SOME RELATIONS OF ORGANIC MATTER IN SOILS A THESIS PRESENTED TO THE FACULTY OF THE GRADUATE SCHOOL OF CORNELL UNIVERSITY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY FRED ALBERT CARLSON FEBRUARY, 1922 Reprinted from Memoir 6i, September 1922, Cornell University Agriculture Experiment Station. SOME RELATIONS OF ORGANIC MATTER IN SOILS A THESIS PRESENTED TO THE FACULTY OF THE GRADUATE SCHOOL OF CORNELL UNIVERSITY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY FRED ALBERT CARLSON FEBRUARY, 1922 Reprinted from Memoir 6i, September 1922, Cornell University Agriculture Experiment Station. SOME RELATIONS OF ORGANIC MATTER IN SOILS F. A. Carlson The effect of lime on the organic matter in soils has been for some time one of the leading problems for investigation. The results that have been recorded, however, are not consistent. Some investigators have reported that there is a greater accu- mulation of organic matter in limed than in unlimed soil, while others have stated the contrary. This difference of opinion is not surprising when the methods of experimentation, the soil variations, and the climatic conditions are considered. There has been, however, too great a tendency to draw conclusions from unreliable data. In many cases, attempts have been made to study the effect of lime on the organic matter in soils without a knowledge of the composition of the soils before treatment. In view of the many discrepancies in the reported results. the present experiment was designed to ascertain the effect of lime on the organic matter in soils under various treatments and cropping systems. HISTORICAL Wheeler and others (1899)' reported that lime decreased the percentage of humus in soils under continuous culture of cereals. They found also that there was an increase of roots and residual organic matter in limed grass plats as compared to those not limed. Hess (1901) studied the effect of lime on some of the Penn- sylvania soils. He stated that liming resulted in a diminution of the nitrogen. Kossovich and Tretjakov (19u2) stated that the addition of calcium carbonate to soil retarded the decomposition of organic matter. Hartwell and Kellogg (1906) pointed out that the amount of humus in limed plats was less than that in unlimed plats. They stated also that the effect produced by lime upon the organic matter of a given soil was dependable to a considerable extent on the degree of acidity or of alkalinity of the soil. 'Dates in parenthesis refer to References Cited, page. 25. 3 4 F. A. Carlson Pot experiments by Clausen (1906) conducted with clover and oats on sandy soil indicated that applications of lime re- sulted in a marked nitrogen hunger, especially during dry, hot weather and with non-leguminous crops. Van Suchtelen (1910) found in laboratory experiments that soils treated with calcium oxide produced less carbon dioxide than did unlimed soils. Alway and Trumbull (1910) say: In a comparison of 22 roialiou plots no distinct relation has been found between the composition of the soil and the nature of the rotation. In a long cultivated field the till was found poorer in humus, nitrogen and organic carbon than the lacustral clay. The amounts of the above three constituents found in any of the plots depend more upon the relative proportions of the two types of soil occurring on the plots than upon the previous treatment. The longer the fields have been kept in grasses mown for hay, the less has been the change in composition of the soil. Continuous bare cultivation along tree rows has caused greater losses than the alternation of fallow and crop in the adjacent fields. The extreme loss of nitrogen, humus and organic carbon in 25 years is about one-third of the amounts originally present in the prairie. Bradley (1912) conducted pot experiments from which he pointed out that the nitrogen loss was appreciably reduced by legumes. Mooers, Hampton, and Hunter (1912) reported that the loss of nitrogen was appreciably greater on limed plats than on unlimed plats, and that the effect extended below the depth of plowing. These investigators stated also that tjiere was an increase in percentage of humus on the unlimed sections. Mclntire (1913) writes: Burnt lime decreased the organic matter when applied alone and lessened the accumulation when applied with manure. Calcium sulphate and ground limestone increased organic