420-710~E~i1i TEXAS AGRICULTURAL EXPERIMENT STATIONS i__________:i BULLETIN NO. 129 June,'1910 STUDIES 0E THE AMMONIA-SOLUBLE ORGANIC MATTER 0E THE SOIL BY G. S. FRAPS AND N. C. HAMNER POSTOFFICE COLLEGE STATION, BRAZOS COUNTY, TEXAS ECKMANN-JONES ., 19 10. TEXAS AGRICULTURAL EXPERIMENT STATIONS. OFFICERS. GOVERNING BOARD. BOARD OF DIRECTORS A. AND M. COLLEGE. K. K. LFGETT; President . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Abilen~ '1‘. D. RQWELL, Vice-President . . . . . . . . . . . . . . . . . . . . . . . . . . ..Jef‘ferso1 A. HAIDUSEK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..La Grang J AhiES CRAxrizNs . . . . . . . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . .Housto1 WALTON PETEET .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Dal1w E. R. KONE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Austi1 A. R. ll/[OCULLUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Wac< ‘W, P, SEBASTIAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Brc-ckenridg< PRESIDENT OF COLLEGE. B. '1‘. MILNER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..College Statior SIATION OFFICERS. H. H. HARRINGTON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Director F. W’. CARSON . . . . . . . . .Assistant to Director and State Feed Inspectol M. FRANCIS . . . . . . . . . . . . . . ." . . . . . . . . . . . . . . . . . . . . . . ..Veterinarian G. S. FBAPS . . . . . . . . . . . . . . . . . .- . . . . . . . . . . . . . . . . . . . . . . . . . .Chemist J. C. BURNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Animal Husbandry H. N ESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Horticulturist H. L. MOKNIGIIT. . . .i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Agriculturisi WILMON NEWELI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Entomologist RAYMOND H. Pom). . . . . . . . . . . . . . . . . . . . . ....Plant Pathology N. C. HAMNER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Assistant Chemist E. C. CARLYLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Assistant Chemist J. B. RATHER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Assistant Chemist O. W. CBISLER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Chief Clerk F. B. N AvAiLlyit“ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..:Stenographer; A. S. WARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . fitenographer? STATE AGRICULTURAL EXPERIMENT STATIONS. GOVERNING BOARD. Hrs EXOELLENOY, GOVERNOR T. M. CAMPBELL . . . . . . . . . . . . . . . .Austin LIEUTENANT GOVERNOR A. B. DAVIDSON . . . . . . . . . . . . . . . . . . . . ..Ouero COMMISSIONER OF AGRICULTURE, HON. E1). R. KONE . . . . . . . . . . .Austin DIRECTOR OF STATION S. H. H. HARRINGTON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . College Station SUPERINTENDTCNTS OF STATIONS. A. T. POTTS, Beeville Station . . . . . . . . . . . . . . . . . . .Beeville, Bee J. L. WELCH, Troupe Station . . . . . . . . . . . . . . . ..Troupe, Smith W. S. HOTOHKISS, Lubbock Station . . . . . . . . .Lubbock, Lubbock J. T. CRUSE, Fort Worth Station . . . . . . . .-.Fort Worth, Tarrant J. H. 7170M, Pecos Station . . . . . . . . . . . . . . . . . . . . . .Pecos, Reeves H. C. HOLMiEs, Denton Station . . . . . . . . . . . . . . .Denton, Denton —-—— , Temple Station . . . . . . . . . . . . . . . . . . . .Temple, Bell T. S YORK, Spur Station . . . . . . . . . . . . . . . . . . . . . Spur, Dickens , Angleton Station . . . . . . . . . . . . .Anglet-on, Brazoria J . K. FITZGERALD, Beaumont Station . . . . . .Beaumont, J efiferson county county county county county county county county county county NOTE.—The lllaaln. lStatlon is located on the grounds of the Agricul- tural anal Zllecha/rzical College in Brazos county. The postofiice address is College Station, ’l’e.ccas. Reports and bulletins are sent free upon application to the Director. [Blank Page in Original Bulletin] CONTENTS. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 PART I-—ESTIMATION_ OF HUMUs. Methods of Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10 Comparison of A. O. A. C. and Snyder Methods . . . . . . . . . . . . . . . . . . . . . . .. 11 Correction by Peter-Averitt Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Filtration through Unglazed Porcelain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 Precipitation of Clay with Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 14 Electrolysis to Remove Clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15 Evaporation to Remove Clay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15 Precipitation of the Humic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1'7 Effect of Extended Washing with Acid . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . .. 18 Effect of Various Strengths of Ammonia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19 PART II-—FORMATION or AMMONIA-SOLUBLE QRGANIC MATTER IN THE SoIL. Method of Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23 Apparent Formation of Humus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24 Added Organic Matter Contains Ammonia-Soluble Material . . . . . . . . . . . . . .. 24 No Formation of Humus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 25 Effect of Amount of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 28 Effect of Nature of Soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 28 Effect of Nature of Organic Matter. . . . . t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 PART III—_-CoMPos1T1oN AND PROPERTIES OF HUMIc Aoms. Methods of Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 Acidity of Humic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 Precipitation of Humic Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32 Further Studies of Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 33 Composition of Humic Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ._ . . . . . 34 Solubility 0i Humic Salts . . . . . . . . . . . . . . . . . . . . . . . . . f . . . . . . . . . . . . . . . . . . . .. 36 Effect of Ammonia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 37 Effect of Carbonates of Lime and Magnesia . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 337 Hydrolysis of Humic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3s Diffusion of Humus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38 Composition of Humic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Alcohol-Soluble Humus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 44 The Clay or Ash Associated with Humus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45 Composition of Clay Precipitate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 46 Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 48 [Blank Page in Original Bulletin] STUDIES OF THE AMMONIA-SOLUBLE ORGANIC MATTER OF THE SOIL. - G. S. FRAPs, Chemist. N. C. HAMNER, Assistant Chemist. Part I—Estima.tion of Humus. Part II-Formation of Humus. Part IIL-Composition and Properties of the Humus. Under the Adams Act of the United States government, providing For scientific investigations by the Experiment Stations, the Chemical Division of the Texas Station has undertaken extensive soil studies. A portion of these studies is concerned with the organic matter of the soil, and this bulletin presents some of the results of the investigation. This bulletin is strictly technical, and intended for scientific readers only. The ultimate objects are for practical agriculture, but the means and methods of the investigation must be discussed in technical language. The importance of estimating the organic matter of the soil has been recognized for a long time. Methods based on the complete oxida- tion of the carbon were used, and are still in use. The total carbo- ‘ naceous matter is calculated on the assumption that it contains 58 per cent of carbon, though the precentage of carbon in the organic matter of the soil is known to vary Widely. All the organic matter of the soil is not in the same condition, but exists. in various stages of decomposition. This fact has also been rec- ognized for a long time. It has been held that the black or dark-brown organic material in the soil, resulting from the decay of animal or vege- table matter introduced in the soil, has a much higher agricultural value than the undecomposed organic matter. We have not been able to dis- cover experimental evidence in support of such opinion. It is well known that the organic materials in the soil are mixtures of various compounds, and are constantly undergoing change. Material is present in all stages of decomposition, from the original unchanged compounds found in plants or animals, to the product of complete oxidation (carbon dioxide), which is no longer organic in nature. The organic matter soluble in ammonia. is supposed to represent the ‘ decomposed organic matter of the soil, and, therefore, if the theory cited above is correct, the more valuable organic matter. Therelation between the two forms of organic matter is largely a matter of color; while. the ammonia does not extract all the organic matter from the soil, it does extract practically all the black organic matter, leaving the’ soil residue nearly white. The organic matter of the soil soluble in ammonia is termed humus in America. The fact that the ammonia-soluble organic matter is of more value than that not soluble in ammonia, has not, in our opinion, 8 TEXAS AGRICULTURAL EXPERIMENT STATIONS. O been established. In Germany, the ammonia-soluble organic matter is not estimated, but the total organic matter is judged from the total amount of carbon in the soil. The term huvnus is used in this paper for convenience in designat- ing the ammonia-soluble organic matter, and in using this term in this way We do n.ot mean to subscribe to any theory concerning the im- portance of the ammonia-soluble material. PART I—ESTIMATION OF HUMUS The estimation of ammonia-soluble organic matter is based upon the work of Grandeau. Compt. rend., 1872, 988.) He said that the black earth‘ of Russia, which is a very productive and durable soil, contained 0.20 per cent phosphoric acid, and 0.16 per cent was soluble in ammonia ' with the organic matter. Grandeau decided that the fertility of the soil was closely related to its content of mineral matter extracted with the organic matter soluble in ammonia. He considered the phosphoric acid combined with humus one of the most important parts of the soil. The theories of Grandeau have found little acceptance abroad, though they have been accepted by a number of chemists in this country. Snyder (Bulletin 30, Minnesota Experiment Station) compares three cultivated soils With three virgin soils from the same locality, and finds that the latter contain more humus, more nitrogen, and more phosphoric acid associated with the humus. l Humus Humus P1105" Per piloyéc C t. c1 en Per Cent. Warren———Native .................................................................. .. 5 .34 .07 Cultivated ............................................................ .. 3 .02 .03 Crookston—Native .............................................................. .. 5 . 16 .06 Cultivated ........................................................ .. 2 .87 .03 Marshall—Native ......................................................... . .- ..... .. 5 . 12 .05 Cultivated .............................................................. .. 2 .60 .03 In Bulletin 40 of the Minnesota Experiment Station, Snyder com- pares two more virgin soils with two cultivated soils, finding here also that the phosphoric acid decreased as the humus decreased. l Humus Humus P 1105f per phonc Cent. Acid Per Cent. Wilkins County, soil cultivated 2 years .......................... .. 5 .30 l .05 Cultivated 10 years .................................. .. . 3.38 .03 Chippewa County, native soil ........................ .. 3 .97 .07 Cultivated 23 years .............................. .. ...... .. 2.59 .03 Dakota County, soil cultivated 35 years .......................... .. 2 .45 03 Cultivated 42 years ................................................ .. 3 .46 03 STUDIES or AMMONIA-SOLUBLE ORGANIC MATTER or SoIL. 9 He makes the following remark in regard to the mineral matter asso- ciated with humus: “The humus materials, usually known as humic acid, when extracted with a 2.5 per cent solution of ammonium hydrate or any other dilute alkali, and then precipitated with acid, yield from 5 to 25 per cent, according to the nature of the soil, of a brownish red ash. This ash is evidently in chemical combination, because if merely soluble in the alkaline solutions used for extraction, the mineral matter would not be precipitated with hydrochloric acid, but would be removed in the filtrate and Washing solutions employed.” The average composi- tion oi’ eight samples of ash from good productive soils yielding 2.5 per cent humus was found by Snyder to be as follows: Per Cent. Silica ............................................................................................ .. 61.97 Potash ........................................................................................ .. 7 .50 Soda ............................................................................................ .. 8 .13 Lime ............................................................................................ .. .09 Magnesia .................................................................................... .. .36 Ferric oxide ................................................................................ .. 3 .12 Alumina ...................................................................................... .. 3 .48 Phosphoric acid .......................................................................... .. 12.37 Sulphuric acid .......... ............................................................. .. .98 Carbonic acid ............................................................................ .. .1 .64 In Bulletin 53 of the Minnesota Experiment Station, Snyder reports a study of the effect- of decaying organic matter upon the mineral mat- ter of the soil, in which it appears that the amount of phosphoric acid and potash soluble along with the humus is increased by the action of decaying organic matter in a period extending over a year. “Cow manure, green clover, and meat scraps produce valuable forms of humus, rich in nitrogen. The humus produced is capable of combining with the phosphoric acid and potash of the soil to form humates.” Bulletin 89 (1905) contains similar studies with glutin, gliadin, etc, in which the same conclusions are reached. Ladd (Bulletin 35, North Dakota Station) found in a new soil 0.192 per cent phosphoric acid soluble with humus, and in an old soil similar to the soil first named 0.179 per cent. The humus in the new soil was _ 2.53 per cent, in the old soil 1.56 per cent. Ladd concludes that the cropping decreases the humic phosphoric acid and the humus. The dif- ference in phosphoric acid soluble with humus in these soils, however, is no greater than might naturally occur, due to error of analysis, error of sampling, and difference in the original soils. The humus and humus phosphoric acid were determined by Ladd at ' different periods, in a crop rotation plot, with the following results: i Phos- Humus ph9rw p l with C f; ‘ Humus e ' J Per Cent 1891 ...................................................................................... .. 5 .35 .079 1894 ..................................................................................... .. 6 . 82 . 09 1 1896 ...................................................................................... .. 7 .86 . 1 17 10 TEXAS AGRICULTURAL EXPERIMENT STATIONS. u Ladd also made analvses of the humus extract from twenty-four soils} A summary of the analyses is as follows: ' Percentage in soil Average lMaximum Minimum - 1 9.150 l 15.260 3.84 Humus ...................................................... ...... .. 4.770 7.900 1.56 Total Phosphoric Acid .................................. .. .269 .400 Trace Phosphoric Acid in .138 .199 Trace Percentage of total Phosphoric Acid in Humus .......................................................... .. 51 .300 112 (i?) Trace Percentage of organic matter in Humatesw] 52 .100 70 .800 40 .60 By “humates” Ladd means the total amount of material removed with the ammonia. Snyder (Bulletin 89, Minnesota Experiment Station) claims that A gliadin and egg albumen, in decaying in a soil, increase the phosphoric acid. soluble With humus. METHODS OF ANALYSIS. In the estimation of humus, the humates of the soil are decomposed with acids,'thereby setting free the humic acids and extracting the lime. The soil is then treated with ammonia, the clay allowed to settle, and the humate solution evaporated, weighed, ignited and reweighed. The loss i.n iveight is taken to be “humus.” The organic matter contains ammonia which comes from the ammonia solution used to extract it. The various methods of analysis used differ; first, in the manner of decomposing the humates and dissolving the organic matter; and, second, in the methods for getting rid of the clay. The method of the Association of Official Agricultural Chemists and that of Snyder differ in the procedure for decomposition of humates and solution of the humus. The differences, however, are only dlTTQTGHCQS in manipulation. In the first named method the soil is extracted with acid on a funnel, while in Snyder’s method the soil is washed by de- cantation in a flask or beaker with successive portions of acid. In the A. O. A. C. method the ammonia is added to the soil in one portion, while in Snyderis method the soil is extracted with successive portions of ammonia, and then made up to volume. Snyder’s method is more nearly like_ the original Grandeau method, although Grandeau extracted on a funnel, and, as Houston has pointed out, did not secure complete extraction. ’ The clay is most difficult to remove. It is deflocculated by the am- monia, and goes in suspension. It contains combined water, which is lost on ignition and is, therefore, calculated as “humus.” If the soil contain much humus, the clay may apparently settle in a comparatively short time, but if ammonium sulphate is then added to the apparently clear liquid, additional clay usually is precipitated. If little humus is present, clay may remain in suspension six months or longer. Such soils appear to contain much humus, yet really contain little. We have ammoniacal soil extracts in which clay and organic colloidal matter have been in suspension for over two years. STUDIEs OF Aitiroxrx-SOLUBLE ORGANIC MATTER OF SoIL. 11 '.l‘hc revised methods of the Association of Official Chemists require filtration of the ammoniacal solution, and provide that “The filtrate must be perfectly clear.” How the filtrate is to be made clear is not specified, and for many soils this provision must be disregarded, or else the method abandoned for these particular soils. Peters and Averitt (Bulletin 126, Kentucky Agricultural Experiment Station) propose to correct for the clay present by subtracting 1O per cent of the iveight of the “ash” from the loss on ignition. As they say, this method is uncertain, but better than none. We shall discuss this method further on. 1*‘. K. Cameron filters through porous porcelain to remove the clay. The clay is removed, Without doubt, but possibly some organic matter also Mooers (Bulletin 78, Tennessee Experiment Station) proposes to evaporate the solution, and to take up the residue in ammonia. This removes a portion of the clay, and, by repeated evaporation and solu- tion, it may be possible to remove more. These methods have been subjected to more or less study by us, and the results of our work Will be presented in the following pages. COMPARISON OF A. O. A. (3., AND SNYDER METHODS. The A. O. A. Cl. method is described as follows: Place 10 grams of the sample in a gooch crucible, extract with 1 per cent hydrochloric acid until the filtrate gives no precipitate with am- monium hydroxide and ammonium oxalate, and remove the acid by washing the soil with water. Wash the contents of the crucible (includ- the asbestos filter) into a glass-stoppered cylinder, with 500 c.c. of 4 per cent ammonium hydroxide, and allow to remain, with occasional shaking, for twenty-four hours. During this time the cylinder is inclined as much as possible, without bringing the contents in contact with the stopper, thus allowing the soil to settle on the side of the cylinder and exposing a very large surface to the action of the ammonium hydroxide. Place the cylinder in a vertical position and leave for twelve hours, to allow the sediment to settle. Filter the supernatant liquid (the filtrate must be perfectly clear), evaporate an aliquot, dry at 100° (l, and weigh. Then ignite the residue and again weigh. Calculate the humus from the difference in weights between the dried and ignited residues. NOTE.—-If the extraction of humus consists merely in the decompo- sition of the humates with production of free humic acid and union of this acid with ammonia, the action should take place immediately, and the extraction should not require so much time. It would appear that ‘the ammonia is reacting with organic material in the soil to form solu- ble compounds in much the same way as the lignin of p-lant- tissues acts with ammonia. ’ Snyder’s method as used by us is described as follows: Weigh 20 grams of the soil into a wide-mouthed cylindrical bottle f of about 500 c.c. capacity’, provided with ground-glass stopper. Add to the soi_l 200 c.c. of the 1 per cent hydrochloric acid. This should 5; be added cautiously or carbonates may cause frothing over and shake from time to time during the day. night and in the morning decant 0E the liquid into a filter when neces- . sary. Add 200 c.c. of the hydrochloric acid to the residue, using a Stopper Allow to stand over 1.2 TEXAS AGRICULTURAL EXPERIMENT STATIONS. part of the acid to rinse back from paper to bottle any adhering soil. Shake the bottle from time to time and again allow to stand over night and again decant. tlepeat this until all lime is extracted from the soil. Ntiw wash the soil from the bottle 0n a filter paper and wash free of hydrochloric acid. When thoroughly washed, wash the soil back into the bottle, using 200 c.c. of 4 per cent ammonia. Shake every half hour during the day and allow to stand over night. In the morning decant the liquid ofl’ in bottles of 1 liter capacity. Add to the soil in the bottles another .200 c.c. of ammonia and again shake from time to time during the day and allow to stand over night and decant in the morn- ing. Repeat the extracting with ammonia until all the humus is re- moved and the extract has little color. The extracts are now poured into a liter graduated. flask, made up to the mark with distilled water, and allowed to settle for one week. Pour off eight to nine hundred c.c. of the solution without disturbing the sediment in the bottom. Wash the bottles and pour the solution back into them. The solution must be thoroughly shaken before each. aliquot is removed for analysis. Weigh a platinum dish, pipette into it 100 c.c. of the extract and evap- orate on a water bath to dryness, heat for three hours in a steam bath, cool in desiccator and. weigh. This weight less the original weight of the dish gives total solids. Now ignite thoroughly and Weigh. Report ash and l.oss on ignition. a TABLE 1. Comparison of Snyder and A. O. A. C. Methods for Humus. . . Corrected Loss on Ignition Ash LOSS on Ignition Soil No. ' A.C. A. C. Snyder A.O. A.C. Snyder A.C. A. C. Snyder 816|Per cent in soil... .88 .70 . 1.63 2 .92 .72 .41 817 Per cent in soil... 1.19 1.29 2.95 4.03 .90 .89 823liPer cent in soil... 1.86 2.39 5.87 9.69 1.28 1.42 829~,Per cent in soil...| 9.10 l 9.12 .60 1.52 9.04 8.97 326 Per centin soil... 2.48 j 3.06 1.77 l 2.06 2.31 1.86 134 Per cent in S0il...l 1.97 l 2.06 3.18 5.89 1.65 1.47 ’ l Average l 2 .91 l 3 .10 l 2 .66 l 4 .36 2 .65 l 2 .50 Table 1 shows a comparison between Snyder’s and the A O. A. C. method. Both extractions were carried on at the same time and with the same solutions. Snyder’s method gives a greater loss on ignition but the solution contains more clay (ash). If we correct by the Peter and Averitt method, by subtracting 10 per cent of the clay, we find that Snyder’s method gives lower results than the A. O. A. C. method. '.l‘he correction for ash is, as we have pointed out, an uncertain quantity. lVe consider that the preference between the two methods must de- pend upon the e-ase of manipulation. The Association method has the advantage of bringing less clay into suspension, while it appears to ex- tract as much organic matter, if not more. With heavy clay soils the soil may gum during the extraction with acid per theA. O. A. C. method, and require a very long time for extraction and washing. STUDIES or AMMONIA-SOLUBLE ORGANIC MATTER OF SoIL. 13 lUorrection by Peter-Ameritt illethod.—-lf no correction is made for water lost on ignition by the clay in the ammonia suspension, the lts of the analysis may be entirely Wrong. Soils which really con- practically no humus may’ give a considerable amount of clay in ension, and, by the method, appear to contain considerable amounts ofhumus. l .