| To investigate the soil moisture characteristics under deep-rooted, perennial plants re-planted in the context of deep soil drying in the Loess Hilly Region, a field experiment was conducted at the Wangwa Soil and Water Conservation Experimental Station. The experiment simulated the re-planting of alfalfa in dried soil and continuously monitored soil moisture at depths of 0~600 cm from 2022 to 2024, while simultaneously measuring alfalfa yield and water use efficiency. The results are as follows: 1) The diurnal variations of soil moisture weaken with increasing depth, remaining relatively stable at the 40 cm soil layer. The occurrence times of the maximum and minimum diurnal soil moisture values gradually delay from May to October. 2) Under the background of deep soil drying, during the first year of re-planting alfalfa, soil moisture storage dominated, with storage primarily concentrated in the 0~340 cm soil layer. The moisture recovery in the dry soil layer reached 76% of the field capacity, with a recovery depth of 290 cm. In the second and third years of alfalfa planting, soil moisture consumption dominated, and the effective soil water storage was nearly depleted by the third year. 3) Compared to the control group, alfalfa yield and water use efficiency showed no significant differences in the first and second years of re-planting. However, yield significantly decreased in the third year, while water use efficiency exhibited no significant changes. This study provides scientific evidence for the sustainable replacement of artificial vegetation and the rational utilization of water resources in the Loess Hilly Region. |