1.. 11 'JJ «4) E1 '23 :0 O ’i‘ > H 2 F! M M W H n 77* H H THS SOME STUDIES UREA WHEN ADDED TO SOILS OF D4FFERENT TEXTURES Thesis for Degree of M. S. lease Davis Romaine ‘925 «5‘. Uln‘tnmw PW: . g THESIS I. E" I ‘lIEIIiI 4. .. AI viii-II.‘ 1.x Inna, . .5 [1,...9 .. ;.\. .‘ .. ..r.FVI.flu.1pr~1.,. o ‘ , . , o ‘ V ‘ . . Hrr. . 2! :1l: rlrpll £317.“: 1. . run. buufi :IULJMU LN Ubdfl "bag ALLDL To twigs UH LJJH‘U 'rali {\ 1' '1' iii'l‘U bi 1: I Ihl MlGniaAN :TETE CULLwiu 9 0L RimlCULTUhi ADE érrplsu lengA: 0‘ (u 0 "I: in Partial Bulfill sub for tne tagr“‘ THESIS :3 [4...) 04 C) 'C) (I) C) ' '3 C‘“ C- :3 H. CI. 103” ’7‘“ . '- "t - 'Liu\ (I: (t; l4Xlun--. lilrLLUCllCu luers is a marked tenjsucy in 12113 ul tur3l tract award the use of mere cc 33ntrat33, 3nd Lt great q titis 3 ct fertilizers. in the sears h fc co sntrets‘ plant feofl carriers, urea net at al'y 0313 Puudsr 3313 3(3- ticu s it has lsng been Kucan o exist naturally and ar- tifiL ially, has 3 high titrcgsu LL Lrteut, and is easily H. s tne 313111331 fLPJJle cf N214JJ, usually written as 03(112)2, and is £13 JJ J3 utly calls 1 LJPuJulJL. lt carries 45.51 titvcg3u or 3E.63 JaLuiJ, “1121 is JLJ- ule Lus amount of 1113113 33rriai Ly A11311JJ :u t tratsl Nitrc53u C3rrier in cem1ou use as lissr. 93 EEFKSLSi by a 33r13u firm it is Que” 'ry 4:3 Nitrcyeu. It is thus pr3parei cc J 3 frcm 1111911131. it is 133313t3l' enj r33Jily soluble in all propertion sin 13' ‘ - ‘I‘J-rflr] . 3 t " 23 eJiai to tue stil. L (‘H I. '2 .‘\ . ‘ ‘. " ,‘x f‘ ‘4 " ‘ f: I ‘ .' ' '- - c I ’- . :' 'I f‘ f" I" I A "L n I" velsjen (11) [seertsl tu3t Lha JCJlLlJn LL . an LL ‘ Reference is maie by numbers in parenthesis to Lit- erature Cited, at end of paper. -Z- 13 soil retardea nitrifiee ion tn 311. e 4:) found that urea 13s as good as 331111 11- a numoer of c €3.531DC ff (17), n» inferior to $311u1 Nit test LitJ 3 nu1oer of areas btut He (42) in 3131131 five veers test in nest trus- sie 3311 that urea was as 1301 as dejium fiit. A 's 3 greater 1 eeovery cf Nitr02en er1 urea then fr31 seaius Nitrete '10;3 SSCU[.':I\JQ 13LL31 (1C) HCCES LUBE ores 1333 trc1 111e— “1trc:er cr O3131J~ Cy31311JL,13s 31131 1 sterier to 3:1111 N1- :33 ibility of 1‘131113, 11131 131 be forms 1 in tnis .- U’. recr< (I; F.) D. A ‘11 \" -.‘.‘ '-. w _ NI.- FT 1.: J (I) <) (u "3 I'— U: (‘7 (M £4 1'1 (/1 03 {10. C) Q: C) LL ”'5 LI l ' (1’2 , ' 53' ~< (1 ("T a D (1. ’9 C"? I: '1 (U 0 Lu 02 .' (L) 0 PT 0) so d f) C Q 1 0- “S (U U! -’ sin; 3, Jaere 1 us tear- 3st results c1 fly Lt 113 c Fflefo. Vitsenerl131, vcn :1JL13r , 311 lt'lenj U (’7' :3 C1 C. C3 "3 w \1 Q3 U1 Qt OJ JL C) _) C) Q.) U; .QKJ U! D (ll 0 ('1; Cl :1 (II g... C..- ,- 0 " ‘3‘ (I :3 C‘. \‘J P.» I "J C‘ U.) :1 A A t... x... V 1.; D L!) D (U >\ C'I (u (1.. [.1 (I 1 Q1 TiUPC/ns DDiVS 1LLJ r33 t1 eelly as po t 3 C L, ('3 H . c... \1 set L‘ eateziuLt s 310331 1 s 3.3 say ct the 1itrcgen carriers, in Dotu work. tomé ray (-3) 3311 tnet Jr: 3 3 serving as 3 source CE octn “le”f n 313 Lerbo plants. on Knieriem (13 wrete that area gave tne bes' II" ( .> C) Q" and field <1: <2 ’ \ nu . (33 3‘73“; of any of tee JitrL en 33rr13rs uses, tJ 31 33113 1111 93131333 311 03313. in; cerr 13 1 out en 33 3r‘ 3 ' ‘ t 193r1131ts, -0J11 tnet uree gave very 2001 results, cc1gar31 witu toe Mtier 11tr313' csrr 13 s. ' ' "111 930 , tncugn. (In the light t nerx this tc:131t1131 1313 been 3133 of Llant ooisins 111L313 DON 11311 as a by- -p'L1Jet in 3013 syntnesizing L Leesses.) CD van aarreveld (16) states that ure: v sults as Ammoniu1 Chloride, as a fertilizer. however, it leached from Java soils in greater quantities than 311on- iu1 Chloride 311, and in about the sa1e quantities as so- diue nitrate. I") 9"! as good re- in this country the most extensive experi13nts retort- 31 with urea here by Ellison, Brah31, and Leiartrey (1). They used urea singly and in combination, along 11th a great nu1oer of other Jitrogen carriers in 11311 tests, camparing their relative efficiencies. These experiments were con- duetei through several sears, with cotton and corn. They summarize their results as follows: "Urea seens to he as reaiily available as Soiium hi- trate ari equally as gooi in all reSpeots as any other na- terial used. Since urea is an excellart naterial physi- cally and leaves neither a tasic nor acii residue in the soil it should prove to te an almost ijeal Nitrogen carr- ier for all types of soils." slliscn, Vliet, Srinner and Reid (2) also retortej the results of some greenhouse exterimcnts in which the; found that urea gave about the same results as Sodium Ni- trate, Anmonium Sulphate, Anhonium Nitra 3, Calcium Nitrate, and Ammoniated Sugerphosghate. McSuinn (BO) shonej that there is no harm to the ger- mination and early growth of several crops wnen urea is in direct contact with the seeis. 6 c with other Nitrogen carriers in pots was as good as any, if Dicsaniiamid were not present. The above reports agree fairly well as to the rela- tive value of urea as a glatt fool carrier, it being as 5001 as any unicr most conditions. The limiting factor in its use at pre‘ent is the high price caused by the laox of a cheap method of manufacturing it from chea; materials. As before mentioned a Sorman firm is selling it in this country in small quantities, chiefly as a fertilizer for garden use. -4- Werner (44) reviews the principal methods used at pres- ent to produce urea on a commercial scale. He also sugge sts that its preparation from Ammonia and Carbon Monoxide in the presence of a catalyst might be developed into an eco- ‘ncmical method of manufacture. Krase and Sadly (20) have worked out a method for its synthesis which they think has commercial possibilities. Their method consists briefly in heating Ammonium Carbamame at 150° C. for four hours un or a pressure of 80-12e atmospheres. According to them the price of Ammonia will largely determine the price of the urea produce . Lipman and McLean (18) outline a method by which commercial fertilizer urea may be made. The esse n- tial feature is the treating of Calcium Cyanamide with Sul- phuric Acid as follows: BCaCN2 + 3H2SU4 + L20 = Cb(NH2)2 + 32H4N4 + 333‘4 The CO(NH2)2 is the urea, while the 02H4H4is Dicyandiamid. It will be not ced that the basis ot' all of these methods of p.eparation is the electrolytic fixation of Nitrogen, either as Ammonia or Calcium Cyanamide. hhcn this is work- ed out on an economical and large scale, a.nd this is grad- ually being done, urea should scone available as a conzmer cial fertilizer. As mentioned in the preceding paragraph, one of the products in sore of the present conuercial processes for nanutac turing urea is D cyandianil. As pointed out by Kap- pen (14) and Lipman and heLean (23), this substance is quite harmful to plants. Cowie (13) states that even in very small Quantitio s it is toxic and also inhibits the an moni- tying“ tacto ria in their ac ition. hcduinn (30) showed that dicyandiamid apparently did not seriously affect the germin- ation of seeds, but was toxic to later growth. He did not get such toxic effects as Cowie described. Unless it were present in quantities greater than 10», it did not affect the value of urea as a fertilizer. The die yanamid stopped nitrification, which result was also the opposite to that secured by Cowie. Lipnan and licLe ar.= (23) 89 y, however, that the urea new on the market contains very little di- cyandiamid, as the manufacturers are careful to remove as much of it as possible hXEhthANTAL wJHh The work for th's p per is diviu ed into four main di- visions or series. The firs t series is preliminary in na- ture. It shows the results of making vei al very lar3e applications of urea to a Coloma Fine nd and determinin3 the Nitrates produce , reaction and concentration of tne soil solution from time to time. The s cond series reports the results of hiking moderate applications of urea to a Fox Sandy Loam and a hiami Silt Loam, determinin3 at inter- vals the Nitrates produnced, reaction and concentration of the soil solutions. The third so ries was su333sted by the esults of the first series and shows the amounts of fin- monia that might be liberated when urea is added to differ- ent soils in various ways and amounts. 1n the fourth ser- ies, the influence of leac hin3 on ti.e reaction of several soils previously treated with urea is reported, and also the residuary effec s of such treatments on the soil re- actions. SI fl b3 swans 1 Large Applications of Urea to Coloma Fine Sand In this s er'es, large applications of urea were made to 3 Selena Fine Sand. The surface soil from a cropped ar- ea which had not received fertilizer recently was used, so as to secure material rather low in Nitrates. The soil was sifted through a sieve with openings about three milli- 'eters square, and wade up to optimum moisture content by thorou3hly mixing the required amount of water with the soil. In case urea was added it was dissolved in the water with which the soil was to be noi tene , thus insuring a uniform distribution of the material throu3hout the soil. The soils were put in pint ja ars and xep t in the dark at a temper ature of 20-23” 3. Every two or three days the soils were remov- ed from the Jars and aerated very thoroughly. Noisture was added as needed to Keep the soils at the optimum moist- ure content. The following treatments were used, each one bein3 run in duplicate: 1- Chec . No urea added. 2- .5w urea, based upon dry weight of soil. 3- 1. 05;) ups , I! I! II M N H 4_ 2.5% urea, u n u n n u 6- 5 '~ ‘ I! I! H II II I! These tre atmoa nts are far in excess to the amounts that would be applied to the soil in the field, but it was the object to determine the upper limit for the use of the ma- terial. A better idea of the ma3nitude of the application may be had by considerin3 that the smallest treatment a- bove, or the .sa, is equivelent to sixteen tons of hgtrate of Soda per acre six inches of soil. It mi3ht be stated that all of these treatments proved to be too heavy for the proper functionin3 of the soil organisms. At the be3innin3 of the experiment, and at the end of 4, 11, 22, 2;, and 36 days each jar was sampled, care b»- in3 taken to secure as representative a sample as possible. The hydrogen-ion concentration, the Nitrate conte nt, and the total concentration of the soil solutions were deter- mined on these saw p . A- Ammonification and Nitrification of Urea in Coloma Fine Sand. Nitrates in tle soil were do terminel by the colori- metric method as outlined by Schreiner and Failyer (38 with a few modifications. The equivelent of 30 3rams of dry soil was weig :hed and put in a shaxer bottle. 