268 SOILS AND FERTILIZERS 



food in organic forms is most essential. Heavy dressings 

 of farm manures may be applied. Where hops are 

 grown there is a tendency to use all the manure on 

 the hops, while the rest of the farm is left unma- 

 nured. Very light applications of commercial fertili- 

 zers may be used in connection with stable manure, 

 but such use should be made only after a preliminary 

 trial on a small scale. 



322. Hay and Grass Crops. Most grass crops have 

 shorter roots than grain crops ; they are surface feeders 

 and not so able to secure mineral food. When a num- 

 ber of crops have been removed, the soil may stand in 

 need of available mineral matter. Farm manures are 

 particularly well adapted for fertilizing grass. Applica- 

 tions of nitrogenous manures result in discouraging the 

 growth of clover. Heavy manuring of grass land has a 

 tendency to reduce the number of species, and one kind 

 is apt to predominate. 82 On some soils ashes, and on 

 others lime fertilizers, have been found very beneficial. 

 The manuring of grass must be varied to meet the needs 

 of different soils. Permanent meadow's require different 

 manuring from meadow introduced as an important crop 

 in the rotation. Permanent meadows should receive an 

 annual dressing of farm manure or of a commercial fer- 

 tilizer containing phosphoric acid, potash, and a fair 

 amount of nitrogen. 



323. Leguminous Crops. - - For leguminous crops 

 potash and lime fertilizers have been found of special 



