Decomposition and nutrient release patterns of the green manure phytomass in irrigated mango orchard.
Gomes T. C. de A., Silva J. A. M., Soares E. M. B., Silva M. S. L. da
Author Affiliation: Embrapa Semi-Árido, P.O. Box 23, 56300-970, Petrolina, Pernambuco, Brazil.
: 183-188
Abstract : A study was conducted to determine the speed decomposition and nutrient release patterns of upper part biomass and leaves of pearl millet (Pennisetum typhoides [P. glaucum] cv. IPA-Bulk-1 BF), sudan sorghum cv. AG-2501-C (Sorghum sudanense × Sorghum bicolor), and a leguminous species (Crotalaria juncea) in an irrigated mango tree orchard in Pernambuco, Brazil. Nitrogen, potassium, calcium and magnesium concentrations in leaves were generally higher than in the upper part biomass of the studied species. Phosphorus concentrations were similar for the 3 species in spite of the considered material. Crotalaria juncea showed the largest values for nitrogen, calcium and magnesium, while the grasses presented larger potassium concentrations. Sudan sorghum and pearl millet showed similar decomposition patterns, mainly when the whole material part of the plant was considered, significantly differing from that of C. juncea. Within each species, the process of leaf decomposition resulted in nutrients release similar to the upper part biomass, except for nitrogen in C. juncea and magnesium in sudan sorghum that were released faster. Nutrient loss rates for both decomposing materials showed the following trend: potassium > nitrogen, phosphorus, calcium and magnesium. An exception it was the slow release of magnesium from the pearl millet upper part biomass and for sudan sorghum, that was strongly influenced by immobilization problems. During the study period, the decomposition process of pearl millet, sudan sorghum and C. juncea leaves did not show nitrogen immobilization. However, when the decomposition material was the upper part biomass, immobilization occurred during the first week especially for C. juncea. At that time, release of nitrogen did start. In both studied materials, more than 60% of the initial nitrogen content had already been released until the sixth week after the decomposition process.