Dec. 15, 1919 



Oxidation of Sulphur in Soils 



333 



amount of calcium carbonate, C. P., the whole shaken every five minutes 

 for half an hour, filtered, and the nitrate determined in an aliquot by the 

 phenol-disulphonic acid method by means of a Duboscq colorimeter. 



The composts were at first kept in a bam and covered with burlap 

 sacks to prevent rapid evaporation. They were maintained at 15 to 20 

 per cent water content throughout the experiment. Tap water was used 

 until November 20, 1917, and distilled water after that date. At this 

 time the piles were moved to the heated part of the greenhouse. They 

 were stirred every 10 to 14 days until October 17, 191 8, at which time 

 X -gallon samples were removed to the laboratory and kept loosely 

 covered but stirred only once afterwards. All determinations were made 

 in duplicate. 



The averages for the various determinations are given in Tables II to V. 



Table III. — Percentage of water-soluble and ammonium-citrate-soluble phosphorus 

 in water-free composts I to 4 



No. I, 

 soil and ma- 

 nure. 



Water- 

 soluble 

 phos- 

 phorus 



Ammo- 

 nium- 

 citrate- 

 soluble 

 phos- 

 phorus 



No, c. 

 soil, manure, 

 and rock phos- 

 phate. 



Water- 

 soluble 

 phos- 

 phorus 



Ammo- 

 nium- 

 citrate 

 soluble 

 phos- 

 phorus. 



No. 3, 

 soil, manure, 

 and sulphur. 



Water- 

 soluble 

 phos- 

 phorus 



Ammo- 

 nium- 

 cit rate- 

 soluble 

 phos- 

 phorus. 



. No. 4, 



Soil, manure, 



rock phosphate, 



and sulphur. 



Water- 

 soluble 

 phos- 

 phorus 



Ammo- 

 nium- 

 citrate- 

 soluble 

 phos- 

 phorus. 



May 12. 



22. 



June 4. 



July 2 . 

 16. 



Aug. 13. 

 27. 

 Sept. 17. 

 Oct. 8. . 

 Nov. 5 . 

 Dec. 10. 



Jan. 15. 

 May 15. 

 Aug. 8. 

 Oct. 10. 



191; 



1918. 



0.003 

 .005 

 .003 

 . 006 

 .005 

 .005 

 . 007 

 . 006 

 .005 

 . 007 

 . 006 

 . 009 

 . on 



008 



on 

 010 



1919. 



Jan. 22 



Apr. 14 



24 



Percentage of total phos- 

 phorus '. . , 



Maximum percentage of total 

 phosphorus made soluble. . 



o. 022 

 012 

 012 

 016 

 012 

 035 

 055 

 027 

 or6 

 050 

 040 

 032 



075 

 070 

 107 

 084 



.063 



o. 006 

 .008 

 .005 

 . 009 

 . 010 

 . 009 

 . on 

 . 009 

 . 009 

 . on 

 . 010 

 . on 

 .013 



012 

 012 

 008 



,005 

 627 

 1-3 



. no 

 .627 

 14. o 



007 



3- 176 

 o. 2 



o. 027 

 . 024 

 . 017 



.058 



. 060 



.079 



. 072 

 . 060 

 . 046 



.085 



. 060 



.058 

 .138 



. 118 

 . 128 

 • 163 



. 160 



145 



222. 



;. 176 

 6. I 



o. 006 

 . 006 

 . 007 

 . 006 

 . 006 

 .003 

 .005 

 . 006 

 . 007 

 . 014 

 . 024 

 . 024 

 .023 



, 012 

 084 

 014 



o. 017 

 . 012 



. 012 

 . 064 

 .023 

 . 069 

 . 067 

 .048 

 .051 

 . 096 

 . 121 

 . 027 

 . 176 



160 

 297 



552 



o. 007 



.008 

 . 008 

 . 009 

 . 009 

 . 007 



. on 

 . on 

 .013 

 . 010 

 . 009 

 .013 

 . 014 



, on 

 146 

 394 



. no 

 .767 

 13-6 



•(>33 

 .767 

 80.3 



• 564 



3- 329 



16.8 



0.047 

 . 016 

 . 020 

 .089 



•054 

 . 072 

 .080 

 .065 



• 063 



•093 

 .082 

 .044 



• 144 



• 134 



•330 



2. 007 



2-451 



2. 280 

 2. 822 



3-329 

 83.6 



