THE UNIVERSITY OF ILLINOIS LIBRARY A6RICULTURAI LIBRARY UNIVERSITY OF ILLINOIS Agricultural Experiment Station BULLETIN NO. 212 LIMESTONE ACTION ON ACID SOILS BY ROBERT STEWART AND F. A. WYATT UKBANA, ILLINOIS, JANUARY, 1919 CONTENTS OF BULLETIN No. 212 PAGE RESULTS FROM THE NEWTON EXPERIMENT FIELD 268 Effect of Limestone on the Surface Soil 270 Effect of Drainage upon Loss of Limestone 272 Influence of Applications of Limestone to Surface Soil upon Acidity in the Subsurface and Subsoil (Series 100 to 400) 273 Comparative Value of High-Calcium and Dolomitic Limestone 274 Effect of Degree of Fineness of Limestone upon Loss and upon Acidity. . 280 Influence of Applications of Limestone to Surface Soil upon Acidity in the Subsurface and Subsoil (Series 500 to 1000) 282 EESULTS FROM THE ODIN EXPERIMENT FIELD 286 Comparative Effect of Light and Heavy Applications of Limestone and Comparative Loss 286 Influence of Applications of Limestone to Surface Soil upon Acidity in the Subsurface and Subsoil 291 Effect of Drainage upon Loss of Limestone 293 Limestone and Acidity in Series 500 294 CONCLUSIONS . . 296 LIMESTONE ACTION ON ACID SOILS BY EGBERT STEWART, CHIEF IN SOIL FERTILITY, AND F. A. WYATT, ASSISTANT CHIEF IN SOIL FERTILITY Lime, marl, or chalk has been applied to soils for many centuries. The early Romans certainly knew of the value of lime for sour soils, and they probably introduced its use into England at the time of the Roman conquest. There the beneficial effects of liming the soil have long been practiced. From the Rothamsted Experiment Station there is a definite record that as much as 100 tons of chalk per acre had been added a number of years before the beginning of the experi- mental work on that famous farm. In America, the beneficial effect of the use of lime has been fully realized only within the last few years. Some of the older experiment stations, among them Pennsylvania, Maryland, and Rhode Island, were the first to demonstrate the benefit derived from liming the soil, and both Pennsylvania and Maryland also emphasized the feasibility of using ground limestone for this purpose. The work of the Illinois Experiment Station 1 has demonstrated the great value of ground lime- stone on acid soils. There are some questions, however, regarding the use of limestone upon which additional information is needed: viz., Can dolomitic limestone be used successfully on acid soils, and what is its value compared with high-calcium limestone? What is the comparative value of the finely ground material and that more coarsely ground, which can be purchased more cheaply ? What is the durability of the various forms and kinds of lime when applied to soils in the field ? What effect does the application of limestone to the surface have upon the acidity of the subsurface and the subsoil? What is the annual loss of limestone from the soil, and what are the factors which contribute to this loss ? A number of years ago some work was done at the Edgewood ex- periment field on some of these problems. The type of soil at Edge- wood is gray silt loam on tight clay and belongs to the prairie land of the lower Illinoisan glaciation. This field, which has now been dis- continued, consisted of three parts: west field, east field, and north field. The east field was divided into Series 300, which received ground limestone, and Series 400, which received freshly slaked lime. Ferris, 2 who made a study of the effect of limestone on this field, shows dolomite to be twice as durable as high-calcium limestone ; also '111. Agr. Exp. Sta. Circs. 110 and 181 and Bui. 193. 2 Ferris, Thesis: Studies in the Use of Lime and Limestone, 1912. 267 268 BULLETIN No. 212 [January, that hydrated lime caused a loss per acre per annum of 192 pounds more nitrogen and 2,529 pounds more carbon from the upper twenty inches of soil than did ground limestone. Hopkins, 1 comparing Fer- ris' averages of eight treated plots and eight untreated, computes that 780 pounds of limestone are lost from the upper twenty inches of soil per acre per year. Investigations to determine the influence of forms, amounts, and degree of fineness of limestone were begun in 1912 on the University experiment field located about one mile west of Newton, in Jasper county. The soil is gray silt loam on tight clay and belongs to the prairie land of the lower Illinoisan glaciation. The land is practically level, having a fall of only a few feet in the entire length of the field. The outline of the investigations and the treatment of the various plots are shown in the accompanying plan. In Series 100, 200, 300, and 400, which are devoted to grain and live-stock systems of farming, Plots 1, 5, and 10 are check plots, re- ceiving no treatment. Plots 3, 4, 7, 8, and 9 receive dolomitic limestone (i^-inch mill-run, that is, fro'm. 14 inch down to dust) at the rate of 3,000 pounds per acre, the application being made every third year for the legume. To Plots 2, 3, and 4 manure is applied for corn once during the rotation, and in proportion to the crops produced. Plots 6, 7,, 8, and 9 receive organic matter in the form of the crop residues and cover crops grown upon these plots. Plots 4, 8, and 9 receive phosphorus in fine-ground, raw rock phosphate, while Plot 