matter. Each form of lime resulted in an increase of nitrogen content, gypsum, limestone, and burnt lime, being effective in the order named. Lipman and Blair (1913) reported that in their experiments the limed plats had lost nitrogen to a greater extent than had the unlimed plats. Gardner (1914) says: "Burnt lime appears to exhaust the humus in the soil more rapidly than ground limestone. Burnt lime with manure gave returns over manure alone. ... It is desirable that the use of lime or limestone lead to larger supplies of organic matter in the soil." Swanson (1915) reported results based on the chemical anal- yses of cultivated and tmcultivated soils in seven representa- tive cotinties in Kansas. He pointed out that the elements Some Relations op Organic Matter in Soils 5 carbon and nitrogen have disappeared from the cultivated soils to a larger extent than from the uncultivated soils. He showed that the cultivated soils had lost, in round numbers, from one- fifth to two-fifths of the nitrogen and from one-fourth to one- half of the organic matter. Potter and Snyder (1916) stated that in a general way the total nitrogen determinations in their experiments showed that there was a smaller loss or a greater gain of nitrogen for the limed soils than for the corresponding unlimed soils. Bear (1916) indicated that quicklime reduced the amount of carbon and of nitrogen in the soil. Potter and Snyder, in a later experiment (1917), concluded that lime in the form of a carbonate, under the conditions of the experiment, appreciably enhanced the rate of decomposition of both original soil organic matter and the organic matter of stable manures, oats, and clover when added to the soil. They stated that two of the more important results of this were the increased availability of plant food and the more rapid depletion of the soil organic matter. They pointed out that the latter effect would be partially and perhaps entirely offset by the fact that with lime larger crops could be grown, which would add more organic matter as crop residue to the soil. Breazeale (1917) found that calcium carbonate had a slight destructive action upon the organic matter of the soil. Jensen (1918) stated that in most cases when lime was added to alfalfa in basins, greater increase in the humus content occurred than when alfalfa alone was used. Christie and Martin (1918) state that it is evident from data considered that all soils do not react chemically with lime in the same manner. Bizzell and Lyon (1918) write: "On Volusia silt loam ad- dition of quicklime increased the amount of carbon dioxide in the soil air. This effect was noticed both on the cropped and uncropped tanks. On Dunkirk clay loam quicklime apparently produced no effect." Swanson and Latshaw (1919) say: In the sub-humid section the fields cropped to grain lost one-fourth of the nitrogen as compared with the surface soil of the native sod. The al- falfa fields contain 5 per cent less nitrogen than the native sod, but 20 per cent more than the fields in grain In the semi-arid section the cropped soil has lost one-fifth of the nitrogen as compared with the native sod. Alfalfa fields contained 15.7 per cent T) F. A. Carlson more nitrogen than the ^^oils in native sod, and 30 per cent more than the soils continuously cropped In the humid section, the cropped soils have lost 36 per cent of the organic carbon present in the virgin sod and those in alfalfa over 21 per cent. Lipman and Blair (1920 a I summarized a series of experi- ments as follows: Lime in the carbonate form was used on a loam soil at the rate of 1 ton per acre for the first 5 years and 2 tons for the second 5 years in a 5-year rotation of corn, oats, wheat and 2 years of timothy. No legume crops were introduced. Twenty plots with different nitrogen treatment were thus limed and twenty similar plots with parallel nitrogen treatment were left without lime. The total yields of dry matter and of nitrogen for the 10-year period were essentially the same for the two sections. Analyses of the soil made soon after the work was started and again at the end of each 5-year period showed that there was a loss of nitrogen from both the limed and unlimed sections. However, the loss from the limed section was distinctly greater than from the unlimed section. Thus at the end of the 10-year period, there was a positive loss rather