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THE PEANUT— THE UNPREDICTABLE LEGUME 



quate when the crop is grown in rotation with peanuts. The results of 

 experiments, reported in table 10, show that when two crops of peanuts 

 were harvested during a 7-year period in a corn, cotton, peanut rotation, 

 the fertility of the soil was depleted to such extent that the cotton yields 

 were approximately one-half of those obtained on soil which had been 

 planted to continuous cotton. The injurious effect of the two harvested 

 crops of peanuts was overcome somewhat by applying more potash to the 

 cotton. 



Table 10. — The Influence of Peanuts in a Rotation with Cotton and Corn 

 UPON THE Yields of Cotton. Alabama Agricultural Experiment Station (2). 



" Cotton fertilized with 600 pounds 6-8-4; corn and peanuts unfertilized. 



!> Cotton fertilized with 600 pounds 6-8-4 in 1933 and 1936; 600 pounds 6-8-12 applied to cotton in 

 1936. Corn and peanuts unfertilized. 



" Cotton fertilized yearly with 600 pounds 6-8-4. 

 ^ The experiment was initiated in 1932. 



Legumes and Nonleguminous Cover Crops in Peanut Rotations 



Very little plant residue is returned to the soil from a crop of peanuts ; 

 thus, as normally harvested, peanuts remove considerable quantities of 

 inorganic nutrients. Furthermore, when peanuts are harvested the soil is 

 left completely bare for several weeks during late summer and fall, pro- 

 viding conditions favorable for the rapid oxidation of the soil organic 

 matter. Certainly it would be difficult to maintain the productivity of 

 peanut soils unless measures were taken to replenish the supply of organic 

 matter. Green manure crops are well suited to peanut rotations and their 

 use may help maintain an adequate level of organic matter in soils. 



Numerous experiments have been conducted to determine the effect 

 of legumes and nonleguminous cover crops upon the yield of peanuts. 

 Investigators at the Alabama Station ( 1 ) have studied the effect of vetch 

 and oats upon the yield of continuous peanuts, and the results are re- 

 ported in Table 11. These data show that the addition of phosphorus and 

 potash to peanuts resulted in a 50-percent increase in yields. When vetch 

 was grown and fertilized with P and K, the yields of peanuts were more 



