156 



THE PEANUT— THE UNPREDICTABLE LEGUME 



Continuous Cropping With Peanuts 



Farmers have long recognized the fact that it is not desirable to plant 

 peanuts year after year on the same soil. The harmful effect of continuous 

 cropping with peanuts was aptly illustrated in a study conducted at the 

 Georgia Coastal Plain Experiment Station (table 9). In an experiment 

 in which continuous peanuts were fertilized with different combinations 

 of N, P and K it was found that with all fertilizer treatments there was a 

 progressive decline in yields with each successive crop of peanuts. There 

 was little effect of withholding nitrogen or phosphorus from the complete 



Table 9. — The Yields of Successive Crops of Peanuts Grown with and without 

 Addition of Fertilizers. Georgia Coastal Plain Experiment Station (11). 



» 500 pounds fertilizer per acre. 



fertilizer ; however, the yields were markedly reduced when no potassium 

 was added. Apparently the lack of potash was the factor primarily re- 

 sponsible for the poor yields on the nonfertilized soil. Perhaps the yields 

 could have been maintained at higher levels on the plots receiving the 

 complete fertilizer had more than 40 pounds of potash been applied. 



Work conducted at the Alabama Experiment Station (2) further 

 demonstrates the harmful effect of planting peanuts continuously on the 

 same soil. It was found that the yield of cotton planted after 7 successive 

 years of peanuts was only 345 pounds despite the fact that the cotton 

 received 600 pounds of 6-8-8 fertilizer. At the same time, plots which had 

 been planted to continuous cotton during this period and fertilized with 

 600 pounds of 6-8-4 yielded 1,269 pounds of seed cotton. Peanut yields 

 apparently had begun to decline also after 6 years of continuous cropping 

 with peanuts. 



It would indeed be difficult to maintain the fertility of peanut soils 

 through such a program of continuous cropping and inadequate fertili- 

 zation. There is no evidence, however, which would indicate that the 



