A36-530-6000-Ll80 TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR College Station, Brazos County, Texas BULLETIN NO. 412 JULY, I930 DIVISION OF CHEMISTRY OCCURRENCE OF NITRITES IN SOILS AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President STATION STAFFf ADMINISTRATION: A. B. CoNNER, M. S., Director R. E. KARPER, M. S., Vice-Director CLARIcE M1xsoN, B. A., Secretary I M. P. HoLLEMAN, JR., Chief Clerk J. K. FRANcKLow, Assistant Chief Clerk CREsTER HIGGS, Executive Assistant C B. NEBLETTE, Technical Assistant CHEMISTRY: G. S. FRAPs, Ph. D., Chief; State Chemist J. F. FUDGE, Ph. D., 'st Chemi , Chemist _ S. E. AsBURY, M. S., Assistant Chemist E. C. CARLYLE, B. S., Assistant Chemist WALDo H. WALKER, Assistant Chemist VELMA GRAHAM, Assistant Chemist_ 'T. L. OGIER, B. S., Assistant Chemist _ ATHAN J . STERGES, B. S., Assistant Chemist JEANNE M. FUEGAs, Assistant Chemist _ RAY TREIcRLER, M. S., Assistant Chemist J. K. FARMER, M. A., Assistant Chemist RALPH L. SCHWARTZ, B. S., Assistant Chemist HORTICULTURE: SIDNEY H. YARNELL, Ph. D., Chief , Horticulturist RANGE ANIMAL HUSBANDRY: J. M. JoNEs, A. M., Chief _ B. L. WARwIcK, Ph.D., Breeding Investigations STANLEY P. DAvIs, Wool Grader ENTOMOLOGY: F. L. THOMAS, Ph. D., Chief; State Entomologist H. J. REINHARD, B. S., Entomologist R. K. FLETCHER, Ph. D., Entomologist W. L. OWEN, JR., M. S., Entomologist J. N. RoNEY, M. S., Entomologist _ J. C. GAINEs, JR., M. S., Entomologist S. E. JoNEs, M. S., Entomologist F. F. BIBBY, B. S., Entomologist CEcIL E. HEARD, B. S., Chief Inspector O'r'ro MAcKENsEN. B. S., Foulbrood Inspector W. B. WHITNEY, F oulbrood Inspector AGRONOMY: E. B. REYNoLDs, Ph. D., Chief_ R. E. KARPER, M. S., Agronomist P. C. IVIANGELSDORF, Sc. D., Agronomist D. T. KILLOUGH, M. S., Agronomist H. E. REA, B. S., Agronomist —————, Agronomist B. C. LANGLEY, B. S., Assistant in Soils PUBLICATIONS: A. D. JAcKsoN, Chief VETERINARY SCIENCE: _ *M. FRANcIs, D. V. M., Chief _ H. SCHMIDT, D. V. M., Veterinarian E. JUNGHERR, D. V. M., Veterinarian W. T. HARDY, D. V. M., Veterinarian F. E. CARRoLL, D. V. M., Veterinarian PLANT PATHOLOGY AND PHYSIOLOGY: J. J. TAUBENHAUS, Ph. D., Chie . N. EZEKIEL, Ph. D., Plant athologist . J . BACH, M. S., Plant Pathologist . DANA, M. S., Plant Pathologist AND RANCH ECONOMICS: . GABBARD, M. S., Chief . PAuLsoN, Ph. D., Marketing . BoNNEN, M. S., Farm Management . CRIswELL, B. S., Assistant . N. TATE, B. S., Assistant RUR L HOME RESEARCH: JEssIE WHITACRE, Ph. D., Chief MARY ANNA GRIMEs, M. S., Textiles —-———--—-——-, Nutrition SOIL SURVEY: **W. T. CARTER, B. S., Chielf E. H. TEMPLIN, B. S., Soi Surveyor T. C. REITCH, B. S., Soil Surveyor A. H. BEAN, B. S., Soil Surveyor BOTANY: V. L. CoRY, M. S., Act. Chief SIMoN E. WOLFF, M. S., Botanist SWINE HUSBANDRY: FRED HALE, M. S., Chief DAIRY HUSBANDRY: O. C. COPELAND, M. S.,‘Dairy Husbandman POULTRY HUSBANDRY: R. M. SHERWOOD, M. S., Chief ***AGRICUL'I‘URAL ENGINEERING: MAIN STATION FARM: . T. McNEss, Superintendent APICULTURE (San Antonio): H. B. PARKs, B. S., Chief A. . ALEX, B. S., Queen Breeder FEED CONTROL SERVICE: F. D. FULLER, M. S., Chief S. D. PEARcE, Secretary J . H. RocERs, Feed Inspector W. H. WooD, Feed Ins ector K. L. KIRKLAND, B. ., Feed Inspector W. D. NORTHCUTT, JR., B. S., Feed Inspector SIDNEY D. REYNoLDs, JR., Feed Inspector P. A. MooRE, Feed Inspector éwes 3'11 m’? Péf‘ 1:» L1H I SUBSTATIONS No. 1, Beeville, Bee County: R. A. HALL, B. S., Superintendent No. 2, Troup, Smith County: _ P. R. JonNsoN, M. S., Act. Superintendent No. 3, Angleton, Brazoria County: R. H. STANSEL, M. S., Superintendent No. 4, Beaumont, Jefferson County: R. H. WYCHE, B. S., Superintendent No. 5, Temple, Bell County: HENRY DuNLAvY, M. S., Superintendent B. F. DANA, M. S., Plant Pathologist H. E. REA, B._S., Agronomist; Cotton Root Rot Investigations _ SmoN E. WOLFF, M. S., Botanist; Cotton Root Rot Investigations No. 6, Denton, Denton County: ’ P. . DUNKLE, B. S., Superintendent No. 7, S15“, Dickens County: _ R. E. ICKSON, B. S., Superintendent , Agronomist No. 8, Lubbock, Lubbock County: D. L. JoNEs, Superintendent FRANK GAINEs, Irrigationist and Forest Nurseryman No. 9, Balmorhea, Reeves County: J . J. BAYLEs, B. S., Superintendent Teachers in the School of Agriculture Carr Ph. D., Marketing and Finance c0A'r_I-:s, A. E., Agricultural Engineering . Smith, M. S., Agricultural Engineering . H. WILLIAMS, Ph. ., Animal Husbandry *Dean, School of Veterinary Medicine. "In cooperation with U. S. W VPV. BILSING, Ph. D., Entomology S P J. F. F. W J. No. l0, College Station, Brazos County: R. . SHERWOOD, M. S., In charge L. J. McCALL, Farm Superintendent No. ll, Nacogdoches, Nacogdoches County: H. F. MoRRIs, M. S., Superintendent **No. 12, Chillicothe, Hardeman County: J. R. QUINBY, B. S., Superintendent _ **J.C. STEPHENS, M. A., Assistant Agronomist No. 14, Sonora, Sutton-Edwards Counties: W. H. DAMERON, B. S., Su erintendent E. JuNGI-IERR, D. V. M., eterinarian W.T. HARDY, D. V. M., Veterinarian **O. G. BABCOCK, B. S., Entomologist O. L. CARPENTER, Shepherd No. 15, Weslaco, Hidalgo County: W. H. FRIEND, B. S., Superintendent SHERMAN W. CLARK. B. S., Entomologist W. J. BACH, M. S., Plant Pathologist No. 16, Iowa Park, Wichita County: N E. J. WILSON, B. S., Superintendent 0. l7, ———-——————— No. l8, —i-——————, Superintendent No. 19, Winterhaven, Dimmit County E. IVIORTENSEN, B. S., Superintendent , Horticulturist No. 20, —, Superintendent , Sup-erintendent ying Cooperative Projects on the Station: A. K. MAcKEY, M. S., Animal Husbandry S. MQGEQRD, M. S., Agronomy S. JAivnsoN, M. S., Horticulture R. BRisoN, B. S., Horticulture R. HORLACHER, Ph. D., Genetics H. KNox, M. S., Animal Husbandry TAs of July 1, 1930. Department of Agriculture. ***In cooperation with the School of Agriculture. The production of assimilable nitrogen from organic nitrog- enous matter in the soil is an important factor in soil fertility, which has been extensively studied, but the presence of ap- preciable amounts of nitrites under some conditions has hither- to been overlooked. Nitrites may occur in large quantity in cultures used in nitrification experiments, contrary to the general opinion that their amounts are generally small and relatively unimportant. This discovery opens a large field ‘of work to ascertain the extent of occurrence, conditions of occurrence, and the scien- tific and practical importance of the production and occur- rence of nitrites in soils. The possibility that nitrites may be present should be considered in all nitrification work. Nitrites may occur in soil cultures alone and in those which have received ammonium sulphate or other nitrogenous addi- tions. They were found in such important types as Norfolk fine sand and Lake Charles clay loam. Soils which have a low capacity for producing nitrates may form large amounts of' nitrites. Nitrites may persist in the soil or in soil extracts‘ for several weeks. Magnesium carbonate and calcium car- bonate may favor the formation of nitrites. Water equivalent to 50 per cent of the capacity of the soil was more favorable to production of nitrites than smaller or larger amounts. The- work on nitrites is being actively continued. CONTENTS ____ PAGE Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Method of Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5 Nitrites in soils Without additions of nitrogenous materials . . . . . . .. 6 Nitrification capacity as measured by nitric nitrogen alone, and by nitric and nitrous nitrogen combined . . . . . . . . . . . . . . . . . . . . . .. 6 Eflfect of time of incubation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Eifect of different amounts of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Effect of calcium and magnesium carbonates . . . . . . . . . . . . . . . . . . .. 9 Effect of varying amounts of ammonium sulphate . . . . . . . . . . . . . . . . 9 Persistence of nitrites in cultures . