10S SCIENTIFIC REPORTS OF THE AGRICULTURAL RESEARCH 



from an aerobically incubated soil. Similar results were 

 obtained when using pure cultures of nitrite formers seeded 

 into these media. 



The effect of excessive quantities of nitrogenous matter 

 in inhibiting nitrification was tested in various soils; in 

 Pusa soil 60 mgm. N per 100 gm. soil was found to be the 

 maximum amount allowing complete and normal nitrifica- 

 tion, either as ammonium sulphate or oilcake; when 

 applied as a mixture of these two, however, it is possible 

 to raise the combined amount to 90 mgm. without pre- 

 judicing the nitrification either by loss of ammonia or by 

 delay. It is of interest to note that nitrification can take 

 place even in a soil in which there is sufficient free 

 ammonia to be detected by smell and litmus reaction. 



Green-manuring. The green-manuring experiments 

 carried out in collaboration with the Imperial Agriculturist 

 on the Punjab experimental plots were continued. These 

 experiments begin to show the valuable residual effect of 

 such treatment on Pusa soils especially with fermented 

 green manure (Crotalaria juncea). Incidentally most valu- 

 able and interesting light has been thrown upon the inter- 

 pretation of the results of field experiments on such soils 

 and in such a climate; the results obtained show clearly 

 first of all the necessity of previously ascertaining the rela- 

 tive fertility of the plots before treatment and the absolute 

 worthlessness of most manurial experiments without this 

 precaution, and, secondly, the equal necessity of taking into 

 account the effect of seasonal variation from one year to 

 another. These points as illustrated by the green-manur- 

 ing experiments referred to, are discussed in an article on 

 this subject in the " Agricultural Journal of India " now 

 in hand. 



Biological analysis of soils. Further work was done 

 on this subject and the question of the use of a standardized 

 method was discussed at the Conference of Agricultural 

 Chemists and Bacteriologists at Pusa in February. A 

 special study was made of certain infertile soils (Manat) 

 from the Konkan Division (Bombay). The First Assistant 



