44 FARM MANAGEMENT 



put on the land as a manure, and is really the 

 returning to the land much of what the crops 

 have taken from it. All, however, that has 

 been taken from the land cannot be returned 

 to it, as a great deal leaves the farm in the 

 form of flesh and crops, and it is the object of 

 artificial manures to make up this deficiency. 



All the crops grown on the farm may 

 receive a dressing of dung, but the bulk of the 

 dung available is usually applied to the root 

 crop, partly because it does not take much from 

 the soil, and partly because the plant-food 

 contained in dung is not quickly available, so 

 that a great deal of it is left in the ground for 

 the benefit of the corn crop that follows and 

 also for future crops. As, however, there is 

 not enough dung produced on a farm to supply 

 all the wants of the crops, the question arises as 

 to how the artificials are to be used as supple- 

 ments, and this is answered by the fact that 

 each kind of crop requires more of one food 

 constituent than of the others. The corn crops 

 require nitrates in particular ; the root and 

 forage crops, phosphates ; and potatoes, potash. 

 Knowing what each crop requires most, the 

 artificials are applied accordingly ; but each 