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Persistence of nitrites in solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 N itrites in field soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Nitrites in laboratory samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Nitrites and nitrates from urea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Relation to soil type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Summary and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 14 BULLETIN NO. 412 JULY, 1930 OCCURRENCE OF NITRITES IN SOILS G. S. FRAPS AND A. J. STERGES é Nitrogen, one of the most important elements of plant food, occurs 25in the soil chiefly as insoluble organic compounds. These compounds pcannot be used directly as food for plants, but must first be changed to soluble organic compounds, to ammonia, or to nitrates. While ammonia can be assimilated by plants (4), it is generally believed that nitrates are used more extensively than ammonia by cultivated plants gin ordinary arable soils. On account of its importance, the process of nitrification has received extensive study both in the field and in the laboratory (1, 7, 8, 9, 10, '11, 12). The capacity of various soils to produce nitrates, the pro- uction of ammonia and nitrates from various fertilizing materials, the ~ ect of temperature, moisture, and other conditions upon the rapidity nitrification, and the quantity of nitrates in field soils under various nditions, are some of the topics which have been studied. It has been own (5) that the nitrates produced in soils are related to the nitrogen ~= en by crops in pot experiments, just as the total nitrogen of the soil 3, 6) is also so related. Nitrification is known to be caused by bac- rial action, the nitrogen in the organic matter being changed first to n uonium compounds, to nitrites, and then to nitrates (4.), thus being ade available for use by plants. It has been generally assumed that nitrites are extremely transitory, d that they occur only in amounts that are practically negligible; f» sequently the amounts of nitrites found have not been determined in a itrification experiments. ‘l, In a comprehensive study of nitrification at the Texas Experiment tation, irregularities were observed which rendered necessary a com- arison of several methods for estimating nitrates. ‘.15 On account of discrepanciesibetween the amounts of nitrates as deter- 'ed by the colorimetric method (phenol-disulp-honic acid) and the uction method (zinc ferrous sulphate), a test was made for nitrites l certain cultures, and they were found in large quantity. As much v 98 parts per million of nitrous nitrogen Was found in cultures of soils ich had received no nitrogenous additions, and as much as 226 parts million in cultures which received ammonium sulphate. Further dies, which are here described, showed the presence of nitrites in siderable amounts. Method of work The method used for the nitrification experiments was similar to the g alled tumbler method. For the usual procedure, to 200 grams of 6 BULLETIN NO. 412, TEXAS AGRICULTURAL EXPERIMENT STATION soil was added 0.1 gram of nitrogen in a solution of ammonium sulphate, together with 1O c.c. of inoculating liquid made from Lufkin fine sandy loam and suflicient water to equal 5O per cent of the water capacity of the soil. The inoculating liquid was made by shaking 100 grams of field soil with 200 c.c. of water and allowing the soil to settle. The supernatant liquid was used. The weighed beakers were left in a moist incubator at 35° C. for four weeks, the water lost being replaced two times a week by adding sufficient water to the surface of the culture to restore the loss in weight. At the end of the period, nitrate nitrogen was estimated by the phenol-disulphonic acid method and nitrites by the diphenylamin method. The procedure was varied for the different kinds of experiments. Nitrites in soils without additions of nitrogenous materials While the quantity of nitrous nitrogen in cultures of soils which re- ceived no nitrogenous addition was frequently small, yet it sometimes reached comparatively large amounts (Table 1). All these cultures had received carbonate of lime, and were incubated 4 weeks in the usual way. The amount of nitrite nitrogen varied from 6 to 98 parts per million. The nitrites exceeded the nitrates in two cases. The per- ' centage of nitrous nitrogen in the combined nitric and nitrous nitrogen varied from 11 to 74 per cent. Nitrification capacity as measured by nitric nitrogen alone, and by nitric and nitrous nitrogen combined The relative nitrifying