MANURES. 203 



to do away with the use of the more bulky manures, and to ac- 

 compHsh the best results by the use of concentrated chemical 

 compounds. 



The truth is now known to lie between these two extreme opin- 

 ions, and all fertilizers are to be regarded as belonging to the same 

 system. The same ingredients are of the same value in all, — if 

 only their condition is such as to render them equally easy of 

 assimilation, — for the nutrition of plants ; the same salts have the 

 same solvent action ; the same materials have the same absorbent 

 power, as affecting the soluble and volatile elements of plant-food ; 

 and they have the same mechanical effect on the soil. All ma- 

 nures, therefore, whether organic or mineral, are to be measured 

 by the same rule, and their value must be estimated according to 

 their ability to perform the various offices of manure. 



So measured, farm-yard maruire is very much the best, in pro- 

 portion to its price, of all that we buy in the market. The old 

 practice is justified by theory, and theory is sustained by practice. 



Probably Dr. Voelcker's analysis would not exactly apply to 

 afiy other sample of farm-yard manure that could be produced. 

 Some would be richer and others poorer. The variations result 

 from the kind and quantity of food and litter used ; the condition 

 of the animal, and the use that is made of its products and of its 

 labor. 



The full-grown horse or ox, standing all day in the stable, neither 

 increasing nor decreasing in size, and fed just enough to supply the 

 natural wastes of the body, produces manure which contains a full 

 equivalent of the nitrogen and earthy matter of its food. 



If used on the road, so much of the elements of the food as are 

 contained in the manure dropped away from home is lost. If 

 growing, by the development of bone and muscle, a part of the 

 nitrogen and earthy constituents of the food is kept in the body, 

 and there is so much less in the manure. 



The manure of a pregnant animal does not contain those parts 

 of the food that are taken up by the growth of the fetus. 



The milch cow turns a portion of her food into milk arid voids 

 so much less in the manure. 



