In response to soil structural degradation and soil organic matter decline associated with arable crop production, alternative approaches including no tillage or reduced tillage systems have been developed. Farmers, researchers and policy makers in Europe are increasingly interested in exploring the possible benefits of these systems. Many studies worldwide have analysed the impact of tillage systems on soil properties and crop yields. However adaptation of reduced tillage systems and optimization of the benefits according to the agroecological and social context is required.

In this context, SUSTAIN project, developed within the European SNOWMAN programme, aims to analyse and document the development of reduced tillage practices in North-West Europe (Brittany, France and the Netherlands) and to evaluate the impacts on soil biodiversity, chemical and physical soil properties, soil functions and ecosystem services such as crop yields. In addition impact on ecosystem services and socio-economic sustainability are being assessed through the development of novel approaches for data integration and modeling. The social analysis gives tools for a better understanding of the will and also the resistance of farmers for changing their agricultural systems. Both conventional and organic arable farming systems are included in our research. This information, as well as the selection and monitoring of soil indicators, is crucial to guide practical implementation and policies and future research.

More specifically the following aspects have been studied and integrated:

• how reduced-tillage systems impact on the biodiversity of soil functional groups and soil functions such as soil structure maintenance, organic matter and nutrient cycling, water regulation and soil filtering;
• effects of reduced tillage systems on ecosystem services such as food and fodder production, soil erosion and greenhouse-gas mitigation;
• socio-economic drivers and impact of reduced-tillage systems;
• development and dissemination of monitoring tools, such as soil-disturbance indicators and evaluation methods for system sustainability.

Data have been collected from long term experimental (LTE) fields within conventional and organic farming systems (from 5 up to 13 years). These data are complemented with data from commercial farms in the same region through close collaboration with farmer networks. The impact of different reduced tillage systems are analysed (reduced tillage, non-inverse tillage, direct seeding, superficial ploughing) and compared to conventional ploughing. Measurements (biological, chemical, physical, agronomical) have been done at several dates which allow an overview of the evolution of the soil properties according to climate variation and crop rotation. All data are formatted and integrated in a database. Via path-way analysis (such as GLM), biological, chemical and physical data are analysed and combined to agronomical data; this approach allows the identification of the main drivers impacting on the different ecosystem services. A scoring approach is developed in order to integrate also data on sociological and economical aspects.