9 also re- ceives potassium in kainit. Series 100, 200, and 300 are tile-drained, while Series 400 is not tiled. The rotation in these four series is : (1) corn, (2) soybeans (or cowpeas), and (3) wheat, with a legume cover crop (sweet clover) seeded in the wheat on Plots 6, 7, 8, and 9, which are devoted to the grain system. Series 400 always grows the same crop as Series 200, and also receives the same application of limestone applied at the same time. The amounts and dates of the applications of limestone are re- corded in Table 1. TABLE 1. LIMESTONE APPLIED ON SERIES 100, 200, 300, 400: NEWTON FIELD (Pounds per acre) Series 1912 1913 1914 1915 Total 100 1 000 3 000 4000 200 300 400 2 000 3000 2000 3000 3' 666 3'666 5000 6000 5000 Hopkins, 111. Agr. Exp. Sta., Soil Report 3, page 8. M19] LIMESTONE ACTION ON ACID SOILS 269 NORTH too JtOO 3oo 40O PLAN or NCWTON EXPERIMENT Pi ELD 270 BULLETIN No. 212 [January, EFFECT OF LIMESTONE ON THE SURFACE SOIL (Series 100 to 400) In May, 1916, about three and one-half years after the application of limestone was begun, samples of soil were obtained from each plot for analysis for limestone and acidity. Samples were taken from the surface (0 to 6% inches), the subsurface (6% to 20 inches), and the subsoil (20 to 40 inches). Composite samples were obtained by taking twelve borings from each plot. The acidity was measured in terms of pure limestone (calcium carbonate) required to neutralize it; and the limestone present was also reported in terms of calcium carbonate, as measured by the carbon dioxid liberated by strong acid. The effect of the application of limestone on the surface soil of these series may be seen from a study of the data recorded in Table 2. The limestone applied had not yet destroyed all the acidity in the sur- face soil, altho in all plots it had materially reduced the amount pres- ent and in most cases had destroyed almost all the acidity present. On the other hand, in all plots on which limestone had been ap- plied a considerable amount was still present in the soil. Even in Series 100, where the latest application had been made in 1913 and where the total application had been only 4,000 pounds, the average amount of limestone remaining in the soil in 1916 was 881 pounds per acre; that is, two and one-half years after the latest application of limestone to this series, appreciable amounts of applied limestone could still be found in the surface soil of the limed plots, while an average of 563 pounds of acidity per acre had been destroyed and an average of 487 pounds of acidity still remained. Computations bring- ing out similar facts may be made for the other series. The amount of limestone which had been destroyed or lost, either by neutralizing acidity present or by being carried off in the drainage as soluble salts of calcium and magnesium, was considerable. The amount of acidity found in the soil of the untreated plots varied from plot to plot ; for example, from 918 pounds on Plot 101 to 1,808 pounds on Plot 102, so that too much importance should not be attached to the figures from individual plots. 1919] LIMESTONE ACTION ON ACID SOILS 271 TABLE 2. EFFECT OF LIMESTONE ON SURFACE SOIL, SERIES 100 TO 400: NEWTON FIELD, 1916 Average pounds calcium carbonate in 2 million pounds of surface soil (one acre about to 6% inches deep) Plot No. Treatment Limestone added Soil acidity Limestone Degree of fineness Amount, Ibs. De- stroyed Found Amount found Annual loss Series 100 101 918 102 M 1 808 103 ML J^ inch down 4000 215 948 404 966 104 MLP 24 inch down 4000 531 632 896 735 105 763 106 R 1 018 107 RL 24 inch down 4000 456 518 997 728 108 RLP 24 inch down 4000 852 122 979 619 109 RLPK 24 inch down 4000 760 214 1 131 602 110 1 140 Series 200 201 2 120 ?0? M 2368 203 ML % inch down 5 000 1 951 330 1 556 426 ?04 MLP 24 inch down 5000 2 152 130 1 817 295 205 2356 206 R. . 2 114 207 RL 24 inch down 5 000 2051 180 1 458 426 208 RLP 24 inch down 5 000 2089 142 1 888 291 ?09 RLPK 24 inch down 5 000 2 181 50 1 808 289 210 2224 Series 300 301 2552 302 M 2 304 303 ML 24 inch down 6000 2 132 142 2450 404 304 MLP 24 inch down 6 000 2 132 142 3 174 198 305 1968 306 R 1 752 307 RL J^ inch down 6000 1 531 252 3613 245 308 RLP 24 inch down 6000 1 691 92 3827 137 309 310 RLPK J4 inch down 6000 1 560 222 1628 3017 406 Series 400 401 964 402 M 598 403 ML 24 inch down 5 000 707 142 1 122 906 404 MLP J^ inch down 5000 746 102 1 852 686 405 984 406 R 1 530 407 RL 24 inch down 5000 930 138 3 051 291 408 RLP 24 inch down 5 000 927 141 3 265 231 409 410 RLPK 24 inch down 5000 684 384 690 965 958 272 BULLETIN No. 212 [January, TABLE 2. Concluded Plot No. Treatment Limestone added Soil acidity Limestone Degree of fineness Amount, Ibs, De- stroyed Found Amount found Annual loss Average of Results from All Four Series 1 1 638 2 M 1 769 3 ML J i (N 1^- CO TC CO O C^ iO CO t^ 00 !> O5 O i 1 00 fO GO(N (MOO'* . O (MOOCO . O CO rH CO 00 C5 19191 LIMESTONE ACTION ON ACID SOILS 277 oo 4.2 Si 03 < < S^ 3 .co IM h- * t-. . O (N O i> CO '. COCO OS 00 O . * IO CO CO TH . CO O CD T-H TfH . i-H TH ' o o K'S pr| o V .COOCOINO . .CO ^ |>- TH t-- . .CO IN CO -. CO . IN O TH COCO . O GOO OS . CO (N GO t^ b- . ^^ co os co TH . rH t-H i-H IN ' X o.2 Si 'o :! iili | -# OS (M CO M . TH iOt> GOO '. TH T 1 1 1 * O l> (N 00 . I-H O GO t- iO . OS OS 0000 GO . i 1 i-H TH TH rH o d 03^3 -a 3 O T3 .OGOCOOOIN . rHGOOSCOTtH . O O5 TH OS T-H . OSGOOI>TH . GO TH CO 1-- rH . ta (N GO * I-H . IN (N TH T-H TH . ' w 00 GO O "* CO GO TH O '. Tj< Tt< CO O O . co o 1002 Tti . t> Cp O O IN . TH IN TH i-H i-H rH i 1 i-H GO CO GO *!