Doubling gains, halting losses: Subsurface drip irrigation reshapes wheat-maize system sustainability

Efficient irrigation and fertilization are pivotal for enhancing yield while conserving water and nutrient resources in winter wheat-summer maize systems, which often suffer challenges of low, inconsistent grain yields and high nutrient leaching, drawing a considerable concern. Nitrogen (N) and Carbon (C) leaching impact water quality and nutrient–carbon balances, yet C leaching is rarely reported in these systems. This study aimed to optimize irrigation and N management through lysimeter-based field experiments conducted over two consecutive years 2022–23 and 2023–24. Three treatments: SDIP = subsurface drip irrigation with precise water and fertilizer, FIL = flood irrigation with low water and fertilizer, and CK = farmer’s practice, were tested in nine lysimeters with three replications. Evapotranspiration (ET a ) was estimated using the water balance, based on mass changes recorded by the weighing lysimeter. Across all treatments, SDIP maintained more stable soil moisture, reduced surface evaporation, and resulted in lower ET a , with maximum 5.9 mm day⁻¹ for wheat and 6.0 mm day⁻¹ for maize, while in CK treatment 7.0 mm day −1 and 7.4 mm day −1 respectively. The results indicated that precise water and fertilizer achieved the highest annual grain yield (22.06 t ha −1 ), crop water productivity (3.0 Kg m −3 ), apparent grain nitrogen uptake efficiency (166%), and partial factor productivity of nitrogen (152.28 kg kg −1 ). SDIP reduced irrigation by 47% (maize) and 39% (wheat) over CK, increasing system water productivity by 19%. Moreover, precise inputs minimized N and C leaching losses by 50% and 38%, respectively, in 2023, and completely eliminated these losses in 2024.These findings demonstrate that precise irrigation and fertilization strategies, such as SDIP, can enhanced yield, resource use efficiency and environmental sustainability. • Precise input by subsurface drip irrigation (SDI) maintains stable soil moisture compared to farmer’s practice. • Lower daily and annual evapotranspiration in precise input. • Precise irrigation and fertilization saved water by 47% (maize), 39% (wheat), and N by 40%. • Precise input eliminated leaching loss without yield penalty.