than gain from the use of lime. From this work it would appear that the practice of using lime on light to medium heavy soils, when leguminous crops are not grown in the rotation, may be questionable. Under such conditions it is quite possible that a slightly acid reaction may be desirable to prevent the too rapid •oxidation of organic matter. The second five-years period showed a distinct loss in carbon from both series, but a greater loss from the limed than from Ihe unlimed plats. Lipman and Blair (1920 b) reported also a series of experi- ments which included rotations with legumes. They pointed out that during the ten years, the limed plots, with only slight exceptions, yielded distinctly larger crops and more total nitro- gen than did the unlimed plots. In analyzing the soil they found that in a number of cases The limed plots contained more nitrogen than did the unlimed plots. The same investigators (Lipman and Blair, 1921) reported the results of experiments in studying the losses of nitrogen and organic carbon from a loam soil (in cylinders with natural drainage) which for twenty years had been under a five-years rotation of corn, oats (two years), wheat, and timothy. They found that in most cases there was a general decline in the nitro- gen and the organic carbon content. They pointed out that there was a lower nitrogen and organic carbon content in the limed soils than in the unlimed soils. They stated also that the legume green-manure crops tended to raise the nitrogen content. It is quite impossible to make any direct comparison of Some Kklatioxs of Organic Matter in Soils 7 the literature cited, clue to the variations in experimental methods and in representation of results. In fact, in many cases there are no data to substantiate the statements made. Furthermore, the making of comparisons of one plot with another on the assumption that the natural variation in fertility is gradual and uniform, is subject to severe criticism. It is likewise impossible to study the effect of lime on organic matter in soils without knowing the original composition of the soils. Also, conclusions drawn from computations leased on analyses of soils taken ad- jacent to plats under treatment and assuming that the results obtained represent the original analyses of the treated plats, are questionable. However, the general conception expressed by the literature is that plats which have been limed contain less organic carbon and less nitrogen than do those which have not been limed. There are some exceptions. This conclusion is based on very limited experimental data. EXPERIMENTAL In the present investigation two series of field plats, each 1-100 acre in size, were used. The plats were sampled both be- fore and after treatment. The soil was analyzed for inorganic carbon, organic carbon, and nitrogen. The soil on these plats consists of glacial material reworked by streams and redeposited from glacial lakes (Lyon and Bizzell, 1918). Owing to its sedimentary origin it is comparatively free from stones. The soil has been classified by the United States Soil Survey as Dunkirk clay loam. It is a heavy, compact soil, and requires careful management. Its average mechanical analysis is as follows: First Second foot foot I per cent ) (per cent) Fine gravel 0.40 0.13 Coarse sand 0.63 0.37 Medium sand 0.83 0..52 Fine sand 1.85 1.C5 Verv fine sand 12.90 11.27 Silt 60.83 53.9.5 Clay 22.63 32.72 S F. A. (\\RLSON The following chemical composition was determined by Lyon and Bizzell from representative samples: First Secoocl Constituents determined foot foot (per cent) (per cent) Nitrogen (N) 0.134 0.062 Organic carbon (C) 1.190 0.300 Calcium oxide (CaO) 0.340 0.280 Magnesium oxide (MgO I 0.350 0.450 Potassium oxide ( K.,0 ) 1.830 2.360 Sodium oxide (Na,6) 0.860 0.860 Phosphoric anhydride (P.O.