> Tfi . COCOt^COO . o _bC.2 S'3 e Limesto . * IN CO 00 * . ioOTHOi-HCD ! TH ' frq CD GO * CO . t~- CO O CD IO . OS O i-H rfH CO . (NINrH GO(N (N O O5 QS COCO5O CO CO i-H i I 1C i 1 CO O5 O3 O5 O O . 00 *< CD Tt< O . O >O >O O> CO ,U3 CO COlMOO O5 OOO5 O3 C * CO CO # CO G | | h 0.2 1 * -* O 00 O C5 T)< t^ C^l t^ 1C 1^ CO -* O CO CO -* CO i-t CO ^ CM COOO *!> CO t^1> O5 x CO rH CO (N 1-1 i-t CO CO ** (M !M O CO(M (N . CO 00 OO 00 O ! co o >o * co t>- -^ I ^HOl i CO 00 i COCO I IO O5 O5CO CO O lO TJH oo co csco lO O5 OO 1-1 OO CO^CO-*(N ' CO CO CO CO CO O OO OO 88888 ^O CO CO O CD egree finene - J3 C C l rH N CO <* *-1 O t- 00 C3i O I-H IM CO 1919] LIMESTONE ACTION ON ACID SOILS 279 a 0} p o SB Sos ^^ g, I O H " ^ "cS E I o K H a 4 m I o ** 3 QS 4.2 o's QS (I 4.2 o--S QS >oo o (M CO CO i>eoo icso IOO ^HCO oO co CO lOI^ > CO O * OS CO (M t-^ OO t>-ooo BULLETIN No. 212 [January, sonably trustworthy in representing the comparative effect of the high- calcium and the dolomitic materials. The amount of residual carbonate found was, as an average, dis- tinctly larger where dolomitic limestone had been added ; that is, this form of stone was more lasting in the soil. However, notwithstanding its more lasting quality, this form of limestone was fully as effective in destroying the soil acidity as was the high-calcium limestone. In every case where high-calcium limestone had been applied, the average results showed a smaller amount of residual limestone, a larger annual loss of limestone, and less acidity destroyed. The data also show that the larger the amount of limestone applied, the more residual caibon- ate found, the more acidity destroyed, and the larger the loss of lime- stone from the surface soil. EFFECT OF DEGREE OF FINENESS OF LIMESTONE UPON Loss AND UPON ACIDITY (Series 500 to 1000) The data in Table 9 show the effect of the degree of fineness of the limestone upon the loss of limestone and upon the acidity in the surface soil. The figures are obtained by averaging the data from all plots receiving like applications of both the high-calcium and the dolomitic limestone. The results are the averages of six separate de- terminations from as many separate plots. TABLE 9. EFFECT OF DEGREE OF FINENESS OF LIMESTONE UPON Loss OF LIME- . STONE AND UPON ACIDITY IN THE SURFACE SOIL, SERIES 500 TO 1000: NEWTON FIELD, 1916 Average pounds calcium carbonate in 2 million pounds of surface soil (one acre about to 6% inches deep) Fineness % inch down ^toKo inch Ko inch down Ho inch down Burnt lime Limestone Found Light application 617 1 613 3899 1 151 2117 4776 631 1 025 3558 272 659 3545 392 648 1822 Medium application . . . Heavy application Acidity Found Light application 289 437 75 356 222 64 322 367 110 450 468 136 395 348 56 Medium application . . . Heavy application Acidity Destroyed Light application 631 863 1368 620 1 059 1 443 709 925 1 458 637 855 1 492 746 1 006 1 634 Medium application . . . Heavy application Average Annual Loss of Limestone Light application 358 721 1351 208 523 1 080 331 871 1419 482 995 1 417 385 953 1 869 Medium application . . . Heavy application 1919] LIMESTONE ACTION ON ACID SOILS 281 In general, the finer the stone, the greater was the loss of limestone. The mill-run stone (14 inch down) was practically as effective as any grade in destroying the acidity and in addition possessed better last- ing qualities. The fine material present in this grade of stone seems to be sufficient for the immediate requirements of the soil, and the residual properties are of value in maintaining an alkaline reaction in the soil. ' The annual loss of limestone from the surface soil, calculated from the residual carbonate and the acidity destroyed, was very high where the heavy application of limestone had been made, especially where the burnt lime had been used. It was therefore thought worth while to make some determinations of the total calcium to ascertain whether the actual loss of calcium was as large as these calculations indicated, or whether the apparent loss was due, in part at least, to the reten- tion of the calcium in some form not shown by the method used or to the decomposition of the carbonate by the acidity which had been produced in the soil since the addition of the limestone. The calcium carbonate equivalent, as determined by the total calcium, is recorded in Table 10 for a few of the plots studied. TABLE 10. EQUIVALENT CALCIUM CARBONATE AS CALCULATED FROM THE DETERMINATION OF TOTAL CALCIUM, SERIES 500 TO 1000: NEWTON FIELD, 1916 Average pounds calcium carbonate in 2 million pounds of surface soil (one acre about to 6% inches deep) Series 500 600 700 800 900 1000 Form of limestone High- calcium Dolo- mitic High- calcium Dolo- mitic High- calcium Dolo- mitic Amount added, Ibs 8000 8000 10000 10000 12000 12000 Plot No. Total Lime in Soil 13 (check) 9645 16277 15765 9925 9385 12552 12102 10175 9510 18472 18245 10012 9645 12950 