ISSN: 1659-2751

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Biomass Production and Nitrogen Fixation by Mucuna pruriens in the Humid Tropics of Costa Rica

Abstract

Mucuna pruriens is a Fabaceae mainly used as green manure in tropical agroecosystems. However, there is insufficient information on the biomass production and N2 fixation by this crop in the humid tropics of Costa Rica. An N2 fixation experiment was established under greenhouse conditions in a completely randomized design with three treatments: M. pruriens plus 60 kg/ha P (P+), M. pruriens without P (P-) and corn (Zea mays). To determine the biomass production in the field, 200 m2 plot was used. It was seeded with M. pruriens at a distance of 1.0 m x 0.50 m (two plants per seed point) at a density of 40 000 plants/ha. N2 fixation in aboveground biomass was 93 %, and in the roots 66 %. The weighted average (aboveground biomass and roots) of N2 fixed was 84 %. The P+ treatment produced a higher content of N in aboveground biomass. M. pruriens produced an accumulation of biomass in the field of 1500 kg/ha at 17 weeks; the growth curve was sigmoid with an R2 = 0.98. As for the contribution of elements of this species, specifically they were the specific fixation of C (707 kg/ha) and the contribution of N (69.6 kg/ha).

Key words: biological N2 fixation, carbon fixation, sigmoid model, Mucuna pruriens, biomass production.

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