Effects of Irrigation Practices on Potato Yield and Water Productivity: A Global Meta-Analysis

The efficiency of water use in irrigated agriculture is a global priority to address water scarcity. A comprehensive meta-analysis was conducted to evaluate the effects of irrigation practices on potato yield, crop evapotranspiration (ETc), water productivity (WP), and irrigation water productivity (IWP) across diverse growing conditions, including soil texture, fertilizer application rates, annual precipitation, and soil organic carbon (SOC). The results revealed that supplementary irrigation increased potato yield by 55% and ETc by 39% while maintaining WP comparable to non-irrigated conditions. The greatest yield and WP improvements from supplementary irrigation occurred under drip irrigation with moderate N, P, and K application rates (150–250 kg ha−1) and irrigation amounts below 150 mm. This practice was particularly effective in sandy soils with 1.5–2.0% SOC and annual rainfall of 200–400 mm. Conversely, deficit irrigation reduced potato yield and ETc by 25% and 24%, respectively, but significantly enhanced WP and IWP by 9% and 28% compared to full irrigation. When a water-saving ratio of 10–20% was implemented under drip irrigation with optimal fertilizer rates (240–360 kg N ha−1, >104 kg P2O5 ha−1, 150–200 kg K2O ha−1), deficit irrigation improved WP without yield loss in sandy soils with annual rainfall of 600–800 mm when compared to full irrigation. The IWP increased with rising SOC levels, indicating that SOC improvement in low-carbon soils enhances water productivity in irrigated potato systems. These findings demonstrate that tailored irrigation strategies can simultaneously reduce water inputs and achieve higher yield and WP in potato production systems.