SOIL FERTILITY 165 



planting, may impair germination. Perhaps fertilizer materials would be 

 found to be more beneficial if a greater effort were made to use them 

 properly. 



There is much evidence that peanut varieties exhibit marked differ- 

 ences in their response to certain nutrients. Furthermore, strains within 

 a given variety have been found to differ greatly in response to fertiliza- 

 tion. These differences may account in part for some of the existing con- 

 fusion regarding the fertilization of peanuts. Certainly the plant breeder 

 must give ample consideration to such differences in evaluating peanut 

 varieties. 



Peanuts remove relatively large amounts of certain nutrients from the 

 soil with the normal systems of management in which both hay and nuts 

 are harvested. Yet, because of the fact that peanuts have not been found 

 to be as responsive to direct applications of fertilizer materials as other 

 crops there is a tendency to supply less of some nutrients than is removed 

 from the soil by the crop. It is by no means a desirable practice to grow 

 peanuts continuously on the same soil. Many experiment stations recom- 

 mend that they not be grown more than once every 3 or 4 years. Peanuts 

 may be grown satisfactorily in rotation with a number of different crops. 

 Generally, it would be desirable to grow well-fertilized crops such 

 as cotton, tobacco or truck crops immediately prior to peanuts in the 

 rotation. 



Little organic matter is returned to the soil from a crop of peanuts. 

 Furthermore, after peanuts are harvested conditions are quite favorable 

 for the rapid oxidation of the organic matter present in the soil. Legumin- 

 ous green manure crops are well suited to peanut rotations and their use 

 may help to maintain an adequate level of organic matter and insure a 

 good physical condition. It is especially important that peanut soils be 

 kept loose and friable because the pegs must penetrate the surface in 

 order for nuts to be formed. 



With the normal methods of harvesting, peanuts are considered to 

 be one of the most soil-depleting crops grown in this country. However, 

 when the crop is harvested by grazing hogs or when the nuts are picked 

 off and the vines returned to the soil peanuts may actually increase the 

 productivity of the soil. Therefore, there appears to be nothing unique 

 about the soil-depleting powers of the peanut as some have indicated. 



It has been suggested (42) that large increases in peanut yields 

 cannot be expected from fertilizer treatments as only the nuts produced 

 in a relatively short period of continuous blooming of the plant can be 

 saved at harvest. However, even though direct responses to fertilization 



