84 REPORT OF THE AGRICULTURAL RESEARCH 



Part of the study of the decomposition of green manure 

 in the soil involved investigation as to the relative rates of 

 formation of humus and nitrate; this enquiry has not yet 

 arrived at the conclusive stage suitable for report. 



A considerable amount of work was done in connection 

 with the changes taking place in fermenting green manure; 

 the manurial value of this material appears to be due to the 

 rapid formation of simple nitrogen compounds such as 

 ammonia, from the proteid content ; the nitrification of this 

 ammonia, however, is interfered with by the fact of its 

 concentration and also by the presence of soluble organic 

 substances some of which at least are strongly toxic to nitri- 

 fying bacteria and in less measure to others ; this condition 

 persists so long as the water extract remains acid to litmus 

 which under ordinary conditions of manufacture might 

 extend to as much as six weeks, and renders it necessary to 

 study the conditions under which such manure can safely 

 be applied to arable or other soil. The mode of preparation 

 may also be varied considerably with corresponding differ- 

 ences in manurial action; such differences are apparently 

 correlated with the rate at which the nitrogen content 

 becomes available and are of importance in field practice 

 with reference to the time of application, the nature of the 

 soil, and the nitrogen requirements of the crop intended to 

 benefit by the use of this form of manure. 



It is interesting to note that the rapid ammonification 

 which takes place when green manure is placed in water 

 and allowed to ferment was found to be accompanied by 

 the development of large numbers of ciliates, flagellates and 

 amoebce, whose presence does not appear in this instance to 

 be prejudicial to the activity of ammonifying bacteria; it 

 may be conjectured that under such conditions as obtain in 

 this case the abundance of organic food would produce a 

 rate of reproduction amongst the bacteria which would 

 more than counterbalance any phagocytic action on the part 

 of the protozoa. 



The conditions under which nitrification takes place 

 in soil have naturally formed an important part of the work 



