TEXAS AGRICULTURAL EXPERIMENT sIXIEIEIIIOm BULLETIN NO. 223 DECEMBER, 1917 DIVISION 0F CHEMISTRY EFFECTS OE LIME AND CARBO- NATE OF LIME ON ACID PHOSPHATE B. YOUNGBLOOD, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS. AGRICULTURAL AND MECHANICAL uuLLEuL urn inxAa W. B. BIzzELL, A. M., D. C. L., President TEXAS AGRICULTURAL EXPERIMENT STATION BOARD OF DIRECTORS JOHN I. GUIoN, President, Ballinger ...................... .. L. J. HART, Vice President, San Antonio .... ....... .. E. H. AsTIN, Bryan.. _ J. R. KUBENA, Fayetteville ...... .................. .. A. B. DAvIDs0N, Cuero.... _ WILL A. MILLER, JR., Amar1llo..... JonN T. DICKSON, Paris ........... .. H. A. BREIHAN, Bartlett. . F. M. LAW, Houston ........ .. .................................................... ..Term expires 1919 ......................... .. ....Term expires 1919 ........... ..Term expires 1919 ........... ..Term expires 1921 ................................................... ..Term expires 1921 .............................. ..Term expires 1921 .....Term expires 1923 ....Term expires 1923 ............ ..Term expires 1923 MAIN STATION COMMITTEE L. J. HART, Chairman WILL A. MILLER, JR. GOVERNING BOARD, STATE SUBSTATIONS P. L. Downs, President, Temple .......... .. CHARLES RooAN, Vice President, Austin....‘.'. .................. i. man ................................... .. W. A. JoIINsoN, Memphis ...................................... .. J. E. Booo-ScoTT. Cole .................................................... ..Term expires 1918 ..Term expires 1919 .Term expires 1923 ........................... ..Term expires 1923 *STATION STAFF ADMINISTRATION _ B. YOUNGBLOOD, M. S., Director A. B. CoNNER, B. S., Vice Director CHAS. A. FELKER, Chief Clerk A. S. WARE, Secretary W. T. BRINK, B. S., Executive Assistant in Charge Library and Publication EDITH H. PHILLIPS, B. S., Technical As- sistant DIVISION OF VETERINARY SCIENCE **M. FRANcIs, D. V. M., Veterinarian in Charge _ _ H. SCHMIDT, D. V. S., Veterinarian D. H. BENNETT, V. M. D., Assistant Vet- erinarian DIVISION OF CHEMISTRY G. S. FRAPs, Ph. D., Chemist in Charge; State Chemist _ _ -—— Assistant Chemist CIIARLEs BUCHWALD, M. S., Assistant Chemist _ _ T. B. LEITH, B. A., Assistant Chemist DIVISION OF HoRTIcIILTURE H. NEss, M. S., Horticulturist in Charge W. S. HOTCHKISS, Horticulturist DIVISION OF ANIMAL HUSBANDRY J. C. BURNs, B. S.,_Animal Husbandman, Feeding Investigations _ J. M. JoNEs, A. M., Animal Husbandman, Breeding Investigations P. V. EWING, M. S., Animal Husbandman, in Charge Swine Investigations _ **L. B. BURK, B. S., Collaborating Animal Husbandman, Swine Investigations DIVISION OF ENTOMOLOGY F. B. PADDOCK, M. S., Entomologist in Charge; State Entomologist H. J". REINIIARD, B. ’S., Assistant Ento- mologist _ W. E. JAcKsoN, M. S. Assistant Entomologist County Apiary Inspectors: R. C. Abernathy, Ladonia; William Atch— ley, Mathis; J. W. E. Basham, Barstow; T. W. Burleson, Waxahachie; W. . Collier, Goliad; E. W. Cothran, Roxton; G. F. DavidsonPleasanton; John Done- gan, Seguin; S. T. Graham, Milano; J. B. King, Batesville; N. G. LeGear,Waco; R. A. Little, Pearsall; S. H. Stephens, Uvalde; M. B. Tally, Victoria; R. E. Watson, Heidenheimer; W. H. White, Greenvillei F. C. Belt, Yslcta: R. A. Nestor, Buffalo; H. A. Jones, Oakville; T. A. Bowdon, Palestine; E.‘ R. Jones, Beeville. DIVISION OF AGRONOMY A. B. CQNNER, B. S., Agronomist in Charge A. H. LEIDIGII, B. S., Agronomist ***H. H. JOBSON, B. S., Agronomist LQUtIs WERMELSKIRCHEN, B. S., Agronom- is DIVISION OF PLANT PATHOLOGY AND PHYSIOLOGY J. J._TAUBENIIAUs, Ph. D., Plant Pathol- ogist and Physiologist in Charge DIVISION OF POULTRY HUSBANDRY R. N. HARVEY, B. S., Poultryman in Charge DIVISION OF FORESTRY: J. H. FOSTER, M. F., Forester in Charge; State Forester DIVISION OF PLANT BREEDING E. P. HUMEERT, Ph. D., Plant Breeder in Charge DIVISION OF DAIRYING W. A. DOUBT, Dairyman DIVISION OF FEED CONTROL SERVICE F. FULLER, M. S., Chief JAMEs SULLIVAN, Executive Secretary J. H. RocERs, Inspector W. H. W00D, Inspector S. D. PEARcE, Inspector W. M. WICKES, Inspector W. F. CHRISTIAN, Inspector SUBSTATION NO. 1: Beeville, Bee County I. E. CowART, M. S., Superintendent SUBSTATION NO. 2: Troup, Smith County \V. S. HOTCHKISS, Superintendent SUBSTATION NO. 3: Angleton, Brazoria County N. E. WINTERs, B. S., Superintendent SUBSTATION NO. 4: Beaumont, Jefferson County H. H. LAUDE, B. S., Superintendent J. B. CocxRELL, B. S., Scientific Assistant SUBSTATION NO. 5: Temple, Bell County D. T. KILLOUGH, B. S., Superintendent SUBSTATION NO. 6: Denton, Denton County C. H. McD0wELL, B. S., Superintendent SUBSTATION NO. 7: Spur, Dickens County R. E. DICKSON, B. S., Superintendent SUBSTATION NO. 8: Lubbock, Lubbock County R. E. KARI-ER, B. S., Superintendent SUBSTATION NO. 9: Pecos, Reeves County J. W. JAcxsoN, B. S., Superintendent SUBSTATION NO. 10 (Feeding and Breeding Substation): College Station, Brazos County E. R. SPENcE, B. S., Animal Husbandman, in Charge of Farm SUBSTATION NO. l1: Nacogdoches, Nacog- doches County G. T. McNEss, Superintendent SUBSTATION NO. 12: Chillicothe, Harde- man County ****R. W. EDWARDS, B. S., Superintendent V. R. HAFNER, B. S., Scientific Assistant SUBSTATION NO. 14, Sonora, Sutton County E. M. PETERs, B. S., Acting Superintendent CLERICAL ASSISTANTS J. M. SCHAEDEL, Stenogra her DAISY LEE, Registration Ierk C. L. DURsT, Mailing Clerk ‘R. C. FRANKs, Copyist W. L. HEARN, Stenographer MAE BELLE EvANs, Sltenographer *As of December 1, 1917. IRENE PEvERLEY, Copyist RUTH CAMPBELL, Stenographer IVIARGARET SHELDON, Stenographer LOUIsE S. BARNETT, Stenographer WILLIE BELLE FULLER, Stenographer H. L. FRAZIER, Stenographer **In cooperation with A. and M. College of Texas. ***On leave. .s._ __IA.L 1r_.:4....1 (was..