Sustainability Assessment Approach Based on Total Factor Productivity Index: Application to Tunisian Policymakers in Agri-Food Supply Chain Context

This paper proposes a policy-oriented framework to evaluate agricultural sustainability and productivity within agri-food supply chains (AFSCs), focusing on the Tunisian context. The Analytic Hierarchy Process (AHP) was applied to identify the most appropriate Total Factor Productivity (TFP) methods, based on criteria derived from expert interviews and literature review. Three approaches, the Solow Residual, Törnqvist–Theil, and Divisia indices, were assessed. The Divisia (AHP weight = 0.918) and Törnqvist–Theil (AHP weight = 0.547) indices achieved the highest rankings, reflecting their suitability for multi-output systems and robust productivity decomposition. Sustainability-related Key Performance Indicators (KPIs) were categorized as inputs and outputs and monetized using shadow prices sourced from academic, institutional, and field data. Applied to 2015–2020 data, overall TFP declined by 59.5%, mainly due to reduced resource-use efficiency, declining agricultural value added, and increasing input costs. Unlike prior studies focused on farm-level productivity, this framework integrates TFP with a multi-criteria sustainability assessment to enhance evidence-based policymaking. The results demonstrate that methodological choices substantially shape sustainability conclusions and highlight the added value of price-aware, multi-output indices for complex agricultural systems. Overall, the proposed AHP–TFP approach provides a transparent, adaptable, and policy-relevant tool for evaluating sustainable productivity in the agri-food sector.