876 EXPERIMENT STATION RECORD. 



excrement of horses, sbeep, and cows treated in different ways were 

 made on oats in ))ots. 



The ]>rincipal conclusions of these experiments maj^ be summarized 

 as fobows: 



(1) The losses of nitrogen and of organic matter in the manure were 

 very small when only a small amount of air was admitted into the flasks. 

 The longer and more rapidly the air was drawn through, the greater 

 the loss of nitrogen, amounting in one case to 42.(5 per cent of the nitro- 

 gen originally present. When the air was simply drawn over the 

 manure the loss of nitrogen was still quite large, amounting to 27.6 per 

 cent of that originally present. 



(2) The action of preservatives was generally contradictory. When 

 air was freely drawn through the flask the loss of nitrogen was not 

 reduced by the use of preservatives to the point it reached in flasks in 

 which no ])reservatives were used, but through which only a moderate 

 amount of air was drawn. 



(3) It appeared that the mechanical condition of the manure exerted 

 a more marked efl'ect upon its preservation than chemical preserva- 

 tives. The latter can be used with advantage only when the former 

 has been properly attended to. 



(4) At a temi)erature of 32 to 34° C. the loss of nitrogen was consid- 

 erably greater than at room temperatures. 



(5) Under certain conditions the nitrogen can be converted almost 

 entirely into the elementary form. In many of the experiments here 

 reported the conditions were such that 42.6 per cent of the original 

 nitrogen present was lost in this form, l)ut the loss of ammonia, except 

 in the case of the higher temperatures and of addition of caustic lime, 

 was comparatively small. 



(6) The setting free of the elementary nitrogen appears to be accom- 

 plished in 2 ways — by denitrification and by oxidation of the ammonia 

 which is formed. In the experiments here reported it was accomplished 

 almost exclusively in the second manner. Denitriflcation is favored by 

 the free access of air. 



(7) The addition of 2 per cent of caustic lime destroyed the denitrify- 

 ing power of fresh solid horse excrement in a short time. The addi- 

 tion of 3 per cent of calcium carbonate and 0.5 per cent of sulphuric 

 acid was without effect in this respect. Three per cent of caustic lime 

 and 5 per cent of marl decidedly reduced the denitrifying power of fresh 

 solid cow excrement in 24 hours. 



(8) The transformation of the nitrogen of ammonia into free nitrogen 

 was due in the main undoubtedly to the action of microorganisms. 

 This oxidation was prevented by the use of a suflicient amount of 

 superphosphate to combine with all the ammonia formed. When 

 smaller amounts of superphosphate were employed the ammonia not 

 fixed by the superphosphate was converted into free nitrogen. The 

 beneficial effect of small applications of superphosphate in practice 



