Drip irrigation with mulching maintains high maize productivity with lower water consumption in arid and semi-arid regions of China

In arid and semi-arid regions, increasing crop yields while reducing agricultural water consumption remains a major challenge for sustainable agriculture. Drip irrigation with mulching has emerged as a promising solution, yet the mechanisms underlying its productivity benefits are not fully understood. This study presents a novel comparison of three mulched irrigation systems—drip irrigation with mulching (DIM), ridge mulching and furrow irrigation (RIM), and border irrigation with mulching (BIM)—against conventional border irrigation without mulching (CK) in the Hetao Irrigation District of China. This study systematically assessed their impacts on soil moisture, root growth, grain-filling, photosynthetic performance, plant growth and yield over two years, with a particular focus on the coordination among soil, root, photosynthetic, and grain-filling processes in maize. The results revealed that plastic film mulching generally enhanced soil water content, root growth, photosynthetic capacity and the grain-filling dynamics, leading to increased grain yield and water use efficiency. Among the treatments, DIM consistently outperformed RIM and BIM. It enhanced soil moisture, root growth, grain-filling rate, and net photosynthesis rate, and improved chlorophyll fluorescence parameters (higher maximum PSII quantum yield in the dark-adapted state and light-adapted state, photochemical quenching coefficient and lower non-photochemical quenching coefficient) during silking and grain filling stages. It also decreased stomatal limitation and increased WUEi, thereby promoting grain filling process and final yield formation. Compared with CK, DIM significantly increased yield by 3876–4457 kg ha−1, WUE by 29.6%–62.3%, IWUE by 52.1%–53.5%, and WUEi by 5.7–13.5% across 2019 and 2020, demonstrating greater advantages than RIM and BIM. Economic analysis further revealed that DIM achieved the highest net income (24054 and 25350 CNY ha−1 in 2019 and 2020), outperforming the other treatments. Overall, DIM is recommended as a highly efficient irrigation practice in arid and semi-arid regions to enhance maize productivity while reducing irrigation water use. These findings provide important insights for optimizing irrigation strategies and improving agricultural water management in water-scarce regions.