FARM MANURES 349 



bacteria that are beneficial to the soil. When the 

 vegetable matter in manure decays in the soil 

 certain acids and ferments are produced which have 

 a decided influence upon the supply of available 

 plant food. In short, the addition of manure to 

 larm soils sets in motion a series of activities which 

 profoundly affect the productivity of the land. All 

 this is in addition to the plant food value of manure. 

 It is altogether probable that we do not know half 

 of the direct and indirect benefits of manure upon 

 farm soils. But we do know enough about it to 

 place its agricultural value far above its plant food 

 value. Commercial fertilisers influence the soil 

 almost solely in regard to its supply of plant food ; 

 farm manures influence all the soil conditions which 

 are essential to the production of profitable crops. 

 There is no comparison whatever oetween the two. 



THE COMPARATIVE PLANT FOOD VALUE 

 OF DIFFERENT MANURES 



The amount of plant food in different kinds of 

 manure depends upon the animals from which it 

 came and the care it has received. Analyses of 

 the excretions of various animals are given in the 

 Appendix. It will be noted that horse manure is 

 richer in nitrogen than either cow or hog manure. 

 An average sample contains about 6 per cent, of 

 nitrogen, 3 per cent, of phosphoric acid and 5 per 

 cent, of potash. It is, however, liable to "fire 

 fang," or ferment, unless kept compact and moist; 

 this lowers its value somewhat. Horse manure 

 varies in composition more than any other, because 

 of the greater variety of ways in which it is handled, 

 particularly as regards the use of bedding. 



Cow and hog manure contain more water than 



