This study estimates how fertilizer intensity, mechanization, and agricultural water dependence relate to agricultural value added in the Mediterranean, and whether marginal effects differ between North (France, Spain, Portugal) and South (Algeria, Egypt, Tunisia). Using a harmonized annual panel (2000-2024), a two-way fixed-effects production model is estimated with Driscoll–Kraay standard errors. Agricultural value added is in logs; fertilizer and tractor density enter in logs (elasticities), while water dependence (agriculture’s share of freshwater withdrawals) enters in levels (semi-elasticity). Baseline estimates show positive elasticities for fertilizer and mechanization. Allowing for water-dependence curvature and water–input interactions indicates diminishing marginal associations in water dependence and weaker marginal returns to fertilizer and mechanization at higher dependence, with economically meaningful North–South heterogeneity in mechanization responses. The results imply that input policies should be tailored to water regimes and regional production structures, and paired with water-efficiency measures where dependence is high.
