Sugarcane is an important crop in Brazilian agriculture, for the generation of jobs and income, as well as for the growing exports of sugar and ethanol. The burning of residues, in order to enable the harvest and transportation of the cane stalks, has been practiced in Brazil for centuries. Currently, due to environmental and economic reasons, the harvest of sugarcane without burning the residues, maintaining a residue cover on the soil, has grown. There is little knowledge, however, about the long term effects of presence of residues on the soil in the carbon dynamics of the sugarcane crop. Ecosystem modeling can be an efficient tool to understand these processes, and to estimate the potential of the sugarcane crop in soil carbon sequestration, which has agronomic, environmental and economic relevance, in the context of global change and the “carbon market”. The goal of this study was to evaluate the effect of burning or not the plant residues prior to harvest in the carbon dynamics of the sugarcane crop, using the CENTURY model. The study area is in Pradopolis, in Southeastern Brazil. Four fields for pre-harvest burning and four fields without pre-harvest burning were selected, using the method of chronossequence. In each residue management, sugarcane had been harvested, without replanting or soil disturbance, for 8, 6, 4, and 2 years. Soil samples were also collected in an area of native forest, as a reference. The following soil attributes were analyzed: pH, bulk density, texture, total carbon and nitrogen, and microbial biomass carbon and nitrogen. The results indicate a general increase in total soil carbon stocks in the unburned sugarcane fields, as compared to the burned sugarcane fields.
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