2G THE CHEMISTRY OF THE FABM. 



loss will occur. Hence the superiority of box manure to 

 that made in an open yard. 



It must also be recollected that the urea, which forms 

 the chief nitrogenous ingredient of urine, is speedily 

 changed by fermentation into carbonate of ammonium ; 

 as this is a volatile substance, a loss of a part of the 

 nitrogen may easily occur, especially if an insufficient 

 amount of litter is employed. 



Farmyard manure rapidly undergoes fermentation. If 

 placed in a heap the mass gets sensibly hot, and a large 

 quantity of carbonic acid is given off. When the fer- 

 mentation occurs in a place protected from rain carbona- 

 ceous matter is destroyed, but little loss of nitrogen takes 

 place. Rotten manure, when well made, is more con- 

 centrated than the fresh, having diminished in weight 

 during fermentation, with but little loss of valuable con- 

 stituents. Some of the constituents have also become 

 more soluble. 



Farmyard manure will contain from 65 to 80 per cent, 

 of water. The nitrogen may be 0.40 to O.Co per cent., or 

 higher, if produced by highly fed animals. The ash con- 

 stituents will be 2.0 to 3.0 per cent., exclusive of the sand 

 and earth always present. Of these ash constituents 0.4? 

 to 0.7 will be potash; and 0.2 to 0.4 phosphoric acid. One 

 ton of farmyard manure will thus supply 9 — 15 lb. of 

 nitrogen, a similar amount of potash, and 4 — 91b. of 

 phosphoric acid. 



Farmyard manure is a " general " manure ; that is it 

 supplies all the essential elements of plant food. The 

 immediate return from an application of farmyard manure 

 is much less than from the same amount of plant food 

 applied in artificial manures. The effect of farmj^ard 



