DETERIORATION OF MANURE 375 



It will be seen from these experiments that milch 

 cows divert more of the fertilizing constituents from the 

 manure than do any other class of animal, that fattening 

 pigs divert much more of the nitrogen than do cattle 

 or sheep similarly employed, and that the work of the 

 horse does not affect the composition of the manure. 



248. Deterioration of farm manure. There is always 

 a loss in the value of farm manure on standing. The two 

 processes most operative in bringing this change about 

 are: (1) Fermentation. (2) Leaching. The first of 

 these is a natural process, common to all farm manure, 

 and not occasioned by any outside agencies; the second 

 is due to the running off of the liquid portion of the 

 manure, and to the exposure of the manure to rain. 



249. Fermentations. The fermentations occurring 

 in heaps of farm manure are produced both by aerobic 

 and anaerobic bacteria, that is, by bacteria requiring 

 oxygen for their activity, and by those that do not. The 

 fermentations of the outside of the heap are constantly 

 different from those on the interior, where air does not 

 readily penetrate; but, as fresh manure is thrown upon 

 the pile from day to day, most of the manure first under- 

 goes aerobic fermentation before the anaerobic bacteria 

 begin their work. 



It is through the action of bacteria on the nitrogen- 

 ous compounds of the manure that loss of value through 

 fermentations occurs. The action of the aerobic bacteria 

 is to convert the nitrogen of the organic matter into 

 ammonia, which, owing to the large formation of carbon 

 dioxid, is partly converted into ammonium carbonate. 

 Both of these substances being volatile, there is danger 



