CHAPTEE X 



NITROGENOUS MANURES 



THE nitrogenous manures are in many respects the 

 most important of the special manures. They are, 

 perhaps, not so universally popular as the phosphatic 

 manures, but the potency of their effects, their relatively 

 high price, and the fact that if ignorantly or carelessly 

 used, they may do harm rather than good, all combine 

 to give them a peculiar prominence. They may be divided 

 into organic substances and salts ; of the latter, sulphate of 

 ammonia and nitrate of soda are the most important. 



ORGANIC NITROGENOUS MANURES. 



This division of the subject must be regarded as 

 practically a continuation of the chapter on phospho- 

 nitrogenous manures. The distinction between the two 

 groups, it has been said, is rather an arbitrary one. Fish 

 meals and meat meals are mainly nitrogenous manures, 

 and are generally treated as such notwithstanding that, 

 in some cases, they contain considerable quantities of 

 phosphates. 



The products now to be dealt with are those in which 

 phosphates are absent altogether, or are present only in 

 negligible quantities. They are all waste or bye-pro- 

 ducts of animal origin. The nitrogen is present in the 

 form of insoluble compounds, and only becomes avail- 

 able to plants as the substance becomes oxidised and 

 decomposed. They are best suited for open soils, and 



