Response of soil water–salt distribution and maize growth to aerated subsurface drip irrigation in saline soils

Aerated subsurface drip irrigation (ASDI) is a promising strategy for improving crop productivity in saline soils, yet its effects on root–zone water–salt dynamics and crop adaptation remain unclear. Here, based on a two–year field experiment, we assessed the effects of ASDI on soil water–salt distribution, root development, crop yield, and irrigation water productivity under conventional (W1) and 20 % water–saving (W0.8) irrigation regimes, each combined with two dissolved oxygen concentrations (12 and 20 mg /L), using non–aerated irrigation as the control (CK). ASDI improved the soil water–salt environment by enhancing water storage, infiltration, and salt suppression, with salinity responses showing clear irrigation–dependent and temporal patterns. Under W1, aeration consistently reduced salt accumulation over two seasons, maintaining soil salt storage below CK. The initially smaller low–salinity zone under W1 compared with W0.8 likely reflected feedbacks between root growth and water–salt redistribution. In contrast, under W0.8, the low–salinity zone progressively contracted by 2024, accompanied by soil salt storage exceeding CK, indicating a potential risk of salt accumulation under sustained water–saving irrigation. Increasing the aeration mitigated this trend and enhanced soil enzyme activity. An improved root–zone environment promoted root development, increasing the maximum root density by 16 % and other root traits. These responses sustained grain yield under water–saving conditions, while increasing the harvest index by 2.5 % and irrigation water productivity by 25.0 %. Overall, aeration alleviated salt accumulation and supported crop performance, while its longer–term effectiveness under continuous water–saving requires further validation.