Title: Controls on soil nitrogen oxide emissions from forest and pastures in the Brazilian Amazon
Abstract:Soil N dynamics and water content are important controls of nitrous (N 2 O) and nitric (NO) oxide emissions from tropical soils. We used a chronosequence of one forest and six pastures to investigate ...Soil N dynamics and water content are important controls of nitrous (N 2 O) and nitric (NO) oxide emissions from tropical soils. We used a chronosequence of one forest and six pastures to investigate how soil N availability and soil moisture content affect emissions of N 2 O and NO. Forest soils had high N availability and large N oxide emissions. Forest conversion to pasture decreased N availability and N oxide emissions. In the forest where N availability was high, seasonal changes in soils moisture led to higher N 2 O fluxes during the wet season, but higher NO fluxes during the dry season. Soil water content exerted the largest control on N 2 O emissions, which seemed to be determined by a threshold value of approximately 29–30%, below which N 2 O emissions were nearly constant and above which they increased (Figure 5a). In pastures, where low N availability constrains N 2 O and NO fluxes, soil water content has a minor influence on N oxide emissions.Read More