capacity of a number of soils for ammonium sulphate was compared with a standard soil, Houston black clay (29423), and some results from two sets are given in Table 2. All these soils except the standard originally had a low nitrifying power for ammonium sulphate. Calcium carbonate (1 per cent) was added to all except the standard, to see if such addition would improve the nitrifying capacity. Blank cultures (not shown) without the addition of ammonium sulphate were made for each soil, and these blanks have been deducted from the total with the results shown in the table. High nitrate production occurred in nearly all the soils here reported. ' When the nitrate production was low, the nitrite production might be high. When the nitrate production was high, the nitrite production was usually low. The production of nitrate nitrogen was low in most of these soils, even though they received calcium carbonate. When the nitric and nitrous nitrogen together were considered, the relative power to oxidize nitrogen was much higher. The exact significance of this fact remains to be seen, but it is no doubt of importance. As pointed out previously by the senior author (2), where there are wide differences in the nitrifying capacity of soils for organic matter, the difierences are much narrower if the pro- OCCURRENCE OF NITRITES IN SOILS 0N 0 E. 0R 0 . . . . . . . . £001..“ S0550 0.05205 .502 00050.0 2:0 050000> 0 dZ 0.0000 0 ............... no w Am . . . . . . . . . . . . . . . . . . . . . . . . | . . 0.0. 0 000 000 0 . . . . . . . . . . . . . . . . . . . . ...0.0=|=0 0.000058 0E5 .020 00:05 000.0 0080 00 0 000 000 2 . . . . . . . . . . . . . . . 5.21:0 .3550 000005 H502 >000 0200000 020A 0080 El h SN 23 om . . . . . . . . . . . . . . . . $1.0 .3550 0000000 .502 >20 020020 020A 0080 C. 0 000 000 o . . . . . . . . . . . . . . . 521:0 .3550 000005 502 >20 020020 020A 0080. 00 o 000 000 0 . . . . . . . . . . . . . . . . 5090 00.500.00.005 .502 >000 0200000 020A 0080 02 000 MEN o 000 . . . . . _ . . . . . . . . . . . . . . 5000.005 3550 =00 A500 02.3 0.0039 000.00 00. 00 000 00 02 . . . . . . . . . . . . . . _ SQNJBA .3550 5000M .502 30:00 05.0 00:02 00.000 0 o Q. o. c ........ ..0....0...0.0.0w0.0..00..000000..000000.00000 00.0 i? o c . . . . . . . . - I 1 0 a 0 a u 00 0. 00 00 00 . . . . . . . . . . . . . . £07.00 .0258 0000000 .020 8000.00 9.5 000m. 80 80 000 . . . . . . . . . . . . 00.0 . . . . . . . . . . . . . . . . . . . 00000005 3550 =00 £000 0005 0000055 000.00. 0:00 000 05505 00000000: 0:00 000 000 $000 c0505 002:5 2005 0:0 00000:: 2005 0000 000 8000 000 00000 5001 0:0 3550 .0003 20w 005005 :0 00000.: co 00000.5 550005 0000005 @0000 250m 0000a 200m 005.0. 0050002 000002 050550 0 000:0 =0 00035 o0 000000000 5000000 50B 0000000 0:00 00 3000000 0>$20-Ifi 0 n00. .0 _ . 0 0A 00 00. 0 00 . . . . . . . . . . . . . . . . . . . 5.31:“. .3550 00523 .502 300000 2:0 .300» 0000000.? 00000 I 00 00 0 00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107...» .0058 000300.000 00.0 3050B 00000 00 00 00 NA 00. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50.7% 30500 00103 .0000 00000000 020A 0080 0n 0.1. 00. 00 I . . . . . . . . . . . . . . . . . . . . . . . . . $0 JR. .3550 000003 .502 >20 020020 020A 0.080 00 00 00 0A 00 . . . . . . . . . . . . . . . . . . . . . . . .. .. .... JR. .3058 000003 .502 >000 020020 020A 0080 3 00 00 00 00 . . . . . . . . . . . . . . . . . . m . . . . .. =0|=0 3550 0000.03 502 .0000 0200000 020A 00.0.00 Am 00 E3 00 00 . . . . . . . . . . . . . . . . .. zAmJb 3550 020.000.0000 00.22005 000w 00000000002 0000 00 m0. 00 00 00 . . . . . . . . . . . . . . . _ . . . . . . . . . _ . . . . 507:0 3550 000003 320 0200.00 020A 0000 0:002 Z 00000 Z 05H 0005005 00050005 . 0050002 00022 250w A50 3550 .003 mom 72000.0 .00 0000000000000 =00 00 02:05 000 00000 0A 000E300 0050050000: 0505:? 0100 Cm GQWOHZE nJOHZG WEN “£35,? _ i§1|1.._.i11_13.r... , 8 BULLETIN NO. 412, TEXAS AGRICULTURAL EXPERIMENT STATION S $5 3 8N oN N2 w.“ QB . . . N23: =22 2220228 25$» 2: 2. $3 2N w? 2 w o w 2 3 . . . . . . . . . . . . . . . $2288 282.» 2: 2. $8 9; 3m Nw 8N M: 2N 3 mmN . . . . . . . . . . . . . . . $26228 22:2: 2: 2.. $3 3 SN NN o3 S $2 E am . . . . . . . . . . . . . . . qmzowgé $2? 