136 



THE PEANUT— THE UNPREDICTABLE LEGUME 



The Importance of Calcium in Peanut Nutrition 



The significance of calcium in the nutrition of peanuts is clearly de- 

 picted in figure 3. The data in this graph were obtained in experiments 

 conducted by the staff at the North Carolina Agricultural Experiment 

 Station (47) on soils ranging in calcium levels from approximately 450 

 pounds to 2,200 pounds of calcium-carbonate equivalent per acre. Very 

 marked increases in yields were obtained from additions of gypsum, a 

 soluble calcium salt, to soils low in calcium. Yet it is evident that little 

 might be gained from amendments of gypsum to soils already well sup- 

 plied with calcium. Furthermore, it is obvious that increases in yields ob- 

 tained from the gypsum on low calcium soils were due for a large part 

 to the effect of the calcium on the shelling percentage. 



CORRECTED YIELD IN 

 POUNDS PER ACRE 



TRUE SHELLING 

 PER CENT 



A - NO TREATMENT 

 B = GYPSUM 



Courtesy North Carolina Agricultural Experiment Station (47) 



Figure 3. — The effect of gypsum upon the yields and shelling percentage of peanuts 

 growns on soils of different calcium levels. 



Chemical Characteristics 



pH -. 



Exchange Capacity — m.e./lOO gms 



Exchangeable Ca — m.e./lOO gms 



Exchangeable K — ^m.e./lOO gms 



Exchangeable Mg — m.e./lOO gms 



Soil Low 

 ■in Calcium 



Soil Medium 

 in Calcium 



Soil High 

 in Caliium 



6.0 



2.66 



0.45 



Oi05 



0.18 



5.5 



3.24 



1..19 



0.08 



0.29 



5.6 



4.02 



2.21 



0.10 



0.38 



