380 THE PRINCIPLES OF SOIL MANAGEMENT 



and a fermentation producing a white appearance of the 

 manure under the surface of the pile ("fire fanging"), 

 are both sure indications of unnecessary loss in its ferti- 

 lizing value. 



Composting farm manure increases the availability 

 of its fertilizing constituents; but, even when carefully 

 conducted, is accompanied by some loss of nitrogen. 

 The total amount of organic matter is decreased by 

 reason of the decomposition, in which process carbon 

 dioxid and water are formed, part of which escapes, and 

 part remains in the manure. The mineral constituents 

 increase percentagely, due to the loss of organic matter; 

 and the water increases for the same reason, and because 

 it is sometimes added to the compost. The mineral con- 

 stituents are not materially changed in their solubilit}*, 

 but the organic matter becomes more soluble. The 

 nitrogen, after conversion into ammonium salts, is 

 oxidized finally into nitrates, but only in small amounts, 

 and after considerable time. The beneficial effects of 

 composing are only in small part due to the chemical 

 changes in the manure, but chiefly to the good physical 

 condition of the composted material, and to the fact 

 that the operations preliminary to the formation of 

 nitrates have largely been effected in the compost, and 

 when applied to the soil nitrification is rapid. Composting 

 manure with soil, sod, muck or other absorbent material 

 increases the manurial value of the latter by increasing 

 its decay, and therefore its availability, and by reducing 

 loss by leaching. 



The following analyses, by Voelcker, show the com- 

 position of fresh and rotted farm manure: 