13755 9125 9630 20375 18590 9657 9742 13852 15340 11000 17 18 19 (check) Plot No. Excess Lime in Treated Plots Over That in Check Plots 1 17 6446 5887 2640 2058 8627 8317 3652 4544 10727 8938 3271 4550 18 1 These calculations are based upon the assumption that the original content of the treated plots lying between the two check plots varied uniformly from one plot to the next. The annual loss of limestone from these plots, as calculated both from the carbon dioxid and from the total calcium determination, is recorded in Table 11. In calculating the loss of dolomitic limestone it has been assumed that such limestone contains 54 percent pure calcium carbonate based upon the theoretical composition of dolomitic lime- stone. From a study of these data it may be seen that the actual loss of calcium was considerably lower than is indicated when the calculation 282 BULLETIN No. 212 [January, TABLE 11. ANNUAL Loss OP LIMESTONE AS CALCULATED PROM CARBON DIOXID AND FROM TOTAL CALCIUM, SERIES 500 TO 1000: NEWTON FIELD, 1916 Average pounds calcium carbonate in 2 million pounds of surface soil (one acre about 65i to 20 inches deep) Amount of limestone added, Ibs. . 8,000 10,000 12,000 Average (10,000) Calculated from Calculated from Calculated from Calculated from Car- bon dioxid Total calcium Car- bon dioxid Total calcium Car- bon dioxid Total calcium Car- bon dioxid Total calcium High-Calcium Limestone Treatment Plot No. Series 500 Series 700 Series 900 Average of series 17 18 1 471 1426 444 604 1437 2017 392 481 1903 2199 364 875 1 604 1 881 400 653 Dolomitic Limestone Treatment Plot No. Series 600 Series 800 Series 1000 Average of series 17 18 1 253 1 462 889 1 197 416 1 741 925 454 2025 2371 1697 1 021 1 231 1 858 1 170 891 is based upon the' carbon dioxid determination. The average annual loss of limestone from the six high-calcium plots, as calculated from the carbon dioxid, was 1,742 pounds, while as calculated from the total calcium it was only 526 pounds. In the dolomitic series the average annual loss, as calculated from the carbon dioxid, was 1,545 pounds, while as calculated from the total calcium it was only 1,030 pounds. As an average of results from both high-calcium and dolomitic ma- terials, the annual loss from the ground-limestone plot (No. 17), cal- culated from the carbon dioxid, was 1,417 pounds and from the burnt- lime plot (No. 18) 1,869 pounds; but when based upon total calcium, the loss was 785 pounds from ground limestone and 772 from burnt lime. These results indicate that the calcium was not removed from the soil more largely when applied in the form of burnt lime than when applied in the form of ground limestone. INFLUENCE OF APPLICATIONS OF LIMESTONE TO SURFACE SOIL UPON ACIDITY IN THE SUBSURFACE AND SUBSOIL (Series 500 to 1000) The data for limestone and for acidity in the subsurface and the subsoil of Series 500 to 1000 are recorded in Tables 12 and 13. In general, the subsurface was found to be distinctly acid. It is very doubtful whether any of the small amounts of limestone found occa- sionally were due to the surface applications. 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CO -03 I> -CO CM CN O "tf * Th t^ CN O t^O CM CO >* 1C * T-H C/-i .5 11 g i CO 43 -ij, S t* _^ T-H CO 8 CO . g 6.2 .CNOOCO .O . CO CM CO CN CN . 1> 1 1 (> l-H I-H CN CD O O . . CN OO 1C 1C . . 51 vc; at ' il O -i a -CM OO 00 CN -CNO CN EH a 5 CN CN CN 1C l-H Tf 1C O - H "S 3 ' s fl O 03 =o | iC "C O 1C 1C '. 88888 : o o o o o . H a T3 03 i !* 1-1 J 43 CQ bC < S HH cu Limestone apj surface D 43 a 43 > Pj 3*0 | | ; J3 fl ' a o a ^ : rt VH _rt "^ ^ * O ""* O -fr 3 S 43 i-i\ JH O "~ ' < O fl -^ _3 ""' " IJ " H ^ Q 11 |l t-l SH 43 43 bC bt 03 03 Acidity destroy e p o 6 r-< (N CO Tt< 1C CO J> OOO5 O-H CN CO * 10 CO t^ 00 C3i 43 fe X i CD O CO1>.T}< OCO T}< !N< S COO (N GO T-I O g TH <* 1C CO CO 00 00 IN GO O O5 CO i-H (N CO CO <* (N CO O O t^ l> 1-H 1-1 CO i 1 CO 00 CO O ai COCOO OCO ScDCOlO IN 0010 COCD m CO C<) Tt* CO en rn a co to co co S S gosococo ^JCOCOO ^^ (N IN 00 CO CO l-H i-H 1-H O O CO O a d a a a a 000000 CDOOOOCOCO U3 I-H O5 O C<1 >O IQGQO CO(N O O t^ * C35 IO CO OOO ooo rt fl G H ^ ^ ' o o o ' OOOSOi-H (N CO - *OOlM CD(N t^ COl^Ol IM CD 00 i^- t-l TH O * -KNCOCO OO5(N t^. i-l O-* CO-* CO CO * O5OO5IN CO !>. CO CO * T-H CO m (N IN CM CO * rtt^t^t^lN CO SCOCOCOININ ' OT3 -O 073 * 1C CO I> CO O5 1919} LIMESTONE ACTION ON ACID SOILS 285 cases into the lower part of the subsurface, while the upper part of the subsurface was acid. The subsurface soil of Plot 607 was sampled in three strata. The results show that per million pounds the stratum extending from 6% to 14 inches below the surface contained 310 pounds of limestone and would have required 1,150 to neutralize the acidity present ; while the stratum extending from 14 to 17 inches contained 200 pounds of lime- stone and would have required 320 pounds to neutralize the acidity ; and the stratum extending from 17 to 20 inches contained 260 pounds of limestone and was neutral in reaction. The results for the subsoil show clearly that in certain areas this stratum is distinctly acid, while in other areas an abundance of lime- stone is naturally present. The limestone present in the subsoil is native and not the result from