The design and management of irrigation systems require knowledge of soil water movement. There are few studies on soil water dynamics of Moistube irrigation (MTI) since it is a relatively new type of subsurface irrigation technology. It was hypothesised that soil texture influences soil water distribution under MTI. We determined soil water distribution, experimentally and numerically, using HYDRUS 2D/3D model for two soil textures (loamy sand and sandy clay loam). The experiment consisted of a soil box filled with soil and Moistube, supplied with water under a constant pressure head of 60 kPa, placed at 20 cm below the soil surface. Soil water content (SWC) was measured using Decagon MPS-2 sensors installed at depths of 5 cm, 10 cm, 15 cm, 20 cm, 30 cm, 40 cm and 50 cm and laterally at 10 cm, 20 cm and 30 cm over a period of 72 h. Results showed that simulated SWC closely matched (R² ≥ 0.70 and RMSE ≤ 0.045 cm³ cm⁻³) observed values for all depths considered for the two soil textures. The model slightly under- or over-estimated SWC (<15.6%). There was no significant difference (p > 0.05) between the soil water distribution in lateral and downward direction for both sandy clay loam soil and loamy sand. However, the SWC upward of the Moistube placement depth was significantly (p < 0.05) lower than both lateral and downward. SWC in loamy sand at 10 cm upward, downward and lateral after 24 h were 0.08 cm³ cm⁻³, 0.23 cm³ cm⁻³ and 0.20 cm³ cm⁻³, respectively. The corresponding values for sandy clay loam were 0.28 cm³ cm⁻³, 0.32 cm³ cm⁻³ and 0.31 cm³ cm⁻³ at 10 cm upward, downward and lateral, respectively. The simulations for wetted distance in both soil textures were also close to the observed values (R² ≥ 0.97, RMSE ≤ 3.99 cm). Soil texture had a significant (p < 0.05) effect on soil water movement with upward movement faster in sandy clay loam than in loamy sand. The lateral and downward distances were 23 cm and 24.6 cm, respectively, for loamy sand after 24 h. Similarly, for sandy clay loam, the lateral and downward distance was 19 cm. These wetting distances should be considered in the design of MTI in terms of depth of placement and lateral spacing. The results of this study demonstrated the usefulness of HYDRUS-2D/3D model in the prediction of soil water movement for optimum design of MTI.

灌溉系统的设计和管理需要了解土壤水分运动。由于Moistube灌溉（MTI）是一种相对较新的地下灌溉技术，因此对土壤水分动力学的研究很少。假设在MTI下土壤质地会影响土壤水分的分布。我们使用HYDRUS 2D / 3D模型对两种土壤质地（壤土和壤质壤土）进行了实验和数值确定，确定了土壤水分分布。实验由一个装满土壤和Moistube的土壤箱组成，在60 kPa的恒定压头下向其供水，并放置在土壤表面以下20 cm处。使用安装在5厘米，10厘米，15厘米，20厘米，30厘米，40厘米和50厘米深度，横向10厘米，20厘米和30厘米深度的Decagon MPS-2传感器测量土壤含水量（SWC）长达72小时。²  ≥0.70和RMSE≤0.045厘米³ 厘米^-3），用于考虑所述两个土壤质地所有深度观测值。该模型的SWC略低估或高估了（<15.6％）。砂质壤土和壤土的水分分布在横向和向下方向上没有显着差异（p> 0.05）。但是，Moistube放置深度向上的SWC显着低于（p <0.05）低于横向和向下。SWC在壤质砂土10cm处向上，向下和横向24小时后分别为0.08厘米³ 厘米^-3，0.23厘米³ 厘米^-3和0.20厘米³ 厘米^-3， 分别。对于砂质粘壤土相应值分别为0.28厘米³ 厘米^-3，0.32厘米³ 厘米^-3和0.31厘米³ 厘米^-3 10cm处向上，向下和横向，分别。两种土壤质地的湿润距离模拟也接近观测值（R ² ≥0.97，RMSE≤3.99厘米）。土壤质地对土壤水分运动具有显着的影响（p <0.05），沙质壤土壤土的向上运动要快于壤质沙土。24小时后，壤土的横向距离和向下距离分别为23 cm和24.6 cm。同样，对于砂质壤土，其横向和向下距离均为19 cm。在MTI的设计中，应根据放置深度和横向间距来考虑这些润湿距离。这项研究的结果证明了HYDRUS-2D / 3D模型在预测土壤水分运动以优化MTI方面的有用性。