CO2 EMISSIONS FROM TROPICAL SAVANNA SOIL UNDER FIRST YEAR OF CULTIVATION

Soil CO2-fluxes were measured with the soda-lime technique during the first year of grassland savannah conversion to agriculture. No signifi cant changes were observed between unplowed and plowed grassland soils , suggesting that the CO2 emitted to the atmosphere emanates (and is p roduced) from a deep layer of soil (i.e. the entire active zone). The application of fertilizer did not show any notable effect. On the othe r hand, as the season progressed stronger emissions were recorded at t he site where corn and sorghum plants were growing, indicating the imp ortance of root activity in the production of CO2 within the soil. Low er emissions were observed at all fields during the dry season. Since soil respiration is likely the most representative manifestation of th e biological activity in the soil, the results indicate that in studyi ng the impact on trace gas fluxes from the conversion of savannah soil to agriculture, emphasis should be made in evaluating the fluxes duri ng the wet season in plots located where clop-plants are growing.