Abstract ID: 523

CO2, NO AND N2O EMISSIONS FROM SOILS TO THE ATMOSPHERE UNDER PASTURE-CROP INTEGRATED SYSTEMS IN THE CERRADO REGION

The objective of the study was to evaluate the CO2, NO and N2O emissions from Oxisols under pasture-crop integrated systems in the Cerrado region (Central Brazil). The studied pasture-crop integrated system was a sequence of the non irrigated bean cultivated under Panicum straw (Dez.2003 to Mar.2004), sorghum-Panicum intercropping (Mar.2004 to Jun.2004), uncovered soil (Jul.2004 to Nov.2004) and pasture (Nov.2004 to Abr.2005). Comparing with an area under native cerrado vegetation, higher NO-N fluxes were measured after planting (8.9 ng NO-N cm-2 h-1) and during the senescence of bean (5.7 ng NO-N cm-2 h-1), after fertilization of sorghum with N (8.6 ng NO-N cm-2 h-1) and under growing Brachiaria (8.2 NO-N ng cm-2 h-1). During Brachiaria cultivation higher N2O-N fluxes (14.1 ng N2O-N cm-2 h-1) were also measured. Higher CO2-C fluxes were measured after fertilization of sorghum (1.6 umol CO2-C m-2 s-1) and again during Brachiaria cultivation (2,8 umol CO2-C m-2). There were no differences in soil C and N stocks (0-30 cm depth) between the area under native cerrado vegetation and after 8 years of pasture-crop integrated system that was implemented after 10 years of soybean cultivation under tillage and 13 years of pasture. The C stock was 58.3 Mg C ha-1 and N stock was 3.5 Mg N ha-1. Rotation systems, as pasture-crop integrated system, are good options to recover degraded agricultural soils and to improved environmental sustainability in agricultural areas already established. However, there is a need of better practices that improve the efficiency of nitrogen fertilization and the use of N by different crops to reduce N losses via NO and N2O emissions to the atmosphere.

Session:  Biogeochemistry - Sources, sinks, and atmospheric chemistry of trace gases.

Presentation Type:  Poster