tf O O Q TH CM B! 2 I) "3 I- 1 [J * 8 d <-> aj c^ s CO * TJ- 00 CM 00 1^ vo tH CM * CO CM CO CO OO VO CM CO VO vo OOO -* vo 00 n co TH CO * co M IH O ji rt 'S o o o o * CM vo Tj- Vf) TH VO TH VO CO vo CM SO O n- oo O CM M 00 00 vo CM * CO vo vo ON * VO vo OOO vo r-i oo TH X ON ON * Th CM 5 H ^ W o Ills 1 tH *T "T 1 1 Q E> H Mil * *J w rt t^" 5- OOO OOOO CM 00 oo * TH > TH tH O O vo ** OOO TH CM Tf g 1*1 KH M W ~ O Soil stratum. Surface Subsurface Subsoil Surface Subsurface Subsoil Surface Subsurface Subsoil Surface Subsurface Subsoil Surface Subsurface Subsoil fc < CO 2 K h o ^ t^" 00 ON oo oo oo TH CM ON ON ON CO * vo O\ ^^ ^H 0N *O ^^ tH CM 01 ooo CM CM CM 2 to , IOWAN GLAC >N POUNDS OF ILLION POUND. By county. Winnebago W.innebago Winnebago Winnebago Winnebago w !> o 3 ^ t2 P to g ^ " w ^ d < ? o CO u fe hH J (1 v L/ocation. By land survey. co . W"o CO PM TT] fr^ T-H co"^ co oi CO 3 PL,' a tt ^ rf CM' CO CO w 1908.] THE FERTILITY IN ILLINOIS SOILS. 291 B < o *~s * H 9 1 55 PH i: K y O K " ss r T i XH 3 ^^ Q t. > o Q H S g CO g PH W O 3 3 1 d a ^ 3 ^-< 2 1 o *? 2 2 , -a 2 fl~ -III t-. o O O t- O O O l>-00 M CO * O M i o O I CO Tf _ . _ i TH> M VO CO rH rH rH CS CO 8 8: 3' MM-* o M ' _ vo t> OA VO * rH CO 1> rH M 1 rf 00 vo o 000 O CO M t-- rH O M :58 CO M i M M rH S 8' 83; fN M rH rH M rH OOO O' * CO M M ' VO M M rH O O ~- -^ 4H *-" ^ ^(H *-" ^0 !_ 3 ,Q IM S A 3 oo 3 3 (/> "- 1 co-to CO w o . o.csra 300 3 3003 3003 3003 to-2 to tO'Sto co-Sco to-Sco to to co co O\OrH OrHM N CO * ^VOVO cO- CO 00 00 ^ O^ ^ O 1 ^5 ^5 vO vo vO I>I.^r>. 000000 0000 00 COOOCO Q\ O\ & rHrHrH c O I c n) S PH T3 PH PH T) M" C PH PH PH d -co CO co ^ CO CO to to to 292 BULLETIN No. 123. o PH *< o PH < >3 3 . to IB CQ 6 W ... - ^ S / w ^ 2 w > i J Si g - a T H H <=> . g I CO CO 5 o z I 1*1 2 s " 03 a rt O -" H n u 5 5 .So a Us! VO 00 O VO 00 M 1>^C O OVOOO OVOOO O l> O O I> C-l O OOO "$ rt r\ ri to ON O"\ ;o o -* 00 O P-l I M d MOO OOO 9 5 r3 * vo VO ro m rH VO . vr. OOO O rH tO VO rH 00 tO rH rH W 43 o rt ^3. o rt 81 J 5s S3 3 3 S? i * rH vo t^ vo O O OOO r^ M * oo vo rH * t^I V v w. o cs : 3 oo 3 co r* IS O\ O to * vo ^ sss o s rt If rt co 8 rt ffi o rt g. rt co PH T3 PL! P-, -TJ s PH' c/i CO w r (/ THE FERTILITY IN ILLINOIS SOILS. 293 si i 8 ^ ^t- Tf t> o o ,T , in .*""i O O VO VO O I> I> O t>* t 1 ^* s -M | 3 j cn I ' d i s- O *O vo rO iO VO rO ogg S,_ gi CO * t- rH rH M iO 00 ro vo O rH 2 , ;. 