S 593 C35 Copy 1 SOME RELATIONS OF ORGANIC MATTER IN SOILS bd z o Sen, ce sir 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 61, pads 1922, Cornell University Agriculture Experiment Station, is ®: SOME RELATIONS OF ORGANIC MATTER IN SOILS A HESS PRESENTED TO THE FACULTY OF THE GRADUATE SCHOOL OF CORNELL UNIVERSITY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY BY FRED ALBERT CARLSON V\ FEBRUARY, 1922 Reprinted from Memoir 61, September 1922, Cornell University Agriculture Experiment Station. e Aebe CQ pe ween em & } ‘ f no | ee f Cine Llawe fe V4 he rf. (94 \ N 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 (1902) stated that the addition of calcium carbonate to soil retarded the decomposition of organic matter. Hartwell and Kellogg (1906) pointed ont 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. 1Dates in parenthesis refer to References Cited, page. 25. 2 ra) 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 rotation 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 there was an increase in percentage of humus on the unlimed sections. McIntire (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 uncultivated soils in seven representa- tive counties in Kansas. He pointed out that the elements ~~ SOME RELATIONS OF ORGANIC MATTER IN SOILS D 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 i F, A. CARLSON more nitrogen than the soils 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 (1920a) 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 the 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 vears. 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 vears 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 RELATIONS OF ORGANIC MATTER IN SOILS = the literature cited, due 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 based 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 (per cent) (per cent) PIT eet anv E limi vererenera sie ie icant reece eects nite cs sta Cie neh actin Spm dats cto teanto poet plies VO ATG Gees 11 i atrene etme reieuryaremiets ec Amat ers sr eon <8 WAGS Me his hast, Coen alspinsvsreh Ae 0.37 VEC CUTIE ES U1) Cl omer chcnencis Reale esh secs creel 41.0 0-tc.c = cpa OO Siemens ea eins ata cas ee eee ae. 0.52 HUTT Gap SELIN Cs seers aiave es evade) soeean <: analecelles tas! siete neers fe 10 I ee a ee 1.05 AWIGTIVAR LING SAMO: ucie scans ce stele cn sisi ee raverensseseuare ets LES () PME, Wie roxttn os ctacch sateen ala EPA SST Bee acess cee eee ia cuss ieee eet kere oiate CUS Re i i gE Se ee ees 53.95 S EF. A. CARLSON The following chemical composition was determined by Lyon and Bizzell from representative samples: First Second Constituents determined foot foot (per cent) (per cent) Nitrogen (ON) sei ae een ee ee ee 0.134 0.062 Organic: Carboni (©) iced cere eases ee eee eee 1.190 0.300 Calcium Oxides (CAO) We pcre ee eee eee 0.340 0.280 Magnesium oxide (MgO) ............6..-+cceessceee 0.350 0.450 Potassium oxide (KGO)e soee- os ee eee ee ee 1.830 2.360 Sodium: soxide SCNasO)) mere Spence eee eee seein tener ee 0.860 0.860 Phosphoric anhydride GP302) anes see cee cee ore 0.084 0.079 Sulfur trioxide: (Ss O2) aetna ar eee rere 0.084 0.053 Carbon dioxide 3( CO.) een ee eee 0.030 0.020 Lime requirement* (CaO) in parts per million...... 1,222 1,285 Lime requirement (CaO) in pounds per acre foot; ..4,454 4,918 *The Veitch method was used for the determination of lime requirement. + 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 pounds in the second foot. SOIL SAMPLING 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. Preparation 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 ORGANIC MATTER IN SOILS 9 from the 1-millimeter sample and was passed through 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 nitrogen 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 N 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 systens The plats in Series I were