Soil CO2 emission of sugarcane fields as affected by topography

Abstract

The spatial and temporal variation of soil CO2 emission is influenced by several soil attributes related to CO2 production and its diffusion in the soil. However, few studies aiming to understand the effect of topography on the variability of CO2 emissions exist, especially for cropping areas of tropical regions. The objective of this study was to evaluate the spatial and temporal changes of soil CO2 emission and its relation to soil attributes in an area currently cropped with sugarcane under different relief forms and slope positions. Mean CO2 emissions in the studied period (seven months) varied between 0.23 and 0.71, 0.27 and 0.90, and 0.31 and 0.80 g m-2 h-1 of CO2 for concave (Conc), backslope (BackS) and footslope (FootS) positions, respectively. The temporal variability of CO2 emissions in each area was explained by an exponential relation between the CO2 emission and soil temperature and a linear relation between CO2 emission and soil water content. The Q10 values were 1.98 (± 0.34), 1.81 (± 0.49) and 1.71 (± 0.31) for Conc, BackS and FootS, respectively. Bulk density, macroporosity, penetration resistance, aggregation and oxidizable organic carbon content explain the changes in soil CO2 emission observed, especially when the Conc position was compared to BackS. The effect of relief form and topographic position on soil CO2 emission variation was dependent on the time of measurement.