3 c.c. of a normal so ution of Copper Sulphate and enough water to make a total of 1bld c.c. were added. This would then mane a 1 to 5 aqueous extract of the soil. The samples were shaken for twenty minutes and then .6 gram of hagnes- ium Carbonate and .24 ram of Calci m Hydroxide were added. The bottles were then hat; ‘ for one minute' to secure a thorough mixing of the che eniicals throng jhout the soil. The flocculent mate rial was then allowed to settle, a clear su- CC' 0 '11. -7- pernatent liquid being secured almost inmxeliate ly except in the case of the very fine soils, or those stron3;ly al- kaline. The solutions were decanted through filter papers, which would remove any particles still in suspension. The Nitrates were then determined as described in the afore- mentioned publication. They are reported as parts per mil- lion in the 1 to 5 extract, the average of quadruplicate determinations being given. The results for the Colona soil are given in Table 1. Many of the extracts from the treated soils were colored, apparently due to the alkaline condition of the soil, and the figures may be higher than they should be. The so utions from the cheek soils were perfectly clear. Table 1 - Nitrates in parts per mi lion in 1 to 5 extract. Coloma hine Sand. Treat. 0 Days 11 Days 22D Days ”9 Days 36 Days Check, 3. 9 9. 1 165. 5 28.1 18. 2 . bib urea .5. 9 2.7 2. 3 ‘4. 4 2. 4 1.0% " 3.9 2.1 1.8 2.5_ 2.6 2. 5:7: " 3. 9 2. 6 . 2. a 3.1 4. 2 5.0% " 3. 9 2. o 2. 3 2. 7 2. 9 The determin ys were lost, ation ns made at the end ol four da as the Nitrate sa uples were 'estroy ed. The ehecx soil increased in its Nitrate content until 9 days, after wh ch it fell off. The increase can proba- bly be ccounted for by the conditions of moisture, heat, li3ht and aeration being made Optimum for biological acti- vity. rhe soil was rather dry wnc taken from the field because of a lacx of rainfall. The decrease at the end is a little harder to account for, but may be due to the devel- opment of many organisms and the depL tion 01 readily avail- able organ'c naatter in which case the or3anisns would pess- ibly consume the Nitrates taster than they could be produc- , -fl ~40 All the urea troatnents reduced the amounts of Nitrates present in the soil solutions. A‘s before explained, even -8- the small amounts shown are probably too high. Apparently the urea added to the soil has not been nitrified, and has even caused the Nitrates of the soil to be lowered. In or- der to give a satisfactory eXplanation of this it will neee ssary to explain some of the biolog ioal proc sses that taxe place with urea in the soil. When urea is added to a soil it is done so with the idea that it will ammonify and nitrify, eventually produc- ing Nitrates for plant food. The first step, or ammonifi- cation, is the changing of the urea to Ammonium Carbonate. This eéhm3e can be brought about by bacteria and molds, probably by several species of the former. These organisms ace onpolish this by means of an enzyme called Urase, which is described by 1arshall as a Zymase 31). The reaction, according to hahn, in Narshall's Nicrobiology (21), is : (NH2)230 + 2h20 = (NH4)2CU§ + 14.3 calories. The organisms thus secure their energy from the process, not using free Oxygen for the purpose. This possibly ac- counts for the results of Christensen (10,11), who found that the process can go on without the presence of any oth- er organic substance. Phelps, in Narshall (31), states that the organis ms are an:1erebic, but Hahn (35) states tha they require so.c nyge n for certain of their life processes, even though they a pear to be a fao ultative aerobic oré an- ism. Littauer (25) did some worx whi ich would tend to show that they do not need much Oxyge . He found that an excess of moisture did not retard the breaking down of urea in the 8011. The formation of the Ammonium Carbonate from urea is very rapid. This had been shown by hipma (24) and Loch- nis (26). After the material is anmonified it is probably nitrified in the usual manne Returning to the data on the Nitrates in Table 1 and the notes taken during the course of the experiment, some interesting things are seen. Two days after the experiment was begun, stron3 fumes of Ammonia were given off from the .5% and 1% treatments when the soils were aerated. Tho urea must have ammonified to an extent sufficient to satur- ate the soil moisture and the absorptive capacity of the soil for the gas. Of course this soil probably had a low absorptive capacity, owing to its low clay and colloidal content. The observations of previous investigators, that urea is quickly broxen down, were certainly being born out. The check soil had no Ammonia comin3 off, and neither did the 2.5% or be treatments. As the experiment continued the two lower treatments continued in giving off more or less Ammonia and later the 2.5; treatment also 3ave it off. The 3% treatment did not give off very much at any time, compared to the amounts given off 3y the otter treatments. Unfortunately, the Ammonia given off was not determin- ed and the observations were made simply on the relative strengths of the fumes that could be smelled comin3 off, a rather rough method of determinin3 Ammonia, to say the least. As the experiment continued, the .5% and 1% treat- ments did not seem to 3ivc off so much gas as at first. This may have been due either to the complete ammonifica- tion of the urea or to the succumbin3 of the organisms. When the experiment was about half way through, the Ammonia that would come from some of the j1rs was so stron3 that it was exceedingly unpleasant for the person ~eratin3 the soils. Some doubt was expressed concernin3 the probability of this action bein3 biological rather than strictly chemi- cal or catalytic in nature. The question as to whether organisms could live in an atmosphere so strong in ammonia and a solution so hi3hly concentrated justified this doubt. however, if this action were chemical rather than bio‘eheu- ical, by the law of mass action, the 53 treatment should react the most quicxly and produce the most Ammonia. hhat actually happened was just about the opposite of this. The 5% treatment produced the least Ammonia of any and the .51 and 1% treatments reacted the most quicxly, apparent- ly producing the most Ammonia. These facts are more easily explained from a biolo3ical than from a chemical standpoint. In the case of the c; tr atrent, tne concentration of the -10- soil solution was very great, so that the organisms might have been Killed er rendered inactive to a large extent, thus not groducing great amounts of Armenia. The frequent aeration and consequent removal of excess Ammonia from the other t'eatnents a parently allowed the organisms to live for a while at least. Millar (32) has shown that the am- monifying organisms can function in soil solutions quite concentrated. He did not work with solutions quite so con- centrated as some of these in this exocrinent, but he shon- ed that the inhibiting concentrations varied with the mater- ials added to the solution. He did not work with urea, but it is possible that the inhibiting concentration for this material is quite high. He points out that other factors than the total concentration of the soil solution may be limiting. There was no nitrification,probably because of the killing of the nitrifying organisms. They possibly could not tolerate the conditions of high concentration and al- Kalinity, with a lack of Oxygen, as were present in the treated soils. The fact that the check or no trea.nent soil {reduced nitrates is Lroof that the soil had at least some nitrifying power. The lowering of the nitrates in the treated soils is possibly due to assimilation by organisms in their life processes, without nitrification going on much to restore then.to the soil solution. It is recog- nized that the above statements nay not fully and adequate- ly eXplain all of the observed facts, but they serve the purpose better than any other that were considered. The data secured in connection with the hitrate deterninations go far to exylain the results secured from determining the Hydrogen-ion concentrations and also the total concentra- tions of the soil solutions. 8 - hffect of Applications of Urea en Reaction of Selena Fine sand. The Hydrogen-ion concentrations were determined elec- trometrieally by means of the Quinhydrone electrode, as described by Biilnann (4). The results from these deter- -11- minations were frequently checked roughly by the use of Seiltex, as 'escribed by Spurway (41). Conparatively close results were secured by the two methods. Two determinaticn; qwere made on the samples of soil from each jar, and as the jars were in duplicate, four readings were made on each treatment. Very close agreements were secured among the readings, and the averages of the four readings are report- in Table 2. As is the general custom, the values are given in eras of pH, rather than as the actual Hydrogen-ion con- centratien. Table 2 - pH Values for Colema Fine Sand. Treat. 0 Days 4 Days 11 Days 22 Days 29 Days 36 Day Check. 6.92 6.68 6.25 5.93 5.85 5.95 .5% urea 8.01 8.94 9.15 8.21 8.12 7.85 1.0% " 8.58 9.01 9.17 8.47 8.83 8.04 2.5% " 8.17 8.99 8.99 8.67 8.51 8.19 5.0% " 7.99 8.67 8.60 8.36 8.04 7.61 The very alkaline figures are possibly not exactly correct, although good checks were secured from the quad- ruplicate determinations. However, the Guinhydrone elec- trode is not supposed to give accurate results at such nigh pH values. The figures could not be checked against the Hydrogen electrode as the great amount of Ammonia present seemed to throw it off when an attempt was made to use it. The urea tends to make the soil more alkaline as lar- ger amounts are added to it, as will be seen by examining the column headed 0 Days. This represents the reaction of the soil innediatcly after the urea is added. As the soil was about neutral to begin with, the urea threw it ever to the alkaline side. This is natural, as a tenth molar so- lution of the material added had a pH of 7.35, while a near- ly saturated solution of it had a pH of 8.77. The largest application made was almost a saturated solution of the urea. The check soil became more acid until 22 days, after ad -12. which it remained about constant in reaction. It happens that this equilibrium is reached at the same time that the soil solution reaches its greatest concentration. This is considered at present to be merely a eoine idence, as the o- ther soils studied did not show this role tienship. The rea- sons for the increased acidity of the soil are probably the nitrification of organ 3 matter, producing Nitric Acid, and bringing into solution more of the slightly soluble acid silicates. As before .entioned, when the soil was brought fr m the field, it was after a period of dry weather. As it was made more moist in the laboratory, it would tend to have more of these slightly soluble acid silicates in its solution. After these materials saturate the soil solution an equilibrium is reached and the acidity of the soil would remain the same. Treating the soil with urea made it quite alkaline. his is not surprising since, as before mentioned, ammonia produced in large quantities. in fact the-PH value of 1 s i1 is considered to be an index to tie amounts of Ammonia formed in this experiment. The pH would be high- est when the greatest amourts of Ammonia would be noti zed coming from the soils. The ST treatment, where very little Ammonia could be noticed coming off, always had the lowest alkalinity of any of the treate" soils. During the course of the eXperiment the alkalinity reached a high point and then decreased. This was probably due to the loss of Ammon- ia by volatilization. The results of the determinations of the total concentration of the soil solution bear this out. fin A c" 1 pr- w (11 I Q n o - Effect of Applications of Urea on the Concentra- tion of the Soil Solution. Coloma Fine Sand. The concentration of the soil solution was determined by the freezing point method as devise d by Bouyoucos and McCool (6,7). The equivalent of 20 grams of dry soil was weighed out, put into a freezing tube and made up to 70b moisture content. This high moisture content was used so as to secure more accurate results. Thus the figures can only be considered from a relative standpoint, and cannot -13- be taxen as absolute concentrations of the soil sclution. The actual concentration of the soil solution would proba- bly be represented by a depression several times that secur- ed. The results are reported as the depression of the freezin3 point below that of water, in de3rees Centi rade. The averages of duplicate determinations are 3iven. Table 3 - b1 eezing Point Depressions in De3rees 0. Coloma Pine Sand. Treat. 