Satellite remote sensing for soil mapping in Africa: An overview

The protection and the sustainable management of soil resources in Africa are of paramount importance, particularly in the context of the uncertain impact of climate change and the increasing pressures of human activities. From the perspective of a policy-maker interested in topics such as food security and land degradation in Africa, this situation requires up-to-date and relevant soil information at regional and continental scales. To provide timely and reliable information on soils at synoptic scales, moderate and coarse spatial resolution satellite data offer many possibilities. The paper reviews how a range of multispectral, thermal infrared, passive microwave and active microwave spaceborne sensors can be used in the delineation of soil units, as well as in the assessment of some of their key properties and threats to soil functions from pressures such as water and wind erosion, landslides and salinization. The paper shows that remotely sensed data can be used for mapping soils in Africa but often need to be combined with ancillary data and field observations in order to be effective. Remote sensing is shown to be a key component of the emerging discipline of digital soil mapping.