__In correcting by Peter’s and Averit-t’s method, we subtract 10 per t of the clay from the loss 0n ignition. is pointed out by the chemists who proposed this method of correc- er contained in the clay of different soils. Yet We are inclined to’ feve that this correction is better than no correction at all. ‘Analyses of a number of samplesof clay precipitated by salts have in made by us, and the results are presented in tables in another por- ‘i: of this bulletin. The amount of loss by ignition in these clays is ewhat variable. On the other hand, the clay contains organic mat- , That is to say, there is no constant correctionwhich can be made. traction of a certain percentage of the clay is thus an uncertain cor- ion, but still better than none at all. his method will be referred to further in succeeding pages. filtration T h/rough. Unglazed Porcelainr-This method of purifying i. dissolved organic matter was used by Cameron, though it was not osed by him as a quantitative method. It has also been used by i‘ s (see Bulletin 82, Texas Experiment Station, page 28). I; order to test this method, the following experiment was performed: ne-half gram air-dry humic acid (prepared by us from soils) was lved in ammonia and made up to 250 c.c. and filtered through an ‘lazed porcelain filter, rejecting the first 50 or '75 c.c. Fifty c.c. of filtrate was evaporated to dryness in a platinum dish, and loss on ion and ash determined. The same determination was made on "goriginal unfiltered solution. (See Table 2.) . _ .ere was an apparent loss of organic material in filtering the humus tion. That is to say, some of the organic matter apparently did pass through the unglazed filter. In two instances, the apparent jwas very great, only half of the organic matter recovered. ‘i filtering these solutions, we used a Pasteur filter, which carried a f glass tube reaching through a rubber stopper to the bottom of the '_ The humus solution came in contact only with glass and por- i . ~ TABLE 2. Filtration of Humus Solution Through Porcelain Tube. Solids Ash Before After Before After 1,»: _ it is not a certain method, on account of the different amounts of - Weight in grams .............................. .. .1003 l .0669 .0051 .0036 , Weight in grams .............................. .. .0999 .0983 .0059 .0202 l; Weight in grams .......... .. .................. .. .0998 .0904 .0054 .0002 "Weight in grams .............................. .. .0988 .0453 .0030 .0022 . Weight in grams .............................. .. .0991 .0571 .0015 .0011 Average ........................................ II! .0996 .0716! .0042 .0054 not corrected by Peters and. Averitt’s method. Filtration through p0 celain gives the lowest results. The greatest differences are With s0' .98 and 137. ' 14 TEXAS AGRICULTURAL EXPERIMENT STATIONS. The water in the pores of the porcelain filter appears difficult, moval. For this reason, we tried another series of experiments. One gram of humic acid (air-dry) was dissolved in ammonl made up to 500 c.c. With 4 per cent ammonia. Fifty cubic cent were evaporated in a platinum dish to determine organic matt ash. The remainder was filtered through an unglazed porcelain‘ (as described above) into a measuring cylinder. The first tw tions of 50 c.c. each were rejected. The third, fifth and seventy; cubic centimeters were measured With a pipette, and evaporated* platinum dish as before. The results are presented in Table 3; ll TABLE 3. Successive Filtration of Humus Through Unglazed Porcelain. N0. s52 No. 934i Wh-"Tirlr-Aenrnm Organic t Ash Organic Grams Grams Grams Original ...................................................... .. .0911 .0048 .0887 0 Third filtrate (50 c.c.) .............................. .. .0847 .0015 .0799 ~ '1 Fifth filtrate .............................................. .. .0794 .0021 .0856 \ Seventh filtrate .......................................... .. .0842 I .0011 .0878 an Raf-i’ It would appear that, even if care is taken to reject the first i tions which come through the filter, the loss of organic matter may 10 per cent of the quantity present. This method is very tedious, it requires considerable time to filter such quantity of the liquid. T is also a possibility that some of the organic matter may not w: through the filter, as shown by the following experiment: ‘ When a solution of gelatin is filtered through this unglazed post“ lain filter, very l.ittle passes through: . '- Organic. solution, in 25 c.c. .......................................... .. .0905 grams First 25 c.c. filtered ......................................... .......... .. .0082 grams , Third 25 c.c. filtered .................................................... .. .0023 grams ,5 Gelatin was deposited on the outside of the tube. (See Bulletin i this Station.) g Precipitation of Clay with Salts-Ammonium sulphate, potassi“ sulphate, and other salts, will coagulate the clay and cause it to p f cipitate. If a non-volatile salt is used, the solution may be evapora J, to dryness and ignited. The diflicultv with this method is that if salt may be decomposed or otherwise partly lost on ignition, there causing an increase in the percentage of volatile matter secured. Table 4 gives the results of an experiment ivith three methods. Eva L. oration Without filtration gives the highest results. These figures STUDIES or AMMONIA-SOLUBLE QRGANIG MATTER or SoIL. 15 TABLE 4. Humus by Three Methods. Filtered, Precipitated Unfiltered, Pasteur with 0.5 gm. settled 24 Tube Potassium hours | Chloride Per cent .................................... .. 1.02 1.24 2 .22 Per cent .................................... .. .90 1 .08 3 .92 Per cent .................................... .. 1.12 ...... .. 5 .27 Per cent .................................... .. 1.00 2 .58 4 .88 Per cent .................................... .. 1.30 2 .20 3 .04 Per cent ................................... .. 1.05 1.48 3 .12 er cent .................................... .. 1.25 1.54 2.70 er cent .................................... .. 1.35 1.48 1.73 i Average................................ 1.12 1.66 3.36 ‘Qlillectrolysis to Remove Clay.—This method, tested in ammonia n, did not appear promising. The clay was precipitated in some ipbut stayed out of suspension only as long as the current was.. on. _ ect t0 .test this method further. ‘Evaporation- for Ziemora-l of Clay.-—"Mooers proposes to evaporate us solution to dryness, take up with ammonia, and evaporate if necessary. Finally, the dried residue is to be Weighed, ignited, ighcd again. r studies, we took up the residue both with water, and with ,_ a. The ammonia-humus which we prepared from precipitated ‘f: is easily, soluble in water, and it should not be necessary to dis- in ammonia. Table 5 shows a comparison between the method t evaporation, of one evaporation and solution in 4 per cent Ta, and one evaporation and solution in water. These solutions from different samples of one soil. _> method of direct evaporation, as is seen, gives too high results. ation and taking up with water brings much less clay into sus- g again than evaporation and taking up with ammonia. In the Ttion, however, a considerable portion of the clay has been ren- f: soluble, even if ammonia is used to take up these residues. A . I B h ' c Evaporated arlild Evaporatedf D‘ t taken up wit taken up ~ lrec Water Ammo i ' Loss on " Loss on Loss on U Ignition Ash Ignition Ash Ignition 1. Per cent of soil ........ .. 1 .78 4.86 .94 .09 r 1.11 2. Per cent of soil ........ .. 1.89 4.15 1. .29 .17 1.18 3. Per cent of soil ........ .. 1_.95 5.10 1.27 .14 1.42 t 4. Per cent of_ soil ........ .. 2.09 4.89 1.20 .15 1.30 5. Per cent of soil ........ .. 1.78 5.51 1.13 .14 1.24 a 6. Per cent of soil ........ 1.83 4.73 1.19 v .12 I 1.37 Average ................ 1.89 I 4.87 ‘ 1.17 ‘ v.14 ( 1.27 TABLE 6. Results of Table 5 Corrected by Peters and Averitt Method. Loss on Ignitiom-Percentage. A B ' C . ' Evaporated Direct ater 1. ............................................................ .. 1 .30‘ . .94 2 ............................................................. .. 1 .47 1 .27 3 ............................................................. .. 1 .44 1 .26 4. ............................................................ .. 1 .50 1 .18 5 ............................................................. .. 1 .23 1 .12 v 6 ............................................................. .. 1.36 1 .18 Average ........................................ .. 1.38 1.16 ' methods of evaporation and solution. Solution in water and solu 16 TEXAS AGRICULTURAL EXPERIMENT STATIONS. TABLE 5. Comparison of Two Methods For Humus. Table 6 shows these results corrected by Peters and Averitt’s met: The method of direct evaporation still gives higher results than g in ammonia gives very nearly the same results, the latter being so i? what lower. ' Table '7 contains a comparison between one evaporation and solu of the ammonium humate in (a) water and (b) in 1 per cent =. monia. These estimations were all made on the same solutions. p agreement between checks run at different times left much to be 1,! sired. It would appear that solution in 1 per cent ammonia is bet than solution in water. The xvater does not appear to dissolve all l‘; organic matter dried down with the clay. The method of evaporation and solution in 1 per cent ammonia, 1 tering off the clay, appears to us to be the best method so far propos for the estimation of the ammonia-soluble organic matter of the so' ‘s. Srunrns or AMMONIA-SOLUBLE Onearvrc MATTER or SoIL. 17 although the agreement between checks run at different times was not alivays satisfactory. TABLE 7. Comparison of Method of Solution of Evaporated Humus in Water and in One Per Cent Ammonia. CLoss ondlgnitganzgz ' - Ash orrecte by . Soil NO. Loss on Ignition A. Method Water Ammonia Water Ammonia Water _ Ammonia 876 ................ .. 1.70 2.04 .72 .76 1.63 1.96 939 ................ .. 1.84 2.28 .73 1.44 1.77 2.14 1203 ................ .. .86 1.48 1.10 1.45 .75 1.34 1075 ................ .. 1.71 3.07 1.40 3.14 "1.57 1.09 834 ................ .. .98 1.70 .35 .26 .94 1.67 129 ................ .. 1.08 1.49 .73 .66 _1.01 1.42 830 ................ .. 3.41 3.50 1.11 1.20 3.30 3.38 1582 ................ .. 3 18 3 .67 .90 2.28 3.09 3 .45 845 ................ .. 1 97 2.45 .66 4.09 1.90 2.04 851 ................ .. 1 68 2.25 .40 1.45 1.64 2.11 1202 ................ .. 1 53 2.94 1.61 3.33 1.37 2.61 844 ................ .. 1 15 1.52 1.35 .75 1.02 v 1.44 893 ................ .. 1 15 1.67 1.05 1.10 1.04 1.56 1595 ................ .. 1.24 1.67 1.20 1.30 1.12 1.54 829 ................ .. 1.20 1.86 .95 3.19 1.10 1.54 933 ................ .. 1.19 1.53 .90 2.49 1.10 1.28 934 ................ .. 1.62 2.58 .92 4.37 1.53 1.14 940 ................ .. 1.52 2.22 .65 ...... .. 1.46 ...... .. 941 ................ .. 1.33 1.80 1.40 3 12 1.19 1.49 Average........ 1.59 2 .19 .95 1.96 1 50 1.84 Precipitation 0f the H iurric Acid.——In this method, the humus is freed from clay by ammonium sulphate, the humie acid precipitated by hydrochloric acid, collected on a platinum gooeh, dried, weighed, ignited, and weighed again. '.l‘he loss on ignition is humie acid insoluble in water. This method may be expected to give low results. The humie acid is, to some extent, soluble in water, as is usually shown by the brown color of the filtrate. The method can not be expected to be quantita- tive ; at the same time, the amount of insoluble organic matter precipi- tated with acid is a matter of some significance. . 4 The results of a number of analyrses made by this method are given in Table 8. The amount of humus precipitated is, in many cases, considerably less than the corrected amount by the Peters and Averitt method. In some cases, it is equal to that quantity’. While, on the one hand, the loss on ignition residue, even when corrected, undoubtedly gives high results; on the other hand, the solubility of the organic precipitate will tend to give smaller results than the above method. These results are, however, of interest in showing the amount of organic matter which may be precipitated from the solution. by acids.‘ In terms of the un- corrected loss on ignition, the precipitated humie acid varies from 8 to A 9]. per cent. A part of this variation is, no doubt, due to the conditions 18 TEXAs AGRICULTURAL EXPERIMENT STATIONS. under which the precipitation takes place, and a part to the differences in the nature of the material. The method of washing the precipitate also affects its quantity. We believe that the Wash water should be slightly aci-d. We find that about two-thirds of the humus is precipi- tated. TABLE 8 Percentage 0f Precipitated Humus, Ete., in Soils. Loss eon Ignition Prefiilgiltgged ———————— Preci itated Divided b SO11 NO. . Cgrrected HgmllS Correctefipgss D123“ by P- & A- ‘itéftéifl? hdethod 816 ........................................ .. .44 .34 .41 117 817 ........................................ .. .75 .57 .59 194 823 ........................................ H 2.48 .56 .19 34 s29 ........................................ .. 1.7g 139 105 326 ........................................ .. 2.0 1. 3 . 78 134 ........................................ H 1.10 .97 1.01 1Q4 741 ........................................ H 3.28 2.95 1.74 58 742 ........................................ H 6.12 5.65 3.53 65 743 ..................... .. ................. H 4.64 4.09 . 74 744 ........................................ H 4.47 4.12 2.84 70 745 ........................................ H 5.87 5.55 3.73 67 746 ........................................ H 3.82 3.45 3.18 92 747 ........................................ ..' 2.77 2.38 1.02 47 818 ........................................ H 1.16 .81 .11 13 824 ........................................ H 1.23 .67 .23 34 829 ........................................ .. 3.22 1.43 .58 41 - 843 ........................................ H 3.85 2.71 .79 29 845 ........................................ H 3.28 2.52 .95 38 851 ........................................ H 1.98 1.46 .74 50 101 ........................................ .. 2.53 1.89 1.37 72 133 ........................................ .. 1.48 .97 1.30 130 180 ........................................ .. 1.24 .89 .62 69 182 ........................................ .. 2.03 1.39 1.14 82 332 ........................................ H 3.98 3.82 1 34 35 Average .................... H 2.73 2.18 1.39 64 Ejjteet 0f Extended Washing 704th xleid.—ln this experiment, two por- tions of the soil were weighed out. One portion was washed with acid the usual number of times; the other Was Washed double this number. The was-hing with water and treatment with ammonia then followed, as with Sn_yder’s method. The results are shown in Table 9. The ettect of the greater number of washings was to increase the quantity of clay which went into sus- pension. This increase varied from about 16 per cent to over 50 per cent in the three soils studied. The loss on ignition was slightly greater with the soils which were washed more times with acid, but when cor- rected by Peters and Averitt’s method the humus is slightly less. The extended “Yashing with acid appears to be unnecessary. STUDIES OF AMMONIA-SOLUBLE ORGANIC MATTER OF SOIL. 19 TABLE 9. Effect of Washing With Acid. Usual ‘Washing Washed twice as much I ._ Correct- I -_ Correct- Ash ed .Igni' tIdlrli Ash ed .Igni' L S tron Loss tlon ‘ Os Loss Loss i946 Percentage in soil .......... .. 4.88 6.28 4 .25 5 .26 9 .96 4.26 947 Percentage in soil............ 5.24 9.09 4.33 5.48 12.43 4.24 Percentage in soil .......... .. 6.36 6.74 5.66 6.39 8.84 5.51 _| ‘Average .................... .. 5.49 7 .37 4.74 5.71 10.41 4.67 jEfiect of Various Strengths 0f .41nm,0nia.—If the function of the a monia is merely to form an ammonium salt of the humic acid and ing it into solution, then the quantity ‘of ammonia used need only be amount necessary for this change, allowing for the absorption of in monia by the soil. If, however, the ammonia acts as a solvent for iganic matter, or causes it to undergo some chemical change so that it jters into solution, then the quantity of ammonia used must have some Qect upon the organic matter dissolved up to a certain point. It does ,1 follow that the quantity of organic matter dissolved must increase the quantity of ammonia. used increases, Without limit. gWe conducted two series of experiments to test the effect of the ength of ammonia. In one series the strength of ammonia varied w 0.1. to .001 per cent. Inthe other series, the strength of the _ onia varied from 0.1 to 8.0 per cent. In both series, the soil was {st treated with acid and washed With water, as in Snyder’s method. e quantity of ammonia solution used was 1000 c.c. to 20 grams soil, l, d in other respects the method was the same as Snyder’s method. I fThe results of the extraction with very dilute ammonia is shown Table 10. When the weakest ammonia was used, 1 mg ammonia is brought in contact with 20 grams soil. In our other work, we f; found that ammonia humate contains approximately 8 per cent monia. One milligram of ammonia would therefore dissolve about _i milligrams humic acid, or about 0.6 per cent, under the condition ,7: above. There is, of course, a possibility that some traces of acid Are retained by the sails, though they were washed thoroughly. The "r grade of ammonia (0.01 per cent) could combine with 6 per cent V, tic acid in the soil, while 0.1 per cent ammonia would suffice for onwith 60 per cent. <4 examination of Table 10, we find that the weakest ammonia dis- about 0.25 per cent humus. With the second strength of am- fiia there is a difference between the soils. With two soils, the nd strength ammonia dissolves more humic acid, but only from but one-fourth to one-eighth of the amount dissolved by the next vngth. With the other two soils, there is little difference in the T tity of humus dissolved by the 0.1 and .01 per cent ammonia. It gar, however, that an excess of ammonia over the quantity required orm ammonium humate, increases the amount of humus dissolved. the quantity of phosphoric acid. and of clav. appears to increase I the strength of the ammonia, the former quite decidedly, as though an error may have been made somewhere. It would 20 TEXAS AGRICULTURAL EXPERIMENT STATIONS. fo- . . . - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . . .?o- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . f0. No. mo~ wx. aw. mm. X§- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . fo- mo. ma. l?£- ww- N¢. .7 mm. £¢- mm. X . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -.?.-@Ow ._@@. .%. .@. ._@@. .%. . 4 . . . . . . . . . . . . . . . . . . . . . . AH." \N@HHOHHHHHM< .%O ®.%.NPHH@OM®m w dz v64 oionmwomm n3‘ semis H no mwoA 1cm .HQQEE< QEIQ m$> 5E5 23w mo mqomxzvfifinmn .2 HAmUflH Sirunrns OF AAIMoNIA-SoLUBLE QRGANIC MATTER OF SOIL. 21 It would appear from this Work that an excess of ammonia over that required to form the ammonia salt is needed. A TFalnle 11 shows the effect of ammonia of strength varying from 0.1_ per cent to 8.0 per cent. As pointed out already, 0.1 per cent am- monia should sutfice to convert humus in 60 per cent of the Weight of soil into ammonium humate. In spite of this, increase of strength of ammonia from 0.1 to 0.5 increases the organic matter in solution, as a rule. This is shown both by the incorrected, and by the corrected. loss 0n ignition. There is also a slight average increase from 0.5 per cent ammonia to 1.0 per cent ammonia uncorrected. According to the cor- rected results, the percentage of humus increases with strength of solvent up to 8 per cent. We consider these facts evidence that material goes into solution which is not “ammonium humate” but is merely organic matter soluble in the ammonia, or converted by it into soluble compounds. The ash or clay taken up by the ammonia increases in quantity until it reaches a maximum, and then decreases. This maximum is not reached with the same strength of ammonia in all soils. With soils 946 the difference between maximum and minimum is about 1.1 per cent and the maximum is reached with 4.0 per cent ammonia. With soil 324, the maximum ash is 9.29 per cent and the minimum 0.82», the maximum being reached with 0.5 per cent ammonia. This strength ammonia also yields maximum results for soils 744 and 745. From this work, 1 per cent ammonia is amply strong to dissolve the bulk of the ammonia-soluble organic matter. There appreams no need to use an ammonia as strong as 4 per cent for soils as low in humus as those we have worked upon. TEXAS AGRICULTURAL EXPERIMENT STATIONS. W _ _ v ‘Q2 5N T; “a N w; _:.m ......................................... ..., ......................... amass‘. ofi cf m9. of 5f we. mfim mmQ ibé wmrw NwQ Winn ........................................................ 46w 5 wwapmooawm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I... . . . . . . . . . . . . . ®%GPQ®UM®@ g. ma. mo. S. S. S. S. S; S. S. fi. Km; ......................................................... 50w QEwQPHSPHQm N . . . . . . ‘ . . . . . . . . . . . . , . . . . . . . . . . . . . . . ‘ . . . . . . . . . . . . . . . . . . . . . . . . ®mwd~wQ®OM®n% .A1w@. @@. @@. m-QQ. @@. fifiw. @ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . and.“ ®%\NPHH®UH®m @@ 5%. M... @@. w ¢ @@. m @$. “T ¢ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . .Q@ ®xxflnvg®nvh®m iin;‘iwl 1J1‘; I %. fi- i % x l ¢ X .€ Tu L .F x ¢ + X . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . .2? ocoggwogm w w eowawz fi€>< Gd mp pwm n UQQQQFHOU W555i _ i l li|l|ll 3w we.“ T; T; V93 vim 3N F; ‘gm vi THE f; ...................................................................... $s§< wmmm Bk ~36 2M wfiv $8M. and 3Q $5 M85. flwflm 31m ....................... ................................... 46w E wwaanxzwm @ § m m ¢ . . . . . . . . . . . . ‘ . . . . . . . . . . . . . . . . . . . . . . ‘ . . . . . . . . . . . ‘ . . . . . . . . . . . . Q,-m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . fisfi 8. NH w». I ma. 2 mm. ogfiw i“. m i“. m 2W m 3. m 5. m Qiw ............................................................ 5cm E Qwfipmofiwm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . £@ .? .% X x x X x ¢ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . l4’ ll‘! l|{|\ il<|l ||\ i ‘l! vl|l| |\ i x i!‘ i l‘ ‘ll 4?l|]|||. H. m. % H m w 7 w H m fi 7 m w ? w , ................................................ ..EQQEE< E wwapnwogwm 4E4 dQSEwH so wmoA $290584. Ho wapwnwhpw mfibfi» mm 23m we cowfiéhpxfi A fi 354s mi ii. fim Q2. m2“ w; mi. 3R fim owa 95 3a dZ :5 Srunrns or AMMONIA-SOLUBLE QRGANIO MATTER or So1L. 23 Houston and McBride (Bulletin 46, Indiana Experiment Station, 1893) studied the effect 01f the strength of the ammonia upon the humus as measured by the loss 0n ignition of the evaporated extract, using, however, soils much richer in humus or organic matter than those which we tested. The amount of “humus” increased with the strength of the ammonia up to the 8 per cent used. The difference between the 2 per cent and the 1L per cent ammonia extract was much greater than between the 4 per cent and 8 per cent. No determination was reported of the clay or “ash,” so we are unable to judge how far the increasewas due to more clay going into suspension. It appears from the results of these investigators, however, that the stronger ammonia will extract more organic matter than the weaker ammonia, from soils containing much organic matter. They also found the time of the digestion to be of influence when 2 per cent am- monia was used, especially on peat soils, but of not so much significance when the ammonia had a strength of 4L per cent. For example, with 2 per cent ammonia, 18.26 per cent “humus” was extracted from a peat soil in sixty hours, 241.40 per cent in seventy-two hours, and; 24.62 in ninety-six hours. Four per cent ammonia extracted 27.6 per cent in sixty hours and 27.63 per cent in seventy-two hours. Ammonia is act- ing chemically upon the peat substance, producing soluble compounds- a manufacture of “humus,” rather than merely a union of humic acid and ammonia. ’ Atfew results are presented by Houston and McBride which indicate that the temperature may have a decided effect on the quantity of humus extracted, especially from a peat soil. Digested thirty-six hours at 50° F, the peat soil yielded 20.70 per cent “humus,” while at 80° F, it gave 28.70 per cent “humus.” These results rvould also point to the manufacture of humus rather than simple combination be- tween ammonia and humic acid, which should be largely independent of the temperature. PART lI-FORMATION OF AMMONIA-SOLUBLE ORGANIC MATTER IN THE SOIL. v v - v V...» "wvl-ar-vv-r" ,-._-sk--_--_--rg, According to Snyder (Bulletin 53, Minnesota Experiment Station), meat scraps, flour, and other organic matter produce ammonia-soluble organic matter when allowed to decay in the soil. Similar work is re- ported by Snyder in Bulletin 89 of the same experiment station with similar results. This work has been previously referred to in this bul- letin (see page 9). Snyder did not correct for ammonia-soluble or- ganic matter in the material he used. “Te have conducted further ex- periments to ascertain the effect of organic matter upon the humus and phosphoric acid of the soil. METHOD OF WORK. 