Soil water deficit was effectively alleviated by higher water infiltration after the short-term forestland-to-farmland conversion in semi-arid area

The increasing global vegetation aggravated the consumption of soil water and caused soil desiccation, which may result in a threat to the survival and sustainability of vegetation, especially in semi-arid and arid areas. How to solve soil water deficit caused by afforestation is an important practical problem. Here, a field experiment of soil water infiltration and replenishment was conducted before and after forestland-to-farmland conversion. Results showed that the cumulative infiltration of each stage (the initial stage, the transitional stage, and the stable stage) was the highest in farmland, followed by forest interspace, and the lowest in forest understory. The non-capillary porosity at 0–20 cm soil layer in farmland was higher than that in forest understory and interspace, which positively improved the infiltration accumulation in the initial stage. Thus, the cumulative infiltration in initial stage of farmland (28.93 mm) was significantly higher than that of forest understory (19.45 mm). Moreover, soil water at the depth of 0–160 cm soil layer was replenished with short term after forestland-to-farmland conversion. It is concluded that forestland-to-farmland conversion could improve soil water infiltration rate and cumulative infiltration by changing porosity, and effectively replenished soil water storage in the short term. These findings have potential implications for effective mitigation of soil water deficit caused by afforestation, and provide a new idea or method for the solution to dry soil layers caused by artificial forestland in semi-arid areas.