2: .6 25m MI NS N. an w t“ Q oN 4 . . . . . . . . . . . . . . $28.5» $22» 21.. QEN . =22; 26...“? @522 2.222 2.22 w52=2 2E2 Win22 2E2 2.222 NNBN =2 wfiwNfi =3 EmNH =¢w mmfi. =5 c255 Sm 28m dwmobmc 25E was 265E 2o GOUQSGOEQ no amino“. 025205 “o uuvtmllw QENH fi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m2 2N mm. =3 2 £2 Nv a?“ . . . . . . . . . . E . . . . . . . . . . . . . . . . . . . .222. m». 2:2 2h, $2 m; 8N I N2 Mm 2m. . E . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222. NN .634. 3 8m 2.. SN 2 2N 2N 3N . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . Q2. 2N 62¢ 5 . fiN NN NN_ S S w N . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222. E 25¢. m 2N 2 N o o Q ¢ . . . . . . . . . . E . . , . . . E . . . . . . . E . . . . .222. b 2:2 2E2 8822 2E2 $822 2E2 2.822 2E2 2822 22F =Tb aNSN E22 NEG =38; E22 éJb .222 =NT=Q 28w. =3 >30 31226 wan; 325m one vzofioz .153 ecu 50.2.2072 >20 woimzU oxmq 25:15 3Q 2:5 E 6E3 Mo wwcion “cvhwwz... .622». comobi vita wan msogtZ|m 22mm. OCCURRENCE OF NITRITES IN SOILS 9 duction of both nitrates and ammonia combined is considered. A similar condition appears to occur, to some extent, with respect to nitrates and nitrites. Soils which have a lOW power to produce nitrates may have a much higher power to produce nitrites. Effect of time of incubation Table 3 shows the quantities of nitrite and nitrate nitrogen found in cultures incubated for different periods of time. The production of nitrites was small the first week, a little more the second; then it pro- ceeded rapidly and reached a maximum in 28 days, after which it decreased. The production of nitrates was much slower than the pro- duction of nitrites in these soils. Effect of different amounts of water Water was added in various percentages of the water capacity of the soil and the cultures incubated for four weeks as described. The maxi- mum production of both nitrites and nitrates occurred with 50 per cent of the water capacity (Table 4). Previous studies have shown this to be the favorable proportion for nitrates, and is the amount used ordi- narily in our work. The percentage of water most favorable for nitrite production seemed also to be most favorable for nitrite production. The cultures designated “50 per cent water capacity with stirring” had been used in the test for the effect of time and a portion had been removed each week, after stirring. The results were irregular, some being nearly the same as those not stirred, while one showed a wide difference, which is, however, in accord with other work (see Table 3). Elfect of calcium and magnesium carbonates The effect of calcium carbonate and of magnesium carbonate on the oxidation of ammonia, is shown in Table 5. The addition of 1 per cent of calcium carbonate to the cultures containing ammonium sulphate, caused a decided increase in the production of both nitrous and nitric nitrogen. Addition of magnesium carbonate increased nitrite and nitrate production as compared with ammonium sulphate alone, but compared with calcium carbonate nitrite production was less in two of the four soils, and nitrate production was less in three of the four soils. The production of nitrite nitrogen was affected by calcium or mag- nesium carbonate in a manner similar to their effect on nitrate production. Effect of varying amounts of ammonium sulphate Increasing the addition of sulphate of ammonia to 1000 parts per million of nitrogen did not affect nitrite or nitrate production in some soils, but decreased both in soil 12594, nitric nitrogen in soil 12648, 10 BULLETIN NO. 412, TEXAS AGRICULTURAL EXPERIMENT STATION $00 0.000 00.0 00.0 00.0 0.00 . . . . . . . . . . . . . . . . 5.07:0. “000000000? 000000 00000000 00000 >000» 0000000.? 00000 000 0000 00 000 000 0K . . . . . . . . . . . . . . . . .000 7:0. 00000003. 000000 00000000 00000 000000 0000000.? 00000 om 00 om om 00 00 . . . . . . . . . . . . . . . . . . . . . . . 50001000 .000B0000M0 x0000 0000000 0000000000 00000 00 00 . 00 N0. 00 N000 . . . . . . . . . . . . . . . . . . . . . . . .=00|=0 .000B0000~0 .0000 0000000 0000000000 00000.. N00 00. 2. 00.. 