'l‘h.e soils selected for the experiment were first mixed thoroughly. Five hundred grams of the soil were weighed out into quart jars and mixed with 2O grams of the organic material to be studied. Water was added equal to one-third of the saturation capacity of the soil, the jar weighed and the weight marked thereon. The loosely-covered jars were stored in a dark basement and from time to time were weighed 24 Tnxas AGRICULTURAL EXPERIMENT STATIONS. and the loss of Weight restored by the addition of water. _At the end of fourteen weeks, one set of the jars was taken and the contents dried and prepared for analysis. The other set was dried at the end of one year, the amount of water present being" maintained in the meantime as before stated. Samples of the soils and of the organic materials which had been added to them Were preserved, the latter bei.ng steril- ized to prevent decay or fermentation. The humus “'38 determined by Snydefs method, as already described. N o COTII§CZE€OD was marlafpr the 12311131011111; oft asfh bfiouightfingto slispené sion. _ ere 1s any varia ion 1n e amonn o as , 1 W1 e re erre to in discussing the experiment. As a rule, the amount of ash was fairly constant. APPARENT FORMATION OF HUMUS. If We compare the quantity of humus extracted from the soil con- taining the organic materials With the amount extracted from the orig- inal soil, We find that in all cases there has been an increase of humus, evidently due to the added materials. The results With one set of soils are given in Table 12. The addition of organic matter has apparently raised the quantity of humus in the soils .38 per cent after one year. The addition of cottonseed meal has raised it .44 per cent, blood .12 per cent and excrement .30 per cent. ' As We xvill see later on, however, this increase is apparent rather than real. ' TABLE 12. Humus in Soils With Various Additions After One Year. _____ _ Per Cent Humus (Uncor- rected) Original soil ............................................................................................ 1.29 Soil + meat .............................................................................................. .. 1.67 Soil + cottonseed meal .......................................................................... .. 1.73 Soil + blood .............................................................................................. .. 1.41 Soil + excrement ...................................................................................... .. 1.59 ’l‘f[-IE ORGANIC MATTER CONTAINS ABIIWONIA-SOLUBLE BIATERIAL. The organic materials used in the experiment all contained matter soluble in ammonia. This is seen in ’l‘able 13. These results were secured by extracting the organic matter, first With acid, and then With ammonia, as in the extraction of humus from the soil. Five grams of substance were used and it was extracted once With 250 c.c. of hydrochloric acid, washed With Water, and then extracted With 250 c.c. of 4 per cent ammonia. After ten hours the ammonia Was de- canted, 200 c.c. of ammonia added and allowed to stand five hours. The treatment was repeated with. 200 c.c. more of ammonia and the filtrates made up to 1000 c.c. The results are presented in Table 13. From 8 to 34 per cent ammonia-soluble organic matter was secured STUDIEs or AMMONIA-SOLUBLE ORGANIC MATTER or SoIL. 25 from these materials. If the ratio of material t0 solvent had been larger, as is the case in the extraction of soil, it is quite probable that a larger amount of organic material would have gone into solution. Nevertheless, these figures bring out clearly the fact that the organic matter introduced into the soil already contains ammonia-soluble ma- terials. This fact should be taken into consideration before any state- ment as to the production of ammonia-soluble organic matter is made. Such a possibility was not considered in the experiment of Snyder which we have cited. The amount of organic matter precipitated by acid was also esti- mated in this experiment. A much larger percentage of the humus of the soil is precipitated than is the case with the ammonia-soluble or- ganic matter of these materials. TABLE 13. Material Soluble From Organic Materials in Ammonia After Extraction With Acid. Organ‘ Per Cent ic Pre- Percentage of Material Used. ' . tate pl¥°ri° Organic Per ACld 1n Organ- Phos- Matter C nt Organic Total ic Ash phoric Precip- ef Precipi- Acid itated Tot l tate by Acid ° a . l Excrement No. 862...'.... 16 .75 15 .48 1.28 .23 5 .88 38 .05 Excrement No. 898 ..... .. 15 .98 14.68 1.30 .18 4.12 29 .05 Crude bat guano. ........ .. 10 .08 8 .64 1.44 .15 4.40 51 .06 Tankage ........................ .. 16 .04 15.14 .90 .21 8.16 54 .06 Wheat bran .................. .. 35.98 34 .62 1.36 .41 14.66 42 .04 Cottonseed meal .......... .. 11 .30 10 .80 .80 .11 6 .26 58 .03 FORMATION OF HUMUS. In order to correct for the ammonia-soluble organic matter con- tained in the organic material added to the soil, we prepared mixtures equivalent to the soil plus the organic matter at the beginning of the experiment and extracted these mixtures with acid and ammonia ex- actly as was done with the soil mixtures which had been allowed to stand fourteen weeks, and one year. The results of this Work are pre- sented in the tables. Table 14 shows the percentage of “humus” se- cured from the ditlerent soils and mixtures at the beginning of the ex- periment, after fourteen weeks and after one year. It should be re- peated, however, that the mixtures were prepared from the original soil and the additions and extracted for “humus” at the same time under the same conditions as the mixtures which had been allowed to “humifyr.” We believe that in this way we secured comparable analyses. A decrease of humus occurs. The ash is given in Table 15. 26 TEXAS AGRICULTURAL EXPERIMENT STATIONS. TABLE 14. Humus in Soils and Mixtures After Various Intervals. PERCENTAGE OF HULIUS. Soil + Soil Soil + Cotton- Soil + Soil + N0. Soil Meat seed Blood Excre— Meal ment 885 Original mixtures ........... 1.36 2 .29 2 .81 1.68 1.71 Mixtures after 14 weeks 1 .30 1 .68 1 .83 1 .76 1 .45 Mixtures after 1 year ..... .. 1.29 1 .67 1.73 1 .41 1 .59 895 Original mixtures .......... .. .94 2 .11 2 .27 1 .42 1 .22 Mixtures after 14 weeks. .96 1.29 1.20 1.40 1.21 Mixtures after 1 year ...... .. .91 1 .24 ...... .. .97 1 .09 958 Original mixtures ............ .. 2 .17 3.03 3.20 2 .42 3 .31 Mixtures after 14 Weeks. 2.40 2.96 2.68 2 .25 2 .03 Mixtures after 1 year ...... .. 2 .17 2.65 2 .08 2.24 2 .18 The increase or decrease of the “humus” after humification is shown in Table 16. After allowing for the ammonia-soluble organic matter originally added to the soil, we find that in only four instances is there any apparent increase in “humus.” There is on the other hand a de— crease in humus in a great many of the other eases. The cottonseed meal mixture particularly showed a considerable decrease in its am- monia-soluble organic matter. Most of this decrease took place in the first fourteen weeks. » . Table 1'7 shows the amount of humus in the various mixtures after evaporation and solution in water. The results are similar to the above, showing a decrease rather than an increase in humus, though in some cases an apparent increase occurs. Similar results are obtained by the method of filtration through porous porcelain (Table 18). 1t appears from this experiment that there is no gain of ammonia- soluble organic matter in the soil. On the contrary, the ammonia- soluble material decreases. TABLE 15. Percentage of Ash of Humus in Soils and Mixtures After Various Intervals. . Soil + _ Soil Soil + C0tton- Soil + Soill-l- No. Soil Meat seed Blood Excre- - Meal ment 885 Original mixtures ............ .. 7 .16 6 .87 7 .11 7 .05 7.03 Mixtures after 14 weeks. 7 .28 6.76 6 .60 6 .98 6 .70 Mixtures after 1 year ...... .. 6 .85 5 .80 6 .33 6.11 6 .26 895 Original mixtures.;............ 1.96 1.40 1.31 1.54 1.71 Mixtures after 14 Weeks. 1 .69 .96 .87 .99 1 .76 Mixtures after 1 year........ 2 .46 1.51 ...... .. 1.29 2.14 958 Original mixtures ............ .. 2 .67 2.20 2 .46 1.73 2 .37 Mixtures after 14 Weeks. 3.05 3 .49 3 .05 2.28 2 .38 Mixtures after 1 year........ 3 .65 4.37 3 .66 3 .26 3.18 STUDIES OF AMMONIA-SOLUBLE ORGANIC MATTER OF SoIL. 2'7 TABLE 16. Gain or Lossuof “Humus” in Soils With Various Mixtures. PERCENTAGE IN SOIL. Soil + Soil Soil + Cotton Soil + Soil + N0. Soil Meat seed Blood Excre- Meal ment 885 After 14 Weeks. (Gain - +, Loss ~) .................. .. —.O2 —.61 —.98 +.08 —.26 After 1 year .................... .. —.01 —.01 —.10 —.35 + .14 895 After 14 weeks ................ .. + .02 —.82 -1.07 —.O2 —.01 After 1 year .................... .. —.03~ — 05 ...... .. —'.043 ——.12 958 After 14 Weeks ................ .. + .23 — 07 —.52 —.17 —.18 After 1 year .................... .. —.23 ——.31 —.60 —.01 + .15 A TABLE 17. Percentage of Humus in Mixtures by Method 0f Evaporation and Solution in Water. ' Soil + l Soil Soil + Cotton- Soil + Soil + No. Soil Meat seed Blood Excre- Meal ment 885 Original mixtures ............ .. .52 1.03 .97 ' .76 .66 - After 1 year ................ .. .50 .87 .63 .70 .61 895 Original mixtures ............ .. .60 1 .35 1 .34 .68 .73 After 10 Weeks ............ .. .43 .72 . . . . . . . . . . . . . . .. .72 After 1 year ................ .. .46 .69 .73 .56 .69 958 Original mixtures ............ .. 1.35 2.07 1.94 1.54 1.48 After 1 year ................ 1.31 1.63 1.63 1.64 1.71 l TABLE 18. Percentage of Humus After Filtration Through Porcelain Filters. Loss on Ignition. I ' Ash. Additions. . Original After - Original After Mix- ' 14 Mix- 14 ture Weeks ture Weeks None .......... ..- .................... ........................ .92 .76 .35 .37 Meat .............................................................. .. 1.42 1.34 .23 .55 Cottonseed meal .......................................... .. 1.98 1.08 .43 .40 . Blood ............................................................ .. 1.03 1.14 .25 .25 Excrement .................................................. .. 1 .13 1 .07 .40 .13 2S TEXAS AGRICULTURAL EXPERIMENT STATIONS. EFFECT OF AMIOUNT OF WATER. 1n this experiment two soils were mixed with excrement and main- tained with diiferent amounts of water for a period of fourteen weeks. The mixtures were then compared with the original soil as before de- scribed. The results are in Table 19. By the method of direct ignition of the soil, the least loss of organic matter takes place with the soil having '7'?’ per cent saturation. With soil 932, there is apparently a gain of humus in the saturated soil. By the method of evaporation and solution there is no apparent gain of K humus with soil 932 and the greatest loss is when the smallest amount of water is present. The differences, however, are not great. The re- sults with soil 914- are somewhat irregular. TABLE 19. Effect of Amount of Water 0n Per Cent of Humus in Soil. Direct Ignition Evaporation and l Solution Soil Soil Soil Soil No. 932 N0. 914 No. 932 No. 914 I l No “Yater ............................................ .: ........ .. 1.58 1.25 .93 .68 22 per cent of capacity ........................... .. 1 .32 86 .85 .74 33 per cent of capacity ........................... .. 1 .37 .89 .88 .73 55 per cent of capacity ................................... .. .96 ,, .85 .73 77 per cent of capacity ......................... .. 1 .42 1 .29* l .95 .69 100 per cent of capacity ............................ .. 1.77 .88 .93 .73 *This estimation contained over twice as much ash as the others. EFFECT OF NATURE OF SOIL. In this experiment, different soils were mixedwith excrement and maintained at one-third their saturation capacity of water for fourteen weeks and for one year. The results are presented in 'I‘ables 20, 21 and 22. With three of the soils, the lc-ss of “humus” was very nearly the same, being about 0.20 on an average. With two of the soils, there was prac- tieally no loss of humus. Whether or not these differences in the power of a soil to oxidize or conserve organic matter would appear in other soils remains to be seen. By the method of evaporation and solution, there is in all cases a loss of this “humus,” being slight, however, with one soil. The range of error in this work is too large for us to be willing to "say what differ- ences, if any, exist in the power of soils to prevent the loss of ammonia- soluble organic matter. That is, we are unable to decide from this work whether the ammonia-sol.uble organic matter disappears more rapidly in some of these soils than others. STUDIES or AMMONIA-SOLUBLE ORGANIC MATTER OF SOIL. 29 TABLE 20. Effect of Nature of S0il——By Direct Evaporation. Soil n + ' E011 . Soil + Excre- Loss + M o. Soil Excre- ment, or ment 1 Year Gain “l9 Percentage ................ ................. .. .52 .78 .60 — . 18 g 0 Percentage ...................................... .. .96 ‘ 1.22 1.23 + .01 A1 Percentage ...................................... .. .47 .98 .75 —.23 g Percentage ...................................... .. 2 68* 3 .061‘ .751 ...... .. 2 Percentage ..................................... .. 2.60 2 .95 2 .75 —.20 .9 Percentage ..................................... .. .24 .70 ‘ .68 — .02 *Ash 8..3 per cent. TAsh 9 .2 per cent. '_ IAsh 2 .2 per cent. TABLE 21. l‘ Effect of Nature of Soil—By Evaporation and Solution. Soil + Soil + Excre- Gain + Soil Excre- ment, - or ment 1 Year Gain — Percentage loss on Ignition............ .40 .65 .56 —.09 Percentage loss on Ignition............ .75 .87 .84 —.03 Percentage loss on Ignition............ .74 1.10 .99 — 11 Percentage loss on Ignition............ 1.53 2 .05 .93 ...... .. Percentage loss on Ignition............ 