E. H. Richards 



305 



One of the first outdoor experiments witli manure, forming part of 

 the general enquiry still in progress, showed that ordinary stable (horse) 

 manure when stored in loosely made heaps for three months in the 

 open, lost far less total nitrogen than similar heaps of cow dung. Dupli- 

 cate heaps of both manures gave results in very close agreement. It 

 is not possible to go fully into the matter here and only those points of 

 interest in the present connection are touched on. 



The proportion of ammoniacal (i.e. the most easily lost) nitrogen to 

 total nitrogen was actually higher in the horse manure originally, yet 

 these heaps lost only 10 % of their nitrogen while the cow dung lost 

 24 %. Two factors believed to favour loss of nitrogen, viz. aeration 

 and temperature, were both predominant in the horse manure. After 

 storage both kinds of dung had lost practically all their ammonia, 

 but while the cow dung had also lost a considerable amount of more 

 complex nitrogen, the horse dung showed an increase of 10 % in this 

 form. 



The nitrogen changes in the two kinds of manure are most easily 

 seen in the diagram below (Fig. 2). 



Hopse Manure 



Cow Manure 



NHrogen 

 as 



Ammonidk 



n i M i i ri M ii 



Original Stored 5toi»cd OTigmal 

 Dung 5 Months OMonths Dung 



5toped Stoned 



5Months 6 Months 



Fig. 2. Change? in manure during storage. 



