126 



THE PEANUT— THE UNPREDICTABLE LEGUME 



striking differences among varieties in their response to fertilization may 

 be reconciled, the anomalous, inconsistent results often obtained in ferti- 

 lizer experiments with a single variety have been more difficult to under- 

 stand. As pointed out in Chapter III, peanuts are normally self-pol- 

 linated, and the plants within a given newly selected strain or variety are 

 essentially homogeneous. Therefore, genetic variability should be at a 

 minimum and observed differences within such a variety must necessarily 

 be a result of environmental influences. Failure to evaluate fully the 

 various environmental factors influencing the growth of peanuts has 

 made it difficult to interpret much of the experimental data. 



Table 1. — Nutrients Removed from the Soil by One Ton of Peanuts and Two 

 Tons of Hay (Pounds per Acre). Collins and Morris (43). 



As pointed out previously, peanuts are often grown on soils of low 

 native fertility. In many cases these soils are already deficient or on the 

 threshhold of being deficient in a number of essential elements. It is 

 common knowledge that under conditions where two or more nutrient 

 elements are limiting growth, little benefit is derived from one nutrient 

 unless all of the deficient elements are supplied simultaneously. The fact 

 that peanuts often fail to respond to certain fertilizers may be due in part 

 to a state of multiple nutrient deficiency. 



It is difficult to evaluate much of the peanut fertility data in the litera- 

 ture because of the lack of information concerning the soil on which the 

 work was conducted. A rather complete characterization of the physical 

 and chemical properties of the soil would undoubtedly facilitate a better 

 understanding of the experimental work with peanuts. Furthermore, an 

 interpretation of peanut-fertilization data must also take into account 

 the previous cropping and fertilization history of the soil. 



Failure to appreciate fully the unique growth and fruiting habits of 

 the peanut has certainly led to some of the confusion regarding the ferti- 