under experimentation for a period of ten years, from 1910 to 1919. A statement of the soil 10 EF. A. CARLSON treatment of each plat, and of the cropping systems, is given in table 1: TABLE 1. Som TREATMENT AND CROPPING SYSTEMS Soil treatment 230 | 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 K,SO,|} None Rotation without legume 7015 |farm manure and K.SO,} 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 legume 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 Ie When corn was growing on the plats in rotation, the unplanted 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 unplanted plats were merely scraped with a hoe. The mixtures of grasses used consisted of timothy, Kentucky blue grass. and redtop. Results Organic carbon and total nitrogen in plats before and after treat- ment The results recorded in tables 2 and 3 represent the aver- ages of duplicate determinations. The percentages of carbon and nitrogen before and after treatment are given, as well as the differences and the percentage of increase or decrease for the ten- years period. The total amounts of carbon and nitrogen added to the plats in manure, have been subtracted from the amounts of carbon and nitrogen determined on analysis after treatment. The data show that in the first foot, in every case but one, the limed plats contained more organic carbon than did the unlimed plats. This is very significant in the plats kept in grass. Plat 7012, kept in grass and limed, shows an increase of 20.5 per cent of organic carbon in comparison to an increase of 14.5 per cent in plat 7006, which had the same treatment and cropping except that it was not limed. Plat 7002, cropped in rotation but not limed, shows a decrease of 24.5 per cent of or- ganic carbon in comparison to a loss of 3.1 per cent in plat 7008, which had received lime. This difference is not attributed en- tirely to the lime. Plat 7002 was exposed to greater erosion and more complete drainage than was plat 7008. All plats in rota- tion show a decrease in organic carbon in the first foot, while there is a marked gain in organic carbon in the first foot in the plats kept permanently in grass. The use of legumes in rotation did not materially affect the organic carbon content. Plat 7009, which was kept bare, lost a marked percentage of organic carbon in the first foot. The percentages of organic carbon in the second foot are a ee eee ae See P ; : : eur, “OS*y ‘ainueyy a 89 600°0 960°0 8zc'0 | 608'T Lego | SOFT normed does CIOL ey ye : ae : cs ' ror: roS’M ‘aanueyy Pree 69:6 sorot+ | orto g09'0 | zzeT L6b'0 | 39FT eoraioa doi FLOL 99 — | goz+ | ggo0o—|cogot | Lego | cent GL¢0 | L8PT so ae ZTOL 06 + | GrI+ | gpo'ot | zgTot+ | SHsO | eypy 0060 | 98°T apres 9002 aU] ‘OINUBIN euunse IM A oz + | 9 — | szo0+ | e6oo—| sero | ret | oovo | Let eayeondeiay | The Z aINUeIAL a : - ; ; auUINS9, [IIA GOO0L ‘S) te | fee gg0°0— G90 OFO'T 06h 0 uo1}B}01 dolD : aM] ‘oInuUeyAL 6002 < V6 =) 28c— || S70 0—— | yO Gero |.) O90 OLP'O | LLPT W01}e}9B9A ON . sINUPVIAL 8002 Fa Pal ZL0°0— sre'o | LZ0'1 0ZF0 Wo}}2}0304 ON SUL] ‘BINUBIAL 8002 0°82 re OZTO— | rro'O0— | Gero | SLE GhSo | 6IF'T woryeyor doip 7 dINUP]L Lvl Gpz— | 6L0°0— | F0¢°0- Lor'0 =| 8860 9690 | Zre'T uorje}01 dorp G00L : JOO] : OO) Oo} OO} 4ooy OO) 100} yoo} puooves | ysaly puossg | 4saly puodses | 4saly puossg | 4saty $$ JUBTAYBILL, 18Id VSBILVOP LO BSBAAZ Seunesin Mecches@ucto nel JUST} BAL} -UL JO JUOOD Jeg BPRS ae Hl 191 V alojJog | SHIWIG “LNAWLVAYT, YWALAV GNV axOdaa SLVIQ NI NO@AVD SINVOYG JO LNAD wg ‘ce ATAVL 12 13 SOME RELATIONS OF ORGANIC MATTER IN SOILS ? : a a ee ee ee a —————EE———————————————— : ; oul, “OS*y ‘ainuey Tirt+t | ozt— | 6000+] zt00— | 0600 | ezto T80°0 | ZPT‘0 U0lzeIOL dod STOL ig z ‘ ; OSM ‘91nuefl qstt+ | 8 LI— Zt0' 0+ | Lz0°;0— | L200 GZT'0 690°0 ZST'0 101}B}04 dog bTOL ; oul, ‘AInuUey, 66 — | 2ii+ L00°;0— | Z00°0+ | #9070 1910 TL0°0 6ST'0 SssBaiy oTOL oINUe