Abstract Irrigation with brackish water is a possible solution to alleviate freshwater shortages in arid and semi-arid regions. However, necessary measures need to be taken to leach accumulated salts out of the root zone. This can be accomplished by leaching with freshwater applied by surface irrigation (LFSI), which needs to be optimized to improve the leaching efficiency. An experiment in a field drip-irrigated with brackish water was carried out during 2017 and 2018 to evaluate the effects of leaching (or no leaching (T0)) during the corn elongation (T1), tasseling (T2), and grain-filling (T3) stages. The HYDRUS (2D/3D) model was calibrated and validated using experimental data collected in 2017 and 2018, respectively. The results of numerical simulations were in good agreement with measurements, which is electrical conductivity (ECw), with mean relative errors of 11.9%, 10.1%, 10.6%, and 9.2% for the T1, T2, T3, and T0 treatments, respectively, during the validation periods. LFSI during the corn elongation stage (T1) had the shortest duration of “high salinity stress” which lasted 42, 56, 57, and 82 days for the T1, T2, T3, and T0 scenarios, respectively. The highest rate of salt reduction in the root zone (i.e., the desalination rate) occurred when LFSI was applied during the corn grain-filling stage (T3). The desalinization rates were 59%, 68%, and 69% in the T1, T2, and T3 treatments, respectively. The cumulative salt flux at a depth of 40 cm increased by 2.0%, 16.3%, and 34.7% for T1, T2, and T3, respectively, compared to T0. Two-dimensional simulations of ECe distributions revealed that the “high salinity stress” area in the soil profile after LFSI was 4%, 48%, and 92% higher for T0 than for T1, T2, and T3, respectively. The simulations showed that optimal leaching time was about 41 days after sowing, which led to the lowest duration of the “high salinity stress” period and a relatively high desalination rate of 59%.

中文翻译：

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在不同作物生长阶段用微咸水滴灌和淡水淋洗的田间评价土壤盐分动态

摘要 用微咸水灌溉是缓解干旱和半干旱地区淡水短缺的可能解决方案。但是，需要采取必要措施将积累的盐分从根区中滤出。这可以通过使用地表灌溉 (LFSI) 的淡水进行浸出来实现，需要对其进行优化以提高浸出效率。2017年和2018年进行了微咸水滴灌田间试验，评价浸出（或不浸出（T0））在玉米伸长（T1）、抽穗（T2）和灌浆过程中的效果（ T3) 阶段。HYDRUS (2D/3D) 模型分别使用 2017 年和 2018 年收集的实验数据进行校准和验证。数值模拟的结果与测量结果非常吻合，即电导率 (ECw)，在验证期间，T1、T2、T3 和 T0 处理的平均相对误差分别为 11.9%、10.1%、10.6% 和 9.2%。玉米伸长阶段 (T1) LFSI 的“高盐胁迫”持续时间最短，T1、T2、T3 和 T0 情景分别持续了 42、56、57 和 82 天。当在玉米灌浆阶段（T3）应用LFSI时，根区盐分减少率（即脱盐率）最高。T1、T2和T3处理的脱盐率分别为59%、68%和69%。与T0相比，T1、T2和T3在40 cm深度处的累积盐通量分别增加了2.0%、16.3%和34.7%。ECe 分布的二维模拟显示，LFSI 后土壤剖面中的“高盐度应力”区域分别为 4%、48%、T0 分别比 T1、T2 和 T3 高 92%。模拟结果表明，最佳浸出时间约为播种后 41 天，这导致“高盐胁迫”期的持续时间最短，脱盐率相对较高，为 59%。