Close Window

We compared fluxes Of CO2, CO, NO, and N2O, soil microbial biomass,and N availability in a 20-yr-old Brachiaria pasture and a native cerrado area (savanna in central Brazil). Availability of N and NO fluxes were lower in the pasture than in the cerrado. N2O fluxes were below detection limit at both sites. The CO fluxes showed weak seasonal variation with slightly higher positive fluxes in the dry season and lower fluxes, including net consumption, during the wet season. The cerrado CO fluxes were higher and more variable than the fluxes in the pasture. Both sites showed a seasonal pattern in CO2 emissions with lower fluxes (similar to2 mumol CO(2)(.)m(-2.)s(-2) 1) during the dry season. There were no significant differences in annual CO2 soil emissions between the cerrado and the pasture, but the temporal trends differed, with higher fluxes in the pasture during the transition from the wet to the dry season. Artificial water addition in the pasture during the dry season resulted in short-lived pulses of NO and CO2

Close Window