- nAw\I\$‘I'V\l\I\‘ n! Anv-h-nHnr-n CONTENTS PAGEV Efiect of Carbonate 0f Lime on Water-Soluble and Insoluble i Phosphoric Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5 Effect of Hydrated Lime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ . . .. ‘I’ The Reactions . . . . . . . . . . . . . . . . . . . . . . .4 . . . . . . . . . . . . . . . . . 8 Objects of Using Carbonate of Lime in a Fertilizer . . . . . . . . . . . . .. 9 Objections to Use of Calcium Carbonate . . . . . . . . . . . . . . . . . . . . . .. 10 Detection and Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10 Eifect of Salts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Effect on Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Pot Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12 i Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Use of Carbonate of Lime in Mixed Fertilizers . . . . . . . . . . . . . . . . . .. 15 Acknowledgments .i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 16 Summary . . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 BULLETIN N0. 223 DECEMBER, 1917 EFFECTS OF LIME AND CARBONATE OF LIME i ON ACID PHOSPHATE BY G. S. FRAPS, PH. D., Orrmvrrsr iN CHARGE, STATE OHEMIsT. In practically all books 0n agricultural chemistry and 0n fertilizers, it is stated that lime, limestone, Wood ashes, Thomas phosphate and similar materials should never be mixed with acid phosphate. The rea- son for this is obvious. The acid phosphate has been made by treating phosphate rock with sulphuric acid. The effect of the lime or lime- stone would be to ‘neutralize the action of the sulphuric acid and change the phosphoric acid back to the less soluble forms. Limestone and hydrated lime, nevertheless, have been and are be- ing used as additions to acid phosphate. The addition is made to some extent as a filler. Another object is to improve the physical character so that the mixture will not become damp, sticky, and dilficult to "apply, especially in wet localities. It is, of course, a decided advantage to have a fertilizer in such good mechanical condition that it may be easily placed in the soil, or distributed easily in fertilizer drills. Some commercial chemists have gone so far as to state that the addition of lime'to fertilizers is of advantage in that it would add lime- stone needed by the soil. However, 200 pounds of acid phosphate con- taining 10 per cent. carbonate of lime would only introduce 20 pounds of limestone into the soil. If the soil is in need of lime, it is hardly advisable to use less than 2,000 pounds per acre of limestone. It is a matter of considerable practical importance to ascertain to what extent the addition of lime or limestone to acid phosphate is harmful or harmless. EFFECT OF OARBONATE OF LIME ON WATER-SOLUBLE AND INSOLUBLE PHOSPHORIC ACID. Table 1 shows the results of some experiments on mixing acid phos- phate with precipitated calcium carbonate. Fifty grams of the acid phosphate were mixed with from 0.5 grams to 10 grams of calcium car- bonate, and analysis made immediately. The mixtures were allowed to stand and analyses made at the intervals indicated. The results are given in percentages of the mixtures used, and are not calculated back to the original acid phosphate. The acid phosphate used in each series was different and had a different Water content. In series F, it con- tained 12.9 per cent. water. TEXAS AGRICULTURAL EXPERIMENT STATION. 6 Table 1.—Effect of carbonate of lime on phosphoric acid of acid phosphate. Series. Added to 50 gms. 0 1 2 5 10 20 50 80 days. day. days. days. days. days. days. days. Water-Soluble Phosphoric Acid- A O . . . . . . . . . . . . . . . .. 13.73 13.75 13.80 13.71 13.88 13.75 . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. 13.50 13.51 13.50 13.16 13.30 13.33 . . . . . . . . . . .. 1.0 gm . . . . . . . . . . . .. 13.65 13.21 13.45 13.98 13.18 13.11 . . . . . . . . . . .. 2.5 gms . . . . . . . . . . .. 12.93 12.29 12.15 11.65 11.60 11.95 . . . . . . . . . . .. 5.0gms . . . . . . . . . . .. 11.98 10.94 10.70 12.59 9.89 9.16 . . . . . . . . . . .. 10.0 gms . . . . . . . . . . .. 11.33 9.09 9.16 8.20 6.66 4.99 . . . . . . . . . . .. Insoluble Phosphoric Acid- A 0 . . . . . . . . . . . . . . . .. .13 .13 .18 .11 .12 .05 . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. .10 .14 .20 .14 .18 .22 . . . . . . . . . . .. 1.0 gm . . . . . . . . . . . .. .16 .26 .26 .20 .20 .23 . . . . . . . . . . .. 2.5 gms . . . . . . . . . . .. .19 .36 .38 .48 .60 .73 . . . . . . . . . . .. 5.0gms . . . . . . . . . . .. .15 .30 .49 .59 .81 1.03 . . . . . . . . . . .. 10 Ogms . . . . . . . . . . .. .13 .34 .51 .69 1.01 1.56 . . . . . . . . . . .. Water Soluble- B 0 . . . . . . . . . . . . . . . .. 12.43 12.54 12.90 13.45 12.20 11.97 . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. 12.38 12.66 12.43 12.65 11.95 11.67 . . . . . . . . . . .. 1.0 gm . . . . . . . . . . . .. 12.43 12.18 12.04 12.05 11.57 11.35 . . . . . . . . . . .. 2.5 gms . . . . . . . . . . .. 11.49 10.31 10.18 10.48 9.83 9.54 . . . . . . . . . . .. 5.0gms . . . . . . . . . . .. 10.11 4.18 4.28 3.75 3.48 3.31 . . . . . . . . . . .. 10.0 gms . . . . . . . . . . .. 9.44 1.09 1.78 1.43 1.08 0.79 . . . . . . . . . . .. Insolub1e— B 0 . . . . . . . . . . . . . . . .. .15 .14 .13 .25 .13 .14 . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. .18 .14 .14 .25 .15 .15 . . . . . . . . . . .. 1.0 gm . . . . . . . . . . . .. .14 .23 .14 .28 .16 ‘.16 . . . . . . . . . . .. 