11 | HI O Q O f) O >O O O O oo o 10 00 ON ro ^ & a rH rH rH N rH a 3 ' S* S il O O O O CO 00 t^ rH ON OS O rH M rO 00 C5 rH rO 00 M r<3 vo O rH O O O O rH IO 1 gl 1 9 3 l-> O O Q O rO OO O iO O O O CO O 00 rO O >O a o O <*> ON ^ 10 rH n rHM rH rH rH 3 - s 8 ^8S O Q O fO ^P ^O 888 ,0 ." H 3 * rH rH CJ * rH 1> O TH rH M M fO J j -1 Q O O rH O 888 | 5 | ^- ON 00 00 r- 00 M rH CO 00 O O O rO iO 00 O O rO iO 00 e V > | 4J 4) O O O rt !-! W ^ ^_i cj rt ^3 W r o rt^3 M 3 rt rt 1 ^ O rt ^^ O rt ^J^ O o <+H i-l t/3 w 3 43 C/J _Jj 3 3 "i 3 3 M 3 3 "> 3 tfl CO CO "2 CO co *2 co CO *2 CO CO CO CO 'o d ON >O vo vo M rH rH rH rH CJ C1 ro ro rO 00 ON ON VO vo vo co O U U) d 1H ^ *"^ CO s *W 4> ^ o o ^ ^ c t>> M N N rt cc H H I 1 S ^ s ^ d .2 PM p | CM CM Vj *TJ rj T3 *o o >; u o u, ^-CO IM CO C >o <- rH CO 4) t- ~ .' *""" a W r ^ w^ ^ J> ^ 10 2JW CO o ^' rH CO a r 5Z ^'Z .^ rizf n ^^ d ^ c\j w 5 ^ frl o s - ^ rw N 294 BULLETIN No. 123. [February, 3 I* < i s w g W r< ^1 . PH 3s PH 1 Q < Z % . < ^ ^ ^ EJ w 3 g H I co _ ^ H S d < g & 55 ^ g o K Stratum sampled. (Inches.) 1> 00 CM Oi> oo to :s :i! I> O O u i i OI>v> i a D 5 B 3 o 5 a (L, " TH 00 CM TH CM * 8 to * rH CO ooo CO O to I> CO -* in OOO * O to 1> CO OS rH CO * . "2 3 y 5 s *a OOO VO CM TH TH CM CM VO 00 * CM OOO CM CM CO CO * vo TH CM CO ooo CO VO I> TH CM CO OOO CO Tj- rH VO Os Os rH t CM 3 a 1 o .2 H p, w OOO Os O vo TH * * 00 TH vo TH O 00 I> CO 1> TH TH O to CM Os CO rH OOO vo CM co c O O TH CM CO rt o -I 1 * s o *; J> H 3 * CO CO TJ- co vo oo TH OS CM vo CO VO O O O C-l CO O OOO ^ O TH OOO 00 1> rH OS CO to l> vo Os CO vo Os OOO !> VO VO VO J> rH CO VO O rH rt '3 o 000 l> 00 OS to vo VO t- r- CO "t 00 CO TH O to O 00 OS TH 1> CO vo ooo CO 00 * 1> r-t CM CO vo OS * 00 CM TH O * TH <* 1> rH rH OOO ci o o OS 00 rH 00 CO O 1^ CO VO CO 00 CM rH i v t CO CO CO CO 00 00 to CO il s l 000 CO O Os CM CO CO 000 t> rf vo CM CO 8OO VO OS H 000 rH CM CO rH CM CO Soil stratum. Surface Subsurface Subsoil Surface Subsurface V v <->^ cd **"* O <_ u en 3 uo 3 CO "2 CO CO V j O^. o rt " rd **~* O 14.4 u tn 3 en 3 co *2 to CO Surface Subsurface Subsoil '3 5 OS TH * to to to VO to 00 Os CM CM CO CO Os OO VO vo vo rH CM CM VO VO vo 00 OS OS *** 00 00 00 3 o o I McLean Jx t) M 3 1 If Location. By land survey. G* CO pv< tJ i 1 U CO * CO w. P4 CM f H^ CO ^Z, ot rH rr, bjo