any soil treatment. Examinations of the subsoil by three-inch strata show that the limestone usually in- creases with depth. Thus, an examination of Table 14 will show that Plot 607, for example, which is an unlimed plot, contained 770 pounds of limestone per acre in the first 3-inch stratum of subsoil, and that the limestone increased steadily in amount to 2,820 pounds in the fifth stratum, and then decreased slightly ; while every stratum was distinctly alkaline, which shows clearly that there was no unneutralized acidity present. In most other plots studied, quite similar results were obtained. How- ever, in some plots the amount of limestone was not sufficient to neu- tralize the acidity present. Thus, in Plot 813 the amount of limestone was very small, while the degree of acidity was comparatively high; but it is interesting to note that the acidity decreased with depth. In sampling the plots, the subsoil of Plot 813 was found to be plastic in nature, and in some places seemed almost impervious to water; while the subsoil of Plot 607, which contained an abundance of lime, was very moist and granular. TABLE 14. LIMESTONE AND ACIDITY IN VARIOUS STRATA OP THE SUBSOIL, 1916 Average pounds calcium carbonate per million pounds of soil Plot No . . | 604 607 612 704 707 813 913 Limestone Found 20-24 inches . . . 1 730 770 840 160 160 290 240 24-27 inches . . . 6 120 1 490 1 430 250 170 160 790 27-30 inches... 4950 1880 2200 210 210 210 1 080 30-33 inches. .. 3400 2530 3000 160 410 1 120 2300 33-36 inches . . . 3 160 2820 3470 170 2030 320 3230 36-40 inches. . . 2080 1 710 1 920 160 1247 280 2600 Acidity Found 20-24 inches . . . Alk. Alk. Alk. 2860 2050 5380 Neutral 24-27 inches.. . Alk. Alk. Alk. 4340 1 860 4760 Alk. 27-30 inches . . . Alk. Alk. Alk. 4270 1 050 4000 Alk. 30-33 inches... Alk. Alk. Alk. 3 150 290 3290 Alk. 33-36 inches. . . Alk. Alk. Alk. 3900 Alk. 1 840 Alk. 36-40 inches . . . Alk. Alk. Alk. 3210 Alk. 350 Alk. 286 BULLETIN No. 212 [January, RESULTS FROM THE ODIN EXPERIMENT FIELD Experimental work was begun on the Odin field in 1902. On Series 100 to 400 the rotation practiced is corn, soybeans (or cowpeas), wheat, and clover. Soybeans (or cowpeas) have been substituted for clover whenever it failed. Lime was applied uniformly to all limed plots (Nos. 3, 4, 5, 8, 9, and 10) prior to 1907, when it was decided to test the effect of different rates of liming by applying, once in four years, 2,000 pounds of ground limestone per acre to the west half of each of these plots and 4,000 pounds to the east half. Since 1907 the limestone has been applied in about this proportion once in each rota- tion in the fall for wheat. The rates of application, together with the dates, are given in Table 15. Plots 1 to 5 in each series are not tile- drained, while Plots 6 to 10 are tile-drained. The plan of the Odin field is given on page 288. The half-plots are designated as east and west, tho as a matter of fact the eastern line of the field approaches northeast and southwest, following the direction of the Illinois Central railroad. COMPARATIVE EFFECT OF LIGHT AND HEAVY APPLICATIONS OF LIME- STONE AND COMPARATIVE Loss (Series 100 to 400) Samples of soil for analysis were taken in the spring of 1917. The east and the west halves of each of the limed plots were sampled sepa- rately; the unlimed plots were each sampled as a whole. The data obtained from the surface soil are recorded in Tables 16 to 19. The results from all four series clearly show that in every case the application of either the light or the heavy amounts of limestone completely neutralized the acidity of the surface soil. In every case where limestone had been applied, a considerable part of it was still present, and in general the amount found was pro- portional to the amount added. Furthermore, the limed soil was now found to be alkaline, except in four plots, three of which were neutral and the fourth but slightly acid. These exceptions all occurred where the light applications had been made. As an average of the twenty-four half-plots receiving limestone, those receiving the light applications still showed a limestone content of 1,362 pounds per acre, with an an- nual loss of 578 pounds; while the half -plots receiving the heavy applications showed an average content of 3,742 pounds per acre and an annual loss of 812 pounds. If limestone is added to acid soil only for the purpose of destroying the acidity of the surface soil, then the application of 2,000 pounds once in three or four years, after the initial acidity has been destroyed, would seem to be ample for keep- ing the soil alkaline. As an average, where the lighter applications had been made (one ton per acre once in four years), the loss (based 1919] 287 r ~o iO >O lO 1C coo coo 1 1 i 1 I-H i-H TT< * O (M COO COO rH i-H i 1 rH CC 88 OS 1 1 ^f t-sfr SOf H LH S04 fPK t-rPK UllLlHCO t-lflED fO3 o.P H t- f H SOI H \ L.K SOI bPH \ t-bPK RLPH RLPH ffLPIt ffLPH no 9.10 310 4IO k ) EHLP ffLP ffLP ffLP 109 | 309 409 I H -j i i 1 L. t. L t~ /OS - aoe 3oa 400 1_ 107 /? ff fl_ 27 3ar - 407 |_ No/ye r lot ffojtf sot NOHC 306 __-* 06 HLPK 'Of ffLPK Zor PiLPK PILPK 40f RL.PK 104 ffLPK a.0* flLPH 304 404 fft. at. 203 303 4*0~3 R 10 Z H 203. * ff None: 101 None. 2.OI NONE 301 