2.5 gms . . . . . . . . . . .. .16 .26 .17 .26 .19 .23 . . . . . . . . . . .. 5.0 gms . . . . . . . . . . .. .19 .28 .18 .28 .23 .26 . . . . . . . . . . .. 10.0 gms . . . . . . . . . . .. .21 .36 .23 .39 .33 .43 . . . . . . . . . . .. Water Soluble— C 0 . . . . . . . . . . . . . . . .. 3.98 4.20 3.98 3.90 3.90 . . . . . . . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. 3.60 3.55 3.55 3.23 3.18 . . . . . . . . . . . . . . . . .. 1 Ogm . . . . . . . . . . . .. 3.35 3.18 2.83 2.63 2.58 . . . . . . . . . . . . . . . . .. 2 Ogms . . . . . . . . . . .. 2.90 2.50 2.13 1.60 1.35 . . . . . . . . . . . . . . . . .. 5.0gms . . . . . . . . . . .. 1.68 1.48 1.23 .95 1.00 . . . . . . . . . . . . . . . . .. 10.0 gms . . . . . . . . . . .. 1.40 1.23 1.00 .80 .18 . . . . . . . . . . . . . . . . .. Ins0luble-— C 0 . . . . . . . . . . . . . . . .. .24 .23 .24 .26 .31 . . . . . . . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. .25 .28 .23 .24 .30 . . . . . . . . . . . . . . . . .. 1.0 gm . . . . . . . . . . . .. .29 .26 .26 .26 .38 . . . . . . . . . . . . . . . . .. 2.0 gms . . . . . . . . . . .. .23 .33 .29 .34 .55 . . . . . . . . . . . . . . . . .. 5.0 gms . . . . . . . . . . .. .41 .44 _ .33 .43 .71 . . . . . . . . . . . . . . . . .. 10.0 gms . . . . . . . . . . .. .45 .43 ‘.39 .35 .51 . . . . . . . . . . . . . . . . .. _ Water S0luble——— D 0 . . . . . . . . . . . . . . . .. 13.92 13.71 13.76 13.80 14.09 13.70 . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. 13.72 13.59 13.57 13.46 13.77 13.51 . . . . . . . . . . .. 1.0 gm . . . . . . . . . . . .. 13.27 12.71 osi. 12.45 12.76 12.59 . . . . . . . . . . .. 2.0 gms . . . . . . . . . . .. 12.64 11.10 10.49 10.35 10.30 9.47 . . . . . . . . . . .. 5.0grns . . . . . . . . . . .. 10.32 7.42 6.69 4.97 4.27 3.55 . . . . . _ . . . . .. 10.0 gms . . . . . . . . . . .. 9.07 4.66 3.62 2.32 1.37 1.10 . . . . . . . . . . .. Ins0luble— D . . . . . . . . . . . . . . . .. .17 .16 .16 .16 .19 .17 . . . . . . . . . . .. 0.5 gm . . . . . . . . . . . .. .16 .18 .18 .15 .19 .17 . . . . . . . . . . .. 1.0 gm . . . . . . . . . . . .. .17 .19 .20 .17 .20 .18 . . . . . . . . . . .. 2.0gms . . . . . . . . . . .. .16 .22 .26 .25 .31 .27 . . . . . . . . . . .. 5.0gms . . . . . . . . . . .. .17 .24 .34 .47 .64 .64 . . . . . . . . . . .. 10.0 gms . . . . . . . . . . .. .16 .26 .34 .47 .72 .81 . . . . . . . . . . .. Water Solnble— E 0 . . . . . . . . . . . . . . . .. 11.95 11.90 11.90 11.95 12.00 11.79 11.94 . . . . .. 0.5 gm . . . . . . . . . . . .. 11.71 11.79 11.75 11.62 11.91 11.77 11.99 . . . . .. 1.0 gm . . . . . . . . . . . .. 11.25 11.17 11.01 11.20 11.16 11.00 . . . . . . . . . . .. 2.0gms . . . . . . . . . . .. 10.69 9.87 9.55 9.47 9.44 9.02 9.54 . . . . .. 5.0gms . . . . . . . . . . .. 6.85 4.84 4.21 3.44 3.09 2.65 2.21 1.96 10.0 gms . . . . . . . . . . .. 4.06 2.44 1.47 .54 .20 .91 .67 .60 Ins0luble— E 0 . . . . . . . . . . . . . . . .. .25 .32 .22 .25 .28 .38 .39 . . . . .. 0.5 gm . . . . . . . . . . . .. .27 .35 .23 .36 .36 .42 .41 . . . . .. 1.0 gm . . . . . . . . . . . .. .32 .34 .34 .38 .34 .41 .42 2.0gms . . . . . . . . . . .. .30 .40 .33 X .44 .51 .61 . . . . .. 5.0gms . . . . . . . . . . .. .37 .45 .38 .53 .64 .86 1.01 1.15 10.0 gms . . . . . . . . . . .. .47 .56 .56 .67 .76 1.37 1.99 3.39 EFFECTS OF LIME AND CARBONATE OF LIME ON A011) PHOSPHATE. '7 Table l.—Efl'ect of carbonate of lime on phosphoric acid of acid phosphate.——Continued. I 0 1 2 5 1O 2O Series. Added to 50 gms. days. day. days. days. days. days. _. Water S0lub1c-—- F . . . . . . . . . . . . . . . .. 12.12 11.92 12.27 11.47 11.75 11.27 0.5 gm . . . . . . . . . . . .. 11.56 11.27 11.56 10.67 10.60 10.65 I 1.0 gm . . . . . . . . . . . .. 10.87 10.77 10.34 9.76 9.65 9.54 2 Ogms . . . . . . . . . . .. 9.61 9.19 8.59 7.61 7.20 6.94 5 Ogms . . . . . . . . . . .. 6.61 5.90 4.57 2.84 2.17 1.69 10 Ogms . . . . . . . . . . .. 3.45 2.25 1.76 1.30 1.11 1.12 Ins0luble-—- _ No addition . . . . . . .. .61 .63 .72 .71 .77 .69 0 5 gm Ca CO3 . . . .64 72 81 .67 .77 .79 1. gm. Ca CO3. .78 68 .78 .69 .84 .80 2.0gms.CaCO3.... .74 82 .76 .78 .90 .82 5.0gms.CaCO3.... .71 .76 .77 .83 .87 .98 10.0 gms. Ca CO3.... .76 .81 .85 .81 .94 .99 An examination of the table shows that “rater-soluble phosphoric acid decreases much more rapidly than the insoluble phosphoric acid. That is to say, the carb-onate of lime acts first upon the water-soluble phosphoric acid, and much more slowly upon the citrate-soluble. EFFECT OF HYDIRATED LIME. The experiments with hydrated lime are similar t0- those with car- bonate of lime, 50 grams acid pho-sphate being used and the results reported in the percentages of the mixture. Commercial hydrated lime was used. (See Table 2.) Table 2.—-Efl'ect o1‘ hydrated lime on phosphoric acid of acid phosphate. _ 0 1 2 5 1O 2O Serles. Addition. day. day. days. days. days. days. ________ _}__________________________________ Wn ten-Sol uble—— (i 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12.99 12.96 13.08 13.10 13.08 12.98 0 5gm . . . . . . . . . . . . . . . . . . . . . . . . .. 12.96 12.86 13.13 13.08 12.95 13.00 1 Ogm . . . . . . . . . . . . . . . . . . . . . . . . .. 12.48 12.40 12.49! 12.40 12.43 12.23 l_'.5gms . . . . . . . . . . . . . . . . . . . . . . . .. 7.91 7.55 7.45 7.57 7.38 7.58 5.0gms . . . . . . . . . . . . . . . . . . . . . . . .. 1.94 1.14 1.18 11.15 .88 1.06 10.0gms . . . . . . . . . . . . . . . . . . . . . . . .. .00 .00 .00 .00 .00 Insoluble- (1 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .10 .14 .16 0.5_szm . . . . . . . . . . . . . . . . . . . . . . . . .. .10 .14 .15| . .0 gm . . . . . . . . . . . . . . . . . . . . . . . . .. .13 .15 .23 .20 2.5 gms . . . . . . . . . . . . . . . . . . . . . . . .. .19 .21 .28 .25 5 0 2m.