Drip irrigation with alternate use of fresh and brackish waters is an excellent irrigation strategy to overcome salt stress problems induced by brackish water. Understanding salt stresses in the soil profile and their relationship with crop growth is critical when optimizing irrigation strategies with alternate use of fresh and brackish waters. The HYDRUS (2D/3D) model was calibrated and validated using experimental data collected in 2019 and 2020, respectively. The calibrated model was then used to evaluate the effects of different irrigation strategies involving the use of only freshwater (FW) or brackish water (BW), or the alternative use of brackish and fresh waters (1B1F, one irrigation with brackish water and one with fresh water; 2B1F, two irrigations with brackish water and one with fresh water; and 3B1F, three irrigations with brackish water and one with fresh water) on the soil electrical conductivity (EC_sw), salt stress, crop growth, and yield. In general, the model performed well, with the average RMSE, M RE , and R² for EC_sw of 0.12 dS m⁻¹, 6.85%, and 0.97, respectively. The average EC_sw in the 0–40 cm soil layer (the main root zone) showed large differences between different alternate irrigation strategies, increasing by 55.9% between FW and BW. There was a strong linear relationship between salt stress (EC_sw of 3.4–11.8 dS m⁻¹, SS) in the main corn root zone and salts introduced by irrigation water. The SS duration and area increased with the frequency of irrigations with brackish water, while the opposite was observed for the average desalination rate (DR) after irrigation during the entire growth stage. The SS duration was 90, 111, 115, 121, and 121 days for FW, 1B1F, 2B1F, 3B1F, and BW, respectively, while the corresponding values for the duration of high salt stress (EC_sw of 7.6–11.8 dS m⁻¹, HSS) were 4, 24, 32, 37, and 46 days, respectively, and the average DRs were 4.3%, 2.4%, 1.9%, 1.7%, and 0.8%, respectively. Average fractions of the SS and HSS areas to the main root zone area for BW increased by 5.3% and 26.6% compared with FW, respectively. When the HSS duration increased by 42 days from the FW to BW scenarios, corn yield, plant height, stem diameter, and leaf area index decreased by 8.8%, 10.4%, 17.7%, and 19.6%, respectively. Additionally, the quantitative relationship between SS and corn yield, i.e., a sensitivity function of the crop yield to soil water and salt stresses, was proposed based on HYDRUS (2D/3D) simulations. The 2B1F scenario can be recommended as the optimal strategy for the studied region, using most brackish water with only a 4% decrease in the corn yield.

交替使用淡水和微咸水的滴灌是克服微咸水引起的盐胁迫问题的绝佳灌溉策略。在通过交替使用淡水和咸水来优化灌溉策略时，了解土壤剖面中的盐胁迫及其与作物生长的关系至关重要。HYDRUS (2D/3D) 模型分别使用 2019 年和 2020 年收集的实验数据进行了校准和验证。然后使用校准的模型评估不同灌溉策略的效果，这些策略涉及仅使用淡水 (FW) 或微咸水 (BW)，或替代使用微咸水和淡水（1B1F，一种用微咸水灌溉，另一种用微咸水灌溉）淡水；2B1F，两次用微咸水灌溉，一次用淡水灌溉；和 3B1F，EC _sw )、盐胁迫、作物生长和产量。总的来说，该模型表现良好，EC _sw的平均RMSE、M RE和R ^{2 分别}为0.12 dS m ^-1、6.85% 和 0.97。0-40 cm 土壤层（主根区）的平均EC _{sw在不同交替灌溉策略之间表现出很大差异，FW 和 BW 之间增加了 55.9%。}盐胁迫之间存在很强的线性关系（EC _sw为 3.4-11.8 dS m ^-1, SS) 在主要玉米根区和灌溉水引入的盐分。SS持续时间和面积随着微咸水灌溉频率的增加而增加，而在整个生长阶段灌溉后的平均脱盐率（DR）则相反。FW、1B1F、2B1F、3B1F 和 BW 的 SS 持续时间分别为 90、111、115、121 和 121 天，而高盐胁迫持续时间的相应值（EC _sw为 7.6-11.8 dS m ^{- 1}, HSS) 分别为 4、24、32、37 和 46 天，平均 DR 分别为 4.3%、2.4%、1.9%、1.7% 和 0.8%。与 FW 相比，BW 的 SS 和 HSS 区域占主根区面积的平均分数分别增加了 5.3% 和 26.6%。当 HSS 持续时间从 FW 到 BW 情景增加 42 天时，玉米产量、株高、茎粗和叶面积指数分别下降 8.8%、10.4%、17.7% 和 19.6%。此外，基于 HYDRUS (2D/3D) 模拟，提出了 SS 与玉米产量之间的定量关系，即作物产量对土壤水分和盐分胁迫的敏感性函数。可以推荐 2B1F 方案作为研究区域的最佳策略，使用大多数微咸水，玉米产量仅减少 4%。