* 0.084 0.079 Sulfur trioxide (SO,) 0.084 0.053 Carbon dioxide (CO,) 0.030 0.020 Lime requirement* (CaO) in parts per million 1,222 1,285 Lime requirement (CaO) in pounds per acre footf ..4,454 4.918 * The Veitch method was used for the determination of lime requirement, t Calculated from weight of soil as 3,645,000 pounds of dry soil per acre foot in the first foot of soil, and 3.827.500 pound? in the second foot. .SOIL .SAMrLIXC The plats in Series I were sampled both before and after the ten-years period. Soil samples were taken from each plat to a depth of four feet, each foot being kept separate. Six borings were made on each plat. The borings for the same foot were carefully mixed together and a 2-quart sample of each foot of each plat was retained. The soil samples were air-dried and placed in tightly sealed jars. The plats in Series II were sampled before and after the eight-years period according to the following method: Each plat was divided into three parts — N (north), M (middle), and S (south). Each one of these sections was sampled as outlined for the plats in Series I. Pre [Kt ration of the sample The air-dried soil was brought to a uniform condition by breaking up the soil lumps and carefully mixing. A composite sample was taken and was placed in a 1-millimeter sieve. All particles of the soil that did not pass through the 1-millimeter perforations were discarded. A composite sample was taken Some Relations of Orc4ANIC Matter in 8<>ils 9 from the 1-millimeter sample and was passed througli a sieve having 100 meshes to an inch. In this case it was necessary to grind the soil in order to pass all of it through the perforations. In the determinations of carbon the 100-mesh sample was used, while the determinations of nitrogen were made from the 1-millimeter sample. The use of the finer soil in the determina- tion of carbon was based on the uncertainty of obtaining complete combustion with the coarser soil. The determinations were made in duplicate. All duplicates having a wider discrepancy than 0.02 per cent of carbon and 0.01 per cent of nitrogen were discarded. Total organic carbon The total organic carbon was determined by the Parr Com- bustion Method, as described in Bulletin 107 (revised) of the United States Bureau of Chemistry, page 234. Total nitrof/en The total nitrogen was determined by the Kjeldahl method. Ten grams of 1-millimeter soil was digested with 30 cubic centi- meters of sulfuric acid (specific gravity 1.84) and 0.4 gram of cupric sulfate, in • 500-cubic-centimeter Kjeldahl Pyrex flasks at low heat for twenty minutes. Ten grams of potassium sul- fate was added and the digestion was continued for three hours. The residue was diluted to 350 cubic centimeters of water and transferred to an 800-cubic-centimeter Kjeldahl flask; from 80 to 90 cubic centimeters of alkali solution was added and the ammonia was distilled into 1-10 X sulfuric acid. The distillate, measuring about 200 cubic centimeters, was titrated with 1-10 N sodium hydroxide, two or three drops of methyl red solution being used as an indicator. SERIES I Soil treatment and cropping systems The plats in Series I were under experimenta,tion for a period of ten years, from 1910 to 1919. A statement of the soil 10 F. A. Carlson treatment of each plat, and of the cropping systems, is given in table 1: TABLE I. Soil Treatment and Cropping Systems Plat Soil treatment Cropping system Fertilizer Lime 7002 Farm manure None Rotation without legume 7008 Farm manure Burnt lime Rotation -without legume 7003 Farm manure None No vegetation 7009 Farm manure Burnt lime No vegetation 7005 Farm manure None Rotation with legume 7011 Farm manure Burnt lime Rotation with legume 7006 Farm manure None Oats, grass nine years 7012 Farm manure Burnt lime Oats, grass nine years 7014 Farm manure and K2SO4 None Rotation without legume 7015 Farm manure and K2SO4 Burnt lime Rotation without legume The applications of farm manure were made in 1910, 1914, and 1918. The three applications were each at the rate of 10 tons per acre, and were given to the plats that were never planted as well as to the cropped plats. The applications of potassium sulfate were made annually to plats 7014 and 7015 at the rate of 200 pounds per acre. In 1910 and 1915 burnt lime was ap- plied to plats 7008, 7009, 7011. 