“ . . . . . . . . . . . . . . . . . . . . . . . .. .52 .32 48 .32 OOgms . . . . . . . . . . . . . . . . . . . . . . . .. 146 1.17 226 323 Waicr——S0h1blc—- H O . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 4 20 4.08 3.90 3.95 0 5gm . . . . . . . . . . . . . . . . . . . . . . . . .. 2 95 2.80 2.65 2.55 1.0gm . . . . . . . . . . . . . . . . . . . . . . . . .. 150 1.40 1.28 1.10 2.0gms . . . . . . . . . . . . . . . . . . . . . . . .. .58 .58 .53 .53 5.0 ems . . . . . . . . . . . . . . . . . . . . . . . .. .05 05 O3 05 10.0 ems . . . . . . . . . . . . . . . . . . . . . . . .. .05 05 03 05 lnsoluble— _ H 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .36 .30 23 2 0.5 gm . . . . . . . . . . . . . . . . . . . . . . . . .. .34 .46 34 34 1 0 gm . . . . . . . . . . . . . . . . . . . . . . . . .. .56 .56 41 40 2 Ogms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1.34 1 39 161 0 gms 41 .98 3 93 8 TEXAS AGRICULTURAL EXPERIMENT STATION. Table 2.—Efl'ect of hydrated lime on phosphoric acid of acid phosphatmr-Continued. O 1 2 5 10 20 Series. Addition. day. day. days. days. days. days. Water-Soluble- . l 0 . . . _ . . . . . . . . . . . . . . . . . . . . . . . . .. 13.82 13 ‘i6 14 02 13.69 . 13 89 13 60 0.5 gm . . . . . . . . . . . . . . . . . . _ . . . . . .. 13.46 13 5O 13 46 13.27 13 61 13 02 1.0 gm . . . . . . . . . . . . . . . . . . . . . . . . .. 12.24 11 91 11 60 11.90 11 95 ll 64 2.0 gms . . . . . . . . . . . . . . . . . . . . . . . .. 9 3O 8 86 9 O7 8.79 8 76 8 66 5.0 gms . . . . . . . . . . . . . . . . . . . . . . . .. 1 62 1 16 1 15 1.08 1 02 95 10.0 gms . . . . . . . . . . . . . . . . . . . . . . . . . O6 O5 O2 O1 O2 O4 Ins0luble— l 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .17 .16 .17 Lost 2.0 16 0.5 gm . . . . . . . . . . . . . . . . . . . . . . . . .. .17 .19 .18 .17 2O 17 1 0 gm . . . . . . . . . . . . . . . . . . . . . . . . .. .20 .20 .21 .17 21 19 2 O gms . . . . . . . . . . . . . . . . . . . . . . . .. .17 .24 .22 19 23 20 5 0 gms . . . . . . . . . . . . . . . . . . . . . . . .. .49 .49 .51 5 42 l0 O gms . . . . . . . . . . . . . . . . . . . . . . . .. .61 67 1.23 1 5O 1 99 2 39 As was to- be expected, the effect of the hydrated lime was more vigorous than the carbonate of lime, and a more rapid decrease in water- soluble phosphoric acid occurs, together with a greater increase in in- soluble phosphoric acid. The Reactions. The reactions thus take place in two stages: First stage: CaH4P,O8-|—Ca.CO3=Oa,H,P2O8-{-H2O+CO, carnigofiora(on),=cia,n,r,os+zn,o Thus 100 parts carbonate of lime or 84 parts of hydrated lime react with 142 p-arts phosphoric acid (P205). Thus 1 per cent. carbonate of lime, if fully acting, would change 1.42 per cent. phosphoric acid from the water-soluble to the citrate-solub-le form. Second stage: ‘ Ca2I-I,P.,_O8+C‘a(_lO3:CagPgOs-l-Hfi-l-CO, Thus 1 per cent. carbonate of lime, reacting fully, would change 1.42 per cent. phosphoric acid from the citrate-soluble to the insoluble condition. If the carbonate of lime carried out both reactions, 1 per cent. would change .71 per cent. phosphoricpacid from the water-solu- ble to the insoluble condition. _ These considerations show that the addition of 1O per cent. car- bonate of lime would be sufficient to change 14.2 per cent. water-solu- ble phosphoric acid to the reverted condition, or 7.1 per cent. from the water-soluble to the insoluble condition, if the reaction progressed to the fullest extent possible. This, however, is not to be expected within solid mixtures, especially if the calcium carbonate is coarsely ground, . as is the case when it is used as a filler. EFFECTS or Lam: AND CARBONATE OF LIME ON A011) PHOSPHATE. 9 Table 3.—Change of phosphoric acid due to carbonate of lime in 20 days. Water~ Calculated Addition. soluble. Insoluble. Total. change. ' A 5per cent . . . . . . . . . . . . . . . . . . .. 1.22 .72 1.94 7.10 10 per cent . . . . . . . . . . . . . . . . . . .. 2.57 1.10 3.67 14.20 20 per cent . . . . . . . . . . . . . . . . . . .. 8.20 1.68 9.88 28.40 B Spercent . . . . . . . . . . . . . . . . . . .. 1.92 .14 2.06 7.10 10 per cent . . . . . . . . . . . . . . . . . . .. 8.29 .15 8.44 14.20 2O per cent . . . . . . . . . . . . . . . . . . .. 10. 97 .40 11.37 28.40 D Spercent . . . . . . . . . . . . . . . . . . .. 3.74 .12 3.86 5.68 10 per cent . . . . . . . . . . . . . . . . . . .. 9.75 .54 10.29 14.20 20 per cent . . . . . . . . . . . . . . . . . . .. 12.33 .83 13.16 28.40 It is of some interest to inquire how far the reaction progressed in ‘our experiment. Tab-le 3 shows the change in 20 days due to carbonate of lime, calculated back to» 100 parts acid phosphate. It is easily seen from the table that the reaction is not complete in 20 days, that the reaction is greatest with the water-soluble phosphoric acid, but that the citrate-soluble phosphoric is also affected. ' OBJECTS OF USING CARBONATE OF LIME IN A FERTILIZER. There are two objects in using carbonate of lime in a fertilizer: first, to dry it out, so that it will drill more easily; second, to act as a filler and so secure the desired composition. Acid phosphate made with an excess of acid, or poorly cured, con- tains some free phosphoric acid. Free phosphoric acid attractsmoisture from the air and thus lnakes the phosphate damp and sticky. The addition of carbonate of lime to such phosphate will convert the phos- phoric acid into monocalcium phosphate, which does not attract moist- ure, and the physical condition of the fertilizer would