ROTATION OF CROPS. 8 1 



181. In the fourth place, different .crops require 

 different modes of cultivation, so that the physical 

 properties of the soil are improved by rotation. 

 Grass-lands in a few years become hard and require 

 to be loosened up, which can be done by the culti- 

 vation of a crop of corn, followed by one of wheat, 

 and the re-sowing of grass. 



182. Not only is a change of crops desirable, but 

 an occasional change of seed is found to be of great 

 benefit. Wheat grown on stiff clay-lands for some 

 years will be improved by getting seed from that 

 grown on sandy soil, and that on sandy soil by ob- 

 taining seed from wheat grown on stiff clay. An 

 occasional change of seed from one latitude to an- 

 other is alo found to be beneficial. 



183. Crops that require the same elements in 

 about the same proportions should not follow each 

 other, nor those that are similar in their mode of 

 growth. Wheat and corn which depend mainly on 

 surface-roots will do well after clover, cotton, or to- 

 bacco, which have long tap-roots that extend down 

 into the subsoil. The greater the difference in the 

 constitution and character of two crops, the more 

 likely are they suited to follow each other. Climate 

 and soil have much to do in determining the best 

 rotation. 



184. A good rotation for three years is 



First year Corn 



Second " Wheat 



6 Third " Clover 



