Impact of Land Use Change on Soil Quality and Health in Volcanic Soils of Southern Chile

ABSTRACT Land use change (LUC) is a primary driver of environmental degradation, significantly impacting soil quality and health. This study evaluated the effects of LUC on volcanic soils in southern Chile, focusing on two soil orders, Andisols and Ultisols, under different land uses, including native forest, grassland, and cropland. Soil samples were collected and analyzed for physical, chemical, and biological indicators, and both soil quality indices (SQI) and soil health indices (SHI) were developed. Results showed that agricultural practices enhance chemical properties, such as pH and phosphorus availability, but often degrade biological properties, particularly in deeper soil horizons. In Andisols and Ultisols, cropland exhibited higher SQI values in surface horizons, while grassland showed moderate SQI improvements. However, the decline in biological properties like soil organic carbon (SOC) and microbial activity in deeper layers suggests long‐term risks to soil health. SHI values showed significant reductions, particularly in Valdivia (Andisol), where cropland and grassland exhibited relative changes of up to −200% compared to native forest values in deeper horizons, indicating degradation of soil health. These results highlight the importance of sustainable management practices that consider both surface and sub‐surface soil health to prevent degradation and ensure long‐term ecosystem functionality.