José Antonio Vera-Núñez

Influence of P Fertilization on Biological Nitrogen Fixation in Herbaceous Legumes Grown in Acid Savannah Soils from the Tabasco State, Mexico

Abstract gThe use of leguminous plants in the agricultural systems of the humid tropics is an alternative means for providing N to soils considered unfertile and marginal. The objective of this study was to assess the biological nitrogen fixation (BNF) in the symbiosis Rhizobia-herbaceous legumes (Mucuna deeringiana, Canavalia ensiformis, Vigna umbellata, Cajanus cajan, Dolichos lablab, Arachis pintoi and Crotala-riajuncea) grown in acid soil amended with P fertilizer by the 15N-isoto-pic dilution technique (“A”-value) using maize, Brachiaria spp. and no nodulating common bean as reference crops. Results indicate a positive effect of P-fertilizer on parameters associated with BNF and biomass accumulation. The legumes Cajanus cajan and Canavalia ensiformis showed good performance in terms of dry weight of nodules (C. cajan = 758 and C ensiformis = 500 mg nodules plant−1 with 49 and 56 nodules plant−1, respectively) at flowering stage, and BNF (C. cajan = 170 and C ensiformis = 366 kg N ha−1 cycle−1) when 80 kg P205 ha−1 was applied to soil. Maize ‘VS-486’ and ‘VS-536’ and non-nodulating common bean ‘DOR 364’ were adequate reference crops to estimate the N derived from the atmosphere by the legume species. The results indicate that C ensiformis and C cajan have a good potential to be used as green manure in the Huimanguillo savannah, Tabasco State, Mexico.