0 Days 4 Days 11 Days 22 Days 29 Days 36 DAys Che 0.000 0.008 0.020 0.043 0.018 0.022 T urea 0.066 0.230 0.297 0.224 0.135 0.097 1.0T " 0.333 0.796 0.600 0.408 0.250 0.21” 2.5% " 0.557 1.063 1.510 1.109 1.161 1.150 5.0T " 0.992 1.247 1.921 2.131 1.931 2.030 In the case of the untreated or check soil, the con- centration of the soil solution iner<31sed up to 22 days, af- ter which it decreased and then decime constant. This is somewhat similar to results reported by Theeting (38). . Worsin3 with a number of soils, he found that the‘ had a maximum epression of the freezin3 point, after which the *epression decrease . It tOCK lon n3er for his soils to re'eh the naxinuflpoint, but he used heavier soils than tne one used here. He found that, in general, it took heavier soils lon3er to reach their maximum dep ession than it did sandy soils. The addition of urea to the soil increased the con- centration of material in the soil solution more or les in proportion to the amounts added. In all of the tr nents durin3 the co rse of the CXperindnt a maximum cen- entration of the soil solution, or doore“1or of the freez- in3 point, was secured. This did not occur at t‘ time in all of tie tr wtnents. Hoaever, after the maxir um was reached, the do LI‘B ssion did not ece e and be; as con- o stant, 13 in the ease of the chads treatnrent. They Kept going down as long as the experiwent continued. This rise and fall may have been due to the rate and amount of the -14- Va U1 prciuetion of Ammonia. The e i: ome eorr relation betn3en the freezing point aepressions ani pH values in the .53, 1%, ani 2.5} treatments, the hi 31est pH 033 rrin3 at about the same time as that of the 3reates ep'ession of the freezing point. Tonari the enl ot the Chi of the experi- ment, when the ph was loner, anl the o ler of Anuonira eelningz from the soils was mu3h less, the 3e pr ssion of the fre3z- in3 point was also mu 33h less. The feetefihat the soil solutions dii not Keep constant after reaehin3 the maximum, but reee oi, ani that the am— monia notiee' 30min3 off at this time was mueh less, inii- eate that either ammonifioation was not 3oin3 on very fast or «as bein5 re novel. The Nitrate ieterninations show that it was not bein3 nitrifiei ani the freezin3 point deter- m1 nations show that it, or omethin? else, was 3oinS out ot solution. Sinee the pH «as lowering at tne same time, it would point to the loss of Ammonia from the solution. The following is a possible explanation of how this toox plree. When the Ammonia velatilized it saturatei the soil solution and the absorptive eagaeity of the colloids, af- ter which it was 3iven off into the atmosphere. It thus set up no re or less of a pressure in the closed atmosphere of the jar. Aeeorling to Henry' 3 law, whi3 h stat3s that t the concentration of the dissolved 313 is aireetly propor- tional to th1t in the tree spa3e above the liquid, the solu- bility of the Ammonia in the soil solution would be increas- oi the more Ammonia there was proiueed. This extra amount isselve i no ulJ probably not have time to 30 off before the treezin3 point uet3 rmination was male ani wouli the tore influelee it. hhen the produ etion of Am,henia stoppei, the pressure of this gas in the soil atwosphe re would be lowered, due to the frequent aeration of the soil. Some of the iissolved *mmonia weuli new 3on3 from the soil solu- tion in order to reestablish the equilibrium of the 3as be- tween the solution and the air in the jar. This wouli 03¢ our at each aeration of the soil ani night eisily bee we appreciable in time, thus :eeountin3 tor the lowerin3 of -15.. the Genet ntratien ct the soil solution. Ut‘ course, the Ahmcnia mi; ht have ii3eg‘earei lue to bielegieil action. This may have cause it to have been s5hthesizel into cr- ganie ecmpeunis thit were more or.less inscluble. This explanation wcull taxe e1r3 of all cf the observel ghene- mena. The results 33 seeurel may have been Jue to a 3cm- 1 binaticn cf these aetie ani {cssibly othe's 3133. The late of the 5% urea treatment are interesting. It will be recalled that very little Anmeniz was nctiee? velatilizing from this soil. however, 3 reaction must have been geinJ cn as the freezin5 point changes eensiierably during tle eeurse ct the experiment. SinA the egressien inereas 33 at first, the urea must have been bre 3kin5 Jean into me pc un is of a 5re ater number cf 3313, or else it was 3f'ee ir 3 tmi sclueilit; of the soil, eit n3r befere er af- ter bre1xin5 Jenn. file clue was feunj to shew what this aeticn ni5ht have been. J ) Ccnelusicns - 33ries 1 vrcm the eXperinents en the 'elena Fine Sani the fol— leding general ecnelusiens may be drawn: 1- Urea aidei to this soil was anmenified very ragii- 1y, although if exeeejin5l1 larg3 agp 'eetions were hale, a point was reaehel where arncnifieitien n-3 uli net 50 Ch. 2- uitritieaticn neulj n3t go on 313r3n11311 when ure «33 aidei to this soil in large 1u1n53iti33, the smallest aprlieiticn male here being tcc great for this process. 3- Ammonifieetien e:1n 50 en unler eeniitions in which nitrification will nct ta Xe plaee. Thus the scil's ammon- ifsing power is net neee 3:1r rlly an iniex to its nitrifying ability. \Wfil 3 2 Meierate Ac; lie itiens of Urea to ch Sanjy Loam ani hiahi Silt Lean. Pased upcn the results cf the prelihinary wcrx with the Coloma soil, 3 new series of expe'iments was beéun. For this work two agric ulturalls ingortant soils were us3j, Fox Benjy Loam anj a hiemi Silt Loam. Both soils had been cropped the 3unwm3' previous to the fell in which they «3r 3 t3 . n, the b‘ox soil to corn 3ni the Miami 3311 to cats. The 3u1 W113 esoil to a depth of elout four inches 133 ta13n, he sur11co debris elweys being removed previous to the saw ling. W L‘* Urea H33 added at the rates of 83.3 pounds, 166.6 "C n13, 333.3 pounds, 666.6 gounis and 1333.3 pounis per six inc hes of soil. An acre six inches was consider- 3 two million pcunls of dry soil. T13 treatments of he two soils were the 3133, except th1t the H‘ox soil re- -d 66 pouan of urea inste11 of 33.3 pounds tor the aptlioation. ( HOflCD £3 0 (D :2 H' Co< ‘1.) 0.9 (+ The treatments given can ale 3 be considerei on another basis. A drill usually mixes the tertilizer through about one and a half inches of soil. Therefore the treatments listei above, dividei by four will represent the conditions resent when these amounts per acre are added to the soil by 3 arill. The follouing table shows these relationships. Lbs. Nah05 per Actual Lbs. h s. N3N05 per .3tual Lbs. acre 6" equive- ure1 11131 33 e 1 1/2" 3- urea adiei lent to urea per acre 6" qual to urea to drill adiei. ' added (drill) depth (1 1/2) 0 - Checg 0.0 0.0 0.0 260 83.3 62.6 20.3 600 166.6 125 41.6 1000 333.3 250 83.3 2000 666.6 500 166.6 4000 1333.3 1000 333.3 All the tiiures in any horizontal line refer to one t eetwent as run in the folloaing series of 3x;3riments. Thus, while the figures in the first two columns may seem to be r1tho r large, the lest two columns show that they -17- represent eoniitions frequently occurring in the soil. rate of Sole is commonly irilled at the rate of 126 anJ ZeO tounis per acre, anj the data secured for the 166 anl 333 pounl treatments are also data for these irillej treat- nents. The pounls of urea ailei are here CPrruuegl in terms of equivelent amounts of Nitrate of Sofia so s to give a better idea of the amounts ajiel. These fi3ures also show the rel1tive concentrations of Nitrogen in the two carriers. Of course, the relationships in the pres ding para- 3rapfl~oull not hell for any length of time in a N811 Hoist- enei soil. heJOol and Uheetin3 (27) and Hheeting (4o) have shown that the novo ment ot soluble salts in the soil so u- tion is nouer1tely rapid, esteeially at moisture contents as use 1 here A rain would also tend to remove these re- lationsr.i{s, owing to the high solubility of the ure . No usta 1re a vail1ble corms rin3 the absorgtion of the hater ial by the soil, but it it were absorbed to 1n aggrec able extent, it would cause the above relationshirs to girsist lon3er. van harreveli (12) has shown that urea lem hes rea:iily from the soils of Java, but that does not no ces ily mc1n that such will be the e se for soils in this e oun- try. 17"- U) The general procelure anj L18 hols of naxing Jeterhina- tions were the she as greviously described for the Cole- sa soil, in the tirst Serie lhe soils were made to eni Keht at ogtimun loisture content ani the urea was 11101 to the soil by dissolvin3 it in the water to be adiei to the soil. Frequent and thorough aeration was given to the soils, and the samples for the nitrate, eeiiitt ani freez- in3 ooint neteru inations were taxen at about the sane in- tervals. Th- experinents were not run simultaneously, how- ever, the b'ox soil being startei about two weeks before the hiami soil. In both c.3e a on e31 or no treatei soil was a 3 run for comparison, anl all treatments ne'e run in dupli- Gate 0 A - hitrifieation Studies in For ani Miami Soils. The esults of the flitrate determinations are given -154- 5.’ .\ in Tables 1 ani 5, for the l to 5 extracts from the two soils. The ave rage of qu1lruplieate ieterhinatiohs is 31v- en in parts per uillion, basei upon the xtr111>i solution, for each treatment. Table 4 - Nitrates in 1 to 5 aqueo us extract of Fox Saniy Loam. (parts per million.) Treat 0 Days 5 Days 11 Days 22 Days 40 Days Checx, 11.8 l".3 24.7 29.3 to O 66 1‘ urea 11. 8 2C). 7 .33. 7 23. 2 4'7. 4 15:: if " ll. 8 26. 8 2-35. 7 6'0. 8 66. 4 333 3 " 11.8 31.4 74.4 82.2 3 .o bob # " 11.8 32.1 103.1 13;.; 14$.u 1533fi " 11.6 21.2 132.9 191.4 181.4 .1 ‘1. r 7 _: .u , . ‘ ‘ . ‘ ,-\ I . ,. ,. .‘ a YT - ’ . ‘ a 'p‘: ‘ ,.-, . Kaela a - hitrates,1n 1 to e aqueous bAtPiCL ct 11a11 Silt Loan. ( arts per million) Treat. 0 Days 3 Days 10 Days 17 Days 37 Days Check. 13. b Zt‘l. O 4.1. 2 43. .1 :38. 2 83 # urea 13.6 41.6 34.2 09.7 58.2 loo # " 13.6 42.6 64.0 64.0 73.4 333 ,9" " 13. o 4‘... b _ 93. 