ROTATION OF CROPS. 383 



land at the present day there was a large and a small white 

 crop, one large yield of hay, then smaller and smaller, then 

 good pasture, then poor. This rotation gave a change from 

 better to worse. The new practice demonstrated that there 

 need be no " worse." It showed that a root crop should 

 follow the sod and should be followed by grain ; that again 

 by grain or grass and clover ; that by pasture and roots. At 

 first it was made a point that a white crop should never be 

 taken two years in succession, and after going through roots 

 and grass it was found, on returning to the white crop, that 

 the ground was so much richer than before, that a number 

 of bushels was taken previously unheard of in the neigh- 

 borhood." 



Liebig says :* " The succession of crops in rotation is al- 

 ways made dependent upon the cereals ; the preceding crops 

 are selected of such a kind that their cultivation will not 

 injure, but rather improve the succeeding corn crop. The 

 selection of the particular kind, however, is always governed 

 by the condition of the soil. In a field abounding in stalk 

 and leaf constituents, it is often found useful to have wheat 

 preceded by tobacco or rape, rye by turnips or potatoes, 

 since these plants, by drawing from the soil a large amount 

 of leaf and stalk constituents, serve to restore a more suitable 

 proportion between the straw and corn constituents for the 

 future cereal crop, and, at the same time, to diminish in the 

 arable soil those conditions which favor the growth of weeds. 



* The Natural Laws of Husbandry, page 227. 



