Decomposição de Diferentes Espécies de Leguminosas

Abstract

The objective of this work was to evaluate the dynamics of decomposition and the half-life of different species of green manure. The treatments consisted of four species of green manure (Crotalaria juncea, Cajanus cajan, Canavalia ensiformis, Mucuna aterrima and the Consortium (C. juncea + C. cajan), arranged in a randomized complete block design with four replications. The green manure was carried out at 97 days after sowing. The sampled area for determination of fresh and dry biomass was 2.16 m². The dry matter loss rates were monitored by collecting the litter bags at 15, 30, 60, 120 and 180 days after cutting the green manures, and then calculating the decomposition constant and the half-life time for each one of the species studied. The highest dry biomass production (11.15 t ha^-1) was obtained for the consortium (C. juncea + C. cajan) and did not differ statistically from the species Crotalaria juncea and Cajanus cajan. The losses of organic waste in the litter bags were adjusted to the simple exponential decay function (x_t = x₀ e^-kt), and the mean correlation coefficient for all studied species was R² = 0.966. The decomposition constant varied between (0.0087 - 0.0052 days^-1) for the species studied. Crotalaria juncea presented the lowest decomposition constant (0.0052 days^-1) and, consequently, the longer half-life (133 days).