Nitrogen recycling in mixed pastures of Calopogonium Mucunoides and Brachiaria Decumbens

Abstract

The nitrogen (N₂) recycling in single Brachiaria decumbens and mixed with Calopogonium mucunoides pastures, under continuous grazing was studied. The growth of grass and legume biomass, and the amount of N mobilized by the pasture plants to the biomass were recorded. Additionally, measurements of total nitrogen and ammonium + nitrate were obtained in the soil profile from layers of 0, 20, 50, 100, 160, 200 and 250cm of depth. The grass in the mixed pasture mobilized 105.57 kg/ha of N/year from the soil to the plant biomass, and the legume added more 81.37 kg/ha of N. The single pasture of Brachiaria decumbens recycled from soil to biomass by growth of 123.10 kg/ha of N/year under the same conditions, and a significant difference- (P < 0.05) of 63.84 kg/ha of N/year was added to the soil-pasture system by the legume. The recycled N resulted in significant increase (P < 0.05) in N and crude protein content in the forage. The legume was also responsible for a significant(P < 0.05) increase in the total N content of the soil surface layer, and of ammonium + nitrate content of the profile.