E. J. Russell and E. H. Richards 555 



The heap experiments, on the other hand, show that these desirable 

 results are not attained in manure heaps, however well put up. How- 

 ever compact the heap some nitrogen is always lost and there is never 

 an accumulation, but commonly a loss, of ammonia. This result is 

 not peculiar to our heaps : it has been obtained by all other investigators 

 whose papers we have been able to find. We conclude, then, that the 

 heap is not the ideal method of storing manure. 



The conditions to be aimed at are complete anaerobic conditions 

 and a temperature of 26° C. and it is obvious that these can best be 

 attained in a watertight pit or tank that could be closed so as to keep 

 out oxygen and to keep in the carbon dioxide produced by fermentation. 

 This would be the ideal method for storing farmyard manure. 



But as this ideal method presents certain practical difficulties we 

 must see how far the best methods of practice approximate to it, and 

 whether any further improvements can be suggested. 



Two cases arise : 



1. Manure that can be left undisturbed under the beasts, e.g. 

 manure made in covered yards or stalls by fatting beasts. 



2. Manure that has to be thrown out daily, e.g. manure made from 

 dairy stock or from the horse stables. 



1. All experiments show that manure left under the beasts suffers 

 a loss of about 15 % of its nitrogen; there is no accumulation of 

 ammonia, but, on the contrary, less ammonia than corresponds with 

 the digestible nitrogen in the food. 



This method, therefore, is far from being perfect; but in com- 

 parative experiments it has always come out better than heaps, and if 

 the buildings are good and the manure is well made there is probably 

 little scope for further improvement. 



Further losses set in as soon as the beasts are removed or the manure 

 is hauled out into a clamp. We have been unable to reproduce the 

 strict anaerobic results in a heap, however well it was compacted, and 

 in only one case, — the compact cow manure heap, — were we even 

 partially successful. There we lost only 4 % of the dry matter, and 

 none of the nitrogen, but we had no accumulation of ammonia. The 

 other compacted heaps showed all the aerobic actions in different 

 degree, in particular there was always a loss of nitrogen. 



The losses become more serious if the heap is not properly com- 

 pacted or if it is left exposed to the weather. 



By omitting to compact the heap we lost an additional 3 % of dry 

 matter, and 24 % of ammonia ; but in two cases out of three there 



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