2 £8.19 95. 8 666 # " 13.6 47.1 105.8 106.7 94.1 13331 " 13.6 53.0 172.6 183.2 228.6 It will be notieei that the soils were ather low in nitrates at the beginning, ani there was about the same amount in each. Examining the ‘csuits ot’ the ehecK soils above will show that the nitrate content increaseu in both soils, but it inorea ei about 50% more in the Miami soil than in the Fox. Biological pro u: see ‘ hai probably been low in each previous to taxinS the sang 'es trom the t'ie lL due to dry weather. 0n maxing co niitions o timunhor bac- terial action, the fiiami soil showei that it had more po- tential nitrifying power, probably due to a combination of nirouhstanees, amoh3 which ma\ be higher organic con- tent, more plant ahj bae erial food elements, and less a- cii reaction. -19.. ‘ The se soils treated with urea gave increases in nitrate content and the larger the treatment, th- 2re r the amount of nitrates formed. This shows that nitrit’ic ation was go- ing on in all of the soils, an1 that agrarently some of the urea was being nitrified. As the exteriment continuei the Kitrates continued to in"easa, with a few excegtions, ani these were ‘ossibly due to experimental error. After forty days the nitrmtes were still increasing. No regular determinations were made after this, 11c to a lack of ma- terial, but deterhinations aaie a month later in connection with some other work, showed that the nitrates were still slowly inc reasiM The esults are not given as it is felt that the y may not be exactly comgarable to those given in Tables 4 ani 5. S: ('0‘ (a) In order to stu1y the rate ani amount of nitrification from another angle, other tables were workei from 1'abl<% 4 and a above. These are given in Tables 6 ani 7 ani were securei by subtracting the nitrates present in the check soil from those o resent in the reated soils. This is real- ly taking for 2rante1 that the atount of nitrification oi the organic matter in the check soil will be the same as the aJount of nitrification of the original organic matter in the tree ei soils, the eX?ess of nitrates being assunei s coming alto2ether from the urea 111e1.1t is readily 1'it to 1 that such is not necessarily the case. It is to be were or ass 3 x;e3ts‘ 1 that the adiitlon of the urea to t.e soil, osteo111ls it in l1r§e quantities, wouli affect its microorganic gopulation, both in xinjs an1 numbers. The results, however, bring out some interesting points, ani show in part whether the above assumption has justifiei. 1.13 CO C 1n the las column, heaici theoretical maximum, the 112 urcs were secured by calculating the amount of nitrates that wouli be termed if all of the urea a11e1 hai its Ni- trogen changei to nitr1tes. ion11ior1rc first the esults from the o lable 6, it will be so on that the increased ra urea can usei greater im1 recess in nitrates over 3 x soil in tee of aiiing chec .. -20- Howeve', this inereese in nitrates in the larger treatments is xot pfoportionel to the 1n,.o.3= in the egglieations of urea. The agglieations icuble each time nhile the inerees- es lo not, exeept in the 31333 of the two lower treatments. The 166 ;oun1 treetnent is tac 3n1 e h11f time 3 the 66 pound treatment, eni the inor3 :13es over en:3 31 in nitrates in these tre 3tr men t3 follow this ratio closely. As the experiment eont inu hes the inere1se3 over eneen beeome greater, as a rule iniieeting that the nitririeetion cf the urea '3 gaining in momentum. Table 6 - Inereeee Cf Nitrates over Cheex. 1 to 3 Extree Fox Senjy Lcem. (;.p.m.) Treat. 5 Days 11 Days 22 Days 40 0353 Tr eoretieal . . .. {a Xinur. Cheex. 17.3 24.8 29.6 31.0 ‘ 66 # urea 3.4 8.9 12.0 11.4 14.5 166 i " 9.6 31.0 31.3 35.4 36.4 333 # " 11.1 49.5 3 “.7 72.9 O 0.2 \1 {\L (3 Q 113 [\U .‘\ l O ?%36 ¥ " 231. '78.:5 1535i " 31.0 107.3 5—.) ( I1 .3. L {\3 co .3;- r—‘ C. ‘1 O 0 (J) (D H D——‘ c); ' r-* \ 7 o (C p...) p...) to) 5—4 C)”- Teble 7 - ln r3133 of Nitrates over Cheek. 1 to 5 hxtr13t. 331 Silt L011. (p.;.m.) "E Treat. 3 l 10 3353 1 \__l SL3 (\1 Ci. 0 C) 3? / Days 37 Days Theoretieel fiexinum. U‘.‘ CheoK. 43.2 43.5 58.2 83 # urea 13.6 9.0 16.2 00.0 3.3 1tfi5 f " 14.t§ 15.6? 20.:3 13.2? :n 333 3 " 14.6 48.9 45.1 37.6 72.9 666 f " 19.1 60.0 63.2 53.3 143.8 13331 " 52.0 127.4 111.7 170.4 29 .o Centering new the total nitrates possible from the urea, she «n in the lest eolunne of '133133 6 end 7, with the ine reeses in Nitretes ever cheek at the eni Cf the ex- 'perinent, in next to the list columns, i‘t will be seen that they are the sfie for the lowest treatments in the Fox soil ‘) -,;1- in Table 3. As the tre athents increase, the aiverger ”333 between the figure 3 increeee. Thus the tno lowest 3; pli- cetions have prolucei the theoretical neximum amount of nitrates over ch33; soil «itl1in the ti.1e of this ex; cri- nent. This would tend to show thet all ot the urea eliel in these trie1tn3ht: hai been nitritiei. howev.r, tr his is only eiuction, ani there 13 the; oesih ilit3. that the ori- ginal soil organic matter was nitritied to a gree or ex- tent in the tr31tei soils then in the untreetei soil, the ti ure; fo: the inereeses over the chreK soil not represnt- 'ng nitr1t 3;roducej from urea alone. The fact that the large r trea trents cause a f1lling off in the aggroeeh to the 11ximum of nitretes groiueel ov checx that is goss- ible, tends to ShCN that the ori‘in 1 soil organic matter to eueh an extent as it is in the untreet- ct ,ecuglei with the many exteriments re- is not nitrifie 1 on soil. This 13 pcrtei on the 6333 of the ammonili31tion 1nl nitrific1tion ct urce aculi ihii31t3 that the inereewe of nitrates over those in the untre Ht 1 soil r33r331ht3 urea ni3rifiei and leads to the conclusion that ell the urea edlei was nitri- fiel in the soils receiveing the two lowest applications. It will be recalled fro1 the lust paragraph that these two treatments nainteinel the ratio of their increases over c1e3k tairls constantly. As before statei, if the urea is going to have an ef- fect on the nitritic ation of the ori jinel soil organic net— ter, that effect shouli s.on up most strongly in these soils‘ receiving the heeviest applications. The falling ott of the heavy treatments in the 3;; o13h of the excess nitrates to the naxieun wouli ihlicete that there was an effect of the urea on the soil, not notieel particularly in the tab lowest tre11tnehts, but 1n3re331rvly uarhei in the hee or treat m1ents. The falling off in the 1n1r>1‘3 of hi trates in the cases of the heavy agtlicetiohs may be due to: 1- A lower percent ct the 31131 urea being nitrified in the heavy treatments, as ce1p1 31 with the lighter. t The length of time of the experiment we uld probably have quite an intluence on thie goint. The longer the exgeri- I I\ {\‘1 I went runs, the greater the pereent of the aided urea that shouli be nitrified. 2- Less cf the original soil organic matter being ni- trifieu in the heavy treatments. If the crgani1ms ”cu i use urea as a source of en3r35, it Nculi be reescnsbl e th 1t theykculi use less cf the ecmgaratively unavailable soil or33nie matter. If this is true, the results in Tables 6 and 7 do nct Show all cf the nitrate 3 pro eiuee 1 tPcu the hee1vy aeliticns of urea to the soil. 3- A 3re.ter eensnngtien Cf the nitrates after they are prciuee' 1, due to the much greater grciueticn of crgen- isms, 33us-e d b) the eiiiticn Cf the urea to the soil. 1ne tinsl result is probably a ecsbineticn cf ell cf the 3beve three gcints. Turh1n3 hCN to the results ter the 413 1 soil in W Lie 7, the 1131 cf regularity in the late 1313s 111t3r retatie n were 1iffieult. Ccnsiiering first the lewest agplieatien, it will be nct23ei that the inereese ever ehe3x at one tine N31 preetieellyhg to the naximue, after which it 1"C‘g i RNn to nethin3.. in this 3313 , end in all eases Nhe the in11reas3 ever eheea leereases frcn one tine to the next, it srcws that hitr1t131t1tn h1s bean 30in3 en faster in the c 1 1 (C L. ”h ck scil than in tne treetel 3 il, or else the nitrates are being ecnsumei in the treate' seils. This eeniitien happens qhite frequently in the eese cf the Miami scil, Nhile it h3egenei cnly cnee in the ease of the Fox soil. 0t ecur-1e, the nitrifie3ticn of the urea was put tc a heri- er test in the hieni scil then in the ch, as shown by the greater amount of Nitrates preiueel in the em13 1 soil cf the former. The Mi3mi so il gossiely h3i 3 :reeter aheunt cf easily nitrifi3ble crgani: setter in it. If it were iue to the greater nitrifyiné peNer of the Viehi scil, the in- ereese of nitrates over the se in the untre1tei scil shculi be the sane :3s th3t oi the ch soil. Nith cne exe 3pticn, the Fox soil proiueei reete r inerez1rs ever eheex then the Miami soil. however, the 'snsril tr<3 ni cf the results from the Miami soil is the 33.3 33 tnc s3 from the Box soil. ’I 'Q - ~ (J- B - Effects of 4r pgliéations cf Urea en Reaction cf Fox Semi; be m 1nd Mieri Silt L011. The pH determi naticns are repert e1 in Ha wl 3 8 ani 9 They are t.e average at quairuplieate 399 9193 run secarete- lg. The l1 3t set of determineticns for the Miami 3cil ha.l to be 113.1rle1 as one Cf the electrodes 113 fcuni to u have had an error in itjafter the «era #13 finishei. Table 8 - pH Values cf ch S1n1y Le1m. O D113 5 9913 11 1133 22 Days 40 Days 53. 27 4. e urea 9.02 4.7 t " £1.84 4. 765 4. 72 4. 83 4 , " ‘6. OO 4. 83 4. 4.5 41. 4’7 4. 1’7 " 5.90 5.13 4.61 4.05 3.90 " 6. 0:3 55. 7.5 4. 66 4. 21 3 ' P3 1 (D 5’ . 7T: 03 H J- C) 1' 'J.‘ D.) 3; O": I: 1~u33> (t (.3 ‘99- w; <91 99: A . r—l CA“ LA; ‘ _ p . Jul 151 Table 9 - CH “1 mes f0 91111 Silt Lcem. Tre1t. O D153 3 Day 3 10 Day3 17 Check. 5.40 6.41 b.32 5.43 83 9 urea 5.56 6.41 5.20 5.41 1665 9 " i3.EV1 5.:11 3.;34 5.;36 393 9 " 5.67 5.12 3.90 5.21 666 9 " 5.72 5.32 5.17 5.07 1919: " 5.9:? 5.90 3.13 4.50 It will be nctieel that in both 30113 the :11111icn cf urea tenieJ tc nexe them le33 9311,13 913 the 0&3 e in the Cclewa Scil. 90th $0113 r11 1H velu93 that were rather low fer the 3V‘"’:“ Cf these tygee. Treis may have been jue t: tTJCiP Path r 1r; ecnjitieflwhen tuge: frcu the fieli, and they were met use1 for acne time after that, although tHe; were met 1110991 tc became air dry. Rest and Fieger 35) have 3hcwu that jrying 3eile lcwerei their pH value a little, and remcie euing th~u 3till ftItnCr rejueed the ' ‘f‘ . ' . *' 3‘ . ‘ ': r .\ ’ ‘ ~ . ' . a u 1 ' it. uter1n; 19 the 1C13t etn.1tier ilnC 339391 1n INClGibC l\, -41 .. in aeiiit» eeecrdihj tc their result3. These fantcr3 3hCnll be eChsi:m red when intergretihg the data. he Tea 0: ea SCil, in T111e F, tehjel tc beecme hcre aeiu jurin; tle ecurse Cf the e gerinc ht, but the char 30 i“ met ereet. The hiehi Stil Changed very little in the PhQUK cr 1c trCatHCut gr'etitells eChsteht. '.1 le exglahatieh of this vild'w ivex lutur. In the treetej 3CCi131tter the fir3t 195 the; all tehlei tC t3- ethe ucre 3e'1 as the GXLCPiLOLL 3Chtinue1. T29 heavier l , the higher wee he iritiel 3F and the lcwcr Eh. There 833191 tC be sese ecrrelatiOh be— 3l nitrates CrClU? .3 the CH Cf the scil. he CCre Litr1ue3 thCr; mere ngJUeej, the lower uculj be the ;H vague. This may be nglaihci by examining tie TC11C HlfiJ gierugral reuétiCh fCr the nitrifieathh Cf urea: i}C(TH*2)2 ‘+ kfllgb (1L4)2*85 + 4 C2 293' Jers, bCatih' Q. ) LA.) L1? '2‘ 5—— ” I f-x (‘. ‘3 \)~ V h.) + k ,— H— U h\ L; C) LN + I" t.