7012, and 7015. at the rate of 3000 pounds per acre. The rotation without legume consisted of corn. oats, wheat, and grass two years. In the rotation with legume, clover was grown with grass for two years in the first half of the ten-years period, and during the second half of the ten-years period a legtmie was grown each year as follows: in 1915. soybeans with corn; in 1916, peas with oats; in 1917, vetch with wheat; in 1918 and 1919, clover with grass. Plats 7003 and 7009 were never planted to any crop, and all vegetation was prevented from growing on them by hoeing. Some Relations of Organic Matter in Soils 11 When corn was growing on the plats in rotation, the implanted plats were hoed at the same time and in the same way as were the plats planted to corn; when other crops were growing on the planted plats, the implanted plats were merely scraped with a hoe. The mixtures of grasses used consisted of timothy, Kentucky blue grass, and redtop. Jx'cSllltS Orgaiiiv carbon l d cc q C5 '•jr t-; r-i =»H '- w o T^ ■^ r- 1—1 ^^^ ^% Q, ■*- ! i 1 + + + 1 0) ^ Lt ri CC L!C LC q 00 ll •^ ^•■ X d ■*' d d d U V. ■M c^ ^H CO II. '-^ 1 1 1 + + 1 TT o: N 10 irt 00 \a 00 00 01 O-w c- cq c^ Tf< U5 1 ^ ■^ t^ t- Oi Cvl 3-. CC q CC '^. t~ CC CO Is. '-^ ~ ^^ 1-H i-i " T-i -c •»c LC C: 10 c- c- o o o o CC Tf C^ D- c^ t— Oi co _ \a IC' ■* Tf '^ ■* irt 10 ■* LO tl CD «-■ d d d ==^' - d d d d d =25 H) ni pq 1 +J ^ cj J: c- t^ c^ C-l m .^8 ■* c^ t- 00 00 ID w •rr •* ■<* ^ ■* ■^ ■«t< fc=M ^^ ^ T-I l-i i-i iH 0) a ;=; ., - c 3 C S 03 •2 a cS — ' S 3 a> (D flee ^0 3 ■J O ■2S :a 5 *3 bC .2 3 S a •Bt^' ?, 5^ 6 cS cS 0) oj Ol '"' •— ^ cd rt c D 4-j Q) -*-> - CD Q^ hfi lioT *J r-l a> of tP 0" 0) aT r s^ ^g s-^ g-fl ^S >fl o§ ^§ :z;§ S (ra ex CO Oi 10 i-i ^ C<1 •«*l Ui c c 1-1 T-l tH T— * 5 ■ t^ l> c- t- t- t^ c- 1^* t^ Some Relations of Organic Matter in Soils 13 z a + + + + 4- o o O o a,. --4- 7} + + + + + , r^ +J CO ■^ c- o o lO lit cj o o o Oi -•« o o o m Ho oo CO as o •S § o I— 1 tq =" o o ^ o o o o o — ' fin pa a 01 rtO j-iCJ a §»?. §02 14 F. A. CA1U.80N less consistent than those in the first foot. This inconsistency may be accounted for by lack of soil uniformity. The limed plats not only contained more organic carbon, but also gave higher yields, than the unlimed plats. The yields are expressed in graph form in figure 1 (page 17). With one exception there was a greater percentage of nitro- gen in the limed plats than in the unlimed plats. The plats in rotation all showed a loss of nitrogen in the first foot for the ten-years period, while the plats in grass increased in nitrogen. Plat 7009, which was kept bare, lost a marked percentage of nitrogen in the first foot. Plat 7011, on which the rotation in- cluded legumes, lost a smaller percentage of nitrogen in the first foot than did the plats in rotation without legumes. These results are consistent with the results obtained on the lysimeter tanks (Lyon and Bizzell, 1918). The soil in the lysim- eter tanks was obtained from The plats used in these experi- ments. It was found that the nitrogen in the drainage water from the lysimeter tanks was less where the tank soils had been kept in grass, than in a rotation. It was shown also that the tank soils kept bare lost more nitrogen than the cropped tank soils. }tatio of carbon to nifroffen in plats hffore and after treatment The ratios of carbon to nitrogen in plats before and after treatment are given in table 4. The data show the close relation between these two elements in the soils studied. The ratio was wider in the first foot of soil than in the second foot. The variotis treatments did not cause any constant change in the carbon- nitrogen ratio. The effect, if any. was too inconsistent to be con- sidered significant. The results compare favorably with those obtained by Hess (1901). He found that the ratio of carbon to nitrogen was not materially affected by the treatment applied. Dyer (1902) also reported that the carbon and nitrogen contents of the upper stratum of the soil were higher than those of the lower stratum, and that the ratio of carbon to nitrogen was wider in the upper stratum. Alway and McDole (1916) likewise found that the ratio of carbon to nitrogen was lower in the second foot than in the surface foot. S(i-ME Rklations of Organic Matter in Soils 15 ~ •— r-, tH 1—1 1-H 1—1 1—1 rH rH rH rH X ra Ci (M !>; rH CO T-< ■^ C/D v: ^ o >3 t^ « t-^ TJ^ T}J d c/i t-^ Lit X 1/ ^ CO "t;; ^ ~ i. 1 ■4-S i-H ^ tH 1-1 1-1 rH rH ^ -H < Tj- c~ ;.; O Oi t- -i' •i' lO ■bJ ^^ T-H o^ ai ai d rH i^ d "^ CO ^ tH ^ rH T-i '"-■ ^ ■aC p C " — ■p '■"■ ■— ^^ 1-1 -^ I— 1 rH rH ^ 1— < 7-t 5 ■r i;' -* LC t~ o rH o rH r^ ^^ ^— o o o o O o O o o c~ ?