None PL.AN or ODIN EXPERIMENT FIELD upon carbon dioxid) was only 75 percent as great as where the larger applications of two tons had been made. From the data recorded in Tables 16 to 19 is computed an aver- age annual loss from the surface soil of 812 pounds and 578 pounds, respectively, of limestone, where the heavier and the lighter appli- cations had been made, as the average of the twenty-four limed half- plots. This loss is accounted for in part by the loss in drainage, and in part by the passing of the limestone down into the subsurface, there partially neutralizing the original acidity or even remaining as carbonate. LIMESTONE ACTION ON ACID SOILS 289 -2 a"^ s d a E ed De Siz; O5 O5 O5 -t^l>.l^ -cococo CO(N ^H(NCOTti 10 OOOOO Oi O3 Oi 'l>t^l-~ -cococo 81 O 03 S B 02 H * *d I N a .3 h3 ^ si -1 *O 1 1 -co-* o -co i i c iiHB E J East half -rH Oi IO -000000 -COrHTt< -CO Oi rH -OOI>O5 ^ Destroyed -cococo -rH rH rH -cococo -cococo -1 1 rH rH -cocoro | 1 -d o C^JJj COlNj^J^ g 000 &GG 1 1 Destroyed -COCOCO 'rH .-H rH CO CO CO * CO CO CO rH i 1 I I -cococo 1 g o O 05 0) .cj.a.a 000 . fl .3 .a 3 -d d ' rH ' ' rH i 1 rH 0) 8 d -d -ooo rH i 1 rH \f)i&\n -ooo rH rH rH o J ! !5 1 ; ioiooco 'COtNCO = !!! 1 3 'co coco rH rH rH 'CDCDCD rH rH rH 3 a B H I : : :w ; . -PHPL, ^d'Hi -4 1 a ^ rH (N CO"*!>O OOOOO (M C^l 04INIM OOOOrH C 1C co co co 000 a c a oo a a a O 00 41 * fl ooo C C 3 CO 00 ^3 ^=^3 O C73 03 03 03 ooo SCO CO 00 (M .CO COCO co co co co co rococo oo ic oo 000000 1C ut 1C -t^t^. t^ -co co co iCC>C ooo >C 1C 1C . ^^ ^^ ^^ co coco co co co co co o co < I 3 fa o 2 i CQ S si g i g^ s s 3 5 fe ^ e-S e s w| OS 03 H 73 J< O H a o "8 -S 1 3 -i>coco . . cO CO 1C -C C 1C 'OOO 1-H i-H i-H 1C 1C 1C 'ooo i-H rH I-H d .a -3 ~2 a 1 'i-HCOCO .-* D C ^ i rH (N CO-* 1C OO O OO 81-- OO C3 O O O O rH 1919] LIMESTONE ACTION ON ACID SOILS 291 In considering the annual loss of limestone from the light and the heavy applications, the following facts should be kept in mind: (1) The initial application of limestone was made in the fall of 1902, more than fourteen years previous to sampling; and (2) during the first five or six years, equal and somewhat larger applications of lime were applied to all plots, so that the average annual application for the light and the heavy applications had been equivalent to 745 and 1,169 pounds, respectively. During the latter years of the experiment, these amounts were about 500 and 1,000 pounds, respectively. From the data obtained, the loss for the light application may be computed as 66 percent and for the heavy application 54 percent; or 60 percent as an average of both the light and heavy applications. INFLUENCE OP APPLICATIONS OF LIMESTONE TO SURFACE SOIL UPON ACIDITY IN THE SUBSURFACE AND SUBSOIL (Series 100 to 400) The amount of acidity in the subsurface of these four series was found in most plots to be very high but also very irregular. In many cases considerable limestone also was found. An examination of the data recorded in Table 20 will show distinct evidence that the appli- TABLE 20. EFFECT OF LIMESTONE ON SUBSURFACE, SERIES 100 TJ 400: ODIN FIELD, 1917 Average pounds calcium carbonate in 4 million pounds of subsurface soil (ons acre about to 6% inches deep) Plot No. Limestone found Soil acidity Limestone found Soil acidity East half West half East half West half East half West half East half West half Series 100 Series 200 1 2 3 4 5 1418 778 1 338 None 698 1498 3656 4760 320 3680 2360 3656 4760 5360 1 600 3040 824 144 554 184 24 24 2552 2892 1 640 1 640 800 2552 2892 4560 1 560 4 120 6 7 8 9 10 3 028 628 1588 "348 588 1028 4792 3220 3480 3200 3040 4792 3220 5960 2520 5680 None None 186 None None 266 4860 2020 1840 280 2000 4860 2020 1 960 160 280 Series 300 Series 400 I 2 3 4 5 320 400 160 160 240 320 3916 5368 2400 620 2360 3916 5368 320 2720 3200 644 564 2 124 ' 404 324 None 3692 4440 3520 2320 1 080 3692 4440 600 480 3200 6 7 8 9 10 ' 928 2808 1 128 ' 328 978 528 4264 5908 2320 680 1880 4264 5908 3120 3880 3640 1 760 3080 1 600 800 1 440 640 1 984 932 1 520 160 880 1 984 932 2320 2320 3040 292 BULLETIN No. 212 [January, cation of limestone to the surface soil is being felt in the subsurface, since much of the acidity of the subsurface has been destroyed; but owing to the irregularity of the limestone and the acidity in the sub- surface of the individual plots, it is impossible to draw very fine distinctions from a study of individual plots. However, a compari- son of the averages of the sixteen untreated plots and of the twenty- four half -plots on which heavy and light applications have been made shows a distinct influence by the limestone, as indicated in Table 21. The acidity present in the check plots was found to be very high 3,703 pounds per acre as an average of sixteen separate determina- tions. Where the light applications of limestone had been made to the surface soil, the average of twenty-four separate determinations showed 2,735 pounds of acidity per acre in the subsurface, or a de- crease of one-fourth of the acidity, with an average of only 451 pounds of limestone present ; while where the heavy applications had been made, the average acidity had decreased to 1,834 pounds, or by about one-half of that originally present, and the average limestone present averaged 1,083 pounds, or about two and one-half times the amount where the light applications had been made. TABLE 21. EFFECT OF LIMESTONE ON SUBSURFACE SOIL: AVERAGES OF ALL PLOTS, SERIES 100 TO 400: ODIN FIELD, 1917 Average pounds calcium carbonate in 4 million pounds of subsurface soil (one acre about 6?