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In Ceara (semi-arid Northeast Brazil), although still fragile, the sociotechnical system "agroecology" has established itself as an alternative to the dominant agribusiness. The controversies and clashes between the respective public and private actors that defend them highlight two polarized visions for the rural territory. In this work conducted in the Jaguaribe region, we questioned these controversies in the face of family farmers' practices and analyzed the determinants of farmers' practices. The methodology associated a participatory systemic and multi-actor diagnosis coupled with semi-structured interviews with farmers (40) and institutional representatives. On one hand, the two socio-technical poles were characterized (actors, visions, rules, instruments and mechanisms for strengthening, etc.). On the other hand, farmers' practices determinantes were analyzed through the framework of sustainable livelihoods and historical perspective. In the field, the two systems coexist, increasing farmers' capacity to adapt. Without getting too involved in the controversies, farmers pragmatically take advantage of the opportunities offered by both systems to implement their life strategies: instruments (public and private), narratives, rules. Innovative practices often arise from this re-appropriation. They are sometimes in contradiction with the initial purpose of the instruments of both systems (such as subsidies, credits, etc.) that were designed within a polarized vision. Access to opportunities remains strongly dependent on key actors, in often clientelistic relationships. Information and debate arenas are informal and not very inclusive. This contributes to the great heterogeneity in the capacity of farmers and communities and to social-environmental inequality. The absence of a formal local governance framework may favors adaptability and innovation at various levels (individual, family, community, ...). But at the territorial level, the lacking of natural resources management increases socio-environnemental vulnerability.

To ensure agricultural land in rural territories is managed sustainably, environmental assessment need to be undertaken to support decision making. However, the development of sustainable agriculture and the sustainable use of natural resources is a major challenge for the Southern countries, which are subject to strong climatic and socio-political constraints, making it necessary to develop environmentally efficient agricultural systems that take into account the social and economic components of sustainability. Life cycle assessment (LCA) is a standardized method (ISO 14000 series) widely recognized for its completeness. It provides full multidimensional knowledge about potential environmental impacts, linked to a functional unit that characterizes a service rendered, in a global and long-term perspective. The aim of this study was to design an innovative operational framework to couple life cycle assessment approach and a participatory approach for developing countries with two objectives: First, to make it possible to perform environmental assessment even with the diversity of small farming systems and despite data scarcity, second to involve all the stakeholders and to facilitate the discussion of the results to enable further decision making for the management of a rural territory. We tested the applicability of our framework on a case study in a semi-arid region in central Tunisia where agricultural is based on scarce and overused natural resources. This framework made it possible to gather local knowledge about the systems under to be analysed, to involve all the stakeholders right from the beginning of the process and to consider all the interests and values as well as the diversity of social representations in the territory. In this way, the stakeholders were empowered by the assessment of the environmental impacts of their agricultural practices and land management in a context of decision making. As a matter of fact, social learning favourable conditions were created.

Soil is a rare natural resource and it is at the center of the main issues in agronomy, environment and land use planning. At global level, erosion is one of the major soil degradation processes and it is responsible for the decrease in agronomic potential of soils and in agricultural land surfaces. Water and soil conservation works (WSCW) are built to protect soil from erosion. The financial and environmental cost the WSCW construction is very high. However, the positive impacts of WSCW are not taken into account in Life Cycle Assessment (LCA). The objectives of this study is to intergrate the impact of WSCW on soil quality in LCA. There are different types of WSCW with different functions and they act differently on erosion process. In this study we focussed on contour ridges (CR) because they are associated to crop systems. CR are generally built in upland areas to reduce runoff and erosion, to increase on-site deposition of eroded particles and to increase local water infiltration. They modify water and soil flows at catchment scale, so it is necessary to use a model able to calculate the inventory flow at the catchment and not at the plot level. In this study we present a methodology to integrate the impact of CR on topsoil erosion at the catchment level and to compute characterization factors in presence of such WSCW. The proposed method was applied in a case study in semi-arid context in central Tunisia (Merguellil watershed) which presents the issues of over-exploitation of water resources, accelerated land degradation and a high expansion of conservation works. In order to investigate the impact of WSCW on topsoil erosion, diffrent catchment scenarios (with and without CR) and land use types were tested using soil redistribution model (LandSoil model). For life cycle impact assessment, we focussed on two midpoint impact categories of LANCA soil functions : erosion resistance and mechanical infiltration. The CFs were calculated using the two models : LANCA and LandSoil models. These CFs were then compared. The results showed how contour ridges can modify topsoil erosion process, the erosion impact depend on location of landuse and contour ridges increase mechanical infiltration of soil. However, these impacts were not considered in LANCA model. In conclusion, It is necessary to integrate the positive impacts of contour ridges in life cycle assessment. It will be also neccessary to integrate the impact of the other types of WSCW in topsoil erosion impact modelling.

Semi-arid agricultural areas are fragile territories where water and soil resources must be preserved. In such zones impact evaluation is difficult due to the lack of data. We focused on the upstream Merguellil watershed, located in central Tunisia, where several water and soil conservation works were built since 1990 to control water erosion and to protect the downstream area. The rapid expansion of such conservation measures raised the issue of their impact on soil and water resources. Our main goal is the impact assessment by LCA of the most relevant farming systems in our territory, taking into account on-site and off-site contributions to local and global impacts. Our strategy is to combine LCA with a participatory approach to integrate knowledge and perceptions of local actors and to provide elements on environmental impacts for all stakeholders. The first step was a territorial systemic participatory diagnosis to characterize the dynamics of the territory, to identify the natural resources and their uses, the developments of the agricultural practices and the characterization of the existing farming systems. This diagnosis was achieved through technical field visits and interviews with farmers. The second step was a territorial LCA of representative systems, mapping the different systems to consider the characteristics of their location (access to water, soil type…). Systemic territorial participatory diagnosis allowed to define a typology of production systems and to model the territory considering the interactions between these systems. Four types of production systems were identified to proceed with territorial LCA: olive and apricot system and olive and cereals system both in rainfed and irrigated combinations. LCA results are discussed for the most important midpoint indicators. This study demonstrated two major issues of LCA use for sustainable development in semi-arid watersheds: i) LCA results communication with stakeholders to fit with their understanding of the system and ii) localized impacts on soil and water resources, taking into account Water and Soil Conservation Works.