332 



Journal of Agricultural Research 



Vol. XVIII, No. 6 



solution, ignited, then lo cc. concentrated nitric acid added, evaporated, 

 and ignited again to destroy organic matter. The residue was taken up 

 with dilute hydrochloric acid, evaporated to dehydrate silica, taken up 

 with hydrochloric acid and water, filtered, and phosphorus determined 

 in filtrate. This process was found to be more satisfactory to destroy 

 organic matter. 



TablU II. — Relative acidity of water-free composts i to 4 



[Expressed in cubic centimeters of Nlso sodium hydroxid required to neutralize 

 100 gm. water-free compost] 



May 8. 



24. 



June 6. 



23- 

 July 6. 



Aug. 3.. 

 17- 

 31- 



Sept. 22. 



Oct. 12 . 



Nov. 7. . 



Dec. 13. 



Jan. 18. , 

 May 2 1 . 

 Aug. 14. 



May 6 . 



1917. 



1918. 



1919. 



No. I, 

 soil and 

 manure. 



Neutral. 

 ..do.... 



1.97 

 2. 27 

 2-39 

 4-97 

 3-09 

 2. 96 



3-38 

 3.18 

 4.81 

 2.44 

 3-41 



4. II 



5-85 

 3.61 



72 



No. 2, 



soil, manure, 



and rock 



phosphate. 



2.31 



5-54 



5-91 

 12. 92 

 21.59 

 36- 49 

 26. 03 

 30-25 

 34-84 

 46. 90 

 61.87 

 48.28 

 46.86 



40-34 



116.43 



84.62 



72.48 



No. 3, 

 soil, manure, 

 and sulphur. 



3-52 



11-37 



61. 52 



70. 82 



64. 60 



83.28 



73-48 



60. 21 



93-31 



155-95 



270. 47 



222. 80 



204. 32 



158. 23 

 I, 049. 03 

 2,821.34 



1,464- 57 



No. 4, 

 soil, manure, 

 rock phos- 

 phate, and 

 sulphur. 



^■S9 

 22. 77 

 38.88 

 56.60 

 61. 71 

 70.76 



66. 29 

 48. 91 

 68. 40 

 61.95 



87-79 

 70.30 

 78.04 



78.95 

 569- 58 

 925- 83 



868. 00 



In addition to the determinations recommended, it was thought that 

 it might prove of interest to make a study of the nitrites, nitrates, and 

 total nitrogen in these experiments. Since nitrification has generally 

 been found to proceed more favorably in a neutral or slightly alkaline 

 medium, this afforded an opportunity to follow its course in an acid one 

 as well as in the presence of phosphate. Determinations of the total 

 nitrogen were made at the beginning and end of the experiment to find 

 out the effect which composting under these conditions would have on 

 the nitrogen content. 



The magnesium nitrate method for total phosphorus, the Griess- 

 Ilosvay method for nitrites, and the Kjeldahl method for total nitrogen, 

 modified to include nitrates, were used for these various determinations. 



The nitrates were determined as follows : To the equivalent of 50 gm. 

 of water-free compost were added 125 cc. distilled water, taking into 

 account the water content of the compost. To this was added a small 