“ '0 C. l ‘ ‘ I I’! ‘L t ‘ ‘I . '.| 1 . 1". u“ ‘ . V: 1 "‘ . ‘ V)‘ i'I‘ in . .hus 1 bbFCh; uLJ 1 9939 1111 1 e tcruel 33 the “C- eult Cf the CrC3e33. The3e 13u11 eLtCCh the 3Cil t13C3 tC 3Cte exteht, grcb1hl3, an} be g1rtl; heutrnlizefl, but thi; grcee33 in tCClI wculd tehf tc lCher tte CH Cf tte seil. Slurwey (40) l93 steam the. treating 3Cils with 3tren5 19113 399393 9C1K 33113 to be sglit Cff, 911 this nCUll te hl tC lChCr the L“ Cf the 3Cil. Cf Ecuree, if plants were grew- in; on this they wCCll 'Chcve the itrate raiiele here quickly th1n tle L930, SC that iL time the 3Cil reactiCh shculJ CCL e tirtlg been tefluri the Crijihel value, if “C leuehihfi 03 eur3. The ee'dit1 e1u3e1 b5 the nitrificatich Cf ure1 is hC t lecnliar tc ,hi3 1 tC111l, but "C911 ceeur filtll any IWitPJinei' attf’l‘l Tris aellklf3l1fi5 ettrxz S Ct. the ritriliee.tiCh Cf Alhcrihn ulrhnte 1r 13 the seecrli 3311 crcjuecj with this material i9 Sul- ghurie, Nhieh i3 nueh strChjer thzer the teraehie Aeij fern- ej frCh urea. ,, . . 1 , o) 1130‘ \" ly/r} ’! \J.“_l\/l , ,. 93 betcre nettiehCi, tle 91911 egeex 3Cil 111 net 3 change much in reactiCh 1urihg the ecur3e Cf the exteri- nent, while the hex 3Cil beeaie more 9ciu. however, he iieni soil groiueei more nitrates and was le 33 9911 to be gin with. Potn or these things shouli naxe the hiani soil 9 ol nge nore than the Fox soil. Equal anounts of urea 9139i to both soils eeueee the Fox soil to change more in initi9l ree~tion th9n the Viami. During the course oi thCe exteri- nent, the hiiui soil iii not elenge in reectio n as much 93 the WC' soil, 59 , 93 9 rule, the “iami soil proiucei more nisratos. Thus in all cases, with equal treetnents, the hiami soil iii not change in reaction 93 nuch as the Fox soil ill. This is EPUbiLl) 1-9 to the buffering action being strongorhn the hiuni soil. This soil is 9 silt lzam and contains 9 high Cereontag e of silt 9nl 9191, while tr 0 Fox Sandy ho1n is low in silt and 9193.. The silt and M1 are the Carts of the soil whieh are suggosei to contain host of the buffering uzterials, and this would ace unt for the stronger buffer action in tho Eleni soil. Arrhen- ius (3l'3t9t93 that the CrC333333 tenlihg to naKo the fine garticles ot the soil also build up the buffer effect of the soil. Breilield (8) 3t9tes that the buffer action of 9 soil is some direct function of it3 eolloidal content. C - Effects of figgliC 9tior3 of Ure9 on the Coneen- tration of the Soil solution. B'Cx S9nli Loan and hieni Silt Loan. The concentrution of the Mil solution in torme oi the degreszion of the freezing goi. is given in Tables 1C‘9nl 11 for e91h oi the tre 9+nert3 of the two soils. The fi- gures re the averages of duglio ate deteémin9tion3. it should be remember 91 that the re 91 3Cil solution was not 391 fort thesc: dc to PLlWithI , but it W93 diluted in order to secure greater 9oCulaC5. lhe results are not absolute, but only relative. lhe actU9l concentrution would be re;- reeonted by a depression probably tueh greater than that given below, in each 0933. (-1» . . . . .. . ,r . . C , 1 The dCCr9331on oi the lr9391n4?o1nt in tne eieek 3C1l3 ino ease 9t fir3t19tter which it stesed Cractie9113 con- stant. This is sohjwhet litierent than what W33 obeervel in the 0330 Cf the Colon“ sic“ and then a re eeiinJ or the HOhPCn\JCH was night pcssibiy be due to the taet that thQch an Jo nct re1eh und that the m~-_ 1018 emi scils 're finer in exture and thus uaxinum gcint 3c sccn. Hheeting (43) [cu extureJ sails usually leJuired lcnge r tc rea Ham degressicn than the starser 30113. It was after thirty or fer [PGSSJCDS in exgeriment. enough eclution. 10115.5 th Table 10 - Treat. 'Jklcle. 66 # urea 16604 " " ‘3“ ~' H t-J’chj 10‘ Treat. Che-01K. E3 ‘ urea 163 1 " 313 1 " 606 § " 13331 " is the extertajnt trcfireesed, “'IbwulChfi anJ the L31 the ‘l .. {D EPBOZIHQ 0.010 0.019 0.040 Freezing greitcr a plieations natural sin3e the ty scils cf 1t wculJ to have 13* 4 l " It Fioodu Ecint De; Scil, in days that he see ure textu'es ecmgaru W lcox as if these soils r3331ons, -2?- which '3ir maximum ecu '\ I Legre Rex Sandy LCHm. Pcint ‘I.’ o . .filiifil Q m... L' L/L’ 5 b 0.0 0.()35, 0,0ZH 0.020 0.035 0.036 Jeriai Barres Silt Loam. sails greats st J31? USS 1.JJ31 11 Days 22 ”.009 0.013 0 021 0.021 0.027 0.028 0. I) 0.04] 0.04 0.0W @0711 O. 03..) sicns, Degre 1...} C‘ I: 13 V U4 0.027 0.036 0.033 0.057 0.062 0.120 O r-\ .v \_ 0 ,CD ; A-cerv ‘ C‘c fr 0 A \.. fi‘ T\J CDSDSDCD C‘CD C>CT L R O ,__x CZ.‘ C‘ lCHS. 1 a naxinuw \‘ ‘ 1.1 a) [.3 17 0333 J the n31ximun tc these in this had not run eentratitn 40 Days 0.016 0.024 0.(L%5 n ”if U. }()() 0.032 0.107 37 Days 0.026 O.(%14 0.(MJJ O.()6&3 0 072 0.134 the treateJ ecils re eeivimg the heavi This is qu and also the nitrateé dengs- secureJ. ; .f’ {"11- tilE‘ finer Ch their maxi- nct until 10- in es CentigraJe. n4. ". ' t ‘ 30 LentlgraJC. 1ve 3t itb fermefl wculd tend to lever the freezing tcint. There is a f11rl5 30011nd re Hul r correlation between the tetal ni- tr1te3 and the depressions 0f the freezing pcints. The u- rea itself depressed the freezin5 geints, 13 will be seen in the column headed 0 0153 in Table 3 10 1n1 1]. chever, the results are irregular and 10 net 33 em to inlieete nueh, xeept that the degressicns are net prepcrticnal to the materiel 1ided.lt eculi 1001 13 if there was scme ebserp- ticn without -epl10ehent, er else greeigitaticn. In the Fox soil in Table 10, after the first ediiticn, the de'res- sien ices net ehz1n3e much until the largest 1;;li01ticn is neie, when it ine reases ecnsider10l5. The abscrgtive 01- paeity 0f the 3011 w13 p03 31015 net exeeeied b5 the lower 1gplieetion3, but ~13 b5 the l1r3est 1‘;li01tien. 1n the Miami scil (Table 11) there is 1 3101 but 3r1Aual increase in the depressicn.. 1013 315 be due tc the urea itse ll tr tc abscrptien with 'egleeement. however, n0 definite ecn- elusiens can be drawn from the few 1nd irregular data 30- eurei. Tables 12 1ni 13 show the in01e1se s in freezing Lcint ie 3 eve' cheex. The results in the Cheek line are u1l de pressicr 3 secured. The figures in the eclunns belcw re tresent the amount in degrees Centi3raie below the eheex 1t whieh the solutions frcze. These figures show the relative effects the urea aiditiens 10tuell5 011 en the scil scluticn. The effects may have been di eet er in— direct, but the are quite eggrseielle in nest 01303. Table 12 - lnereese ct’ tr seein3 fcint Degr 333 icns helcw Sheek. h'ox San15 L013. (Degrees C.) Tre1t. 0 0153 b 2153 11 0153 22 0153 40 Days. Cheek. 0.00] 0.011 0.009 0.014 0.010 66 # urea 0.013 0.000 0.013 0.007 0.008 130 3 " 0.013 0.003 0. 018 0.015‘ 0.019 333 3 " 0.003 0.013 0. 029 0.020 0.040 03 1 " 0.013 0.017 0.040 0.133 0.033 H"? (A: -.. (A- U 3’ "' 0.033' 0.030 0.033 0.031 0.091 Table 13 - lnereese of Freezing hoint Depressions Below Ghoex. 0111i Silt Lo1m Soil. (Degrees Centigrale.) Treat. 0 015s 3 013s 10 law 17 Days 37 Days Cheex. 0.010 0.015 0.041 0.027 0.026 ,3 § urea 0.003 0.010 0. 0.109 0.018 166 a" " 0.003 0. 011 333 # " 0.007 0.013 6613;? " 0.()11 0.()20 333$ " 0.016 0.023 ' 0.012 0.025 0.030 0.040 0. 03.3 0. 0 1'3 0. 033 0. 108 (D O O O O C O ('5. «>- DJ ‘ O (“0‘ P . A; gl. 0 O \3 N In the lighter tree uerts, the inere1se d iofr essiors below eheel 011 not very much, while the heavier treatments oausei the increased depressiozs below cheek to tezone greet- er. There w1s scne correlation botxeen the increase of hi- tr1tes over cheek eni the ine reese of freezing point 1e- ;ression below check, but it was not very elose fiell defined. The theoretical ineroeso of freeziné goint 15;! essicn belcv eheex was euleuleted using the inere ezsoi amount of nitrates over eheex as the meteri1l that woulj can 8 the degre ission. For this pUPCCSG, figures were chosen iron re- sults where all of the urea n11 egge‘erztl) bee en nitrifie , so that none of the urea would be present to atfeet the de- pres sion. The nitrates were 13.5uue1 to be in the form of Calcium hitrete 1hj eon; wl tel; 11>\L eted, wtie. was pro- eel) the ease in the «eako soil solu tion. However, even on this basis, the theoret el de gression is Very nueh less then the observed depression. This is not so strange when it is oonsiJered that the nitrifioetion proeess, with its production of 3 strong 1ni 1 neex acid, and the subsequent salts, probebl; effects the solubility of Juite a few of the soil constituents. Anothe' indication that n1teriel other then the nitrates fies causing the ine‘eesed freez— ing Loint letrossions was t o taet th1t oeo1sion1lly the increase en nitrates over oheex NCUlj dro it off without the ine ease of freezing point de;*essio n telling off. Also, when the total nitrates would tell oti, the total depression of the freezing point would not be lowered. 2 (f2 Conclusions - Eerie The esults t‘rom the treceding ex; erinents h1ve le‘1 to the followin3 genera conclusions: 1- Urea 33 led to soils at rates uo to 1.333 gounis ger six inches, is reedil5 nitritic d. 2- The nitrification of the added u*c1 is agrarently r1ther cowglete in the smellor egtlieetiens, but falls elf consice-ebly in completeness in the ler.5er applications. 3- The nitrific :1tion groc ess 1111rentl5 causes an in- crease in twt acidit5 ot the soil, at least for a time, the incree'e being more or less correlated with the enount of nitrification. 4- The addition of ure1 c1uses an increase in the con- centration of the soil solution, the JllCCt being greetc the more urea thet is ailed and the longer the time after the egglieation, at least u; to forty d15s. L‘ t) (.3 '3 (1 F—n V": ’ C I") .1. 0 Studies on Voletilizetion of Aunohie upon 11515- iné Urea to Celene, Fox, and ~11 mi Soils. ther series of BXIePlHBL, wt 1 b5 the results secured with the Celene soil , where greet 11ounts of Ammonia were given or? by the at; licetio s ot ve r5 large 11o unts of uree to the soil. It w1s de ired to ascertain ahet her the urea would volatilize Ann on; when 1dle j in duenti ties conger1ble to atplications nede in the field. If such would be the eese, it would be 1 serious liniting factor in its use. No Am— nenie was noticed coming from the Fox and 11111 soils in Series 2, but more definite and exec inforretion on tl‘i s ucstion was desired. :; (f. 5 LL 0) CC C :3 (T ,1. U (v 3.... C ”—1 (“1 J. A - Volatilization of Annonie Tron Coleus Soil. 1‘: per this tur ose, Celene Tine Send similar to th1t I‘ sed in series 1, waS'; seed in jars, given the desired treatments, and an5 Ammonia volatilized determined by draw— ing the soil air throu3h standard acid. The air was first drawn throu3h dilute Sulghuric Acid to remove an5 Ammonia that mi 3ht ha e been in it. It then went through two bot- tles ot' distilled watc', in or er to thoroughly wash it. The water bath also served to increase the pe'cent of water vapor in the air, and thus 3reatl5 lowered the ar5in3 in- fluence of the aspirations on the soils. 