AND COLLEGE, PUSA, FOR 1915-16 89 



Weekly borings and nitrate determinations throughout 

 the year were made in three sets of duplicate plots under 

 grass, cold weather and rains crops (wheat and maize), and 

 fallow respectively. Only in the last of these was there any 

 accumulation of nitrate in the first foot of soil, a much 

 smaller amount occurring in the cropped soil and only very 

 small quantities under grass. Experiments will be made 

 to ascertain whether the grass effect is due to interference 

 with the upward movement of water resulting from eva- 

 poration from the surface, to lack of aeration, or possibly 

 to the toxic action of the specific bacterial flora associated 

 with the grass plants. The nitrate accumulation was high- 

 est in February and reached a minimum in August; this 

 was only in the first foot of soil and no doubt represented 

 the vertical movement of nitrates parallel with that of the 

 soil water. 



Green-manuring. Experiments with fermented green 

 manure were carried out on tobacco to which fermented 

 sann hemp (Crotalaria juncea) was applied. Very large 

 increases in yield were obtained, and a Bulletin (No. 63) 

 describing this modified method of manuring was publish- 

 ed, inviting suggestions and criticisms from agricultural 

 officers in the Provinces from whom many useful and ap- 

 preciative communications have been received, pointing out 

 the applicability of the method to various manurial prob- 

 lems and special cases in their several districts. It is 

 hoped that the experimental trials of this method which 

 are now being made throughout India may lead to more 

 satisfactory and certain results from the use of green 

 manures than are generally obtained. A field trial of the 

 method at Pusa carried out by the Imperial Agriculturist 

 on the rabi oat crop gave very high returns : the Officiating 

 Imperial Agriculturist is carrying out a further experiment 

 this year. 



Saltpetre. The enquiry into the conditions favour- 

 ing the occurrence of saltpetre in Indian soils and the 

 methods adopted by the native for extracting it, was 

 continued and the results published in a Bulletin. 



