Nitrogen availability for metabolic processes of microorganisms can be an important factor in the control of the emissions of nitrous oxide (N2O) in tropical soils. To better understand of the dynamics of gas flows in the pastures in the Amazon, the present work sought to explore the N, C and water availability effect in the emission of N2O in soils with pastures submitted or not to managing practices that seek its maintenance. In this case, herbicide application and the consequent elimination of plants from the soil was one of the observed practices. To better understand the results, the study was accomplished incubating soils from different areas in order to compare them and better interpret the results. In this scope, the chosen areas were: The treatment Control and the treatment Rice of the experiment for pasture recovery, just after herbicide application, a forest area and a pasture area established in 1987 and managed in the traditional way according to the Amazon region. The experiment was accomplished adding nitrate, dextrose, and water in the soil as well as, using the acetylene to block the oxidation of the N2O for N2 considering for this, the proportion of N2 emitted from the soil. The largest flows were observed when nitrate was added to the soil in conditions of high humidity. The dextrose addition elevated the flows in a more intense way in the soil that had received herbicide application, where the availability of N was also larger. With the application of acetylene it was possible to observe that great part of nitrogen lost in the form of gases is as N2. With that, the denitrification process was dominant in this incubation study and the nitrogen was limiting factor in pasture systems in the Amazon.
Submetido por Janaina Braga do Carmo em 17-MAR-2004