SOIL FERTILITY 127 



lization of this crop. Since nutrients may be absorbed by the developing 

 pegs as well as by the roots (34, 40, 110), the problem of fertilizer 

 placement becomes of greater importance with peanuts than with many 

 other crops. Recent experiments (20, 38, 45) indicate that to obtain the 

 most beneficial effect of some nutrients, they must be supplied to the 

 zone of fruit formation rather than to the plant roots. On the other hand, 

 there are indications that it is best to supply certain other nutrients to 

 the rooting medium (20, 37, 40). Another problem associated with ferti- 

 lizer placement results from the fact that stand injury may occur when 

 certain fertilizer materials are placed too close to the seed at planting 

 (20, 31). Obviously the effectiveness of fertilizer materials may, to a 

 large extent, depend upon proper placement, and such materials may 

 lower yields unless they are used correctly. 



The yield of peanuts may be influenced greatly by the stage of ma- 

 turity of the plant at harvesting. If the crop is harvested early, a large 

 proportion of the nuts is immature. Yet, if harvesting is delayed too long, 

 an excessive number of the nuts may be separated from the vines and 

 remain in the soil. There is evidence in the literature that certain fertility 

 treatments may hasten or delay the maturity of the plants (30, 89). 

 Certainly, plants must be harvested at comparable stages of maturity if 

 the effects of fertilizer amendments are to be measured accurately. 



Recent work has indicated that fertilizer treatments may influence 

 the number of nuts which are shed and remain in the soil at harvest (35, 

 58). Therefore, this differential effect of fertilizers upon shedding may 

 influence the yield of peanuts as normally measured. Perhaps the effect of 

 certain fertilizer materials upon shedding is related directly to their in- 

 fluence upon maturity. 



It should be evident from the foregoing discussion that peanut ferti- 

 lization practices are not as well defined as with many other crops, and 

 many of the anomalies associated with peanut fertilization are yet to be 

 explained. Without question, experimental work with peanuts presents 

 problems and requires techniques which are quite specific to this crop. 

 However, when due consideration is given to the peculiar fruiting habits 

 of the peanut plant as well as to the many important, but often unrecog- 

 nized, environmental factors which influence its behavior, the available 

 information pertaining to the fertilization of peanuts begins to assume a 

 much more orderly pattern. 



No attempt will be made in this discussion to review all of the experi- 

 mental work with peanut fertility. Such a review would undoubtedly tend 

 to confuse rather than clarify the issue because of the difficulty in eval- 