• t- t- t- t- c^ t^ L^ c- 16 F. A. Oaulson Removal of iiifrorjeii from the soil in crops grown on the plats in iSeries I The amounts of nitrogen removed in the crops were esti- mated and are recorded in table 5. The nitrogen is expressed in pounds per acre for the ten-years period. TABLE 5. Amount of Nitrogen in Crops. Series I Plat Crop Fertilizer Burnt lime (pounds) Nitrogen in crops (pounds per acre, total for ten years) 7002 Rotation with- out legume Farm manure 684 7008 Rotation with- out legume Farm manure 9,000 798 7005 Rotation with legume Farm manure 817 7011 Rotation with legume Farm manure 9,000 948 7006 Grass Farm manure 325 7012 Grass Farm manure 9.000 .354 7014 Rotation with- out legume Farm manure and K2SO4 844 7015 Rotation with- out legume Farm manure and K2SO4 9,000 868 It appears that the nitrogen varies with different crops. The greatest removal of nitrogen was in the crops in rotation with legumes. The hay crops removed less than half the amounts of nitrogen estimated in the crops in rotation with legumes. These results are of extreme importance in consider- ing the total nitrogen in the soils of these plats recorded in table 3, in which, as already stated, it is shown that the plats kept in grass increased in nitrogen in the first foot, while the plats in rotation with legumes and those in rotation without legumes decreased in nitrogen. The fact that less nitrogen was removed from the grass plats may aid in some degree in explain- ing these differences in percentages of nitrogen. Some Relations of Organic Matter in Soils 17 Total yields of crops on plats in Series I The total yields of crops in Series I are represented in figure 1. Field weight (lbs.) 40" 300 200 14r/TMOl/T L/Af£: WITH l.7M^ I I Plat I i 1 I i 7002 7008 7005 7011 7006 7012 7014 7015 Crop rotation Crop rotation Grass Crop rotation without with without legume legume legume, + K,SO, FlO. I. TOTAL PLAT YIELDS FOR TEN-YEARS PERIODS^ SERIES I In every case there was an increase in crop yield on the limed plats over that on the unlimed plats. It seems logical to 18 F. A. Carlson assume that an increase in yield is associated with an increase in roots and residual organic matter, which may explain why the organic carbon and the nitrogen were generally higher in the limed plats than in the unlimed plats. The total yields were less on the plats kept permanently in grass than on the plats in rotation with legumes or on those in rotation without legumes. It has already been pointed out. in tables 2 and 3, that the plats in rotation lost more organic car- bon and nitrogen in the first foot than did the grass plats. SERIES II In order to obtain further information on the effect of treatment and cropping on the organic carbon and the nitrogen in soils, the plats in Series II, located adjacent to plats in Series I, were analyzed. These plats, as already stated, received ap- proximately the same treatment as the plats in Series I, the only marked differences being that the plats of Series II were started one year later than the plats of Series I, and that they received only two applications of manure. Only the first foot was analyzed, due to the failure of the second foot in Series I to show any consistent results of experi- mental value. The results obtained are recorded in tables 6, 7, and 8. These tables are not discussed separately, due to their close correlation with the results of Series I. The points emphasized in discussing the results of Series I may well be applied to Series II. However, the results in Series II are much more striking. The limed plats, as was found in Series I, show in general a higher percentage of organic carbon and of nitrogen than do the unlimed plats. The limed plats also gave higher yields than did the unlimed plats. There was a decrease in organic carbon and in nitrogen in the plats cropped under the rotation without legumes, with one exception. The most interesting phase of these results is that the plats In rotation with legumes showed an increase in nitrogen. The percentages are very significant. Plats 7205 and 7211. in rota- tion with legumes, increased 4.2 and 6.7 per cent, respectively, in comparison to plats 7202 and 7208, in rotation without leg- umes, which decreased in nitrogen 12.2 and 7.1 per cent, re- spectively. Some Relations of (Organic Matter in Soils 19 u ° = ^ ^ to — OJ 53 00 "^ lO C5 tH CO (M t~l ^^ t-; ?^ ^ S 1-! CO CO t-^ s C>1 T-J ^-1 C^3 T-H o -f CD s tH CO oo ^ < d d d d d d r-i T-1 d d 7i li ■^ ^ ^ r" M X fJ^ o Oi tC CO T-( T-H O «D CO C t> •t^ a o t^ t^ I- o (35 Oi T-I (M lO A C5 oo t>; t- o O Oi o O as l! S d d d d T-i rA d T-i r-i d J^ ■*^ t» o <; a3 ^ ^ ^^ ^ ., ^ .' _/. ■* <3i CO CO .