S8 SOILS AND CROPS OF THE FARM. 



acidity. Over much of the United States lime is 

 rarely used and its cost, in many regions, will prevent 

 its use. In some parts it is largely used. English 

 writers usually attach more value to it than do Ameri- 

 can farmers. 



Gypsam, or sulphate of lime, often called land 

 plaster, is a valuable manure on some soils, especially 

 on clover. On many soils it has no perceptible effect. 



Aslies may be called a complete mineral manure, 

 but are especially valued for the potash they contain. 

 Where attainable at moderate price their use can be 

 safely recommended. Coal ashes are not considered 

 of much value as manure. 



Bones are valued especially for phosphoric acid. 

 They also contain nitrogen. The principal objection to 

 their use is the long time required before they decom- 

 pose in the soil. The finer they are crashed the bet- 

 ter in this respect. Steamed bones have less nitrogen 

 but the phosphoric acid is more readily soluble. 



Superphosphate of Liiiue may be formed by 

 treating bones with sulphuric acid or by so treating 

 any mineral phosphate. The bone superphosphate is 

 often called dissolved bone. On many soils this is 

 one of the best manures. On others it has little ef- 

 fect. Generally speaking, its use is not profitable on 

 naturally fertile land still in good condition. 



Nitrate of l^odinm and {Sulphate of Ammo- 

 nium are two manures valued for their nitrogen. 

 They are quick-acting manures, and on some soils, 

 usually clayey soils, have a marked effect both on 

 grain and grass crops. It is advised that they be 

 used generally in connection with superphosphate. 



Large quantities of valuable manures are made 