^ to 20 inches deep) Number of plots Lime added to surface soil Limestone found Acidity Limestone net gain for subsurface Found Destroyed 16 plots None None 451 1083 3703 2735 1834 24 half-plots. . . . 24 half-plots. . . . Light application. Heavy application 968 1869 1419 2952 The data recorded in Table 21 indicate that as a result of the ap- plications during fourteen years' time the sum of the limestone de- stroyed in neutralizing acidity in the subsurface and that found remaining in that stratum amounted to 2,952 pounds where the heavy applications had been made and 1,419 pounds where the light appli- cations had been made. These figures represent an annual gain of 211 pounds and 94 pounds of limestone, respectively, in the subsurface stratum. If these numbers be subtracted from the annual loss from the surface soil, the unaccounted annual loss from that stratum amounts to 601 pounds and 484 pounds, respectively, for the heavy and the light applications. The data for the limestone and acidity in the subsoil of these series is recorded in Table 22. The occurrence of limestone and acidity is very irregular and as one increases in amount the other decreases. The indications are that this limestone is native to the subsoil and has not been influenced at all by the applications to the surface soil. 1919] LIMESTONE ACTION ON ACID SOILS 293 TABLE 22. LIMESTONE AND ACIDITY IN SUBSOIL OF SERIES 100 TO 400: ODIN FIELD, 1917 Average pounds calcium carbonate per acre in 6 million pounds of subsoil (one acre 20 to 40 inches deep) Series 100 200 300 400 100 200 300 400 Plot No. Treat- ment Limestone found Acidity found 1 2 3 4 5 0... 17112 11 550 1 500 462 1 194 19908 6096 456 462 2808 None None 11 268 522 516 1 452 516 462 5970 1 194 None None 1 854 15 978 2 106 None None 5202 5988 216 18564 19728 None 5430 9126 9732 9792 954 None 11 976 R RL RLP RLPK... 6 7 8 9 10 None 960 1 374 1 110 1 374 4338 8262 1 182 14616 13 122 3912 None 15468 6294 234 1 188 1 914 None 516 510 126 246 396 150 246 426 None 246 None None None 1 056 None 246 11 796 156 5334 24126 21 678 36522 R RL RLP RLPK... JUFFECT OF DRAINAGE UPON Loss OF LIMESTONE (Series 100 to 400) On Series 100 to 400, one-half of the plots of each series are tile- drained while the other half are undrained. Of the plots which re- ceive limestone, then, there are twelve drained and twelve undrained. These plots furnish an excellent opportunity for studying the effect of drainage upon the loss of limestone from this type of soil, gray silt loam on tight clay. The average results for limestone found and for the annual loss of limestone are recorded in Table 23. These results show that there is no distinct influence from tile drainage on the loss of limestone from this type of soil. TABLE 23. EFFECT OF DRAINAGE UPON Loss OF LIMESTONE, AVERAGE OF ALL UNDRAINED AND DRAINED LIME-TREATED PLOTS, SERIES 100 TO 400: ODIN FIELD, 1917 Average pounds calcium carbonate in 2 million pounds of surface soil (one acre about to 6% inches deep) Number of plots Total limestone applied, average pounds per acre Undrained Drained Limestone found Annual loss Limestone found Annual loss 12 12 10425 16375 1207 3694 589 814 1517 3790 567 808 LIMESTONE AND ACIDITY IN SERIES 500 On Series 500 a five-year rotation of corn, oats, and three crops of hay (clover and timothy) is practiced. Altho this series is de- voted primarily to a phosphate test, the east half of each plot is limed while the west half is not limed, so that limestone data are furnished as well as phosphate. The limed halves of these plots have received a total application of 11,000 pounds of limestone : 3,000 pounds in 1904, 3,600 pounds in 1909, and 4,400 in 1914. 294 BULLETIN No. 212 [January, The data for limestone and acidity in the surface soil, obtained in 1916, are recorded in Table 24. TABLE 24. EFFECT OF LIMESTONE ON SURFACE SOIL, SERIES 500: ODIN FIELD, 1916 Average pounds calcium carbonate in 2 million pounds of surface soil (one acre about to 6% inches deep) Plot No. Treatment Limestone Soil acidity Annual loss of limestone Added Found Found Destroyed 501 )w 502 |E 503 { |r 504 (w 505 jf^ 506 -!w LK bone P 11 000 1694 Alkaline 294 Alkaline 1348 Alkaline 1 450 Alkaline 810 42 1 894 Alkaline 334 294 1 348 1 450 810 1 852 334 819 622 690 766 716 768 K bone P LK.. 11 000 2808 K LK acid P 11 000 1 962 K acid P LK rock P. ... 