河套灌区典型夹砂层农田水分通量模拟与灌溉制度优化

Water Dynamic Simulation and Irrigation Scheme Optimization in Typical Sand-interlayered Soil in Hetao Irrigation District

摘要:

为揭示不同灌溉制度下河套灌区典型夹砂层农田水分运移机制，在砂层埋深大于40cm农田设置高水（W1）、中水（W2）、低水（W3）3个灌水水平，高氮（F1）、中氮（F2）、低氮（F3）3个施氮水平，观测土壤含水率，基于田间试验结果，利用HYDRUS-1D模型对典型夹砂层农田土壤水分运移过程进行模拟，分析了不同砂层埋深及不同灌溉制度对根区土壤水分通量与玉米根系吸水量的影响规律。结果表明：根区土壤水分渗漏损失量随砂层埋深增加而减小，可提高根系对砂层以上根区水分的利用。随灌水量增加，根区土壤水分渗漏的减少效果更加明显。当砂层埋深为20~40cm时，砂层上边界土壤水分向下迁移量占灌水量的12.39%~98.19%；当砂层埋深大于 40cm 时，土壤水分向下迁移量降为灌水量的2.73%~7.00%，水分有效利用率显著提高。根系受到的最大水分亏缺发生在第2次灌水后至第3次灌水前，占总亏缺量的56.04%~68.56%，拔节期至第1次灌水的水分亏缺最小。根系受到的总水分亏缺量随砂层埋深增加而逐渐降低，砂层埋深越深，水分亏缺量越低，与砂层埋深20~40cm相比，根系受到的总水分亏缺量降低10.76%~45.63%。不同生育阶段根系受到的最大水分胁迫均在砂层埋深20~40cm，随砂层埋深增加，水分亏缺量逐渐降低，最大降幅达82.61%。综合考虑夹砂层土壤水分迁移、根系受到的水分亏缺，建议在夹砂层土壤农田春玉米灌溉时根据砂层分布因地制宜定灌溉制度，砂层埋深20~40cm，推荐春玉米在生育期灌溉定额为189~216mm，砂层埋深40~60cm，推荐灌溉定额为243~270mm，砂层埋深大于60cm，推荐灌溉定额为216~270mm。研究结果可为河套灌区典型夹砂层土壤农田水分高效利用与灌溉制度制定提供理论依据。

Abstract:

In order to reveal the influence mechanism of soil water movement in typical sand-interlayered soil under different irrigation systems in Hetao Irrigation District (HID), HYDRUS-1D model was used to simulate the process of soil water movement in typical sand-interlayered soil, and the effects of different sand depth and irrigation regimes on soil water dynamics were studied based on the field experiments with three irrigation levels of high water (W1), medium water (W2) and low water (W3) , high nitrogen (F1) , medium nitrogen (F2) and low nitrogen (F3) were set in the farmland at sand depth more than 40cm. The results showed that the deeper the depth of sand layer was, the more effective it was to reduce the loss of soil water leakage and improve the root water uptake above the sand layer. With the increase of depths of sand layer and irrigation amount, the effect of reducing soil water leakage was more obvious. When the depth of sand layer was 20~40cm, the soil water leakage at the upper boundary of sand layer accounted for 12.39%~98.19% of irrigation amount. When the depth of sand layer was greater than 40cm, the soil water leakage was decreased to 2.73%~7.00% of irrigation amount. The maximum water stress of roots occurred between the second irrigation and the third irrigation, accounting for 56.04% ~68.56% of the total stress, and the water stress from jointing to the first irrigation was the smallest. The total stress on root was decreased with the increase of sand depth. Compared with the stress on 20~40cm, the total water stress of root was decreased by 10.76%~45.63%. The maximum stress on roots at different growth stages was on the depth of 20~40cm, and the stress was decreased gradually with the increase of sand layer depth, the maximum decrease was 82.61%. Considering the soil water movement and root stress in the sand layer, it was suggested that the irrigation scheme of spring maize on the typical sand-interlayered soil should be set due to the distribution of sand layer. The recommended irrigation regime for different depths of sand layer was as follows:189~216mm for the depth of 20~40cm, 243~270mm for the depth of 40~60cm, and 216~270mm for the depth greater than 60cm. The research results can provide theoretical guidance for the formulation of irrigation system on typical sand-interlayered soil in HID.