1.02 1.23 1.07 — 16 Percentage loss on'Ignition............ .44 .73 .58 — 15 TABLE 22. Effect of Nature of. Soil on Ash of Humus. _ Soil + Soil + Excre- Original Excre- ment, Soil ment After 1 Year ire. cent Ash .................................................... .. .21 1.20 1.12 ' er cent Ash .................................................... .. 2 .35 2.60 2.10 ; er cent Ash .......................................... ........ .. 3 .19 3 .00 2.58 er cent Ash .................................................... .. 8.34 9.24 2.18 er cent Ash .................................................... .. 10.10 9 .26 7 .98 .20 .28 1.00 . er cent 30 ‘ TExAs AGRICULTURAL EXPERIMENT STATIONS. I EFFECT OF CHARACTER OF ORGANIC MATTER. The data in the preceding Tables 14. and 15 allow us to a the content and the -loss of ammonia-soluble organic matter of cottonseed meal, and some other materials. A series of expef with other substances is presented in ‘Table 23. The results of? experiments are not all in the same direction. It is evident th extraction of ammonia-soluble material depends somewhat upon Q tions. L When extracted alone, wheat bran (Table 13) gave the highest Q‘ followed by excrement and tankage; cottonseed meal comes nex _ bat guano last. The mixtures of soil and various substances most soluble material to be from cottonseed meal; meat came _ blood next and excrement last. (See Table M.) After the .1” had humified a year, cottonseed meal loses its first place to the ‘?_ That is, the ammonia-soluble organic matter of cottonseed meal d‘ more rapidly than that of meat. Blood and excrement come app” mately in the same order. The results of the experiments with the 3 soils are different, and the preceding discussion refers to the av ' position. - _ Y; Of the other mixtures which were studied, rice bran gave the i ammonizi-soluble material to the fresh mixture, followed by 1.3 bat guano and excrement, shorts, and corn chops, in the order 11 ; The order is different after one year. Bat guano now comes first,‘ bran second, wheat bran, corn chops and tankage third, and shorts * This difference in order is due to difference of rate of decompositi the ammonia-soluble material in the various materials when placid the soil._ The results are interesting, but the percentage of erro, work on such amounts is too large for us to undertake to draw f general conclusions. l ‘i TABLE 23. Effect of Nature of Organic Matter on Percentage Humus, Etc., in Soili Humus by E -‘ Loss on Ignition Ash oration and ‘ tion ' Original After Original After Original if Mixture 1 Year Mixture 1 Year Mixture 1 Wheat Bran .............. .. 1.21 .95 .73 1.25 1.21 Shorts ........................ .. 1.17 .55 .73 1.37 1.19 Bat Guano ................ .. 1.22 1.16 1.12 .86 1.18 Corn Chops ................ .. .91 .96 1.21 1.33 .66 . t Rice Bran .................. .. 1.48 1.12 1.68 1.02 g 1.11 1. i Tankage .................... .. 1.45 .93 1.22 .86 1 .07_ PHOSPHORIO A on). The question of the formation of humus-phosphoric acid wast‘ studied in connection with the above work, and the details will hep, l.ished at some future time. - STUDIES on AMMONIA-SOLUBLE QRGANIC MATTER or SOIL. 31 ART III——COMPOSITION AND PROPERTIES OF HUMIC ACID. this section, we deal with the composition and properties of the c acid precipitates which We prepared from various soils. MIETHODS OF PREPARATION. o methods were used. flmmonia M eth0d.-—The soil was Washed several times with 1 per i? hydrochloric acid to remove lime, Washed With water, and digested 4 per cent ammonia. After allowing the soil to settle for several " the ammoniacal solution Was drawn off and filtered. The soil was ed several times with the ammonia, the extracts combined, and onium sulphate (or chloride, in some cases), added_to precipitate i.» _The precipitated clay v/a-s allowed to settle, filtered off, and the acid precipitated by making the liquid slightly acid. It was thoroughly, and air-dried on clay or paper plates. The pre- A= Was very bulky When fresh, decreasing in volume considerably dry. As the humic acid was not entirely free from ammonium It it was, in most cases, further purified. The dried material Was ‘g powdered and digested with ‘water, "the water filtered off, the di- :3 repeated and the material finally washed on a filter. The puri- umic acidwas again dried, and ground. i» clay was washed thoroughly, and dried for analysis In most it was purified as described above for humic acid. e filtrate from the humic acid precipitate was not always color- debut was sometimes of a dark-brown color. We precipitated this rial from some of the solutions by means of metallic salts. The _ cts will be referred to below. ‘1 Phosphate-Soda illethocii-Thc soil was extracted with a solution ining 1 per cent caustic soda and 1 per cent sodium phosphate. ,1 extracts were allowed to settle, and the dissolved material precipi- w by means of a slight excess of acid. This method does not re- so much manipulation as the ammonia method but the extraction so complete either. 'Humus prepared by this method contained a ash. The results of the two methods will be compared later on page 40). " i." AOIDITY on HUiuIo ACID. I. Salt ll/aterr-One gram humic acid was shaken with 250 c.c. of solution (Hopkins method for soil acidity) and filtered and 125 'trated with caustic soda and phenolphthalein, after boiling to expel dioxide. The solution was acid. - oe gram humic acid 1940 extracted with phosphate from soil 896 f» c.c. N/IO NaOH. ‘ Le am humic acid 1941 extracted with phosphate from soil 896 l; c.c. N/lO NaOH. e-half gram humic acid: 1950 by ._ammonia:3.1 c.c. N/10 NiaOH. 1949 by am1nonia:2.9 c.c.‘ N/10 NaOH. '_a 940 by ammonia:2.9 c.c. N/10 NaOH. i’. ~ e. i“ ganic material is not nearly so complete, and the acid precipitation i 32 a TEXAS AGRICULTURAL EXPERIMENT STATIONS. No. 1940 by phosphate—_—:1.9 c.c. N/10 NaOI-I. No. 193'?’ by phosphate:0.'7 c.c. N/lO NaOH. No. 1805 by ammonia_—_3.3 0.0. N/]O NaOH. No. 1941 by phosphate:1.1 c.c. N/10 NaOH. No. 1939 by phosphate:2.2 c.c. N/IO NaOH. No. 1948 by ammonia:3.3 0.0. N/lO NaOH. Maximum is 6.6 0.0. N/ 10 caustic soda. to 1 gram hum.ic acid, is equivalent to .O1121 gram ammonia. As we have found the amm compound of humic acid to contain about 8 per cent of ammonia, evident that the acidity which goes into the salt solution is only i! 12 to 15 per cent of the neutralizing power of the humic acid at maximum. " It is evident that free h-um-ic acid has little power to decom sodium. chloride. That is to say, the acidity estimated by Hop method would be much too low if due to humic acid. ~ By Carbonate of Linter-Humic acid was boiled with carbonat lime and water (previously boiled). The gases were passed into ' water. Carbon dioxide was rapidly evolved, showing that the h r- acid has the power to decompose carbonates. 7 PRECIPITATION OF HUMUS AS SALTS. The object of this work was to study the precipitation of humic by various bases. f. Humic acids from soils Nos. 134, 934, and 324 (prepared by the =' monia method) were dissolved in ammonia and evaporated over sulph acid until the ammonia had disappeared, and then dissolved in water .9 made up to volume. - Aliquots corresponding to 0.5 gra-mhumic acid were treated various salts. Solutions of.the salts were prepared and subjectedf analysis to ascertain their strength. We assume that the calcium Q of the humate contained '7 percent lime (CaO), and the equival amount of the other salt we term the theoretical quantity to form humate. The assumption is based on analysis of salts (see page 35)= The results are as follows: = xllnml. One-fifth the theoretical caused a small precipitate. two- a larger one, three-fifths precipitated all of No. 134, nearly all of _ 934, not so much of No. 924. Six-fifths precipitated the humic acid l the filtrate from the addition of three-fifths of the theory and left? colorless filtrate. Alum is an excellent precipitant. ‘ Manganese SuZphate~.—No precipitate with one-half of theoreti. or with the full amount. With one and one-half times the theoretic, a slight precipitate occurred. With twice the theoretical, 934 and 15 nearly all precipitated, 324 not so much; thrice the theoretical co, pletes the precipitation of No. 324. Manganese does not precipita humic acid readily, and an excess must be present. I a Zinc .S’ulplzate.-—Vl7ith one-half of theory andone times theoretic no precipitate was formed; with one and one-half times theoreticaLf small precipitate. With twice theoretical, Nos. 934 and 134 nearly a precipitated; No. 324 much less but nearly all. With thrice theore cal, zinc precipitated all of No. 324. The behavior of zinc and m ganese was very similar. ' I STUDIES or ABIMONIA-SOTJIIBLE ORGANIC MATTER or SoIL. 33“ M ercvrrig (.l]lZO7"t'(Z€.-——A slight precipitate appeared when the addition lad reached one and one-half the theoretical, but further additions, up zo five times theoretical, produced no further precipitate with any of :he humic acids. fllerczzrous Nitrate.—-No precipitate occurred with one-half times ;heoretical or the full theoretical. VWth one and one-half times theo- retical, there was a good precipitate; much larger with Nos. 934 and 134 than xvith No. 324. The filtrates from Nos. 134 and 324 were 3ompletely precipitated and gave a colorless filtrate with double the theoretical. Filtrate from No. 934 was partly precipitated with two times, and with triple the theoretical it was completely precipitated. Barium, Uh-Zoréder-No precipitate with one-half times theoretical and one times theoretical. With one and one-half times theoretical partly precipitated. With double the theoretical, Nos. 934 and 134 com- pletely precipitated; No. 324 nearly so. Zllagnesiuwt Chlorider-No precipitate up to one and one-half times theoretical, when a slight precipitate occurred. With double the theo- retical, no further precipitation. With triple the theoretical, No. 934 precipitated partly; the others did not. With four times the theoreti- cal, no further precipitation of No. 934 occurred, no precipitation of No. 134, some precipitation of No. 324, but not so much as No. 934. With five times theoretical, which was added only to 134, no precipi- ta.te was produced. Magnesium is not a good precipitant for humus. Magnesium humates are easily soluble. Summary.——Humates do not behave towards precipitants like ordi- nary reactions, but, as a rule, require an excess of the reagent before precipitation occurs. A difference is to be observed in the behavior of the humates from different soils. Humates from No. 2324 was less easily precipitated with alum, manganese, and zinc, barium, and perhaps mercuric mer- cury, than the other humates. The differences in the humates are most strikingly developed by the magnesium salts, humic acid from soil 134 forming practically no pre- cipitate, while No. 324 required more of the reagent, and produced less precipitate than No. 934. Further idtudies of Precigiiiation.—A solution of ammonium humate was prepared by dissolving humic acid (prepared by ammonia from soil No. 939) and causing it to evaporate over sulphuric acid. It was then dissolved in water. Nearly equivalent amounts of solutions of calcium chloride, barium chloride, magnesium chloride and copper sulphate, were added. The strength of the solutions was determined by analysis. The results are shown in the table: ‘acid by lime is not merely caused by the formation of an insoluble salt‘ 34 TEXAS AGRICULTURAL EXPERIMENT STATIONS. TABLE 24. Baryta Lime Magnesia (BaO) (CaO) (MgO) First Addition ............................ .. .0948 .0353 .0268 Precipitate .................................. .. None. None. None. Comple j Second Addition ........................ .. .0948 .0353 .0268 Precipitate .................................. .. Heavy. Heavy. None. ........ .. Third Addition .... .............................................................. .. .0268 ........ .. Precipitate .......................................................................... .. Same. ....... Fourth Addition ................................................................ .. .0268 ........ .. i Precipitate .......................................................................... .. Not com- l plete. The tiarium salt appears to be the least soluble, the calcium salt ne ff, magnesium most. The solution above the barium precipitate is colo less; that above the calcium salt is brown. ' l Tn another series of experiments, conducted at the same time ; above, a small amount of ammonia was present. The only diiieren: apparent was that the copper salt was not all precipitated by the =-i_ addition, and the solution above all the other precipitates was darker. it It is a striking fact that the addition of a lime salt containing i-{i- cient lime to form the calcium salt containing 7 per cent lime, shoul, not cause any precipitate at all. The lime salt, when formed, is no easily soluble in water. It would appear that the precipitation of humi but that an excess of lime must be present before this salt can I2 formed. The same applies to the barium salt. The magnesium sal, is easily soluble in water, in many cases. ' ‘ In another experiment, a solution containing 3 grams humic acid about four liters of water required 140 c.c. of calcium chloride (of j. strength stated above) to precipitate it. The precipitate was allowe to settle, decanted, filtered, and Washed, and again suspended in water; It was reprecipitated by 25 c.c. of calcium chloride solution. " COMPOSITION OF HUMIC SALTS. A Salts of various bases with “humic acid” have been prepared by us’- by precipitating ammonium humate with a slight excess of the saltflj The ammonium humate was prepared by dissolving humic acid in am- monia, and evaporating the solution over sulphuric acid until all odor of ammonia had disappeared. Sometimes we allowed the evaporation ’ to proceed to complete dryness. In Table 25, we show the composition of some of the humates. The combining weight of the humic radical, if univalent, would appear to vary from about .328 to 327, calculated from the composition of the ammonia salt. We have calculated the theoretical composition of the; other salts, from the combining weight given in the table, and in- ,3.‘ serted it in the. table. The humic acid is not,‘of course a definite p“ chemical compound, but is a mixture of various bodies. It is possible i, STUDIES OF AMMONIA-SOLUBLE QRGANIC MATTER OF SOIL. 35 some of these bodies may be precipitated by some of the bases, and = not so well. There is also the possibility of the formation of "salts, or even of double salts with ammonia and the precipitating TABLE 25. I Salts of Humic Acids. sml Sdl sml smi smi sat sai No. N0. N0. N0. No. No. No. 946 947 948 949 852 939 934 "tage N. as Ammonia . . . p monia Salts ............ .. 5.45 5.78 4.93 4.07 5.35 ...................... .. _: ent weight of Organ- ~ Acid Radical Body "Ammonia Salt.......... 24o 22s 271 327 244 234* 250* fretical percentage "of 1CaO in Salt based on ‘Equivalent Weight... 10 .5 10 Tfound in CaO Salt.... 10 .5 9. '__'cal percentage of 10in pBaO Salt based "Equivalent Weight. 24.1 25 .1 22 .1 19 .0 .......... .. 24 .6 23 .4 ffound in BaO Sal's... 21.5 20.8 19 .4 16.5 .......... .. 27 .9 21.9 'cal percentage MgO ‘iMgO Salt .................................................................. .. 7.5 7.9 7.4 found in MgO Salt... .............................................. .. 4 .5 7 .6 7 .4 Based on the lime salt. ‘calcium salts contain more or less lime than the calculated, jching quite closely to it in several cases. The barium found is irably lower than the calculated. The magnesia. is, in one case, ower than the calculated; in the other, quite near to it. ,rding to these results, the “humic acid” is an acid body, and has ly definite combining weight. k analyses referred to above were calculated to a moisture and j.- basis.‘ That is to say, the salts always contained ash other 1 main precipitant, but our calculations are so made that the nsists only of organic matter and the precipitant- It is quite ;- that the other ash constituents affect the composition of the fthe combining value of the humic acid. ‘_- 26 shows the analysis of the lime salts of two humic acids. It ws the copper oxide found in the copper salt. ' i 36 TEXAs AGRICULTURAL EXPERIMENT STATIONS. TABLE 26. f Analysis 0f Salts. a 324 32 939 852 939 First Seco Lime Lime Copper Alum Al Salt Salt Salt Precipi- Pre s tate ta = Moisture ...................................................... .. 11 .16 ................................... .. Ash .............................................. .. 12 .80 9 .40 ........................................... . Iron and Alumina Oxides ........ .. 1 .90 1 .44 .............. .. 1 .06 10 .1_ Lime .......... ................................ .. 10.80 6.28 ........................................ * Copper in Copper Salt .............................................. .. 17 .4 ....................... .. Silica ............................................................ .. 1 .08 ........................................... . . SOLUBILITY OF HUMIC SALTS. Salts of humic acid from soil No. 934, ammonia method, preci tated, washed and air-dried, were suspended in _cold water and allow At the end of that time, the residue w" filtered ofi’, and 50 0.c. of the filtrate evaporated to dryness, w.‘ to stand twenty-four hours. weighed, ignited, and weighed again. The insoluble residue was heated with Water three hours in a b0il' water bath with a reflux condenser, filtered, and 50 c.c. evaporated v The residue Was extracted a third time. ' before. The results are presented in the table. TABLE 27. Solubility of Humic Salts. Grams Dissolved in 50 c.c. Soluble in Cold Soluble in Hot Water Water I. II. Organic Ash . r Organic Ash Organic Ash~ Magnesium Salt ........ .. .0325 .0126 .0339 I .0096 .0272 .0085 Calcium Salt .............. .. .0019 .0027 .0065 .0029 .0096 .0083 Barium Salt .............. .. .0033 .0001 .0055 .0319 .0078 .0073 The solution from the magnesium salt had an intense color Accord ing to this experiment, the magnesium salt is the most soluble, th calcium and barium salts much less so. Srunrns or AMMONIA-SOLUBLE ORGANIC MATTER OF SoIL. 37 EFFECT or AMMONIA on SOLUBILITY or CALCIUM SALT. This experiment was similar to the above, excepting that calcium carbonate, magnesium carbonate, and ammonia, were added to separate suspensions of calcium humate in water. The amount of ammonia used was 5 c.c. of N/10 ammonia to 100 c.c. solution. ' The ammonia solution was most highly colored, the solution with no addition next, the magnesium carbonate next, and calcium carbonate least. In spite of this, however, the calcium carbonate and magnesium carbonate has no effect upon the calcium humate. The results of the experiment are as follows“: TABLE 28. Effect of Additions on Solubility of Calcium Humate. -} ‘ Organic ' Matter in 50 c.c. No addition ................................................................................................ .. .0075 Magnesium carbonate .............................................................................. .. .0078 Calcium carbonate .................................................................................... .. .0082 Ammonia .................................................................................................... ._ .0192 Addition of ammonia, therefore, increased the solubility of calcium humate decidedly. EFFECT OF CARBONATES OF LIME AND LIAGNESIA ON SOLUBILITY OF HULIIC ACID. ' Fresh, moist, humic acid was placed in test tubes with 15 or 20 c.c. water. One tube received no addition, a second some carbonate of lime, a third some carbonate of magnesia, a fourth carbonate of lime and caustic soda and a fifth carbonate of magnesia and caustic soda. The tubes stood twenty-four hours, being shaken occasionally. At the end of that time, the results were as follows: TABLE 29. Solubility of Humic Acid. l . No. 946 1 No. 947 No. 94s No. 949 Water alone Ligzgiltostraw Wine color Light straw Light straw Carbonate of Lime Vergrtllégyht Light straw Dasijcllfg; Light straw Carbonate of Very dark Black Dark straw Straw Magnesia brown Carbonate of Lime e Caustic Sod Black Black Black Black Carbonate of Mag- " nesia, Carbonate Black Black Black Black of Soda 38 TEXAS AGRICULTURAL EXPERIMENT Srarrous. The color of the solution is an indication of the solubility of the humic acid. p Carbonate of lime decreases the solubility of the humic acid, but does not render it completely insoluble. Carbonate of magnesia causes the humic acid to be more soluble than in water. The addition of caustic soda increases the amount of humate in solution, even though car- bonates of lime or magnesia are present. HYDROLYSIS OF HUMIC ACID. One-half gram humic acid from soil No. 852 prepared by ammonia was placed in a flask with 100 c.c. of 1 per cent hydrochloric acid, heated in a boiling water bath for five hours, neutralized, and the re- ducing sugars estimated. Reducing sugars found were 2.25 per cent. Another portion of one-half gram humic‘ acid from soil No. 852 pre- pared by ammonia was dissolved in 10 c.c. of concentrated sulphuric acid, di.luted to 200 c.c. and heated five hours in boiling-water bath, neutralized, etc., as before. Reducing sugars found were 2.40 per cent. DIFFUSION OF HU MUS. It has been claimed by some investigators that humus will not pass through parchments. This is denied by others. Experiments were made to test this matter. First Experiment.—One-half gram of humus is dissolved in as small a quantity of water and ammonia is possible, placed in a diffusion shell (CS&S) and this is supported in a Jena glass vessel containing 500 c.c. of 4 per cent ammonia. After twentuv-four hours the ammonia is evap- orated in a platinum dish, dried, weighed, ignited and weighed. This is repeated with further quantities of ammonia (four diifusions made). That the humus diffused was evident from the dark color of the solu- tion outside the shell. Approximately 10 per cent of the ammonium humate passed through the capsule in four diffusions. (See Table 30.) TABLE 30. Diffusion of Humus. Loss Insol- Total on Ash uble Igni- Ash tion A | | 747 Percentage diffused in first 24 hours................ 6.60 5 .84 .76 .48 Second 24 hours ........ .. 2 .70 2 .44 .26 .06 Third 24 hours ............ .. 1.24 1.52 .22 .06 Fourth 24 hours .......... .. 1 .94 1 .34 .06 .54- Second Experiment.—One gram humus is dissolved in as small a quantity of Water and ammonia as possible, placed in a diffusion shell, and supported there in a vessel of Jena glass containing 500 c.c. of 4 per cent ammonia. It is protected carefully from acid fumes. After twcntyr-four hours the ammonia is evaporated in platinum dish and ash Sfrunrns OF AMMONIik-SOLUBLE ORGANIC MATTER OF SoIL. 39 and loss on ignition determined. Again, 500 c.c. ammonia is placed in the vessel, allowed to diffuse, and so on, for eight successive diffusions. A blank determination is made, using the same ammonia and a dif- fusion shell. " a Resrz¢lts.—'1‘he results are presented in Table 31. The humus prep- aration appears to contain easily diffusible matter. After the latter has separated out, which takes two or three diifusions, the residual humus diffuses at the nearly constant rate of 1 to 2 per cent of the humic acid. The diffused solution was colored. Extraction with alcoho-l removes the easily diflfusible material. The figures in the table are not corrected for the blank. TABLE 31. Diffusion of Humus. 910 EX- . 910 tracted 894 934 Blank Orig- Alco- l inal hol First Diffusion.———Loss on Ignition in grams .................. .. .0061 .1620 .0123 .0486 .0519 Ash in grams ........ .. .0146 .0182 .0150 .0171 .0146 Second Diffusion-Loss on Ignition in grams ........ .. .0039 .0240 .0099 .0146 .0275 Ash in grams .... .. .0138 .0131 .0117 .0128 .0416 Third Diffusion.——Loss on Ignition in grams ................ .. .0055 .0168 .0107 .0127 .0364 \ Ash in grams ........ .. .0109 .0099 .0121 .0108 .0216 Fourth Diflusion.—Loss on Ignition in grams ........ .. .0041 .0135 .0069 .0269 .0300 Ash in grams .... .. .0042 .0035 .0053 .0044 .0193 Fifth Diffusion.—Loss on Ignition in grams .................. .. .0062 .0102 .0084 .0252 .0192 Ash in grams ........ .. .0026 .0027 .0039 .0034 .0128 Sixth Diifusion-——Loss on Ignition in grams .................. .. .0050 .0099 .0071 .0256 .0137 Ash in grams ........ .. .0036 .0039 .0035 .0030 .0077 Seventh Diifusion.—Loss on Ignition in grams ........ .. .0073 .0125 .0096 .0239 .0140 Ash in grams .... .. .0043 .0045 .0061 .0044 .0098 Eighth Diffusion.—Loss on Ignition in grams .......... .. .0045 .0125 .0064 .0245 ............ .. Ash in grams ..... .. .0070 .0066 .0060 .0084 ............ .. COMPOSITION OF HU.MIC ACID. Table 32 contains estimation of water, ash and phosphoric acid in a number of humic precipitates. Oxides of iron and alumina, lime, and magnesia, are also estimated in a few of the precipitates. The quantity 0-f ash varies from 1.53 to 8.01—-average 3.29 per cent. This is considerably less than when the clay is no-t precipitated previous to separating the -humic acid. _ The quantity of water is a matter of little consequence. The percentage of phosphoric acid varies from 0.13 to 0.54 with an 40 TEXAS AGRICULTURAL EXPERIMENT STATIONS. average of 0.30. This is a comparatively small amount of phosphoric acid. i - Part descriptions of the soils from which these preparations were made are as follows: Analyses and full description of the Texas soils have been printed in Bulletins 99 and 125 of this Station. DESCRIPTION OF SOILS USED FOR HUMIC ACID. No. 134——San Antonio clay loam_, San Antonio, Texas. No. 324.