CHAPTER II 



Manures in General 



The Necessity of Manures. 



Plants, like all living things, require that ten 

 elements should be put at their disposal under 

 fixed conditions, but to give crops they do not 

 require equal quantities of each of these elements. 

 They show a greater need for some than for 

 others. 



Thus, among these ten necessary elements, 

 seven are generally found in sufficient quantities in 

 the soil and in the air. 



They are Hydrogen [H], Oxygen [O], Carbon [C], 

 Calcium [Ca], Magnesia [Mg], Iron [Fe], and 

 Sulphur [S]. 



Three others exist universally and generally, in 

 insufficient quantities to give good crops, and plants 

 require them in relatively large quantities. They 

 are Phosphor [P], Nitrogen [N], and Potash [K]. 

 These are the elements which are universally regarded 

 as manures. In certain cases the magnesia and 

 calcium associated with these manures have also 

 given favourable results, which seems to prove that 

 in these particular cases there was too little magnesia 

 and calcium in the soil, and that therefore they also 



