Relative efficiency of legumes in utilizing soil and fertilizer phosphorus

A pot-culture study was made at Indian Agricultural Research Institute, New Delhi to study the native P feeding power of six rainy season legumes (green gram, black gram, cowpea, pigeon pea, soyabean and groundnut). Ordinary superphosphate tagged with 32P was used in the study. At the first harvest (30 days after seeding) soybean and cowpea and at the second harvest (45 days after sowing) cowpea and groundnut removed more P than the other legumes. Pigeon pea removed the least P due to its slow growth. The tracer studies showed that during the first 30 days, groundnut, pigeon pea and soyabean were relatively better feeders of native soil P than the other legumes. Some varietal differences with respect to their capacity to feed on native soil P were also observed and in groundnut the varieties AK-12-24 and Jyoti removed more soil P than the variety NG-268. Differences between the legumes with respect to feeding on native soil P were much less at the second harvest (45 days after seeding). (author)