3 00 . . . . . . . . . . . . . . . . . . . . . . . . $010. 00030000000 >000 000.0000 000000030 $000 00 00 00 00 0N 000 . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . {filth 002000500 000000 $000000. 00800 00 00 00 00 00 g . . . . . . . . . . . . . . . . . . . . . . . . . ......=00:0.0 0003000000 .0000 000000000. 0800 000 000 ~00 00..., 000 000 . . . . . . . . . . . . . . . . . . . . . . . . . . . $070.0 00000000 x0000 00000000 0000A 00.000 000 00.0 00.0 000 000 000 . . . . . . . . . . . . . . . . . . . . . . . . . . 100000.50. 0000000 00.000 000000000 0000A 0080 N000 0E0 0000 0E0 000 000 . . . . . . . . . . . . . . . . . . . . . . 5000.000. 000.0000 .5000 >000 00000000 0000A .0080 0.0000 000000 0000000 0000000 00050000000000 00000000000000 0.0 0. 0:. 0.0 000000 000 000003 00 00000 00.0.30 000.000 000.04. 000.000 000003 0 000.0000 000000 000 0000005 0000000000 000 0000 000 0000000000 0000 000000 .0000 000 000M050: 000000000 0000000 0000000000 .00 0000.37.10 000000. %%. @ Q Aw . . . . . . . . . . . . . . . . . . . . Uwnwnhoikflnv EHZW¢=®NE ww fi fi V . . . . . . . . . . . . . . . . . . . . . . . QHNH-Ofihflnv EQFZNU mm com o0 M0000 o 0 0v owm .. . . . . . . .. . . . . .. . . . . . . . . . . .... 0000000000 000000000000 00000 .000 .00 .70 oom 00000000000 00500000000000. m: ww 0K0 we 0.000 00 m0 om . . . . . . .........00000000000 0000000000 00000 .000 .00 .70 0mm 00000000000 00000000000000.0000. ww mam 00m m0m o0 m0 N00 can ...............................00000000000 0000000000 00000 000.00 .70 ooo0 00000000000 00000000000005. o: 00m mw 0mm M00 w0m $0 mmm . . . . . . . . . ......................00000000000 0000000000 0:00 .000 .00 .70 com 00000000000 000000000000000< ax a Aw © @ Mm .....-....-.-.-......-.-.-..-.-.AMMQ=.@@E 0000 0000000000 000000 oomv 00000000000 00500000000004 c000 w 00m o 0m o w o .................................00000000000070 0000070 000000070 0000070 000000070 0000070 000000070 000002 00000002 00.80 000m 00.000 000m 000030 000w 00% 000w 0000000000 0000 000000 .QQUOHZ0.0 000:5 00000 000000000 m0 00000000000000 00.: 0.00 00000000000 000000000 m0 .~O0.Cm|m. $036k.» OCCURRENCE OF NITRITES IN SOILS 11 and nitrous nitrogen in soil 20720 (Table 5). Decreasing the sulphate of ammonia to 250 parts per million of nitrogen decreased the produc- tion of nitrites, but increased that of nitrates with three of the four soils. The failure of ammonium sulphate to nitrify in some soils has been ascribed (4) to an injurious action of the ammonia on the bacteria. The decrease caused by the smaller amount of the ammonium sulphate and the increase by the larger amounts seems to be in favor of this theory so far as nitrates are concerned. Persistence of nitrites in cultures Some of the cultures were set aside at room temperature for six weeks. The nitrites before and after standing are given in Table 6. In some cases there were increases, in others decreases, but the striking point is that the nitrites were not quickly converted into nitrates, but persisted for several weeks in the soil in large quantity. Persistence of nitrites in solution The extracts from the cultures which had stood for six weeks were set aside, and nitrites, determined after 24 and 48 hours. The results im- mediately after extraction, in the second column of Table 6, can be com- pared with those after standing. It was thought that nitrites were so unstable that inaccurate results would be obtained if the solutions were not tested immediately, but these solutions are evidently stable, since all the results are in the limit of error. Even after several weeks, the quantity of nitrites had hardly changed. Nitrites in field, soils To what extent nitrites occur in field soils remains to be ascertained. Nitrites were estimated in 12 samples of field soils (April, 1929) but only .04 to .06 parts per million of nitrous nitrogen was found. It is possible that nitrites occur in much larger amounts, especially on certain soils in the presence of organic or commercial fertilizers, or under some conditions of moisture or temperature. Nitrites in laboratory samples Nitrites were found in small amounts in 24 samples of dry soils on hand in the laboratory. The amounts found are not significant, ranging from .02 to .05 parts per million. Nitrites and nitrates from urea The nitrates and nitrites formed from urea were compared with those formed from ammonium sulphate in a standard soil. The results are given in Table 7. A sample of each soil with no addition was included, 12 BULLETIN NO. 412, TEXAS AGRICULTURAL EXPERIMENT STATION Aw . . . . . . . . . . . . . . . .