192 THE PRINCIPLES OF 



considerations which explain why a fully developed and 

 large crop of clover, even when cut and carried away as hay, 

 leaves a field in better condition than does a constantly 

 nibbled crop of clover. 



The fourth year of the rotation on stiff soils will again 

 probably be wheat. We cannot do better. The ground is 

 in good condition for wheat, and is naturally suited for it, 

 and therefore into wheat it must go. 



The fifth year, according to the Holderness rotation, we 

 take beans. Beans are well adapted for clay land such soils 

 often being designated as "wheat and bean lands." Beans 

 also form a very excellent preparation for wheat, acting in a 

 manner somewhat similar to what has already been found in 

 the case of clover. They too pump up nitrates from the 

 lower layers of the subsoil, and absorb solid matter from the 

 air; and they too drop their leaves upon the surface soil 

 during the period of their growth and maturation. The 

 sixth year of the rotation accordingly is devoted again to 

 wheat. Thus, in the course we have proposed, half of the 

 land is under wheat, and two-thirds is under wheat and beans, 

 the remaining third being devoted to fallow and fodder crops. 



The four-course rotation may be adapted to stiff land by 

 devoting the first year to root crops suitable for heavy lands, 

 and taking wheat instead of barley the second year. Barley, 

 it is true, may be, and often is, grown upon clay land, but 

 the quality is inferior, and the grain is not suitable for malt- 

 ing purposes. It may be ground up for pigs, or sold for 

 grinding or distilling, but the crop is at a disadvantage when 

 grown on clay soils. Wheat, on the other hand, is always a 

 crop upon which w r e may rely to give a fair return upon 

 retentive clay soils. Wheat may be taken a second time in 

 the rotation after the clover, the rotation then reading roots, 

 wheat, clover, wheat ; or oats may be substituted in the last 

 year of the rotation. 