thus be improved. Calcium carbonate does not absorb moisture, and in its reaction with phosphoric acid, monocalcium_ phosphate, or dicalcium phosphate, it produces moisture. It is therefore difficult to see how the addition of carbonate of lime in excess of the quantity needed to convert free phos- phoric acid into monocalcium phosphate, would be of any advantage in drying the fertilizer. The amount of carbonate of lime required to change the free phosphoric acid should be comparatively small. As already shown, 1 per cent. would change 1.42 per cent. Two or three per cent. carbonate of lime should be sutficient for this purpose, un- less the acid phosphate is very badly made indeed. Free phosphoric acid rnayr be estimated by drying the sample, eX- tracting the phosphoric acid with anhydrous ether, and estimating the quantity dissolved by the usual method. Table 4 shows the quantity of free phosphoric acid in some acid phosphates. Table 4.——Free phosphoric acid in acid phosphates. Labratory Number. Per cent. 679 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72 679 With 1 per cent carbonate of lime . . . . . . . . . . . . . . . . . . . . . . . . . . . .08 712 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44 712 With 1 per cent carbonate of lime . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 25076 0 .31 26187 QIIIIIIfIIIIIIIIIIIIIIIIIIIIIIIIIIIIIfYIIIIIIIII§IIIIIIII .54 10 TEXAS AGRICULTITTJRAT, EXPERIMENT STATION. The use of calcium carbonate as a filler is not to be commended. There is no reason why a filler open to fewer objections should not be used. OBJECTIONS TO USE OF’ CALCIUM CARBONATE. There can be little objection to the use of 3 or 4L per cent. calcium carbonate in an acid phosphate for the purpose of making it drier and more easily applied. This quantity may slightly reduce the water-sob uble phosphoric acid but will hardly affect the reverted. There are decided objections to the use of more than 4 per cent. calcium carbonate in an acid phosphate. In the first place, the water- soluble phosphoric acid will be largely changed, converting it into less soluble forms, less fitted for distribution in the soil. In the second place, it will reduce the available phosphoric acid by increasing the insoluble. The latter effect will depend upon the mechanical condition of the carbonate of lime and the character of the acid phosphate. A coarsely -ground limestone will not act so much as the finely ground precipitated carbonate of lime used in these experiments. If the pile of acid phos- phate heats, the reaction will go further than if it does not heat. In some cases, fertilizer manufacturers are surprised to find their goods run below guarantee and claim that the State analysis is not correct, when, as a matter of fact, the trouble is due to the limestone filler they used. In the SBEISOII of 1915-16, we found two samples of acid phosphate guaranteed 1f; per cent. available but containing only 13 per cent. available. Farther examination showed the presence of carbonate of lime. The total phosphoric acid was 18 per cent., and the insoluble was 5 per cent. The deficiency was due to reversion of the phosphoric acid caused by the carbonate of lime. - DETECTION AND ESTIMATION. Limestone in a fertilizer may easily be detected by pouring dilute acid on the fertilizer. It may be estimated by the various methods for estimating carbonates, measuring the carbon dioxide evolved or other- wise. It is not necessary to describe these well known methods here. If the acid phosphate has used all the calcium carbonate, it cannot, of course, be estimated. The estimation shows the calcium carbonate which remains unchanged. Table 5 gives the carbonate of lime found in various commercial acid phosphates. ' Table 5.—-Carbonate of lime in commercial acid phosphates. Laboratory number. Per cent. NJ 61 M M I-l w-mwov-oa QMQOOUDUT EFFECTS or LIME AND OARBoNATE or LIME ON AoID PHOSPHATE. 11 It is a question whether part of the reaction does not take place in the filter paper, when the fertilizer is being washed with water to re- move the water-soluble phosphoric acid. To test this, we mixed carbonate of lime with acid phosphate and determined carbon dioxide directly in one portion; in another portion We determined carbon dioxide after washing the mixture with water, as in the estimation of water-soluble phosphoric acid. Table 6.—-Carbonate of lime before and after washing the mixture. Carbonate of lime. Water-soluble phosphoric acid. Laboratory number. Corrected Dry. Washed. Loss. Original. original. Washed. Loss. 26097 . . . . . . . . . . . . . .. 12.9 12.8 0.1 12.10 10.01 8.42 1.59 26192 . . . . . . . . . . . . . .. 14.5 13.9 0.6 8.40 7.00 6.27 0.73 26225 . . . . . . . . . . . . . .. 13.9 13.2 0.2 12.92 10.77 9.66 1.11 The results are in Table 6. There was a slight loss of carb-onate of lime during the washing, but this is within the limits of error of the work, so we may consider that little if any reactio-n took place on the filter paper. Some TQElClIlOIl had taken place, however. In another experiment, we mixed 0.5 grams dry carbonate of lime with 2.5 grams acid phosphate in a bottle connecte-d with a gas meas- uring apparatus. The amount of carbon dioxide evolved in 10 minutes was 2.5 c.c. equal to about 0.8 per cent. The reaction, of course, goes on slowly. EFFECT‘ OF SALTS. - Table 7 shows theeltect oi’ nitrate of soda and sulphate of potash on the insoluble phosphoric acid. Two grams of carbonate of lime and 0.5 gram sodium nitrate or sulphate of potash were added to 2 grams acid phosphate, mixed well, and allowed to stand seven days. The nitrate of soda, which is hygroscopic, increased the insoluble phosphoric acid, due to the action of the lime, decidedly more than did the rsulphate of potash. Table 7.