Effect of Nitrogen and Phosphorus on Soybean Yield and Nitrogen Fixation in Soils with Different Phosphorus Fixation Capacity

  • S. L. Maskey Nepal Agriculture Research Council Khumaltar; Lalitpur; Nepal
  • S. Bhattarai Nepal Agriculture Research Council Khumaltar; Lalitpur

Abstract

A pot experiment was conducted with three soils having diferent phosphorus fixing capacity from three sites - (i) Agronomy Farm, Khumaltar, Lalitpur, (2) Agriculture Bhairahawa Farm, Rundandehi and (3) Farmer's field, Panchkhal, Kavre. Phosphorus application increased nodule number and weight at Bhairahawa and Panchkhal in the pot experiment. Biomass collected at physiological maturity increased significantly due to the application of phosphorus at all sites. Addition of nitrogen markedly decreased the number and weight of nodules at Khumaltar but this decrease was not significant at other two 1ocations. The result of pot experiment was verified in a field at all the locations. Application of nitrogen decreased N derived from atmosphere (p fix) in two locations from 81 to 66 in Khumaltar and 83 to 56 in Panchkhal. Application of phosphorus increased grain and stubble yield of soybean at Khumaltar and Bhairahawa sites only.