CHAPTER IV 



MANURES 



The prime object of manuring is to supply 

 to the soil something it lacks, to enable it to 

 produce crops of the quantity and quality 

 desired. Obviously then, we must know what 

 it is the soil lacks. Now the plant feeds on 

 certain chemical substances it gets from the 

 soil and the air. It has been ascertained, by 

 research, that there are only four of these 

 substances of which the soil is likely to be 

 depleted by the continued growth of crops ; 

 consequently, to the farmer, the whole subject 

 of manuring resolves itself into maintaining the 

 supply of these particular four substances in the 

 soil. The other substances need not concern 

 him, as the supply of them is always sufficient. 

 The four substances we have to consider 

 may be termed nitrates, phosphates, potash 

 and lime, and the growth of any crop is largely 

 dependent on an adequate supply of these in 