-—Houston black clay, San Marcos, Texas. No. 882—Wabash clay, subsoil, 10-36", two and one-half miles north- west, Stockdale, Texas. No. 896—Norfolk fine sandy loam, Lufkin, Texas. No. 910—H0uston black clay, 0-10", Elgin, Texas. No. 915—Houston black clay, 10-36”, Cooper, Texas. No. 934——Wabash clay, 0-10”, Stockdale, Texas. No. 939—Houston black clay, 0-10", Cooper, Texas. No. 946—_Soil from virgin prairie, North Dakota. No. 947—Soil from alfalfa field, North Dakota. No. 948—Soil from a garden, North Dakota. No. 949—Soil from old field; substation at Edgley, North Dakota. No. 1739——Soil from Arroyo Grande, California. No. 1'740—Soi1 from Berkeley, California. No. 895-—Lufkin fine sand; Lufkin, Texas. No. 982—Cameron clay, subsoil, Brownsville, Texas. No. 896——Norfolk fine sand, Lufkin, Texas. No. 882——Wabash clay, Stockdale, Texas. TABLE 32. Composition of Humic Acid. l OX- ides Soil Loss Phos- of- N o. Water Ash on phor- Iron Lime Mag- Igni- ic and nesia tion Acid Alum- ‘ x ina 742 Humic acid ................ .. 11.60 7 .16 81.24 .54 1.40 .19 .17 743 Humic acid ................ .. 15.16 2 .54 82 .30 .27 1 .00 Trace. Trace. 743 Humic acid purifie A - by 11.91 2.35 85.74 .32 .42 Trace. Trace. 127 Humic acid ................ .. 11.26 2 .54 86 .20 28 .................................. .. 133 Humic acid ................ .. 14 .42 2 .72 82 .86 32 .................................. .. 180 Humic acid ................ .. 12 .07 3.07 84.86 45 .................................. .. 182 Humic acid ................ .. 17 .50’ 3 .10 79.60 36 .................................. .. 332 Humic acid ................ .. 10 .88, 1.53 87 .59 23 .................................. .. 134 Humic acid ................ .. 4.63 ' 5 .50 89.87 17 .................................. .. 324 Humic acid ................ .. 12 .20 2 .05 85 .75 24 .................................. .. 934 Humic acid ................ .. 9 .51 8 .01 82 .48 13 .................................. .. 852 Humic acid ................ .. 10 .04 2.48 87.48 .............................................. .. 1505 Humic acid ................ .. , 10 .92 1.40 87 .70 .............................................. .. 1506 Humic acid ................ .. 12 .79 1.60 85 .76 .............................................. .. Average ................ .. 11.77 s 29 s4 .96 30] I l STUDIES OF AMMONIA-SOLUBLE ORGANIC MATTER or SOIL. 41 COMPOSITION OF HUMIG ACIDS PURIFIED BY AMMONIA. able 33 shows the chemical composition of a number of humic extracted by ammonia. In some instances more complete analyses not made on account of the small quantity of material which we jsecured. All these products were purified by shaking the dried “c acid with Water several times excepting Nos. 852, 1.27, 910 and mmple of No. 134, for which nitrogen is given. All the samples iare not purified contain appreciable quantities of ammonia. This ‘nia was expelled by boiling the humic acid with magnesium oxide ater, and collected in standard acid. Other preparations of humic ipnot purified also contained ammonia. (See Table 34.) These are on air-dry samples. i ' p, TABLE 33. ntage Composition of Purified Humic Acids Extracted by Ammonia— ‘ Dry Basis. Hydro- Nitro- Carbon gen gen Ash Purified from soil No. 54.13 3 .27 4.31 8.85 EPPurified from soil No. 324.. ............ .. 55 .39 4 .77 6 .22 2 .64 Purified from soil No. 852 .............. .. 63 .58 5.45 4 .94); 2 .75 .Purified from soil N0. 134 .............. .. 55.15 3 .48 ...... .. 6.11 iPurified from soil No. 949 ........ 44.09 3 .14 3 .981‘ ...... .. ‘Purified from soil No. 946 .............. .. 56 .45 3 .33 5 .38* 1 .57 ’._Not Purified from soil No. 127 ...... .. 56 .04 4.18 ...... .. 2 .94 ‘Purified from soil No. 948 .............. .. 54 .32 3 .32 4 .58* . 15 .74 fPurified from soil N0. 947 .............. .. 55 .63 4 .15 5 .44 1 .94 Not Purified from soil No. 910 . . . . . . . . . . . . . . . . . . . . . . .. 4.14 ...... .. , Not Purified from soil No. 134 . . . . . . . . . . . . . . . . . . . . . . .. 6 .241 ...... .. Nitrogen on air-drycsubstance. ik- Per cent N. as Ammonia present. Nitrogen on air-dry substance. c‘ Per cent N. as Ammonia present. ’-dry. A Per cent nitrogen as ammonia. TABLE 34. Nitrogen and Ammonia in Humic Acids—Not Purified. Per Cent- Total Nitro- Nitro- gen as gen Ammo- nia ‘soil No. s49 ...................................................................... .. 5 .80 2 .18 a Soil No. 934 ...................................................................... .. 4.96 1.72 ‘Soil No. 324 ...................................................................... .. 5.32 1.12 $0il N0. 745~7 .................................................................... .. 5.16 ...... .. 42 TEXAs AGRICULTURAL EXPERIMENT STATIONS. It is evident that the humic acid may contain ammonium sal less special care is taken in purifying it. This is further evident? We study the alcoholic extract of the humic acid. (See page 44.) Examination of the composition of these humic acids, prepa first precipitating the clay from the ammonia solution, “shows to have succeeded in securing a product with a comparatively ].ow The carbon content of these humic acids varies from 44.09 to i The majority of the samples contain between 54.13 and 56.45 pep carbon. The two soils which contained humic acids not Within" limits are as follows: 1 Soil No. 949, soil from an old field, North Dakota, humic aci_ in carbon and also low in nitrogen. Soil No; 852, soil from a rice field, Texas, humic acid high in -'_ moderate in nitrogen. The soils yielding humus a little high in if gen both came from the same locality in the western part of the Preparations of humic acid from other soils in the same section a Z high in nitrogen. ' The following table shows the composition of some humic aci tained by Eggertz and by Snyder. Eggertz’s work is based on thQ, ' analyses, Snyder’s on four. The table shows the variation in their < position. Our samples average higher in carbon content than i, samples. The content of nitrogen may probably be the same asii samples analyze-d by Eggertz, though none of our samples run as 1 his. Snyder’s preparations all contain considerably more nitrogen i ours. E34} PERCENTAGE COMPOSITION OF HUMIC ACIDS. Eggertz Snyder‘. Carbon .............................................. ................ .. 40 .8 to 56 .2 44 to 50 Hydrogen ............................................................ .. 4 .3 to 6 .6 3 t0 6* Oxygen .................................................................. .. 25 .1 to 38 .0 28 to 35f Nitrogen .......... .................................................... .. 2 .6 to 6.4‘ 6 .5 to 10 Silica ...................................................................... .. .4 to 10.5 ........ ..... Phosphorus ......................................................... .. .15 to 7 .6 ............. .. Sulphur ................................................................. .. .6 to 2 .1 ............. .. Alumina and Oxide of Iron .............................. .. .4 to 3 .9 ..................... . Ash ................................................................................................ .. 4 to 12 HUMIC ACID EXTRACTED BY PHOSPHATE. , This method of extraction has already been described (see page 3p The composition of the products is shown in Table 35. This met does not give as good a product as our ammonia method, as the .5 content of the precipitate is high. The carbon and hydrogen and nit =f gen. are made upon the material dried at 100°, the other estimations the air-dry substance. These materials were all purified by shak' with water (5 c.c. water per gram of substance), then filtered washed. . i. The humic acid prepared by the soda-phosphate method conta' considerable ash, or clay. The presence of the ash introduces an e q, STUDIES or‘ AMMONIA-SOLUBLE ORGANIC MATTER or SorL. 43 57} it. undoubtedly contains some water o-f: hydration. For the pur- '_ of comparison, we have calculated the analyses to ash-free ma- l. On account of the water in the clay, we did not think it worth g to calculate the percentages of hydrogen. For the same reason, carbon and nitrogen as calculated are probably a little low, as a F1 of the ash-free material is ‘water belonging to the clay. The i _t of this error would increase with the quantity of the ash and depend upon the nature of the clay. We have at present no means itroducing a correction for this water of clay. I do not consider peter and Averitt method of correction at all applicable to these ; rations. The low carbon content is in a preparation from a soil Lufkin, Texas. The low nitrogen is in the same soil. The high 1n is in the sample of Norfolk fine sandy loam from Lufkin. th the exceptions of soil No. 895 (preparation No. 1937), the en content of these preparations is remarkably similar. The soils ‘i California were secured for the express purpose of studying the en content of the humus, and. the preparation by means of soda- gate was used so that there could be no question of ammonia ‘ed by the preparations. The California soils, however, do not ans humic preparations containing any more nitrogen than our soils. Two of these Texas soils came from arid or semi-arid sec- samples of California soils were sent to- us by Dr. B. H. Lough- > Berkeley, California, for which we hereby ‘express our" appreci- 7 (Numbers 1739 and 1740.) 4‘ i TABLE 35. 4 Percentage Composition of Humic Acid by Soda Phosphate. 1937 1938 1940 1941 2382 2383 From From From From From From Soil Soil Soil Soil Soil Soil No. No. No. No. N0. No. 895 982 896 882 1739 1740 “- on water-free sub- nce ............................ .. 39 .53 25 .43 35 .85 15 .53 48.43 39.10 1 en on water-f r e e ' bstance ...................... .. 3 .51 3 .82 3 .72 1.76 2 .96 2 .36 ‘ n on water-free sub- fnce ............................ .. 2.81 2 .24 2.83 1.27 3 .59 3 .33 ry substance—— 1TH .= ............................... .. 13 .29 49 .32 33 .71 60 .26 10 .69 19 .22 ater .......................... .. 10.67 8.02 10.64 11.59 9.70 11.10 f»: on Ignition ............ .. 76 .04 42 .66 55 .65 28 .15 79 .63 69 .68 osphoric Acid .................... .I ................ .. .28 .34 .......................... .. ‘oluble Ash ...... .......... ...................... .. 25 .09 47 .29 .......................... .. ; 'des of Iron and Alu- _ Zmina ...................................... .......... 5.05 8.11 .; ........................ .. ........................................... ..T ........... .. .01 .02 .......................... .. gnesia ............................................... .. .19 .75 .......................... .. '": -free material— “ i 52.00 59 .60 64.40 53 .20 60.80 56.90 trogen ....................... .. 3.69 5 .25 5 .08 4.51 4.51 4.78 ' it is true, but the other one came from a humid part of the State. a 44 TEXAS AGRICULTURAL EXPERIMENT STATIONS. Humic Acid from Copgier Precipiiate.—After precipitating n- acid from ammonia with acid there remains in solution some org matter which can be precipitated by copper sulphate. The precipit material was extracted with acid to remove copper, dried and subj to analysis. The quantity secured was small. Product No. 1816 c, from soil No. 946 and Was almost White. No. 1817 was black, i, soil No. 947. No. 1818 was brown, from soil No. 949. The anal’ show that these precipitations are largely inorganic. The ash t found, on analysis, to consist largely of silica, though alumina and were also present. A Calculated to ash-free material, these precipitations contained following amounts of carbon: ‘ No. 1816, 27.0 per cent carbon. No. 1817, 48.9 per cent carbon. No. 1818, 53.8 per cent carbon. TABLE 36. Composition of Humic Acids from Copper Precipitate—Water Free. Hydro- . Carbon gen gen As w , I 1818 Brown Humic Acid from Copper I , Precipitate .................................... .. 9.09 2.11 ...... .. 83L 1817 Black Humic Acid from Copper Precipitate .................................... .. 9 . 15 2 .01 .60 81 .7 1.816 White Humic Acid from Copper ; a Precipitate .................................... .. 2.70 1.44 ...... .. 90p N itro- i acid has not previously the following table. ALCOHOL-SOLUBLE HUMUS PRODUCT. A A small percentage of the humus is soluble in alcohol. In order. separate it, the dried humic acid was extracted with boiling alcohol z eral times, the filtrate evaporated to dryness, pulverized, and extra f, with water to remove ammonia salts which were present when the hut been purified. The analyses are presented f The quantity of alcoholic extract is comparative small. TABLE 37. Percentage Composition of Alcoholic Extract. Oven Dried No. Hydro- Carbon gen 1811 From Humus of Soil No. 934 ........................ .. 63 .72 6.33 1812 From Humus of Soil No. 915 ........................ .. 59 .38 4.18 1813 From Humus of Soil No. 910 ........................ .. 66.50 6.73 1815 Residue from Extraction of Humus, Soil No. 910 59 .15 4.08 Second aiébfiéiiié 'é'>'<£i~'é¢é£"8'f“ é5ii"i