INSTITUTE AND COLLEGE, PUSA, FOE 1913-14. 85 



of this section during this as in previous years; it was 

 found in connection with numerous experiments made to 

 determine the optimum moisture content for nitrification 

 in various soils, that not only is the amount of water all- 

 important, but that the greatest amount of nitrification 

 obtainable depends upon treatment which takes into account 

 the fact that ammonification is the necessary antecedent to 

 nitrification in the case of organic matter, that this process 

 is furthered by a high percentage of moisture, that high 

 concentrations of ammonia inhibit nitrification, but that 

 such ammonia is absorbed by the soil and can then be nitri- 

 fied. Experiment showed that the most rapid and complete 

 nitrification of any given quantity of nitrogenous organic 

 matter could be effected in soil by producing anaerobic 

 conditions witfi water saturation and subsequently drain- 

 ing and aerating; the rapidity with which nitrification 

 takes place under these conditions depends upon the rela- 

 tive completeness of the anaerobic and subsequently of the 

 aerobic conditions. This was the case in all the soils experi- 

 mented with but may not of course be of universal applica 

 tion. It was found that much more rapid ammonification 

 took place in the case of organic matter kept under anaerobic 

 conditions in soil than when free aeration was allowed, 

 whether such anaerobic conditions were produced by water 

 saturation, or replacement of air by nitrogen or carbon 

 dioxide or simply by tightly closing the vessel containing 

 the soil. At the same time toxins were produced which not 

 only inhibited nitrification before the ammonia concentra- 

 tion was sufficient to do so, but afforded water extracts 

 which were toxic to seedlings and to bacteria; subsequent 

 aeration removes this toxic condition and the formation of 

 nitrates takes place, the ultimate result being a high per- 

 centage of nitrification of the nitrogen of the organic 

 matter; this apparently represents the cycle of changes in 

 the case of the fermentation of green manure described 

 above; its application to field practice is now being studied. 

 In connection with the nitrification of green manure it 

 was found that a loss of nitrate invariably occurred between 



