128 THE PEANUT— THE UNPREDICTABLE LEGUME 



uating much of the data in the literature due to the lack of information 

 regarding the conditions of the experiments. Instead, certain data will be 

 presented which tend to illustrate specific principles regarding the fertili- 

 zation of peanuts and the maintenance of the fertility of peanut soils. 

 From these data, it should be possible to formulate some fairly definite 

 ideas regarding the use of fertilizer materials with peanuts. 



EXPERIMENTS WITH NITROGEN, PHOSPHORUS 

 AND POTASSIUM 



Nitrogen 



Being a leguminous plant, peanuts might not be expected to respond 

 to large applications of nitrogen, and some of the experimental data would 

 tend to verify this supposition. However, there is also considerable evi- 

 dence which would indicate that nitrogen is of value in peanut fertilizers. 



Recently, Prevot (91) has emphasized the importance of nitrogen in 

 the nutrition of peanuts. The data presented by this French worker indi- 

 cate that relatively large quantities of nitrogen are translocated from the 

 leaves to the developing fruit, suggesting the importance of maintaining 

 the peanut plant at a high level of nitrogen metabolism prior to the fruit- 

 ing period. However, no evidence is presented by Prevot to indicate that 

 amendments of nitrogen would be necessary when the peanut plant was 

 properly inoculated with nitrogen-fixing microorganisms. 



Responses to nitrogen might be expected if peanuts have not been well 

 inoculated. While it has been generally assumed that no inoculation is 

 necessary if peanuts are grown on land used previously for this crop, little 

 has been done to determine if the most satisfactory inoculum is commonly 

 present in peanut soils. Symbiotic nitrogen fixation may be inhibited 

 somewhat in acid soils (69) ; hence response to nitrogenous fertilizers 

 might be more pronounced on such soils. Unfortunately, most nitrogen- 

 fertilization data in the literature are not accompanied with information 

 relative to soil pH and to the degree of inoculation of the peanuts grown 

 in the experiments. 



It has been suggested (30) that nitrogen may be beneficial on soils 

 which are extremely low in organic matter. Certainly differences in ni- 

 trogen levels in soils would be expected to be reflected in the response 

 of peanuts to additions of nitrogenous fertilizers. 



Workers at the Georgia Experiment Station (9) have found that 

 nitrogen applied to Spanish peanuts caused a marked reduction in the 

 disease. Southern root rot (Sclerofiiim rolfsii), and it was observed that 