—-Eflect of nitrate of soda and sulphate of potash on the insoluble phosphoric acid. A i B C Carbonate of lime and nitrate of soda . . . . . . . . . . . . . . . . . . . 6.95 4.07 5.05 Carbonate 0f lime and sulphate of potash . . . . . . . . . . . . . . . 3.40 2.87 3.82 Earner ON AVAILABILITY. Kellner and Bottcher (Jahnesber Agr. Chem, 1901, 112) found in pot experiments on mustard that lime decreases the availability of pho- phates. They used large quantities of lime. (See Table 8.) 12’ TEXAS AGRICULTURAL EXPERIMENT STATION. Table 8.—Efl'ect of carbonate of lime on availability of phosphoric acid. Super Thomas Bone phosphate. phosphate. meal. I N0 lime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 100 100 Carbonate of lime 15 gms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77.7 81.7 72.6 Carbonate of lime 30 gms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75.5 81.5 50.0 In another experiment, they found the availability of double phos- phate with lime was 89, when that without lime was placed at 100. _In these experiments, large amounts of lime Were used, compared with the amount of phosphate. POT EXPERIMENTS. We made some pot experiments to test the eifect of lime on acid phosphate, but We are not altogether satisfied with the xvay some of these crops grew. Details: 4 Soils 3653, 4643, 4580, 4596, 4581, 4589, 4591. Additions: Ac 1 gram acid phosphate. AcL 0.1 gram calcium carbonate mixed with the acid phosphate be- fore putting in the soil. One gram sulphate of potash and 1 gram ammonium nitrate added» to all pots. Corn planted May S, harvested July 10-14, 1911. Four stalks. One gram ammonium nitrate added to all pots. Sorghum planted July 25, harvested October '7, 1911.. No. 2 Ac replanted July 31. Soil 3976 planted May 8; second crop planted August 9. Ac 2L had 0.2 grams carbonate of lime added to the acid phosphate. Ac 3L, 0.3 grams carbonate of lime added to the 1 gram acid phosphate. In another series, acid phosphate was compared with acid phosphate mixed with 10 per cent. carbonate of lime. There Were used 0.259 grams acid phosphate or 0.286 grams phosphate with carbonate of lime, which contained an equal amount of available phosphoric acid. The pots received 1 gram each of sulphate of potash and ammonium nitrate, contained 5,000 grams soil, and Were planted with corn April 20, 1915, and harvested June 21, 1915. One gram each ammonium nitrate and sulphate of potash were added, planted June 22; harvested August 2'7, 1915. Results A summary of the results is given in Tables 9 and 10. Details of the test are given in Tables 11 and 12. EFFECTS OF LIME AND CARBONATE or L111}: ON A011) PHOSPHATE. 13 Table 9.—Loss of phosphoric acid due to the addition of 10 per cent. carbonate of lime. Corn removed Lab. Corn. Sorghum. Totai. without N0. lime. 3653 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0023 .0126 .0149 .0599 4604 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0013 .0128 .0141 .0580 4643 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0085 0 .0085 .0457 4580 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0084 0 .0084 .0665 3976 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0040 0 .0040 .0168 4596 1911 series . . . . . . . . . . . . . . . . . . . . . . . . 0 .0004 .0004 .0284 4581 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0285 0 .0285 - .2261 4584 1911 series . . . . . . . . . . . . . . . . . . . . . . . . 0 . . . . . . . . . 0 .0480 Average gms . . . . . . . . . . . . . . . . . . . .0066 .0037 .0099 .0687 9272 1915 series . . . . . . . . . . . . . . . . . . . . . . . . 0 0 0 0172 9275 1915 series . . . . . . . . . . . . . . . . . . . . . . . . 0 . . . . . . . . . . 0 0195 9276 1915 series . . . . . . . . . . . . . . . . . . . . . . . . 0. . . . . . . . . . . 0 .0127 9282 1915 series . . . . . . . . . . . . . . . . . . . . . . . . .0009 .0003 .0012 .0177 Table l0.—Loss of phosphoric acid due to 21'! per cent. carbonate of lime. . Corn Lab. . Corn. Sorghum. Tota . without i‘ o. J me. _ I 4604 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0004 0 .0004 .0580 3976 1911 series . . . . . . . . . . . . . . . . . . . . . . . . .0015 .0011 .0026 .0168 4596 1911 series . . . . . . . . . . . . . . . . . . . . . . . . " 0 0 0 a . .0284 4581 1911 series _ . . . . . . . . . . . . . . . . . . . . . . . .0433 0 .0433 .2261 Average gms . . . . . . . . . . . . . . . . . . .0113 .0002?! .0116 .0623 The crops did not grow as well as they should in the series of 1915. The summary shows that there is an average loss due to the addition of the lime to the acid phosphate, small in some cases, large in others, but on the average suflicient to make a decided difference in the value 0f the fertilizer. That is to say, the addition of 10 per cent. or 20 per cent of carbonate of lime to acid phosphate reduces the value of the fertilizer t0 crops. Table 11.——Details of pot experiments, 1911. {m}, Per cent. Gm. Average. Loss. N()_ CrOp. PQ-Og Plrog 1-AC corn . . . . . . . . . . . . . . . . . . . . . 34.5 .16 .0552 .0599 3653 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40.4 .161 .0646 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 39.6 .14 .0554 .0576 .0023 4-ACI . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31.3 .19 .0595 3653 l-AC sorghum . . . . . . . . . . . .'. . . . . 16.7 19 .0317 0356 2-AC . . . . . .. . . . . . . . . . . . . . . . . . . . .. 