Decomposition of green manure biomass in dystrophic Yellow Latosol in Piauí state, Brazil

Abstract

Although most research demonstrates the importance of green manure, some aspects have yet to be elucidated. Thus, the present study aimed to determine the biomass decomposition pattern of plants used as green manure in dystrophic Yellow Latosol (coastal caatinga phase), under a dry megathermal climate, with a small water surplus. A completely randomized design was used, with nineteen treatments and four repetitions. The decomposition constant (k), remaining dry biomass and half-life (T1/2) of the residue after 120 days in the field were assessed. Cowpea, jack bean and sunflower (cv. Catissol and IAC Uruguai) are rapidly decomposing species with a half-life ranging from 98 to 112 days to decompose 50% of biomass. Dwarf pigeon pea, crotalária juncea, sorghum 1 and siratro are slow-decomposing species, with a 315 to 630-day half-life to decompose 50% of biomass. Both groups are recommended for intercropping because the decomposition rate of their plant residue is compatible with soil protection and nutrient supply, in addition to being sync with the nutrient requirements of cash crops.