Factors Affecting Soil Desiccation Spatial Variability in the Loess Plateau of China

Abstract

Core Ideas Soil desiccated patterns varied with soil layers in the Loess Plateau (LP). Soil in grassland and forestland was more desiccated than that in cropland. Soil desiccation in the LP was jointly controlled by climate and non‐climate factors. Soil desiccation has occurred widely across the Loess Plateau (LP) of China because of excessive depletion of soil water by artificial ecosystems and limited long‐term rainfall recharge. This may lead to soil degradation and failure of afforestation efforts, which threatens ecosystem health in the LP. However, spatial characteristics and controlling factors of soil water generally vary within different soil layers. This has implications of vegetation recovery in the LP and has been overlooked in previous studies. This study investigates the spatial characteristics of soil desiccation in different layers from the 0‐ to 5‐m depth across the entire LP and explores the relationships between soil desiccation and environmental factors. The soil desiccated index (SDI) in the 0‐ to 1‐m soil layer was patchy, while in the 1‐ to 5‐m soil layer, the degree of soil desiccation generally increased from southeast to northwest following a gradient of decreasing rainfall. Soil desiccation in the forestland and grassland were more severe than that in the cropland because of higher evapotranspiration, lower precipitation recharge and lower soil water holding capacity. Soil desiccation at the shallow depth (0–1 m) was mainly attributed to climate factors whereas deep soil desiccation (1–5 m depth) was more likely attributed to the joint effects of climate factors and non‐climate factors. The results of this study can help develop practical sustainable land management practices, regional water budgets and help restoration of environment in the LP of China.