474 SOUTHERN FIELD CROPS 



grown without due attention to rotation. The result 

 is a notable decline in yield, due to the exhaustion of the 

 supplies of humus, potash, phosphoric acid, and lime, 

 and in some cases to the occurrence of disease or insect 

 injury. 



The best rotation varies with a number of conditions. 

 Where peanuts constitute the main sale crop, they are 

 often rotated with corn. An improvement would be the 

 sowing of either cowpeas or of crimson clover among the 

 corn rows. Peanuts can also be rotated with small grain, 

 the oats or wheat being followed by cowpeas and this crop 

 by peanuts. When cotton is the preceding crop and when 

 the germs of cotton wilt are not present in the soil (para- 

 graph 380), crimson clover seed should usually be sown 

 in the cotton plants in September, and the young clover 

 plants can then be plowed under for fertilizer the next 

 spring, in time for the growth of a crop of peanuts. 



456. A recommended rotation. A suitable rotation 

 for those fields in the southern part of the cotton belt in 

 which the presence of cotton wilt prevents the frequent 

 growing of cotton, is the following : 



First year : corn with Iron cowpeas between the rows. 



Second year : cotton. 



Third year : peanuts. 



Fourth year : fall-sown oats, followed by Iron cowpeas. 



From such a rotation, crimson clover is omitted because 

 it might be the indirect means of increasing the amount 

 of wilt in the next cotton crop. This is because crimson 

 clover is attacked by nematode worms (see paragraph 385) ; 

 but the peanut is exempt from this injury, and hence the 



