134 



THE PEANUT— THE UNPREDICTABLE LEGUME 



Other experiments conducted in North Carolina (18, 37, 47) in 

 1942, 1943 and 1944 revealed some interesting relations regarding the 

 response of peanuts to potash. It was found that on a soil low in both 

 potassium and calcium there was a significant increase in yield from 

 the addition of potash when adequate calcium was supplied. Without the 

 addition of calcium, potash was found to decrease the yields of peanuts, 

 however. This relation is illustrated in figure 1. Apparently the deleteri- 

 ous effect of potash in the absence of applied calcium was due to the re- 

 duction in shelling percentage (figure 1). As shown in figure 2, the re- 

 sponse of peanuts to potash was found to be dependent upon the initial 

 level of potassium in the soil. On soils at a medium potassium level, ferti- 

 lizers containing this element were of little value. It was observed that 

 the vegetative growth was stimulated by the added potash and that the 

 increased yields were due to the effect of the potash on the plant size and 

 number of fruit rather than on kernel development. Other workers (40, 

 76, 96) have also observed that potash may stimulate vegetative growth 



CORRECTED YIELD 

 IN POUNDS 

 PER ACRE 



O = NO TREATMENT 

 K = 48 LBS KjO 



O 



SOIL LOW 

 IN POTASH 



SOIL MEDIUM 

 IN POTASH 



TRUE SHELLING 

 PER CENT 



SOIL LOW 

 IN POTASH 



1 1^1 



ho I 



SOIL MEDIUM 

 IN POTASH 



CALCIUM REQUIREMENTS MET ON BOTH SOILS 



Courtesy North Carolina Agricultural Experiment Station (47) 



Figure 2. — The response of peanuts to potash amendments on soils containing 

 different amounts of exchangeable potash. Soil low in potash was a Norfolk 

 sand with 0.04 m.e. exchangeable K; soil medium in potash was a Norfolk 

 sandy loam containing 0.10 m.e. exchangeable K per 100 grams. 