%mm+£fioq . . . . . V . . . . . . . . . . . . . . . . . . . . . . . .~%HQ§OU HAfiQWQHJ »\\¢nls\@ asfio > MMNW @=@ Q ho m ma“ H H H H H .H .......... . .3; ............................ . >22; 2mg: swva. .50" 29a 2e “ism Aw . . . . . . . . . . . . . .mfl@zflcflm . . . . . . . . . . . . . . . ‘ . . . . . . . . . . . . . . . .~%w=5QQ Owvflhniou Q\\@@|I=@ >ENQ— ~%@~HNW nnafi . . . . . .Z . . . . . . . . . - .@mv.~5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .%Q=-OQ Qtfikoiuu -\\@@I.=@ Jnmfloi >%@=NW a . . . . . . . . . . . . .QQE._QOQ . . . . . . . . , . . . . . . . . . . . . . . Qhuimwonv NQZQWQ< I=§MIQQ XVJ£N£Q¢~QV .@QNW Q=€ mm pow .. . . . . . . . . . .mo.~= . . . . . . . . . . . . . . . . . . . . . . 15550 mczowc< Ymfllzo Ainwnokav ficmm 0cm cfiisd 2: m E . . . . . . . . . .. _ .. .. . . Twmwioc . . . . . . . . . . . ‘ . . . . . . . . . ..~$::oo QsBSEoU ckmizm A52 xufin 96w Evfifiwuog 0mm ohm . . . . . . . . . . . . . . . mo; . . . . . . . . . . . E . . . . . . . . . . 4355a ococaEoU QANJAw Juflfi xofin uoom fiofifiouowa a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - .>#H~H~OU WONNNm »\\§|\\@ ~ENQ@ x/wviflw Qmmz 2: ohm . . . . . . . . . . . . . . . . 4W3: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3355c moumkm uRlzo .Ewo_ >623 vac cfiisd o mfi . . . . . . . . . . . . _ . . @1133 . . . . . . . . . . . . . . . . . . . . . . . Zhpcsou £23m .§N~I2O Afinmnohd SEQ mwiwsU oxmA x? . . . . . . . . . . . . . . . . .NU.~§ . . . . . . . . . . . . . . . . . . . . . . . . .>QF~:QU wTnhflm Q=@%|\\@ A%~@QQNQCLQQ .>N@O wUTmfl-ku 035A O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ‘ . . . . . . . . . . . . . . . . . . . . QAQGSOO =.Qmm .Uifi— XON—Q UG~£QD Q . . . . . Nflufi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . QAQCUOO .Ui®~ XUMZQ wuiwimHfl mw Q Qwflfiniim EUMQOEEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v . . . . . . Qmufln-OO “@GN— X023 UGN—QD Z wscbmZ Z oftz 2233K QSOGQWQHQMZ nozmfi .6.» 2:5 E do“: Bob cvmobm: 265E wan ottZllm 01GB OCCURRENCE OF NITRITES IN SOILS 18 so that the change caused by the addition could be ascertained. Much more nitrate was produced from the ammonium sulphate than from the urea in the standard soil. Nitrites were produced from the urea in many of the soils, less often from the soil itself. The urea caused a reduction in the nitric nitrogen produced in several of the soils, but if both nitrites and nitrates are considered, there is an increase in oxidized nitrogen in many of these soils. Relation to soil type The work has not progressed sufficiently to discuss the relation of nitrite formation to soil type, but nitrites were produced in large amounts in cultures of the surface soils of such important types as Lake Charles clay, Lake Charles clay loam, and Norfolk fine sand. Nitrites were not produced in the sample of Houston black clay used as a standard (Table 2). The soil types are named in the various tables. Many of the samples are subsoils, but the occurrence of nitrites was observed in connection with work on a study of nitrate formation not planned for a study of nitrites. It must be observed that nitrites did not occur in appreciable quantities in a number of the cultures. DISCUSSION It has been shown in the preceding pages that nitrites may occur in considerable amounts in some cultures of soils. This Bulletin only in- troduces the subject. The practical and scientific importance of nitrites in soils remains to be ascertained, but it is clearly a matter that calls for extensive study under various conditions. Appreciable amounts of nitrites no doubt have been formed in many cultures made in nitrifica- tion work previously reported, but since no test was made for their presence, they were not reported. Nitrites may occur in quantity in field soils of