— 1 T— 1 LCt' LC GO L;:><3ii^i--o0i-i-«fc C- t- CO C<1 •* tH CO CO c- t- Oi rH OO c- o CD •^ o Oi 00 C5 as CO CO C- t~ t-; c- t- c- o a> 05 iHr-HCTiOOiOOOCO T-I Ol Oi O 00 OS ^ ^ Xi d d d d <:i 'd' s s s S S (S rA id 'd l-i T-i d tH d T-1 T-I T-I O T-i d d ^ o o ^ o ;r ZScn Z^Ui ^gco 'Z^mZ^Ui ^gcc^goj ^^CO issw ;zi^!:n A ,a X' s *^ 4-> __j •^ •^ > S o Ig § 3 g a> §03, 0, 4-> o cp 'i-i u p ° O . O 0) oo r.-^ OS LO ^ CD IM •^ lO -~ o d o o T-I O T— 1 tH T— 1 - c^ CM CM c- 20 F. A. Carlson °°a; C Q) oj CO T-; c-^ O M t-; O O O OS 0) £0 cp M l> d Irt M^ d oo lo d d O CS ^H i-H rH tH 03 O u ^ ^ 1 1 1 + + + + 1 i S "xi I1..9 _ (D O 13 ■>* 00 00 « LO 00 OS ^ t- , 1—1 o 1—1 iH O o o o — — CP o o o O O o o o -. ^ 03 o o d d d o d d o — ■ ^ 1 1 1 1 + + + + 5 03 M T— 1 •*! o 1-1 CO 00 CO Lft OS t— +J 173 o o o; 05 Cq M M (M o o *-H ;h T-; T— 1 o O r-H l-j I-i ^H tH a o o 03 > < o d d d d S c6 d> d =■ cS *H CP EC 0) E CO lO 05 05 OS •* O C.'J t- 05 ?0 05 •<*< OS CO ■*-.i 03 O 03 .2 a O O) o =5 .2 a .2 +j « 03 So ? S S ?> O 03 £ -=- C3 § a B °^i O a 03" 0) 03" P Q)* 3* C' H 2| 2| P.Sg gg |g as o.^§ Sl 2| 2| 2| oS qS zs Zg o § o S O^ Og Qg 5s -tJ «S'cr?r.s // The total yields of crops in Series II are represented in figure 2. The limed plats show a greater yield than the unlimed plats. This was true also of the plats in Series I. The total vields. SdME KkLATIONS of ORGANIC MATTER IN SOILS 23 however, of both the limed and the unlimed plats in Series II are less than those in Series I. It may be pointed out here that the plats in Series II contained less organic carbon and nitrogen than the plats in Series I. This may indicate that there is some relation between organic carbon and nitrogen, and yields of crops. Field Aveight Ubs.) ^ kviTHOLrr limb /fvr/y I. /MET 600 Plat 7202 T20S 7205 7211 7206 7212 7214 7215 Crop rotatio'i Crop rotation Grass Crop rotation without with without legume legume legume, + K,SO, Fig 2. TOTAL PLAT YIELDS FOR EIGHT-YEARS PERIODS, SERIES II 24 F. A. Carlson The most important result shown in figures 1 and 2, as related to the present investigation, is the increase in yields of crops on the limed plats over those on the unlimed plats. SUMMARY A study of the effect of various treatments and cropping systems on the organic carbon and the nitrogen in soil is re- ported in this paper. The soil is classified as a Dunkirk clay loam. The plats were each 1/100 of an acre in size and were arranged in two series. The treatments included manure, potas- sium sulfate, and lime. The cropping consisted of a rotation without legumes, a rotation with legumes, and grass perma- nently. The experiment was conducted for periods of eight and ten years, respectively. The plats were sampled for the first- and second-foot strata before and after treatment. The organic carbon and the nitrogen were determined. The results of the two series compared favorably. In general the limed plats in both series contained more organic carbon and nitrogen than did the unlimed plats. There was a decrease in organic carbon and in nitrogen at the end of the period of experimentation on the plats in rotation without legumes. The plats kept in grass showed an increase in organic car- bon and in nitrogen. The plats in rotation with legumes contained more nitro- gen than did the plats in rotation without legumes. The plats in rotation with legumes in Series II showed a marked increase in nitrogen. The increase was greater in the limed plats than in the unlimed plats. This fact seems to indicate that the leg- umes had some influence on the nitrogen content of the soil studied. The organic carbon and the nitrogen were lower in the plats of Series II than in the plats of Series I. The limed plats produced higher yields of crops than did the unlimed plats. The plats in Series I gave higher yields of crops than did the plats in Series II. The results suggest that there is some relation between or- ganic carbon and nitrogen, and yields of crops. Some Relations of Organic Matter in Soils 25 The crops in rotation with legumes removed more nitrogen from the soil than did the crops in rotation without legumes. The plats kept in grass lost less nitrogen in the crops than did the plats in rotation with legumes. There is a close relation between the organic carbon and the nitrogen. The ratio is wider in the first foot of soil than in the second foot. REFERENCES CITED Alway^ Frederick J., and McDole, Guy R. The loess soils of the Nebraska portion of the transition region : I. Hygro- scopicity, nitrogen, and oro-anic carbon. Soil sei. 1 :197-238. 