19.7 .20 .0391 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.9 .19 .0207 .0230 .0126 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . .. 14.0 -18 .0252 4604 1-AC corn . . . . . . . . . . . . . . . . . . . . . 26.1 .22 .0574 0580 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 34.4 .16 .0585, 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.2 .23 .0557 .0557 .0013 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.2 .29 .0557 5-ACLL . . . . . . . . . . . . . . . . . . . . . . . . . . 26.2 .22 .0576 .0576 .0004 4604 1-AC sorghum . . . . . . . . . . . . . . . . . 31.6 .19 .0600 2-AC . . . . . .._ . . . . . . . . . . . . . . . . . . . .. 31.2 .20 .0624 .0612 3-ACI , . . . . . . . . . . . . . . . . . . . . . . . . . .. 25.3 .21 .0531 4-ACI , . . . . . . . . . . . . . . . . . . . . . . . . . . . 29.1 .15 .0436 .0484 .0128 5-AC2L . . . . . . . . . . . . . . . . . . . . . . . . . . 28.9 .22 .0656 .0656, O 14 TEXAS AGRICULTURAI. EXPERIMENT STATION. Table 11.——Details of pot experiments.—Continued. Lab, Per cent. Gm. No. Crop. P120; 19,0; Average. Loss. 4643 1-AC ("orn . . . . . . . . . . . . . . . . . . . . . 36.8 .12 .0442 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34.0 . 14 .0476 .0457 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.5 .12 .0378 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.6 .12 .0367 .0372 .0085 4643 1-AC sorghum . . . . . . . . . . . . . . . . . 20.0 .13 .0260 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 12.8 .17 .0217 .0239 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . .. 18.6 .14 .0260 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1 .18 .0308 .0284 .0000 4580 l-AC corn . . . . . . . . . . . . . . . . . . . . . 24.2 .30 .0726 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.2 .25 .0605 .0665 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.6 .25 .0540 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 .28 .0581 .0622 .0084 4580 1-AC sorghum . . . . . . . . . . . . . . . . . 23.7 .27 .0640 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 .23 .0511 .0526 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.0 .24 .0552 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.5 .24 .0588 0570 0 3976 1-AC corn . . . . . . . . . . . . . . . . . . . .. 10.1 .17 .0172 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11.0 .15 .0165 .0168 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . .. 11.8 .14 .0165 4-ACL . . . . . ... . . . . . . . . . . . . . . . . . . . 7.5 .12 .0090 .0128 .0040 5-AC2L . . . . . . . . . . . . . . . . . . . . . . . . .. 8.5 .17 0145 6-AC2L . . . . . . . . . . . . . . . . . . . . . . . . .. 9.5 .17 0162 .0153 .0015 3976 1-AC sorghum . . . . . . . . . . . . . . . . . 11.5 .16 0184 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.8 .21 .0143 .0164 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 .17 .0024 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . .. 12.0 .16 0192 .0192 0 5-AC2L . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 .20 0106 6-AC2L . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6 .20 0192 .0153 .0011 4596 1-AC vorn . . . . . . . . . . . . . . . . . . . . . 28.6 .10 .0286 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.6 .11 .0282 .0284- 3-ACI 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.8 .12 .0298 4-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 30.7 . 10 .0307 .0303 0 5-AC2L . . . . . . . . . . . . . . . . . . . . . . . . . . 26.4 . 11 .0290 .0290 0 4596 1-AC sorghum . . . . . . . . . . . . . . . . . 20.2 .14 .0283 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18.3 .13 .0238 .0261 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . .. 19.6 .12 .0235 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.7 .14 .0276 .0257 .0004 5-AC2L . . . . . . . . . . . . . . . . . . . . . . . . . . 20. 9 .14 .0293 .0293 0 4581 l-AC corn . . . . . . . . . . . . . . . . . . . . . 54.4 .42 .2285 - 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.9 .40 .2236 .2261 52.6 .42 2209 51.1 .38 1942 1976 .0285 40.8 .39 1591 49 .1 . 38 1866 1728 . 0433 50.6 .37 1872 1872 .0389 4581 8.3 .58 .0481 15.0 .53 .0795 .0638 13.7 .51 .0699 17.8 .53 .0943 0737 16.3 .51 .0831 14 .4 .52 .0749 .0790 0 18.3 .48 .0878 .0878 0 4584 1-AC rorn . . . . . . . . . . . . . . . . . . . . . 21 .0 .20 0420 2-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.5 .22 0539 .0480 3-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.5 .20 0490 4-ACI 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . 239' .23 .0550 0520 0 .;1;_ | |...§,\,1 \q,~,t nnnqrrrnnnr ———-urn'||nu|r EFFECTS 0F LIME AND CARBONATE OF LIME ON A011) PHOSPHATE. 15 Table 12.—-Details of pot experiments, 1.915. L311 Weight Per cent. Gm. Na crop. Pfog ~ 131,0; Average. Loss. 9172' 1-O corn . . . . . . . . . . . . . . . . . . . . .. 6.1 .20 .0122 . 2-0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.2 .15 .0093 .0108 3-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.5 .26 .0169 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7.4 .26 .0174 .0172 5-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9 .26 .0205 6-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8 .25 .0170 .0188 0 1-O sorghum . . . . . . . . . . . . . . . . . . 1x9 15 .0029 2-O. .°. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 14 .0048 0039 3-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10.5 13 .0137 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.5 16 .0104 0121 5-ACI . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.3 23 .0145 6-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.7 22 .0213 0179 0 9275 1-O corn . . . . . . . . . . . . . . . . . . . . . . 