Effects of soil profile configuration‐based weathered coal residue addition on soil water infiltration and evaporation

Optimizing soil profile configuration is crucial for ensuring food security in arid and semi‐arid regions by regulating soil water distribution. Applying exogenous materials is an effective method to construct functional soil profiles. Most existing studies focused on amending topsoil with exogenous materials, while the impacts of applying them to both topsoil and subsoil on soil water infiltration and evaporation remain poorly understood. This study investigated soil water infiltration and evaporation under four weathered coal residues (WCR) rates (0%, 1%, 2%, and 3% wt.%), applied to 0–20 cm and 20–40 cm soil layers. The results showed that WCR application significantly promoted cumulative infiltration. Relative to 0% topsoil + 0% subsoil (P 0+0 ), cumulative infiltration increased by 25.88% under P 1+1 , by 4.65% and 26.77% under P 2+1 and P 2+2 (compared with P 2+0 ), and by 70.36%, 78.19%, and 89.20% under P 3+1 , P 3+1 , and P 3+3 (compared with P 3+0 ). Regarding evaporation, P 1+1 slightly increased the average evaporation loss ratio by 5.38%, compared with P 1+0 . In contrast, P 3+1 , P 3+2 , and P 3+3 were reduced by 13.57%, 8.17%, and 7.60%, compared with P 3+0 . Relative to P 1+1 , P 2+2 , and P 3+3 decreased evaporation loss ratio by 3.07% and 18.05%. Overall, increasing exogenous material application rates in topsoil effectively enhances water infiltration in rainfall and reduces soil water evaporation during drought. However, such optimization must account for the contrasting properties of topsoil and subsoil. These findings provide a scientific basis for improving soil water retention via profile‐based exogenous material amendment in arid and semi‐arid regions.