1916. Alway^ F. J., AND Trumbull, R. S. A contribution to our knowl- edge of the nitrogen problem under dry farming. Jonrn. Indus, and eng. chem. 2 :135-138. 1910. Bear^ Firman E. Effect of quicklime on organic matter in soils. Amer. Soc. Agron. Journ. 8 :111-113. 1916. Bizzell^ J. A. AND Lyon. T. L. The effect of certain factors on the carbon-dioxide content of soil air. Amer. Soc. Agron. Journ. 10:97-112. 1918. Bradley, C. E. The soils of Oregon. Oregon Agr. Exp. Sta. Bui. 112 :l-48. 1912. Breazeale, J. R. Formation of ''black alkali" (sodium carbon- ate) in calcareous soils. Journ, agr. res. 10:541-590. 1917. Christie, A. W.. and Martin. J. C. The chemical effects of CaO and CaCOs on the soil. Part II. The effect on water-soluble nutrients in soils. Soil sci. 5 :383-392. 1918. Clausen^ H. [German title,] Can calcareous fertilizers be held responsible for a deficiencv of nitrogen in soils? Illus. landw. Ztg. 26:674-675. (Cited in Exp. sta. rec. 18:622-623. 1907.) 1906. Dyer, Bernard. Results of investigations on the Rothamsted soils, U. S. Office Exp. Sta. Bui, 106:1-180. Reference on p. 29.) 1902. Gardner, Frank D. The use of lime on land. Pennsvlvania Agr. Exp. Sta. Bui. 131:167-204. 1914. 26 F. A. Carlson Hartwell, B. L., AM) Kellogg, J. W. Ou the elfect of liming iipou certain cou.stitiients of a soil. Rhode Island Aur. Exp. Sta. Kept. 1905 : 242-252. 1906. Hess, Enos H. Effect of various systems of fertilizing upon the humus of the soil. Pennsylvania State Coll. Ann. rept. 1899- 19002; 183-202. 1901. Jensex. Charles A. Humus in mulched basins, relation of liumus content to orange production, and effect of mulches on orjuige production. Journ. agr. res. 12:505-518. 1918. KossoviCH, P.. AND Tretjakov, I. [Russiau title.] On the influ- ence of cahium carbonate on the progress of decomposition of organic matter. Zhur. Opuitn. Agron. 3 :450-484. ( Cited in Exp. sta. rec. 14 :427. 1903.) 1902. LiPMAN. J. G.. AND Blair, A. W. Field experiments on the avail- abilitv of nitrogenous fertilizers. New Jersey Aur. Exp. Sta. Bui. 260:1-33. 1913. The lime factor in permanent soil improvement. I. Rotations without legumes. Soil sci. 9:83-90. 1920 a. Tiic lime factor in i)ernianeiit soil improvement. II. Rotations with legumes. Soil sci. 9:91-114. 1920 b. Xitrogen losses under intensive cro)>ping. Soil sci. 12:1-19. 1921 Lyon, T. LvTTr.ETox. and Bizzell^ James A. Lysimeter experi- ments. Cornell Univ. Agr. Exp. Sta. Memoir 12 :1. 115. 1918. McIntire, W. H. Results of thirty years of liming. Pennsyl- vania State Coll. Ann. rept. 1911-122:64-75. 1913. MooERS, C. A., Hampton, H. H., and Hunier, W. K. Fertility experiments in a rotation of cowpeas and wheat. Part III. The effect of liming and of green manuring on the soil content of niti-ogcu ;md liumus. T^'niv. Tennessee Agr. Exp. Sta. Bui. 96 :25-43. 1912. Potter. R. S., and Snyder, R. S. Carbon and nitrogen changes in the soil variously treated: soil treated with lime, ammo- nium sulfate, and sodium nitrate. Soil sci. 1 :76-94. 1916. Decomposition of green and stable manures in soil Journ. agr. res. 11 :677-698. 1917. Some Relations of Organic Matter in Soils 27 SucHTELEN^ F. H. H. VAN. Ueber die Messang der Lebenstaetig- keit der aerobiotischen Bakterien im Boden durch die KoMen- saeureproduktion. Centbl. Bakt. 2:28:45 89. 1910. SwANSON^ C. O. The loss of nitrogen and organic matter in eiilti- vated Kansas soils and the effect of this loss on the crop-pro- dncing power of the soil. Journ. indus. and eng. chem= 7 :529- 532. 1915. SwANSON^ C. O., AND Latshaw^ W. L. Effect of alfalfa on the fertility elements of the soil in comparison with grain crops. Soil sci. 8 :l-39. 1919. Wheeler, H. J., Sargent, C. L., and Hartwell, B. L. The amount of humus in soils and the percentage of nitrogen in the liumus, as affected by applications of air-slacked lime and cer- lain other substances. Rhode Tshnid Ai^v. Exp. Sla. Ann. rept. 12:152-159. 1899. Memoir ,17. A Study, by thi: Cro/j Survey MeUiod, uf b'actors Inltuencing the I'ield of fotatnes, the fourth preceding number In this series of publications, was mailed on September 27, 1922. ^ LIBRARY OF CONGRESS e p>o>9 683 476 4