IAL v6I— | 9F 4+ ETO O— | 9000+ FS0'0 LETo 190°0 TST 0 SSBID 9002 aul, ‘enue . — zo'o+ j= sg 0)" BET: 690'0 IFL'0 aumnse, WIM TLOL oezt | Lt Oza 9000 680'0 6810 SPI woryejor dorp dINUPIN, ; san os TAM} Pee “7 ; £90°0 mata euNnse9, WIM S00L T6e+ S600 680°0 SIO deri on cede eu] “aINUB]T 6002, Pale tibet | ST0°O— | 8To;O— | sg0°0 LITO 0L0°0 gsT0 U01}181939A ON ‘OINUPIA 2002 (VEY cise Uh US UE Vera) as Lg0°0 6010 1L0°0 tee uol1e1930A ON sUTT ‘ANUP, 691— | sz — | tro0—| ot00—| #¢e00 | stro ¢90°0 | gzto uorye104 dorg 8002 oINUPIA eze— | see— | tz0'0—| Troo—] 9600 | zgo'0 LL0°0 | s2t0 uoreior dog 6002 yO03 00] yoo} 00} yoo }O0} Joo yoo puodses | isa puoses | Isat puoses | isa puoseg 4SIL7 aSRalep 10 asvade eonerent yuewyRe) yuourvan JUS} BALL, 181d -UL Jo yue. Jag ‘ coaae IdVWV alojeq ————— a a ee ee ee eee Oo —eses—soaoooooooooooaOOOOoOwnmwsaoaahRaRpo)oaaaa T SHAS “LNAINLVAY], WALdY GNV AYxOdaa SLVIG NI NADOMLIN TVLOT, dO INID wag *€ FIGVIL 14 F. A. CARLSON 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. Ratio of carbon to nitrogen in plats before 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 various 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. SOILS ATTER IN 1 ELATIONS OF ORGANIC R —~\ 4 SOME T:9°S T:S'0T T:9°9 1:66 era) T:9°0T TaOah 1:96 L:¥'8 eo Ls [: 6 TE OL Te) 00 LG 1:8°6 T:8'F 1:66 seb ds) EEO ll? T:0°6 1:9°9 se Es Tene) Te1¢ TiL'9 T:6°0T aT er CTT ioe ee evar L:6°L ev agi Li*’s re a [:2'8 LIP LT L769 T:LOr JOO] PUODIS - JOO] ISAT JOO} Puovas JOO IS.ALy JUSUWTPRA) 10d, V JUBUT} RIA} | VLOJOY oa (0000 _—_—_—_—_— —_—_ OOoOoOoqnmo>nmomos ooo mx Two “ENUINLVAY TT Waldv GNV ayOrdd SLVTq) NI NdOOULEN OL NOUUV ) AO SOILVY T salias SOR UdsOIjU-Uo GARD out “OS*M ‘amue yy umorjeyoOu doa) ‘OSM ‘oanue yy TOT} BIOL CO) OU, ‘OINUB IT SSR OANA SSRI) oT ‘AINUB IAL Somnso]| YUM uoTMejoI dor oINUPeB I SouNnse] YjIM Worejor dor eu, ‘aInuey U0T}B1BSOA ON oINUe IN UOI}BJOBIA ON om, ‘aINueyA, uor}e}0I Cory oINUB IAL uoryeJOI dow) VUIUTVOL GTOL POL éTOL 9002 TTOL b VIGVL 16 F’. A. CARLSON Removal of nitrogen from the soil in crops grown on the plats m Series 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 | Burnt {Nitrogen in crops Plat Crop Fertilizer lime |(pounds per acre, (pounds )|total for ten years) 7002 Rotation with- Farm manure 0 684 out legume 7008 Rotation with- | Farm manure 9,000 798 ‘ out legume 7005 Rotation with Farm manure 0 817 legume 7011 | Rotation with Farm manure 9,000 948 legume 7006 | Grass Farm manure 0 325 7012 | Grass Farm manure 9,000 354 7014 | Rotation with- | Farm manure and K,SO, 0 844 out legume > 7015 | Rotation with- | farm manure and K.SO, 9,000 868 out legume 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 ii: percentages of nitrogen. SOME RELATIONS OF ORGANIC MATTER IN SOILS yd Total yields of crops on plats in Series I The total yields of crops in Series I are represented in figure 1. WITFHIOUT LIME WITH LIME Field weight (ibs. ) 600 ad ye 7 400 Y r . i 1) i ag Y Flat 7002 7008 7005 7011 7006 7012 7014 7015 Crop rotation Crop rotation Grass Crop rotation without with without legume legume legume, +K,SO, Fic. 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 EF, 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. abs) OME RELATIONS OF ORGANIC MATTER IN SOILS a! 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Saeeraen oSRIoAV suo10eg aseloAV | su01909g 10 9SBaIDUl) sdUdIOTIG JOOS YSATH WOOF SATA JUST BOLT, 11d gO -guep ted quewyeed} 101W quomyReI} a10Jeg II SHWag “LNAWLVaY], WALdV GNV a@xOdaA SLVIG NI NAOOWLIN’ TVLO]T, JO LNAD wdg “4 FIGVL SOME RELATIONS OF ORGANIC MATTER IN SOILS 21 TABLE 8. Ratios oF CarBon To NITROGEN IN PLATS BEFORE AND AFTER TREATMENT. Series II, First Foor or Soin Carbon-nitrogen ratios Plat — Treatment Before treatment After treatment 7202 SA) BS ee 7.9:1 7.9:1 Manure ; Crop rotation “4 os i208 Manure, lime (e pees Ese No vegetation 2. : 7202 RIsEnERG ferspal 6.6:1 fy No