Yield and water productivity responses to deficit irrigation: A meta-analysis from Ethiopia

To meet global food demand, strategies promoting efficient water use are essential for sustainable agricultural practices. Deficit irrigation (DI) is increasingly promoted as a water-saving strategy, though reports on its effect on yield and water productivity (WP) remain inconsistent. To address this inconsistency, we conducted a meta-analysis on eight crops from 62 studies: maize ( Zea mays ), wheat ( Triticum aestivum ), sesame ( Sesamum indicum L. ), bean ( Phaseolus vulgaris L. ), onion ( Allium cepa ), potato ( Solanum tuberosum ), tomato ( Solanum lycopersicum ), and pepper ( Capsicum annuum ) for their high socio-economic importance for Ethiopia. We used PRISMA 2020 reporting guidelines. Effect size was computed using response ratio of means as effect size measure. Our results indicated that sesame, tomato, and wheat are resilient crops to water stress. Applying DI at 50–70% ETc in wheat increased WP by 48% (95% CI:1.34–1.64) with only 16% yield loss (95% CI: 0.77–0.91). Similarly, in tomato, WP improved by 51% (95% CI:1.35–1.69) with a 21% yield reduction (95% CI: 0.71–0.87). Across all moderators, DI at 80% ETc produced yield comparable to full irrigation (p > 0.05). Applying DI under drip irrigation below 80% ETc appeared suboptimal, causing substantial yield loss (up to 45%) with marginal WP gains. Alternate and fixed furrow irrigation performed effectively at 100% ETc with a 50% increase in water productivity (95% CI:1.32–1.71) with only 18% yield reduction (95% CI:0.74–0.92). These findings provide evidence to optimize irrigation strategies and inform sustainable agricultural water management in Ethiopia and for regions with similar agro-climatic conditions.