Abstract:Soil drying are the main limiting factor for regional vegetation restoration and ecological environment improvement, Understanding the distribution and drying of dry soil layers in different plantations has important theoretical and practical significance for the sustainable utilization of soil water resources and the construction of artificial vegetation. Different plantations on Typical Slopes in southern Ningxia Mountainous Region were selected as research objects. Stratified sampling of 0~600 cm soil layer, distribution characteristics of soil moisture and vertical profile of soil moisture in apricot, poplar, elm, locust, pine and control farmland were analyzed, soil desiccation index, soil water relative deficit index and redundancy analysis were used to evaluate soil desiccation intensity and water deficit degree and to analyze environmental impact factors. Result show that the Soil moisture of apricot, poplar, elm, locust and pine trees were moderately variable, and the average soil water content of 0~600 cm was 31.17%, 24.15%, 23.19%, 29.67% and 18.35% lower than that of farmland, respectively. The initial depth of soil dry layer, the thickness of soil dry layer and the distribution of soil moisture in vertical profile are obviously different in different plantations. The initial depths of apricot, poplar, elm, locust, pine and farmland trunk layers were 90, 160, 140, 140, 160 and 600 cm, respectively. The thickness of dry layer is 510 cm, 460 cm, 480 cm, 480 cm, 460 cm and 0 cm respectively. The soil drying index of 0~600 cm profile of apricot, poplar, elm, locust and pine were 63.48%, 91.88%, 95.17%, 73.97% and 111.91%, respectively. The relative deficit index of soil moisture was 0.68, 0.59, 0.52, 0.63 and 0.41, respectively. The order of soil moisture desiccation intensity and deficit degree from high to low was apricot tree > locust tree > poplar > elm tree > pine tree. RDA analysis showed that the arbor type,clay content and topographic conditions were important factors affecting soil dry layer. Because the soil water deficit and the degree of dryness are serious in southern Ningxia, measures such as adjusting planting density and reasonably pruning branches should be taken to promote the sustainable development of ecological environment in the study area.