85 means of 3la s tubin3, the air entered the jar of soil at the bottom, and was drawn off at the to; of the jar, thus insuring a thor- ough ac ation of the soil. After leavin3 the soil, the air was drawn throu3h tenth normal Sulphuric Acid. The Sulghuric Acid was titra ed with tenth nernal Potassium H5droxide to dcternine the amount of acid that had bee neutralized b5 hnmonia. Tye asgirations were conductei ever5 two or three da5s, and the air was drawn slowl5 through the soil for one hour at each aspiration. Hheh not bein3 aspirated, the Jars were closed ti3ltl5 ani the5 were alwa5s Kept out of the direct light, were or less in the darx. ‘I b The exgerineht was allowed to run for two and a half eks, after which it we sflfign down and the nitrates de- teruined in 1 to 5 aiueous extracts of the soils When the urea was to he added and nixed through the soil, it was dis solve d in the water used to 1.1Ke the soil u; to C1- timum moisture content. In the c1se o the to; dressin3 treatuoxt the ar'o a ot the jar was H1 Llated and the per- centage of an ac1e dcternined. The ”pounds of urea that we e to be applied per acre were nultitlied b5 this per- contage, 'hich gave the act 11 wci 3ht of the urea to be put on the soil in tle jar. he to; drssoinS was. made at the rate ot 1333 pounds of urea per as ro-, sh'ch is the e- quivalent of two tons of Nitrate of Soda per Vere. This figure is rather high for a top dres sin? , but it was uses in order to secure an a: zount that could he s; ead unifornl5 over the surface and also in order to secure .oie positive results, it an5 were to be secured. The treatments nixed through the soil were: 83 pounds of urea per acre six in- ehe s cf scil (equivelent to 250 pounds of Scdiun Nitrate), 1b6 pcunls of urea (equivelent to 500 pounds of Sodium Ni- trate), 666 pounds of urea (equivelent to 2000 gcunds of Sodium Nitrate), and 1333 pounds of urea equivelent to 40C0 rounds cf Sedium Nitr1te). Twc jars hai nc urea 33d- ed, serving as a check. All of the treatments were run in duplicate. Table 11 gives the results of this experiment, the fi- gures being the aver1 es of duplicates. The nus bars are the cubic centime ers ct tentn normal Anmcniun Sulghete formed at e ch asgi iraticn These were secured by subtract- ing the cubic centimeters of tenth normal Potassium Hydrox- ide n1eessary to neutralize tie aeii, from twenty-five, the number ct cubic centimeters of tenth nC rn:1l Sulphuric 1 acid use 1. Table 14 - Amounts of Kunoni1 Vcl1tiliaeu, EM resse u as c.c. 1 cf . u (uh 4)2004, uni nitrates preiuceu. Celene Soil. T'cat. 1 Day 2 Days 5 Days 7 Days 10 Days Check. 0. 00 0. 00 0. 00 0. 00 0. 00 83 # uree 0.00 0. 22 0.00 0.00 0.0? 166 1 " lost 0.00 0.00 0.00 0.32 666 1 " 0.00 0.00 0.00 0. 02 0.0- 1533# " 0.00 0.C0 0.00 0.12 0.30 14:13:! " 0. 00 0. 00 0. (‘0 0. (£0 0. 58 tap dress. I“ [Vt/3 prod. Treat. '12 Days 14 Days 17 Days Totals p. p. m. Checx. 0.00 0.00 0.00 0.00 17.8 83 ¥ urea 0.00 0.C0 0.00 0.24 42.1 166 f? " 0. 035 0. 2L5 0. 3‘2, 0. 294 38.1 O’rC L? " O. ()0 U. ()0 O. (10 U. 02 72. 7 1333s " 0.00 0.00 0.45 0.07 22.9 13331 " 0.00 0.65 0.60 1.83 17.0 tOp dress. it will he even that the results are not very conclu- sive owing to small differences and many irregularities. The to; dressing treutnent appearei tc be velatilizing scne Ammonia toward the end of the eXperiaent, although not a great deal was being produced. The 165 pound treatment also seemed to be 3ivin3 off some Ammonia quite regularly toward the end of the experiment. The 666 pound treatnent did not give off any Atmonia to speax of, while the 1333 pound treatnont mixed in, gave off some, although not as much as the 166 pound treatment. These irregularities make it difficult to draw any definite conclusions except that the amounts of Ammonia given off are not very great at any one time, or even in thea a3jregae It can be seen that the figures in any one case are not l1r ;c, and might be due in part at least, to experimental error. T1e results from the top drossin3 are the only ones that ni L3ht be call- ed at all signifiea.nt, and even these should be treated with circ n.s spec tion. Looking at the total amount of Am- nonia produced without considerin3 the siz as of the numbers that go to naxe up these totals is liable to 3ivc nisle ai- in3 conclusi ions . The total amount of hwnnoria given off was never nmo e than a small fraction of the Nitrogen added in the urea. however, by conparin3 the last two columns in Table 14, which givdthe total Ammonium Sulphate produced and the nitra es 'n the 1 to 5_aqueous extract at the end of the experiment, 'e spectively, an interestin3 apparent correla- tion is not co . The 3rcater the amount of nitrates p o- dueef, the lower the volatilize tion of tune nia. This cor- relation holds fairly well through-out the whole experi- ment. This is a lo3oca result, since the more rapid the nitrification, the less will be the tendency for Ammonia to accumulate in the soil. ho explan1tion can be offered as to why some treatments 3ave this rapid nitrification and others did not. It does not appear to be correlated with the anount of urea added, and with theo exception of this, conditions were as uniforn as possible in all the jars. B - Volatilization of Ammonia From Box and M'ami Soils. Anothe e perinent was run in the sane series, usin3 Fox Sandy Loam an] Miami Silt Loam soils similar to those used in Series 2. The general plan of the exporinent was kept the sane as in the Coloma eXperinent, except that here sore of the irtsrneli te trea aents we e o11ttea.hnother difference was tle use of 20 c.e. of Litan11rd aciJ instea of 23 3.0., but this ices not aflect the results.- The followin3 treatments were usej: 1- Fox soil - Ches‘, no aiiitions male. 2- Fox soil - urea ailei as a top ire ssin3 at rate of 1333 rounds per acre. 3- Fox soil - urea aijei at rate of 1333 pouan per acre six inches of soil, and nixei in. 4- 3iawi soil - Check, no additions naie. 5- 1-11 soil- urea adiei at rate of 1333 pounds pe aare, as a to'p 1ressin3. a- riaxni soil - urea added at re 3 of 1333 pounds per acre six inches of soil ani mixei in. The treatments were run in iuplicate, the average of then being reportoi in Table lo as before. The data for the Fox soil in Table 15 show that much greate- regularity existed than in the case of the Colona or Miami soils. The top firessin3 show:, 3 regular volatili- zation of Pmmonia, the total amount bein3 slightly higher than was secured for tho Colona soil. None of the oth r results from this expcr went are of any great significance. While there is cviuenco of some volatilization in the ease of the Fox soil with 1333 pounds of urea mixei in, ani also with the tOp dressing of the Miami soil, yet it is felt that the results are not re3ular or lar3e enou3h to warr- ont drawing conclusions from then. Here again the'e is a correlation in both soils be— tween the total amount of Ammonium Sulphate produced and amount of Nitrates produced. In both soils the top dross— in3s volatilized more Anwonia and producei less Nitrates, while the applications incorror.ue1 into the soils 'ol- atilizei less Ammonia ani Erniuccj more hitrares. Table 15 - Amcunts cf Anmonie Volatilizei, 1xpressed W3 3.3. of .1N (M14)230 4, 3n1 Nitrates Eroiueed. H'cx ani Eiami bile. Treat. 2 01;" 5_De33 7 Bass 9 i233 11 Days Cheek 0.00 0.00 0.00 0.00 0.00 133:111 urea O. :32 0.14 O. 48 O. 34 O. 38 Top Drona. 1355? urea 0.00 0.10 0.1? 0.38 0.00 Mixed 1 no 1 ani Scil . 3193:. Q.(() 0 (@ O,Q{1 0.L(1 0.0C1 1333* urea 0.00 0.0. 0.1C 0.00 .O.26 Top Dress. 13554 urea £L(K) 0.00 0.10 (L(N3 0.00 Mixed in.' .- 1“ prcd. 14 Days 16 Days Total p. p. m. FCX Soil Checx. 0.00 0.00 0.00 16.3 1333 # urea 0.32 0.20 2.14 trace TOp Dress. 1333 1 urea 0.02 0.00 0.52 55.7 Vixed in. niini Soil Sneak. 0. 00 0. 00 0. 00 32. 0 13331 urea 0. 22 0.0(1 0. 8‘2. 30. 8 Top Dress. 1333* urca 0. 00 0. 00 L. 17 83:1. 9 Mixed in. es 3 F’- Ccnelusicns - Ser NC ie iinite ecnelusicns can be drawn from the vela- tllizaticn work, cwing to diae'e‘Lneivo and small differ- ences, but the lelcaing indications are given: 1- Tc; regain.) with larie arLliL atiLns ct urea ma; cause a 1033 cf Ammonia by elatilizaticn, if ecnditions ere dang. The loss will probably hct be very great. At- tention is called tc the feet that the ccniitions in this series cf LKLOP1VLL.» are not really ecmgerable to a ter dr 3 L3 in tne tieli. The; are similar only in that the 3 :v- i ial is on to; ct t scil in both cases. In the field D C» w-a O '1 U: the surface of the oil is usually such the t the urea would not be ac tel on nue h by tie organisms, owihg to the lack ot moisture and sterilizi r3 action of the sun's rays. In this scrio s the surtace or the soil was moist and in the dark, so that bacterial action could taKe place there.. In the field, the urea would probably not be broxen dowr until it was washed into the soil, so it is tho ug ht that there is not nuch danger of an apprec able loss of Ammon- ia from surface applications. 2- The u ea in the soil may volatilize a little Ammon- 13, but the loss will not be'much, if any, according to the esults ecured he "1 vftects of Applications of Urea, ani of chi n3 on the Heaction of Fox ani "la“.i 50118. The last series of experiments conducted was an at- teupt to stuiy the resiiual ettcc s on the soil reaction of the application ot urea. Eor this purpose, Hex Sandy Leah ani Miami Silt Loam soils, befo e icscribed, which had been treatei with various amounts of urea, were leach- ei several tiaes with distilled water and the reaction or pH lLtO rained. The soils were the sane as those used in the seconJ series of experiwents on thL nitrification and effects of urea in the soil. They hai been running three months when this work was ione on them. 20 grams of cry soil, or its equivelent, were we iého i out aui sproar over a filter per ina a ten centimeter Euchnor funnel. The soil was then- washei tour tin.es with distilled water. The first washing was 50 c.c., the second was 150 c.c., the third was 50 c.c., and the last was 50 c.c. Each leachate was saved ani a sarple of the soilfiaxen atte? each wLLn1L.. The pH value was then deteruinci by the Quinhyirohe electrode on each of the solutions ani soil samples, as well as on the ori- ginal soil. The washed soils wece then placed in Erlen- myer flasas and Kept for'ten days, after whict time the 3- mm l‘ ”I - .To- the pH values were a3ain detcrnihed. The moisture durin3 this ten is s was slightly above Optimum in the soils, but well below saturation. The wore was done with iuplicate jars, and the data are presented in Tables 16 and 17, the ti3ures bein3 the averages of the dupliea.es. ‘4 Lookin3 at the data for both soils, it will as seen that each wasilig tenis to na he the oil ani the eXtP°3 obtaine' from the soil less acid. This wouli injiea e that the material ce.us iI3 the aciiity is 10 ache his The. first 30 c.c. of leachih3 usually removes ore of the acil components than the latter leachin3s, as measure} by means of the inc re se in pH over that of the soil before leaching. The socohi lLL,lir‘ ot lbO c.e. usually increases the the pH to 3o he extent, but the two additional leachihgs of 50 c.e. each so not change the pH of the soil very much. Thane is usually a tendency for the soil to become higher in ph in the last two leae kin3s, but the dilteronces are, in Lost cases, within the e'gerinemtal error. 