particular types, or under special conditions, especially when fertilizers are used, and they may be of agricultural importance. N itrites may be, under many conditions, as unimportant as they were generally believed to be, but it is obvious that until the subject has been closely invesitgated and their importance or non-importance has been demonstrated under the particular conditions under consideration, it will be imprudent to disregard their possible presence in work on nitrification or nitrates in field soils or cultures. The Texas Agricul- tural Experiment Station is actively engaged in work on this subject, and no doubt work will be undertaken by others in various sections. ACKNOWLEDGMENT Dr. J. F. Fudge made the estimation of many of the nitrites and assisted materially in the adaptation of the method for nitrous nitrogen to the work to be done. 14 BULLETIN NO. 412, TEXAS AGRICULTURAL EXPERIMENT STATION SUMMARY AND CONCLUSIONS 1. Nitrites have been found in large quantity in cultures of soils containing sulphate of ammonia. They have also been found in the cultures which receive no additions of nitrogenous materials. 2. Soils which do not nitrify ammonium sulphate or which have only low nitrifying power for ammonium sulphate, may produce large amounts of nitrites. 3. A low production of nitrates may be accompanied by a high production of nitrites. 4. The relative capacity of a soil to oxidize nitrogen may be con- siderably larger for nitric and nitrous nitrogen combined than the nitric nitrogen alone. 5. The production of nitrites was small the first Week, a little larger the second, and much higher the third and fourth weeks of incubation. The production decreased after 28 days. 6. The most favorable amount of water was 50 per cent of the Water capacity of the soil. The production of nitrites as well as nitrates, is usually lower with both larger and smaller amounts of water than 5O per cent. ' 7. The addition of calcium or magnesium carbonate increased the production of nitrous and nitric nitrogen from ammonium sulphate. 8. Nitrites persisted in the cultures for more than six weeks in considerable amounts. They also persisted practically unchanged for over a week in soil extracts. 9. N itrites are more stable than they are generally believed to be. 10. Nitrites Were present in very small amounts in the samples of field soils and laboratory samples examined. 11. Nitrites were produced from urea in some soils. 12. Nitrites were produced in cultures of important soil types such as Lake Charles clay and Norfolk fine sand. 13. The possible presence of nitrites in cultures and field soils can- not be disregarded and the matter requires further investigation. The work is being continued. REFERENCES (1). Brown, P. E. and Gowda, R. N. 1924. The Effect of Certain Fertilizers on Nitrification. Jr. Am. Soc. Agron. 16, 137. (2). Fraps, G. S. 1908. The Production of Active Nitrogen in the Soil. Texas Agr. Expt. Station, Bul. 106. (3). Fraps, G. S. 1912. Relation of the Total Nitrogen of the Soil to Its Needs as Shown in Pot Experiments. Texas Agri. Expt. Sta. Bul. 151. _ t (4). Fraps, G. S. 1917. Principles of Agricultural Chemistry, page 219. The Chemical Publishing Co., Easton, Pa. OCCURRENCE OF NITRITES IN SOILS 15 (5). Fraps, G. S. 1920. Nitrification in Texas Soils. Texas Agricultural Expt. Sta. Bul. 259. (6). Fraps, G. S. 1921. Relation of Soil Nitrogen, Nitrification and Ammonification to Pot Experiments. Texas Agr. Expt. Station, Bul. 283. (7). Harper, H. J ., and Boatman, B. 1926. Studies on Nitrifica- tion of Ammonium Sulfate in Soil. Jr. Am. Soc. Agr. 18, 876. (8). Kelley, W. P. 1916. Nitrification in Semi-acid Soils. Jr. Agr. Research 7, 417-37. (9). Kelley, W. P. 1916. Some Suggestions on Methods for the Study of Nitrification. Science 43, 30-33. (10). Kelley, W. P. 1915. The Effects of Calcium and Mag- nesium Carbonates on Nitrification. Centr. Bakt. Parasitenk; II Abt. 42, 577-82. (11). Lipman, C. B. 1916. Comparison of the Nitrifying Powers of Some Humid and Some Acid Soils. Jr. Agr. Research 7, 47-82. (12). Scales, F. M. 1915. Relation of Lime to the Production of Nitrates and Mineral Nitrogen. Science 42, 317.