Modelling

Lead organisations: Rennes 1 University and Agrocampus Ouest-INRA UMR SAS (Soil Agronomy Spatialization)

The aims of WP6 are:

• To assess how soil biodiversity and soil functions previously described in WP2 and WP3 will impact on the soil ecosystem services as food production (crop production) and greenhouse gas mitigation (task 6.1). This approach will lead to the definition of indicators that will be used to identify when soil systems are approaching limits of their functioning,
• To assess impacts of agricultural activities in tillage systems on soil quality with Life Cycle Assessment (LCA), including an indicator of soil biodiversity (task 6.2),
• To evaluate the eco-social sustainability of tillage systems by using the modelling tool MASC (Multi-Attribute Assessment of the Sustainability of Cropping Systems, (INRA, 2008) that will be applied at the Cultural System scale (task 6.3). The sustainability of reduced tillage systems has been assessed more often in a non-integrative way i.e. environmentally, or economically, or sociologically. These systems have rarely been assessed using an integrative approach. However a broad, integrative approach bringing together environmental, social and economic methodologies appears necessary to have a holistic overview of the sustainability of agricultural systems. In this study, we propose an overall evaluation of the systems based on integrating the variability of soil, production systems, and within reduced tillage systems. This method is suitable to our approach as it has been already tested in a national network (Mix Technological Network on innovative cultural system: RMT).

Task 6.1 will be accomplished by multivariate analysis of data from WP2, WP3.
Task 6.2 will be performed integrating biological, chemical and physical parameters in LCA.
Task 6.3 will be performed applying a model of system sustainability.

Task 6.1. Detect and develop indicators
The relationships between soil functional biodiversity (WP2), soil functions (WP3) and soil ecosystem services (WP4) will be assessed through multivariate analyses. The results obtained in WP2, WP3 will give a picture of what happens at individual times at specific sites. In order to have an overview of the relationships between soil parameters (soil functions) and ecosystem services at medium and long-term scales, the multivariate analyses will also include the amount data previously recorded by each team on Kerguehennec site. Currently, France has 10 site years of data which will be used to reinforce the measured parameters.

Task 6.2. Evaluate environmental impacts of tillage systems on soil quality with LCA
The GESSOL 3 project ACV-SOL is currently developing multi-criteria indicators of impacts (e.g., erosion, soil organic matter change, compaction) of agricultural activities on soil quality in the framework of an LCA approach. LCA is used to estimate environmental impacts of an agricultural product or system throughout its life cycle, including the energy, resources, and emissions necessary to extract, transport, and transform raw materials into the product(s) of interest (Guinée et al., 2002). Finalisation of these indicators in ACV-SOL is planned for the end of 2011, making them available to apply in this task to the tillage systems studied in this project. This application will permit evaluation of the sensitivity and robustness of the LCA indictors, as well as the soil-quality impacts of the various tillage systems studied. In addition, the data collected in this study will permit the development of an indicator of tillage activities on soil biodiversity, with the aim of adding it to the set of soil-quality indicators from the ACV-SOL project. This task will integrate data from WP2, WP3, WP4 and WP5.

Task 6.3. Evaluate the eco-social sustainability of tillage systems
The sustainability evaluation will be applied on the farm network i.e. 11 paired farms (detailed in A.II.3), which could integrate more farms to be relevant according to regional heterogeneity. The evaluation method developed by INRA is adapted to our approach and will allow for the evaluation of sustainability at a systems scale. This method is called MASC (Multi-Attribute Assessment of the Sustainability of Cropping Systems). MASC is used by applying DEXi software, which is a decision making tool. It allows for the development of qualitative multi-criteria models in many domains. One application is the evaluation and the analysis of scenarios such as reduced tillage systems. MASC is a qualitative multi-attribute decision model for ex ante assessment of the sustainability of cropping systems. The surveys done in WP5 will be used in MASC.