11 000 1 758 K rock P LK.. 11 000 1 266 K. . LK slag P.. 11 000 2214 KslagP In every case where limestone had .been applied some of it could still be found in the surface. In only one of the limed half -plots was there any acidity found and then only 42 pounds per acre, while in all the other limed areas the soil was distinctly alkaline. Large amounts of acidity had been neutralized in all the limed plots. The annual loss of limestone varied from 622 pounds per acre to 819 pounds. The data for the acidity and limestone in the subsurface of Series 500 is found in Table 25. It is evident that the average acidity of this stratum was greater in this part of the Odin field than in any other part. The application of limestone to the surface apparently resulted in the neutralization of considerable of the acidity in the subsurface. This conclusion is confirmed by a study of the results obtained from the subsoil (Table 26), where it may be seen that the subsoil of the limed part of the plots was more acid than that of the unlimed por- tion, clearly indicating that the limestone present in the subsurface resulted from the applications to the surface and was not derived from native limestone. In Table 26 are recorded the data for the subsoil of Series 500. The subsoil of the limed portion of the plots was found to be distinctly more acid than that of the unlimed portion. In fact, in half of the cases the subsoil of the unlimed plots contained no acidity but con- 1919} LIMESTONE ACTION ON ACID SOILS 295 TABLE 25. EFFECT OF LIMESTONE ON SUBSURFACE, SERIES 500: ODIN FIELD, 1916 Average pounds calcium carbonate in 4 million pounds of subsurface (one acre about 6% to 20 inches deep) Plot No. Treatment applied to surface soil Limestone Soil acidity Added to surface soil Found Found Destroyed 501 |w 502 j*| 503 )E 504 {E 505 jE, crvfi t E I W LK bone P 11 000 None 1 596 7340 1 348 4248 2324 5784 3824 3628 3848 3720 648 1 328 5 744 K bone P LK.. 11 000 None 2900 K LKacid P 11 000 472 3460 K acid P LK rock P 11000 None None None K rock P LK.. 11 000 None K LK slag P 11000 300 680 KslagP TABLE 26. EFFECT OF LIMESTONE ON SUBSOIL, SERIES 500: ODIN FIELD, 1916 Average pounds calcium carbonate in 6 million pounds of subsoil (one acre 20 to 40 inches deep) Plot No. Treatment applied to surface soil Limestone Soil acidity Added | Found Found 501 {$, 502 {E 503 {E 504 JE 505 jE 506 j^ LK bone phosphate 11 000 2946 1 194 None 2430 252 1500 1 188 10014 None 12864 462 6240 19296 648 30402 282 23160 336 30948 None 22320 None 21408 None K bone phosphate LK.. 11 000 K LK acid phosphate 11000 K acid phosphate LK rock phosphate 11 000 K rock phosphate LK.. 11000 K LK slag phosphate 11 000 K slag phosphate siderable limestone, while the subsoil of the limed plots contained an amount of acidity that would have required several thousand pounds of limestone to neutralize it. Therefore, the reduced acidity and the limestone found in the subsurface of some of the limed plots must have resulted from the surface application. 296 BULLETIN No. 212 CONCLUSIONS 1. From the evidence thus far secured, it appears that for the common prairie land of southern Illinois an application of one ton per acre of limestone once in three or four years is sufficient to keep the soil alkaline, or sweet, after the initial acidity has been destroyed by heavier applications. 2. Dolomitic limestone can be used successfully on acid soils. It is slightly more effective than high-calcium limestone in neutralizing the soil acidity, is more durable, and has no injurious effects on the crop yields. 3. As the result of nearly four years' work on the Newton field, there is no evidence that finely ground limestone is more effective in correcting soil acidity than is the total product from a 14-inch screen, which contains both the finer material for immediate use and the coarser material for greater durability. This "mill-run" product seems to be the most economical form to use ; but final conclusions must await further data concerning crop yields. 4. The destruction of the acidity of the soil is not a rapid process, for it is dependent upon the complete mixing of the applied limestone with the surface soil, which is a slow process. Limestone applied to the surface slowly penetrates into the subsurface. This process, however, requires considerable time. On the Odin field after fourteen years, one-half the acidity in the subsurface was neutralized where the larger applications had been made to the surface, and one-fourth where the lighter applications had been made. Applica- tions of limestone to the surface soil seem to have no effect upon the acidity of the subsoil. The amount of native limestone found in the subsoil is a variable quantity. In some cases there is none present even at a depth of forty inches, whereas in other cases it extends up- ward even slightly into the subsurface. 5. The annual loss of limestone from the soil depends upon a number of factors, among which are the kind, the 'form, and the amount added. The data presented show that the annual loss of limestone is not so large as is generally assumed. As an average of all determinations, the annual loss from the surface twenty inches was 760 pounds per acre from the Newton field and 542 pounds per acre from the Odin field. A study of the total calcium indicates that the actual loss of bases may have been less than is shown by these figures, which are based upon the carbon dioxid and acidity determinations. 6. It is very evident from the data presented that chemical analysis may be depended upon to measure the acidity in the soil, the reduction in acidity due to the action of limestone applied, and also to find the limestone still remaining in the soil, whether from applications made or from a supply native to the soil. UNIVERSITY OF ILLINOIS-URBANA