92 REPORT OF THE AGRICULTURAL RESEARCH INSTITUTE 



which it is the nuniah's practice to return to the heap of 

 residual earth. This practice may be harmless or even 

 valuable up to a point, after which it must tend to lower 

 the rate of nitrification. 



The addition of wood ashes is another practice which 

 probably might be modified with advantage after examina- 

 tion. The addition of organic matter will no doubt prove 

 the most likely source of possible improvement; experi- 

 ments on this point on a considerable scale are in progress. 



Potato Rot. The enquiry into this subject referred to 

 in my report for 1913-14 was completed and a Memoir on 

 the subject was submitted for publication. It was shown 

 that the rotting of potato tubers in store was in many cases 

 due to the action of bacteria common in Indian soils; the 

 conditions under which such bacteria were able to attack 

 the tubers were described and preventive measures recom- 

 mended. The practice of storing tubers in sand as a pro- 

 tection against potato moth appears to be responsible for 

 many cases of rot in consequence of the increased chances 

 of moisture condensation due to the use of earth instead of 

 sand or inrperfect ventilation. 



V. Programme of work for 1915-16. 



Major Subjects. 



(1) Nitrogen fixation by Azotobacter. 



(2) Nitrification of organic matter; including condi- 



tions severally favourable to ammonification 

 and nitrification. 



(3) Greon manuring with special reference to 



organisms responsible for breaking down of 

 buried plant tissues and their conversion into 

 humus, ammonia and nitrates. 

 Field experiments in green manuring will be car- 

 ried out in the Bacteriological area attached to 

 the outside laboratory. 



(4) Activity of soil bacteria with regard to the 



rendering available of phosphates and other 



