A large part of the world’s crops grow on hillsides where the original forest has been felled and severe soil degradation and erosion has occurred through poor planting practice. Careful management of such situations could avoid any detrimental consequences of farming on sloping land, but both fundamental and applied research is required to determine how best to plant, manage and harvest depending on land use, species mixtures and topography. Therefore, Fixsoil will investigate the ecosystem service of soil fixation provided by different crop / forest systems whilst focusing on plant root traits and soil microbial communities. The project will be hosted at AMAP (Montpellier, France) and CEH (Wallingford, UK) with field-sites representing natural forest, agro-forest and organic farmland in temperate oceanic and Mediterranean regions. The relationships between root structural /functional traits and soil microbial communities with soil aggregate stability, soil physical/chemical properties and infiltration, will be studied with the both standard and cutting-edge techniques. The ambitious objective of this project is to determine how the function and role of different parts of a root system (in a variety of species mixtures) and the composition of soil microbial communities provide (or not) the service of reducing soil erodibility. The results of this project will provide data to allow stakeholders and (agro)foresters better determine species mix, spatial and temporal compositions and management strategies with regard to soil degradation and erosion.