Background Organic matter in is a vital component of soil functionality and its associated productivity. Land use and soil cultivation methods can significantly affect the status of organic matter in soil. Decline is accompanied by a decrease in soil fertility and biodiversity, and loss of structure, whose factors, in turn, increase the overall soil degradation. Unless organic matter is quickly replenished, the soil system can rapidly degrade, compromising the economic and environmental sustainability of soil functions. The decline of soil organic matter (SOM) content represents a considerable threat to the long-term productivity of crop production areas in the Mediterranean region. Key problems relate to intensive soil exploitation and discarding of crop residues and agricultural byproducts. These factors can result in a low amount of organic carbon inputs and in a negative balance of SOM content, which in turn can lead to soil degradation, depletion of soil fertility and increase demand for progressive increases of both mineral fertilisation and irrigation. Objectives The LIFE CarbOnFarm project intends to address the basic requirements concerning the sustainable use of agricultural soils through the restoration and preservation of soil functionalities. It will help to valorise the economical and environmental role of soil resource in the agro ecosystems and improve the recycling of agricultural biomasses. Environmental sustainable methods of SOM management will be used that are tailored to non-livestock farms from Southern Europe. Target areas include those characterised by limited access to organic matter sources, the progressive decline of SOM content and the steady increase of soil erosion and desertification processes. On-farm composting facilities will be introduced to promote the productive and financially-viable valorisation of residual biomasses from local agricultural activities. Project monitoring actions will provide new and valuable data concerning soil organic carbon (SOC) quantity and quality, greenhouse gas (GHG) emissions from cultivated soils, soil stability and crop productivity, as well as the environmental, energetic and economic sustainability of the applied methodologies. These indicators will represent an important tool to support decision-making processes concerning sustainable agriculture at both national and European level. Project actions will thus help complement implementation of the EU Soil Thematic Strategy, particularly for cultivated land in the Mediterranean area. Dissemination actions will focus on demonstrating that recycled biomasses can efficiently combine environmental protection with crop productivity, emphasising their valorisation as important local bio-resources in terms of carbon sequestration, maintenance of soil functions and prevention of landfilling. Expected results: The main expected outcomes relate to improvements of soil status in terms of organic matter, structure and biodiversity. This will result in: An appreciable increase of SOM level through the stabilisation and sequestration of SOC; Improvement of soil aggregation and soil structural stability; Enhanced soil biological fertility; Maintenance of crop productivity; and Lower GHG emissions. Stakeholder collaboration will result in: The transfer of knowhow and uptake of improved on-farm composting technology; Appreciation about the valorisation of agricultural residues as important local bio resources; and Collection and modelling of land use and SOC sequestration data in agro ecosystems in order to support the technical and political commitments required for mainstreaming sustainable soil use methods amongst Mediterranean arable farmers.