174 AGRICULTURE 



is called upon to deal with this substance. 

 Farmyard manure is a substance of very 

 indefinite composition, depending as it does 

 for its quality and character upon the food 

 that the animals consume, upon the litter 

 with which they are bedded, and upon the 

 way in which the substance is stored and 

 handled. Speaking generally, it contains 

 about 75 per cent, of water and 25 per cent. 

 of dry matter. The fertilizing ingredients 

 are, of course, entirely confined to the dry 

 material, which holds nitrogen usually about 

 one-half per cent, of the total weight of 

 manure and mineral matter. The latter 

 is the so-called " ash " of the chemist, and 

 contains the phosphates, potash, lime, mag- 

 nesia, and other mineral substances which 

 serve as plant food. Phosphoric acid is 

 usually present to the extent of about one- 

 fifth per cent., while potash and lime amount 

 to about one-half per cent. A ton of farm- 

 yard manure will, therefore, contain about 

 12 Ib. of nitrogen, a similar amount of potash, 

 and 4 to 5 Ib. of phosphoric acid. From 

 the point of view of plant nutrition, we can, 

 of course, obtain these substances from 

 other sources. Thus we might purchase 

 commercial nitrate of soda to supply the 

 nitrogen, 77 Ib. of that substance being 



