FARMYARD MANURE 117 



and contents are now moistened with ammonium 

 nitrate solution and ignited until the whole of the 

 carbon is removed. The weight of the residual 

 insoluble material gives the amount of carbon by 

 difference from the first weighing. 



Commercial cyanamide contains on the average 

 about 14 per cent, of free carbon, and about 6 per 

 cent, of insoluble material — chiefly alumina, iron oxide, 

 and silicious matter. 



CHAPTER XI 

 Organic Nitrogenous Manures 



Farmyard Manure. 



Farmyard and stable manures are mixtures of urine, excrement, 

 waste portions of fodder, and the litter used for the animals. 

 All of these bodies contain nitrogen, phosphates, and potash ; 

 but an ordinary analysis is a difficult proceeding, owing to the 

 great patience and care which must be exercised in sampling. 

 Besides this, one of the most valuable assets of farmyard manure 

 is its mechanical condition, which is difficult to gauge ; it introduces 

 into the soil large quantities of humus bodies, whereby the 

 physical state of the soil is profoundly modified, generally for 

 its improvement. 



100. Examination of Farmyard Manure. 



(a) Nitrogen. — The nitrogen in farmyard manure 

 exists in all stages of complexity, from undecomposed 

 protein material down to ammonium compounds. 



Ammonium Salts, Amides ^ etc. — Fresh manure fre- 

 quently smells distinctly of ammonia and reacts 

 alkaline to litmus paper ; older manure is more nearly 

 neutral in character. On heating with dilute (5 per 



II 2 