9.3 14 .0130 2-O . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10.0 18 .0180 0155 3-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 .8 18 .0202 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10.4 18 .0187 0195 5-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.7 22 .0279 6-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4 19 .0236 0258 0 1-O sorghum . . . . . . . . . . . . . . . . . .. 0 2-0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-ACL . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9276 1-O corn . . . . . . . . . . . . . . . . . . . . .. 6.7 17 .0114 2-O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 16 .0098 0106 3-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.8 19 .0129 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 19 .0124 0127 5-L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 21 .0126 6-L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 20 .0126 0126 0 1-O sorghum . . . . . . . . . . . . . . . . . . 2.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9282 1~O corn . . . . . . . . . . . . . . . . . . . . . . 5.6 23 .0129 2-O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.8 23 .0133 0131 3-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6.5 27 .0176 4~AC . . . . . . . . . . . . . . . . . . . . ._ . . . . . . . 6.1 29 .0177 0177 5-L . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7.9 .22 .0174 6-L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.6 .29 .0162 .0168 .0009 " 1-O sorghum . . . . . . . . . . . . . . . . . . 3.7 14 .0052 2-0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.0 14 .0042 0047 3-AC. . . . . . . . . . . . . . . . . . . . . . . . . . . 7.0 20 .0140 4-AC . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8.1 13 .0105 0123 5-L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 .20 .0070 6-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8.5 .20 .0170 .0120 .0003 USE 0F CABBONATE OF LIKE IN MIXED FERTILIZERS. The use of carbonate of lime in mixed. fertilizers has been advocated by some for the purpose of correcting the acidity of the soil and also for releasing potash of the soil. We have shown in Texas Bulletin N0. 190 that lime has little effect in rendering soil potash available, con- trary to preconceived ideas on the subject. If needed to- correct soil acidity, lime should be added separately, and not mixed with fertilizer which it affects injuriously. In Bulletin N0. 220 of the lVorth Carolina Department of Agricul- ture, J. L. Burgess, Agronomist, discusses. this sub-jec-t and concludes that limestone is beneficial in a. fertilizer and will replace potash. With this conclusion, We are obliged t0 dissent. He recommends various mix- tures of fertilizing materials, with from 600 to 1200 pounds ground 16' TEXAS AGRICULTURAL EXPERIMENT STATION. limestone, mostly of 1200 pounds. We recommend that limestone, in cases Where needed, be applied separately from fertilizers. The ques- tion is not whether lime benefits the soil or not, but whether the lime- stone, if needed, be applied mixed with a fertilizer, or separately. _ The use of ground limestone in a fertilizer in excess of 3 or 4 per cent. is objectionable for the following reasons: 1. It will revert the water-soluble‘phosphoric acid to citrate-soluble. 2. It will revert a small or larger part of the phosphoric acid to an insoluble form. _ 3. It will counteract the purpose of putting in the sulphuric acid with the rock phosphate in the original manufacture of the acid phos- p ate. 4-. It will cause the application of lime to soils which already con- tain an abundance, or its application in insufficient amounts to soils ‘Which really need lime. 5. There is no reason to believe that the carbonate of lime will re- lease any additional amount of soil potash. _ 6. The use of carbonate of lime as a filler in fertilizers involves the danger that the fertilizer will fall below guarantee in available phosphoric acid. ACKNOWLEDGMENT. Analytical and other work involved in the preparation of this bul- letin has been participated in by J. H. Summers, W. E. Stokes, T. L. Ogier, and, especially, S. E. Asbury. SUMMARY Carbonate of lime added to an acid phosphate acts first upon any free phosphoric acid present, next on the wa.ter-soluble phosphoric acid, and much less readily upon the citrate-soluble phosphoric acid to form insoluble phosphoric acid. These three reactions may go on at the same time. Carbonate of lime may be used as a. drier for acid phosphate in quantity suflicient to combine with the free phosphoric acid, which at- tracts moisture. The use of more than 3 or 4 per cent. is not advisable. Carbonate of lime liberates water when reacting upon acid phosphate. ‘ Unchanged carbonate of lime in a. fertilizer may be estimated by gasometric or gravimetric methods. Some samples of acid phosphate which fell badly below guarantee in available phosphoric acid contained carbonate of lime and a high percentage of insoluble phosphoric acid. The use of carbonate of lime as a filler is likely to cause the fertilizer to‘ fall below guarantee in available phosphoric acidl Nitrate of soda. increased the deleterious elfect of carbonate of lime. Acid phosphate mixed with lime was less available to corn and sorghum grown in pot experiments than the acid phosphate alone. The pot experiments were not entirely satisfactory. . The use of carbonate of lime in preparing home mixed fertilizers is not to be advised. When lime is needed by the soil. it should be applied separately from the fertilizer, and at different times. Hydrated lime should not be used in mixed fertilizers.