Large-scale afforestation has seriously aggravated the consumption of soil water and caused soil desiccation and even the dry soil layers, which has been restricting the survival and sustainability of vegetation in semi-arid areas. How to solve soil water deficit reasonably is an important practical problem we are facing. Here, a field experiment of the decayed roots with different times on soil water infiltration processed was conducted in planted forestland by a double-ring infiltration instrument, to determine the contribution of decayed tree roots on soil water infiltration process and replenishment. Results showed that the decayed process of tree roots in forestland could significantly reduce root density (RD) and increase the relative porosity improved by the roots (RPIR) (P < 0.05). The macropore formed by root decay could not only significantly increase the infiltration rate at each stage (P < 0.05), but also reduce the decrease rate of infiltration rate. Compared with bare land, the decayed roots of the 1–4 yr, the 5–8 yr, and the 9–12 yr increased the amount of soil water replenishment by 37.12%, 217.52%, and 259.85%, respectively. Overall, the decayed tree roots could maintain a relatively high and stable infiltration rate by reduced root density, which increased the effective replenishment of soil water of dry soil layers in forestland. These findings have potential implications for understanding the effect of decay process of tree roots on soil water replenishment, and provide a theoretical basis for the solution to dry soil layers and sustainable management of forestland in semi-arid areas.

大规模植树造林严重加剧了土壤水分的消耗，造成土壤干燥甚至土层干涸，制约了半干旱地区植被的生存和可持续性。如何合理解决土壤水分亏缺是我们面临的重要现实问题。在此，利用双环入渗仪在人工林地进行了不同时间腐烂根系对土壤水分入渗处理的田间试验，确定了腐烂树根对土壤水分入渗过程和补给的贡献。结果表明，林地树木根系腐烂过程可显着降低根系密度（RD），增加根系改善的相对孔隙度（RPIR）（P < 0.05）。根腐烂形成的大孔不仅可以显着提高各阶段的入渗速率（P < 0.05），而且可以降低入渗速率的下降率。与裸地相比，1-4年、5-8年和9-12年的腐烂根系分别增加了37.12%、217.52%和259.85%的土壤补水量。总体而言，腐烂的树根可以通过降低根系密度来保持较高且稳定的入渗率，从而增加了林地干土层土壤水分的有效补充。这些发现对理解树根腐烂过程对土壤水分补充的影响具有潜在意义，为解决半干旱地区干旱土层和林地可持续管理提供理论依据。