Moistube irrigation (MTI) is a type of technology which uses a semipermeable membrane to emit water continuously in response to soil water potential and applied pressure. Soil water dynamics under MTI incorporating plant water uptake have not been studied. Therefore, this study aimed at determining the soil water distribution under MTI, using cowpea as a reference crop. The effect of Moistube placement depth on the soil water dynamics under MTI was also determined. The experiment was carried out in tunnels with MTI and subsurface drip irrigation (SDI) as a control. The HYDRUS 2D/3D model was calibrated and thereafter used to simulate soil water dynamics for different placement depths. The soil water content above the Moistube/drip lateral was higher under SDI than MTI, while the lateral movement of water was similar for both irrigation types. The simulated soil water contents closely matched (coefficient of determination [R²] ≥ 0.57, root mean square error [RMSE] ≤ 0.029 cm³ cm⁻³, normalized root mean square error [NRMSE] ≤ 14.7% and efficiency [EF] ≥ 0.20) the observed values for both MTI and SDI. This showed that HYDRUS 2D/3D could be used to simulate water dynamics of irrigated cowpea. There was no significant difference (p > .05) between the root water uptake (RWU) in SDI and MTI. The Moistube placement depth did not significantly affect (p > .05) the RWU in loam soil but increased with increased placement depth in clay soil. The optimum placement depth of Moistube laterals for cowpea was 15 cm in loam and 20 cm in clay. This study forms the basis for design of MTI in terms of optimum placement depths for cowpea grown in loam and clay soils.

中文翻译：

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在Mo水灌溉下对ist豆（VIGNA unguiculata（L.）Walp。）作物进行土壤水分分布模拟*

水分灌溉（MTI）是一种技术，该技术使用半透膜连续响应土壤水势和施加压力而排放水。还没有研究MTI结合植物水分吸收的土壤水分动力学。因此，本研究旨在以cow豆为参考作物，确定MTI下的土壤水分分布。还确定了湿润管放置深度对MTI下土壤水分动力学的影响。该实验是在以MTI和地下滴灌（SDI）为对照的隧道中进行的。对HYDRUS 2D / 3D模型进行了校准，然后用于模拟不同放置深度下的土壤水分动力学。在SDI下，Moistube / Drip侧上方的土壤水分含量高于MTI，而两种灌溉类型的水的横向运动相似。R ² ] ≥0.57，均方根误差[RMSE] ≤0.029 cm ³ cm ^-3，归一化均方根误差[NRMSE]≤14.7％，效率[EF]≥0.20）是MTI和SDI的观测值。这表明HYDRUS 2D / 3D可用于模拟灌溉cow豆的水动力学。SDI和MTI的根系吸水量（RWU）之间没有显着差异（p > .05）。Moistube的放置深度没有显着影响（p> .05）壤土中的RWU，但随黏土中放置深度的增加而增加。cow豆的Moistube侧枝的最佳放置深度为：壤土15 cm，粘土20 cm。这项研究为在壤土和黏土中生长的cow豆的最佳放置深度提供了MTI设计的基础。