76 THE MANURE HEAP AND SEWAGE. 



not allowing it to accumulate, and undergo the fermentation that 

 inevitable means loss of nitrogen. Whether this will always be 

 feasible will depend upon conditions on the individual farm; but 

 it is certainly to be highly recommended in all localities where 

 climatic conditions and the exigencies of farm occupations make it 

 possible. 



It is to be borne in mind that in using manure as a fertilizer 

 the soil receives advantages that are not derived from mineral 

 fertilizers. Not only does the manure contain a considerable list 

 of substances of value to the crops, present in small quantities 

 only, and not present in mineral fertilizers, but manure contains 

 considerable organic material in a partly decomposed condition 

 that aids in forming a permanent humus. The texture of the soil 

 is improved by this so that the final result is a soil superior to that 

 containing only mineral fertilizers. The soil thus treated becomes 

 more tenacious, richer, washes less with rains and is generally to 

 be preferred. Mineral fertilizers, with the exception of nitrates 

 may be mixed with manure. The nitrates, if thus mixed, would 

 be lost by denitrification. 



SALTPETER PLANTATIONS. 



These nitrifying forces are not confined to the soil, but may 

 occur in other localities, always resulting in the production of nitrates. 

 Before the discovery of the nitrate beds of South America it was the 

 custom of agriculturists to prepare their own nitrates by a simple 

 process, not then understood, but now known to be due to nitrifying 

 bacteria. The places where nitrates were thus formed were called 

 saltpeter plantations, and the saltpeter was produced by exactly the 

 processes we have already considered. The method was as follows: 



Masses of chalky soil were mixed with various organic bodies 

 and the whole heaped into a pyramidal pile, rendered somewhat 

 porous by the admixture of brushwood. The heap was still further 

 furnished with fermentable nitrogen by frequently watering it with 

 liquid manure. In this heap occurred the various kinds of nitrogen 

 decomposition already mentioned, and later the nitrification process 



