Water content and land use history controlling soil CO 2 respiration and carbon stock in savanna soil and groundnut fields in semi-arid Senegal

Decomposition of soil organic carbon (SOC) regulates the partitioning between soil C-stock and release of CO2 to the atmosphere and is vital for soil fertility. Agricultural expansion followed by decreasing amounts of SOC and soil fertility is a problem mainly seen in tropical agro-ecosystems where fertilizers are in short supply. This paper focuses on factors influencing temporal trends in soil respiration measured as CO2 effluxes in grass savanna compared with groundnut (Arachis hypogaea L.) fields in the semi-arid part of Senegal in West Africa. Based on laboratory experiments, soil CO2 production has been expressed as a function of temperature and soil water content by fit equations. Field measurements included soil CO2 effluxes, soil temperatures and water contents. Effluxes in grass savanna and groundnut fields during the dry season were negligible, while effluxes during the rainy season were about 3–8 μmol CO2 m−2 s−1, decreasing to less than 1 μmol by the end of the growing season. Annual soil CO2 production was simulated to be in the range of 31–38 mol C m−2. Furthermore, a controlled water addition experiment revealed the importance of rain during the dry season for the overall turnover of soil organic matter

Agroforestry · Agronomy · Arid · Biology · Dry season · Growing season · Soil carbon · Soil fertility · Soil organic matter · Soil respiration · Soil water · Water content · Wet season · Climate variability and models · Ecology · Environmental Science · Soil and Unsaturated Flow · Soil Carbon and Nitrogen Dynamics · Soil Science