0 > Comparin3 the pH values of the Miami soil after the last loachi 1n3 (Table 7), it will be seen that the inter- mediate treatments with urea left the soil about neutral. The highest and lowest treatments aha the chess soil were left sli3htly acifl. Tre owering of the pH of the check soil by them last loaehinfi is possihl flue to an error in sampling. Nils 1i iht easily occur then it is censiiered that the \ater Lay not 30 through all of the soil in the same 'hount, thus not eachin3 all of the 301 l in the sa he aLount. However, in an attempt to secure as re;rese ntative, a 3.3 m;le as possible, the Ssamplc tor the ph reaiin3 was ta son from sev; ral plae e on the gaper. 1n the ease of the Fox soil, the pH value set a 1 ot the soils after le~cnin3 were a sent the same, although there was a tendency for the he‘1v1l1 treatc 1 soils to be slijnto 11 more acia than the other r CBtIhS ts. The To. soils 11:1 not becoae neutral nee+¢ei as lie many of the Hiami soils after leaenih3 iTaole 18). This may be iue to t" initial acidity of the H'ox 3L ils, althL ugh the p' of the soils do not increase very much in the la A Table 16 - pH Values cf coils ani Leachin3.. ch 3011. 3!’d . 411; '1'? 3-13 1'1 . lst. WBSh. 211:1 . Hush. Week Lat Later Original Scil 'Y ‘ ”BSD. L4henk. ." ‘- f" ;." " L4 'o \l (I 4 1". p011 0.09 0.83 0.9. p.03 b.3. ”.14 Extract 6.10 0.31 6.46 6.83 86. fi urea ~ W“ F p n n A . n 1 Sell :3. of. a. 9-.) ‘0. u 4 (3. 19 6. 1'0 0.14 “xtrast 6.15 6.29 6.43 6.41 55 * ur'a t... u - ,.. . , éCll a“. {33 '3. E29») b. E)] 0. 9‘0?! 6. 1‘4 b. 0:9 Extraat 6.07 6.25 6.41 6.37 993 # urea tan-1'. . . - ,- .-..- A ,. . 7. 0611, C).- (’L) b. 11' O. ()3 ixtrast th.5 6.23 (u;i3 0.70 35“ # urea . .. - .. -. n u 3.011 11. 22.3 13.3! o. ht}- .. 7‘: a. 3.? 5.01 thr~13t 5.8%i “.fIZ 6n 19 6.252 13 n _, - , ~ p cc 4. a- a. .11 0- o. 79 a. 47 p p C 00 ’5 C; c O O O (T; C (Y) Scils 3nd fiiaui ’1 : HACK ‘ r‘ '-. w / « ,o r. a I 3311 t./4 0.85 6.70 1.80 0.46 6.71 Extract 5,99 5.33 6.37 8-55 83. # urea g n N, b011 0.07 0,00 0.44 7.04 Extract 15513 urea 6.§38 0C1 6.2? 6.62 6.91 7.18 7.27 7.15 Wxtract 6.3 6.67 6.74 .79 ”35 # urea gOll Extract 666 f urea coll Extract 6 H4 6.02 6.50 6.28 I. I' k (3. (BL) 01 5.131 5.3%2 C.115 b.235 (L 04- b.;&7 thraa 5.83 6.0L 6.14 6.17 - V v -33- leachings. This woul1 indicate that an equ librium is be- ing aggroache1, ani the neutral point has not be reached by the Fox soils even with mush greater washings. The heav- 'er tre tM13rts wit h urea caused the soil to have a much loner pH value ctcre leachin5 be—g 3n. After the soils were leachei, this difference was relucei, showing that hashing tenlei to make the 1ifte rentl, tre atei soils more alisc. he above results from this BXPBPlflCnt agree well With some data recently published by Crostner (14). He 313 t u i that leaching soils with wa er tenlei t: reluce 1 was increasei b5 1ner3131n5 the amount of washing. Even with a soil that was alKaline to begin with, washing increasei the alhalinit y. He states: 1 3 n their Hylre'3n-im ccncentration,<1n1 that the amcunt of n "The increase in pH value of the soil after extraction is not the result of the reroval of a 1efinite amount of water soluble 3311, because no amount of this order can be jeterminei by titration of the percolate, ani the change due to the removal of a certain amount of the soluble ha- tcrial is greater than that jue to the ajiition of an e- qual amount to the soil? gConsiiering the pH valu:.=s of the extracts from the soils in Tables 16 and 17, one thing is very notieable, namely, the extract from the 1131i soil is nearly alwass more 33 ii than the soil is atter the extractic n is male. The opposite is true in the case of the Hex soil, where the ext -ct is nearly always less acii th 3n the soil after r3 being extractei. No wholly satisfactory ex;lanaticn ca be offerei for this, but a possible reason for these 3;- arently ccntraJietcry results is clfll re1. The pH values of the extracts from the t-c soils do not vary nearly so much as 1c the pH values of the two soils themselves. It has been shc 1n by Bradfieli (8,9) and 333001 an1 Jhceting (29) that ccllei1s extractei from soils are acid. It is quite probable that many colloids were leached out of the soils in securing the extra acts, as -39.. c+ J (D latter ner:3clou1y. These oolloi1s may be largely re- . sgon s1 M11 for the re ction of the extra3t, anJ thus account for both of the soils producing extracts that are acid. The results of icCool and Wheeting (29) show that the EH Cf the colloils from the surtac;3 'orizon is about the same in the three soils the; stu11311f it is true that the colloids in t1e surface horizon of soils in the sane local- ity 10 not differ a great 1331 from eich other, this ifiht account for the similarity in the ;H values of the ex tracts from the two soils, evenithe soils variei somewhat in re- action. The surt13e h3riz=n was usei in these studies. D :d The 133 ts tlat the colloiis are 3:11 an1 t1 probably remove1 to some extent from the soil b led to the 1133 that this may account tor the ris of the soil «hen lea 3he1 with wate . It wouli $303 3 son- able th1t the rcuoving of an acid constituent from the soil wouli be the cause Cl tht lowering of its aoiiity. Melool anj Sheeting (2h,23,unpub.1ata) have founi oontra1ictcry 3sults on this point. At one time they founi that the r noval of the collciis lowers 1 the ac iiiti or the soil. However, in some later nor1 tt1ey toun1 that the removal of the colloids sometimes lett the soil more acid, even though the colloids «ere more acid than the soil. This is very 1ifficult to expl1in at present. Owing to these contra1ietory results, a definite statement cannot be maie that the removal of the colloi1s is what cause1 the soil to become less acil on be ing leachei. However, there are in1ications that this may be part of the cause. ‘3; at 103311 e annin ng no» the figures seeu r'31 b1 jetermi nin5 the pH oi the soils after being extracte1 with water ani left to stani ten days (last column Table s 1o 1n1 17), it will be seen that , in general, no great chan‘es have taken @1133. The results are more or less ir egular an1 in the Miami 53 r treathent an excettion is hotel. Here the ;M has Jumpe1 a great 1331 ani is up with the other treatments. The most heavily treatel soil be31ne slightly nore soil on stan1in3. he's the noii reducing factors agrarently 1 are still at WCPK after the soil has been leached. In the -40- case of the soils in which the pH did not chahg 3, the ecii proiucing factors were either emovei or renderei ineetive for at least ten 13/3 by the leechinfi. .3 Conclusions - Series 4 The tollowing general conclusions may he 1r3wn from this series of exceriments: l- LeT hing 3 soil nith weter tenis to 123311 less 3eii, possibl1 iue in p3rt to the remCV3l of the aciu soil colloids. 2- The first 133chin3s are more 3311 that the latter leachihés. 3- After being le3ehel, the soils t3“l(l to st3y the aue, except in thz 3333 ;f the heaviest treatnents, :he'e l on st3niing. The large amounts of An h‘onie formed in the first Ser- 'es, without the subsequent torh3tion of nitr1te3 shows that ammonificetion stulies 3re not necessarily 3 true in- iic3tion of the availabilit1 of the materials to the plants, assumingt h3t the1 use nitrates 3; the main source of hi- trogen. It h3s been 333u11ei by some het nitrific3tion follows along 3tter nighwflcttien 3t about the 3333 r3te, 3ni th3t 133sur in; one will also .o33ure the other. This hey usu3ll1 be the 0333, but it has been shown 3bo e tnzt nitrific3tioh not 3ln3ys hozessar l1 tollow after 33— menifieetion has t3 on p ace. Lipmeh 3nd Qurgess (22 ) have also brou5ht this t3 t out, where the1 founj thet high hi- 1 but) 0 tritication was not neces 1 ri1l1 correlated with high 33.3on- ificetion, working with se Kl org3nic ergenie Nitrogen 03rriers in several soils.v As will be seen by centering Ber es 1 uni 2, the eonlitions unler whieh the 3sts are conlucted would have some intlu hce oh the esults oct3in- r~ \1 ed. The larfie 13;; lioeti.hs ct uree iii no t tr:m nitrates after JiJnin- mr on13, while the sheller agglicetions 3ll tnohei nitrates. -41- The aptlications of urea as naie in the first series could not be a 13 in the tieli to a soil of this texture, since much of its nitrogen wouli be est as annonia. How- ever, the.e are other factors which nigl1t teni to limit its use efore amounts umeiP’Wlu to these nouli be used. The law of diminishing returns nouli probably be one of the first factors liniting its use, even though the price of t the naterial was comgaratively low. Another factor is t.he question of whether glants noull live in a soil so clution as con33ntrat31 as that of those exteriments. Ml s experi- ment does serve to show that there is a biological limit above which urea cannot be agglied with the ext cotation of securing nitrates. lt weuli be interesting to see whe- ther the limiting caneentrations for plant growth wouli be reached before the limit for complete biological acti- vity nouli be reaehe ,5 Then adiei in amounts comparable to and slightly in excess of amounts of nitrogenous fertilizers now usei, urea proved to be entirely satista,eor; as a nitrogen carrier, juiging by the nitrates groiuced ani consiiering only that phase of the requirements of a 2331 nitroge carrier. ‘ Since t 3 smaller agolioations of the urea were apparently a. comple tely nitritie1, an1 the larger 3 33 were not, it would appear as it' the quic {est and greatest returns per iollar seent on the material woul1 be secured from smaller attli-' cations at one time. This does not nee ssarily ncan tha th3 rzaterial unnitritied juries the course of thiso eageri- ment will not later bee no available or nitrifiei. Thre very ra§i1 nitrification of urea should be consiiered _when agplying i. to crogs such as the gra ins, where an ex- cess of nitrates early in the growing geriod na5 search the giant. A genera l oharacte ristie of all of the ta‘o W1 s is that the lighter attlioations rea3te more quickly in the soil than 111 the heavier applications. The large amounts of material aiaei s oned o be more or less of a ‘MCOK to the soil, the effects 31 which haj to be overcone before the advantageous results of the heavier treatments wouli be (L notie1 ble After the shoex n13 ovetdpome, the more heav- ily treated soils would usu1lly forge ahead of the soils with 311 m1 applications, although as 1 rule not in pro- portion to the extra amounts aidei. In some eases, where the agglieations were very he1vy, these effects would no- ver be wholly oversees. SW31 .iz'iiiY A 331011 bine 31ni ~13 treatei with uro3 in amounts ranging from .53 to 53 the «eight of the soil. These were kept at optimum moisture 1ni fre1uentl5 1eratei.From time to time the nitra e3, hyiro5en-ion ee oeutration , and to- tal concentration ot the 3oil extra 3t we re jetorminei, on the var ous treated 1nl untre1t31 soils. ihO esults shox- ed that urea n13 111onifie1 very quiexly, but was not nitri- tied. In the 5% treather t, very little amixonitie etion a;- parently toox el1e3. hith the: exeegtion of the ehee1 eel 55 treated soils, ammonitie1tic on was 33 great that ammonia was given off in large 1u1ntiti e3 lrom the soils. 