Reduced soil aggregation and increased wind erosion in disturbed semi-arid loess soils

Soil aggregation as reflected in the size distribution and stability of aggregates is a critical factor influencing soil erodibility by wind and/or water. Wind erosion leads to significant soil resource loss of clays and nutrients, and contributes to air pollution from dust. This study provides quantitative insights into the role of soil aggregation in wind erosion in a semi-arid region based on both field and laboratory experiments. The soil erosion was explored in natural soils and in areas subjected to various land uses, including agricultural fields, open areas, grazing plots, and road constructions. A boundary-layer wind tunnel was employed to simulate soil erosion and dust emissions. The results clearly demonstrate the impact of human-induced topsoil disturbances on soil aggregation and erosion. It reveals that soil erodibility under wind stress is primarily controlled by dry aggregate characteristics, aggregate size distribution (ASD) and aggregate density, rather than other soil properties. Substantial loss of fine-dust particles (clays and nutrients) was recorded under most experimental conditions due to aggregate disintegration during the erosion. Such reduction in ASD in response to wind erosion subsequently impacts the dust emission potential in future wind events. With increasing population growth, changes in land use, and the scenarios of climate change, soil erosion rates may rise, potentially triggering desertification processes in disturbed semi-arid soils.