Modelling spatial and temporal soil organic carbon dynamics under climate and land management change scenarios, northern Ethiopia

摘要

Soil organic carbon (SOC) depletion is a threat for the present and future agricultural production in Ethiopia. Hence, investigation of the influence of land management and climate change on SOC is required to facilitate climate change mitigation practices. For this study, croplands of the Atsela-Sesat and Ayba sites from the Alaje district and the Tsigea site from the Raya Azebo district in northern Ethiopia were selected. The RothC model was used to predict future SOC trends and evaluate impacts of climate and land-management change scenarios on SOC stocks. The RothC model was run for two scenarios, (i) business as usual (scenario 1) and (ii) improved crop residue and manure management (scenario 2), to predict SOC stock changes in the cropland under current and future climate change. The current SOC content and SOC stock of the croplands are 14.4 g kg(-1) and 26.7 t ha(-1) in Atsela-Sesat, 14.8 g kg(-1) and 27.9 t ha(-1) in Ayba and 14.8 g kg(-1) and 26.9 t ha(-1) in Tsigea, respectively. The RothC model-predicted SOC accumulation for this century in scenario 1 was 0.26 t C ha(-1) in Alaje and 0.18 t C ha(-1) in Raya Azebo, whereas in scenario 2 it was 0.52 t C ha(-1) in Alaje and 0.36 t C ha(-1) in Raya Azebo. Although the predicted SOC accumulation in scenario 2 is higher than in scenario 1 and the baseline scenario, it still has a decreasing trend due to climate change. However, the organic carbon return into the soil is generally small and thus it will not be possible to improve soil productivity and attain food security. Therefore, future soil fertility strategies need to include both organic and inorganic fertilizer application. These findings will help to assist land managers to make informed decisions during land-management practices to mitigate the impacts of climate change.