1he soil was 1113 alxeline by the aiiition of the urea an} suwi eguont formation of ammonia. A to rioi oi m1ximuu 1141linit1 was reeehei, after which it deere1se1. 1ne 3on- eentretion of the soil solution was increased by the treat- ments according to both the size of the treatment ani the length of t'e GXgeriment. A period of m1ximun concentra- tion was reacheL after which it declined. l'nere W13 seme correlation between the time of maximum alkalinity 1;d Jon- 'oentr1tion, inJie1ting that the in3r31se concentration of the soil solution was prob1bly due in p1rt 1t le1st to the ammoni1 fornei. A Fox Fine San}; Loam 1ni a Miami Silt Lo1m were run in the 3113 was, the treetnents ranfing trom no urea aii- ed to 1333 gounls per acre six inches of soil. The nitretes inereasel in every tre1tment the longer the exg3riuent ran. The larger the amount of urea ailed to the soil, the more nitrates there were fermei, but the iner31:3e u nit r:1tes were not in proportion to the extra amounts of urea aiiei. In only the two smallest aliitions was the e an inlieation that all the urea aiiei 113 uitrifiei in the time of the xperime nt, The eeility of the soil inere1eed more or less with the time of the experiheht eel the amount of urea aid— ed. Tnie meene that the more nitrates there were trelueel the more the acidity inereze i. (D lhe ecuerletretien of the soil solutien inereasei with the 1ilitm on 01 urea 1ni 1uring the time of the ex This 1 ans that the more nitrate; the'e were greiugei, the were con eéntr1tel the solution became. hone ver, t W1 13? de ion was net all due to the extr1 nitrates re im1 f themselve3, 11thcu5h theJ ; 331 ibly in- l The Selena, hex 1nd 5 ezi soils were treated with urcje 13 1 top iressin5 of 1333 tennis per acre, 1130 with urea nixed in the oil at re 33 u: to 1333 geunl3 per acre sizx iner13 . The" were aspiratei trom time to time ani any ammon- ia given off W13 ietarm inel. The esults werellneonelu- sive but iniie1t3 that urea nixej with the soil in the a- mounts u3e 1 iii not e1u33 ammonia to be lost b5 volatili- zatien in any 1g;'*e113l amount . The to; dressings of the Fox and Colema soils lost eiwenia, while that of the Miami soil lost little if 3L3. The were nitr1te3 there were preluee‘, the e33 e: .nehia there was velitilizei. Tex 1nl fiiami soils that hei urea aiiei in amounts ranging from none to 1333 peanie ter aere six inches, 1nl kett three months, were leached with water. Four leachinge were male 1ni tne pH values of the extraets 13 well as of the soils before and efte eeeh extraeticn we 3 determined. The washel soils were «egt tor ten 1153 afte' which the pH was again determinei. '3 The results Show that the soils eeeame lees 1eii with each leaching, although thet greatest ehuhfie" 13 1 rule were brought about by the first l211u1ng With the execu- tion of the heaviix 3t tre1tze its, we n 'l 3 the 5”1 3 sans; the iiiferent treatments in each soil to become about 111x; in th. The loaere 1eiiity of the soils [rem waei1ng 1) thought to be partly iuet to the wzsning cut cf scne of tne 3311 00110113 frcm the 3c1l. T e 0 tree 3 frcn the hiam' soil were usually were 3311 than the extreeted soils, twe 1th the FOX 3011.TL 3:1 tree SCI 1. 1'1 :3 311 eae sci vil H I {\3 I csite being the 3133 w nus the ex- ts from the two 36113 ere sleet r in ;n then were the 13 themselves. This 13 thought possibly to be due to 30116113 in the extracts from the sails he1n3 nearly :3. 1he extraets from the 30113 beee me 1-333 3311 with h leeeh1n3.fitter 3t3n11n3 for ten 1313, the extracted 13 111 not eh3.3e 1n: n in p. except that tn most hee- 5 t eatei 3c113b13'3311 ' f (D \J (x '1 (D ‘9'; n (J P1 1.4.- o Alliscn, F. 5., Tr3h31, J. 1., enn W‘Murtr35, J. G. F1311 experiments with nitrogenous fertilizers. U. 3. Dept. Afr. ?u1. 11(0 (Jan. 22, 1321) Allison, B. n., Jl'et, 1.3., SKinner, J. J., 3nd Hei1,F. 1 s with atmospheric nitrogen fer- latei OCW1;WUI15. qur. Afr. nee. v. “’1-376. (May 31, 1924) Arrhenius, U. The potential acidity of soils. Soil Sci. v.14, pg. 233. (1922) Eiilmann, 5. 0n the measurement Cf hyiregen-ion neentretions in soil by means ct the quinhsdrcne eieetrc e. do ur. r. 331. v.14, no.2 gr.&’ 233, (1921) PCfiCPH3, T. Ure 33 3n1 SC1e other source" cf nitrcgen for green plants. 111n3_er ' 3 " 35161. v.172, {p.4eg- 49*. (191:) in Exp. Sta. Ree. v.15. 1,519. k‘: (I: p P: o '1 OJ :7 Bouycuecs, 3. J., ani «eiccl, 1. M. The freezing point 13th01 as a .ew means of measur- ing the ecneentraticn cf the 3:11 scluticn lireetly in the 3:11. fliehigzn Tech. Bul. 21. (1915) r1 .., 51 ,‘ .', 1",. ." a.“ LCU30U3CD, a ., 3n) meeeel, n. 1. . J Further studies of the ‘reezing point icnering of -40- r1- soils. Michigan 13th. Bul. 31. (1915) f The nature of the acidity of the 3clloiial 3lay of 3313 soils. Jour. 133.. Chem. Soc. v.45, no.11, ;. 9- Bradfield, H. The chemical nature of a colloidal clay. Missouri 333. Bul. EC. (1333) 10- Christensen, H. B. On the influence of humus naterial in urea jeeem;osi- tion. Jentbl. 33Kt. 2 Aet.27, no. 13-16, Lp.33'- 302. (1310) in iXp. Sta. I 33. v.23, p.732. 11- Shristensen, H. R. On tn'3 intlursa nee cf humus snbst3n33s on th3 33 ago- siticn of area into annonia. Tidsehr. Landbr. n eavl.1/, no.1, pp.79-109. (1310) in Exp. Sta. 833. "W'N v.44 , p.343. 12- Colenan, L. C. Investigations on nitrifieaticn. Centbl. Bakt.2 Abt.30, no.1Z-11. (1308) in 3x3. Sta. Ree. v p.513. 13- Cowie, 3. A. Decomposition of Cyanamide anl dieyenodiamiie in the soil. Jour. Air. Sci. v.3, part 2, p.113, (1919) 11- CI’O’L‘Ithm' 5;. M. Stud 33 cfi soil reeeticn Ill, The determination of the hydrogen-itn concentration ct soil susgensiong by means of th3 hyirogen electrode. Jour. Agr. 331. v.13, part 2, pp,201-221. (Agril, 1325 15- Serlaeh, Tne action of new nitrogenous fertilizers. Mitt. Dent. Laniw. Ges3ll.31, no.7, gt. 30-.~. (1916) in Wxg. Sta. Ree. v.33, p.323 {3‘ 16- van Barre veld, 3. H. Absorgticn ani legening of the nitrogen when 1P8? and ammonium enlori‘ ie are 3931131 33 fertilizers. 17- 18- {\t ”‘3 21- 23- {V1 C) ‘1 I -4137- Lake. Arehiv. vcer d3 Suixcriniustrie in Ne1erlan1- iseh IndiO. no.8 Seerabaja. (1924) in Int Rev. cf 3:1. anJ Prae. Agr. as. v.2, nc.4, p.857. (1923) haselucff, E. Experlments nith nitrogeneus fertilizers. Landw. V3r3. Stat. v.81, nc.1-2. (1914) in pr. Sta. Ree. v.31, p.519. K 1;;3 n, H. F'1131tilia 3r 3xy3riments Cf lime-nitrogen. (1915). in Ex;. with transfermaticn {rciuC1ts Vers. Stat. v.83, ne,1-Z. v.34, ;.25. Lanjn. Sta. 833. '7 1| . vcn Knieriern, E‘ertilizer experirents with iifferent new nitregu - eus tertilize r3 3. Witt. Dent. Lanifl. 335011. v.37, nc.13 (1922 l. in Ex; Sta. 533. v.48, p. 721. p 651. Krase, N. H., and Saidy, V. L. 33nthesis of urea from :11mcnia anj Jeur. Indus, and Eng. Chew. v.11, (1922) carbon dicxi1e. ne.7, gy.511-616. 13r11nn O lnv V33tigatieus on I 1.1 :1"- 1ifferent f3rtilizatien 4‘3stjeus. Arb. Deut. Lania. 333311. c.297. (1319) in Ex;; Sta. 303. V0 441, Po {31’70 Lima-1n, '3'. 8., 9.111 311123335, 19.3. Am1cnifiability versus nitrifiability as a test for tne relative availability of nitrogenous fertilizers. 1119112111, J. 53., 3111 113113-111, H. C. Tne agricultural value cf some cf the no we r nitregm 1- eus fertilizers. Ame FertiliZ3r, v.62, no.4, 1; 25-33. (Feb. 21, 1323) Litman, J. 3., et 31. Repert of the soil 313 ist anl b113t3 r1 ielegist. New Jersey Sta. H3; . 19CB, p;.91-147. Littauer, F. CA3 (‘ CD *3. - [17- 1b oomgo ositicn of urea in soil. Zoit 3hr. Pflanzon- ornaahr. u. Duon un3. v.3, no.3, niss. pp.135¢173. (1321) in Exg. Sta. 833. v.51, ;.818. Loonnis, F. entribution to the Knowledge of nitrogen bacteria. Contbl. Baxt.2 Abt.14, no.13-20, pp.582-604. ( 903) in Exp. Sta. H33. v.17, p.447. ’1 WzCool, M. W., and Nheeting, L. Q. Wovenont of soluble salts tnroujh soils. Joan. Agr. Hos. v.11, no.11, {p.531-34/. (033. 10,1917) (2 O M33001 M. W., and Hnootin3, L. Tho infuuonoo c1 the P3 aoval “3113113 on som3 soil proportios. 3011 831. v.15, no.2, pp.99-1OZ. (1324) (3 W3Cool, M. M., and (heatin;3 ,L. C. Stuiies on the colloidal 1L1t3 rial ct certain soil “C111?S in W13nigan. Ropt. B'itth Ann. teat. Amer Soil Survey Assoc. Bul.6, v.2, 1p.133-125. (1321) 111': juinn, A. F. Th3 a3tion of di3yandiam ij ani guanyl proa "ulghato cn plant grofltn. Soil S31. v.17, no.6, pp.487-EOO. (Juno, 1&24) W W Marshall, 9. 1. Wiorobiolojy. Zni. oi. rov.& onl. F. Blakiston's Son & 80. 1hila1olphia. (1917) ‘I Willar, o. E. Relation botw3en 3101031331 33 tivitios in tho pros- 3 of various salts and the concentration 31 the 11 solution in Ji1fer3nt Class:3 s of soil. Jonr. 1?. Has. v.13, no.4, {p.213-221, (Agr. 22, 1918) 1unitscherlicn, 1. 1., Von :3u3 ban, 3., ani lffiqnd, P. Exgen11ont: aitn various nitrogenous fertilizers. J u c r. ban in. 86, no.3, pg.187—19&. (1915) in ixg. Sta. 803. V. 41, 1.23. 909p, M, Pot f3rtiliz3r BXporimonts with 11on nitro; enous 13r- tilizsrs. Witt. Dent. Lanix. 333311. v.31, no.4, 3&- 05 (f 11- finnn, U. m . \ ~ 1.3 beetor 1" . .7.) i OlrJ'u (1312 5 in soil as a function of grain re content. Vienigen Teen. 3u1.1o. '3 Rest, 3. b., ani Eieger, E. n. infect of drying. ani storage llth t’ne nyirogen-ion concentration of 301 ;;.121-136, (AnJ .3" - ~ I at . ~ 7‘ c ’ ) 'nrles. 3011 C31. v.10, no.4, ,nneineaini. Fieli eXparinents on the -etion of new forms of ni- trojen. iitt. Dent. Lenin. 393311. v.31, “0.3, 1?- 16-20. (1915) in ixp, Sta. Ere. v.35, p.437. 0 cnneiieaini. Heealts of further nitrogen exgerinents. Lenin. Mennsehs Siensei. v.20, no.16, ;;.153-155. (1318) O ' I‘ .N ' T} ’ » I h‘ .‘ ’ O) in bxg. :ti. no}. v.14, ;,fe4, (I) 5—. V (/4 ’3 ,hreiner, 0., inl Feilyer, 3. H. Dolorimetriz, turbiiit), uni titration m‘ u i in soil investigations. U. 3. Bar. Soils Bu1.31 (1306). :4.uinr13, C. H . Stniies on aetive bases ari excess 33113.. Niehigan Tech. Eu1.57. (1 “ids in mineral ' V._,_.n' vgurdiy, .J. h. k m Soiltox method for soil reaction. eement, kill anl Quarry, June 5, 1923. Stutzer, A., et 31. Five years fertilizer exgerimsnts in East Prussia. Arb. Deut. Lanln. Desell. no.258. (1914) in Ex;. Sta. R33. v.31, p.521. Taexe, B. Tne action of certain new nitrogenous fertilizers cn saniy and roor soils. Kitt. Ver. Fceri. Eoornultur Dent. Roiene. v.32 no.23, p.411 (1914) inn Exp. 9 fi , . ,, a 3. Hes. v.0 , p.50, 44- Werner, E. A. ‘11‘ 3 r" - '« ~ ’ ,. nlr h S n n '-- .no uHCfllotP) ot urea. one 10 rapno on bitcmx .15- try. LOD’M! n3, Green, 1 60. London. (1L33) 45- JABStiné, L. C. Some physical ini JLQL’ r gert'es of several soil grofiles. Eienigan Tech. 801.62. (1324) 46- WhOOting, 1“ CL UGrtain relationetigs between 3”Jel salts and the nci: ture of soils. Soil :31. v.13, no.4. FF. “”7- 0 L," .' t)" 3;]’_/. (AIP.’ t‘fi;()) - ,9? '51! , $9”? 1:331; 1::an w" ;'I, ‘15‘