Analysis of productivity and soil carbon in response to time-controlled rotational grazing in the West African Sahel region

Preliminary data from Mali indicate that soil carbon levels are higher under pastures than croplands. Rotational grazing allowing biomass growth during periods (days or weeks) with no livestock grazing could result in more root and aboveground mass residues added to the soil. It is therefore hypothesized that rotational grazing will increase both soil carbon and pasture biomass production. A rotational grazing area (150 ga) was established in Torokoro, Mali (West Africa) to test this hypothesis. Because it could take many years to experimentally evaluate whether soil carbon levels are indeed increasing, a simulation-based sensitivity analysis was performed to evaluate potential changes in production and soil carbon and to assess critical factors that might affect the performance of this management practice. A cropping systems model, CropSyst, was used to conduct this analysis. For this purpose, an improve soil carbon and a new rotational grazing submodel were incorporated in the model.