Soil and water are basic for any agricultural production system. They are available under a huge pressure due to the increasing population and climate changes (Kumawat et al., 2020). Among the various degradation processes, soil erosion contributes seriously to the deterioration of soil and water resources. Soil erosion has also hampered agricultural productivity and economic growth in many regions and countries (Hengsdijk et al., 2005; Balana et al., 2010). Food production reduction in a specific country or region due to natural resources degradation, may not have a significant effect on food supply because of the potential substitution from other producing areas. However, the effect could be dramatic to food security of large number of people and to local economic activity (Scherr & Yadav, 1996). Practices related to soil and water conservation (SWC) enhance crop production, food security and household income (Adgo et al., 2013). Therefore, investments are promoting SWC technologies for improving agricultural productivity, household food security and rural livelihoods. Different SWC technologies have been encouraged among farmers to control erosion for example. However, investments by farmers in SWC are influenced by the ecological, economic, and social impacts of the SWC technologies (Huang et al.,2018). In Tunisia, since antiquity, inhabitants of arid and semi-arid regions have constructed water harvesting systems to cope with limited water supply. Impoundments were built to capture surface run-off. These structures are known to reduce soil erosion (Oweis et al., 2004). The Tunisian government has invested into soil and water conservation practices through institutional and legislative measures. A national strategy for soil and water conservation and agricultural development was launched since 1990. More than 600 000 hectares received conservation measures (Abouabdillah et al., 2014). The rapid expansion of soil and water conservation practices has raised questions concerning their economic and environmental impacts. The economic impact of SWC practices is mostly evaluated in monetary terms (cost-benefit analysis) (Bizoza and Graaff, 2012; Teshome et al., 2013). However, social, and ecological impacts as well as the interactions between different impacts are not easily quantified in monetary values (Tenge, 2005). Many evaluation methods of SWC measures are used to quantify the monetary and non-monetary value of SWC practices to enhance the decision-making process. Farmers' goals and motivations for investing in different SWC alternatives are different from those of researchers and extension staff, as they have other objectives besides reducing soil loss and maximizing benefits. These objectives may be conflicting, so no SWC measure can provide the best outcome for all farmers (Tenge, 2005).
The objective of this work is to provide a technical guide on the different methods of economic evaluation of soil and water conservation practices for an efficient scaling up of SWC technologies, under different agroecosystems in Tunisia.
This technical guideline is fulfilled in the framework of the SWC @Scale project that has concentrated its efforts and investments in two different sites in Tunisia (Northwest, Siliana, and Central west, Kairouan).