vegetation ; 5 (209 Manure, lime T2017 79:1 ae Crop rotation with (205 legume 8.5:1 1. oL8 Manure = Crop rotation with 7211 legume Sue 8.521 Manure, lime 7206 Grass : F 7206 inners 8.8:1 9.5:1 212 Grass : 8.2:1 9.721 Manure, lime 7214 Crop rotation 8.9:1 ee Manure, K.SO, si 7215 Crop rotation 8.9:1 8.8:1 Manure, K.SO,, lime The plats in grass showed a decided increase in organic carbon and in nitrogen. The carbon-nitrogen ratios were lower than those in Series I. Removal of nitrogen from the soil in crops grown on the plats in Series IT The amounts of nitrogen removed in the crops grown on the plats of Series II were estimated and are recorded in table 9. The nitrogen is expressed in pounds per acre. The results compare favorably with those obtained in the study of the plats in Series I. In considering the nitrogen in the soils of the plats in rotation with legumes, as recorded in pip EF. A. CARLSON TABLE 9. Amount oF NITROGEN IN Crops. SERIES II Burnt Nitrogen in crops Plat Crop Fertilizer lime (pounds per acre, (pounds)|total for eight years) Rotation with- 0 em aOR ; Bt 7202 out legume Farm manure \DD Rotation with- _ 2 ‘ ° 9,000 7 7208 out legume Farm manure 714 Rotation with 2 0 ( 7205 leeanne Farm manure 690 Rotation with ; 72 9,000 399 1211 legume Farm manure 89 7206 | Grass Farm manure 0 312 7212 | Grass Farm manure 9,000 397 7O14 Rotation with- ao, xe out legume Farm manure and K,S0O, 0 652 coz, | Rotation with- |marm manure and K.SO,| 9,000 703 out legume fod table 7, and that removed by the crops, the advantage from the growing of legumes is fully substantiated. The crops in rota- tion with legumes removed more nitrogen than did the crops in rotation without legumes. In this connection it is important to note also in table 7 that the plats in rotation with legumes con- tained more nitrogen than did the plats in rotation without leg- umes. While the plats kept in grass contained more nitrogen than did the plats in rotation, there is a marked difference in the amount of nitrogen removed by the hay crop as compared with the crops in rotation with legumes. The results show that the rotation with legumes used in these experiments supplied more nitrogen than did the rotation without legumes or the grass. Total yields of crops on plats in Series IT 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 yields, SOME RELATIONS 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. U, SS WITHOUT LIME | | er Ten LIME Field weight Cbs.) 600 500 1/7, 40) Y, 300 GG a V Piatt 7202 7208 7205 7211 7206 7212 7214 7215 Crop rotation Crop rotation Grass Crop rotation without with without legume legume legume, +K,SO, Fig 2. TOTAL PLAT YIELDS FOR EIGHT-YEARS PERIODS, SERIES II a4 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 vields 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. 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The effect of liming and of green manuring on the soil content) of nitrogen and humus. Univ. Tennessee Agr. Exp. Sta. Bul. 96 :25-43, 1912. Porrer, R.S8., AND SNyper, 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, I’. H. H. vAN. Ueber die Messung der Lebenstaetig- keit der aerobiotischen Bakterien im Boden durch die Kohlen- saeureproduktion. Centbl. Bakt. 2:28:45-89, 1910. Swanson, C.O. The loss of nitrogen and organic matter in culti- vated Kansas soils and the effect of this loss on the crop-pro- ducing 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. 8:1-39. 1919. WHEELER, H. J., Sargent, C. L., AND HARTWELL, B. L. The amount of humus in soils and the percentage of nitrogen in the humus, as affected by applications of air-slacked lime and cer- tain other substances. Rhode Tsland Agr. Exp. Sta. Ann. rept. 12:152-159, 1899. Memoir 57. .4 Study, by the Crop Survey Method, of Factors Influencing the Yield of eae the fourth preceding number in this series of publications, was mailed on September 27, 1922. ke cer, a Hee