132 THE PEANUT— THE UNPREDICTABLE LEGUME 



(66) has indicated that appHcations of 250 to 500 pounds of phosphate 

 to peanuts in Hawaii have been very beneficial. 



In a recent experiment conducted by Massibot and Vidal (71) in 

 Senegal, phosphate at the rate of 132 kilograms per hectare (approxi- 

 mately 125 pounds per acre) was found to increase markedly the yields of 

 peanut hay and nuts. The large responses to phosphorus were obtained on 

 a soil which had been fallow for 2 years. These workers also observed 

 that peanut yields were increased as the result of the residual effect of 

 phosphatic fertilizers applied the previous year to millet. 



Numerous field experiments with peanuts conducted by the North 

 Carolina Agricultural Experiment Station (46, 47) have failed to show 

 any marked beneficial effect of phosphatic fertilizers when peanuts were 

 grown in rotation with other crops which had received liberal applica- 

 tions of phosphatic fertilizers. However, when peanuts were grown con- 

 tinuously on the same soil, yields were increased by additions of phosphate 

 on soils low in available phosphorus (16). 



The results of a 10-year study at the Georgia Coastal Plain Experi- 

 ment Station (13) in which peanuts were grown after crops which had 

 been "fairly well" fertilized showed no effect of additions of 48 pounds 

 of P2O5 on peanut yields. In experiments conducted at several locations 

 by the Georgia Experiment Station (6) on soils which had been "well 

 fertilized in past years," little response was observed from applications 

 of phosphorus. 



The behavior of peanuts toward amendments of phosphatic fertilizers 

 appears to be dependent upon a number of factors. If the crop is grown 

 on "new" land or land which has been fallow for a number of years, or in 

 a rotation with other nonfertilized crops, phosphatic fertilizers would un- 

 doubtedly be beneficial in many instances. However, when grown in ro- 

 tation with other well-fertilized crops, peanuts might be expected to give 

 little response to phosphorus amendments. 



In view of the rather exacting demands of some varieties of peanuts 

 for calcium, some of the increases in yields which have been attributed to 

 phosphorus may have been due to the calcium supplied in the phosphatic 

 fertilizers. Evidence of this is found in the work of Albrecht (27) which 

 shows that the addition of superphosphate to Spanish peanuts favorably 

 influenced yields while triple superphosphate was of no value. O'Brien 

 (82) has also found that superphosphate and dicalcium phosphate were 

 superior to triple superphosphate as a source of phosphorus for peanuts. 

 Ordinary superphosphate is approximately 50 percent by weight of cal- 

 cium sulfate. 



