Variations in soil aggregate stability due to land use changes from agricultural land on the Loess Plateau, China

摘要

Soil aggregate stability is a feasible and effective factor to understand the complex interactions between physicochemical properties and soil structure. To reveal the distributions of soil aggregate stability and its influential factors following land use change from apple orchards abandonment and development in the Nangou watershed of the Loess Plateau, China, this study selected five ages of apple orchards and their planting years were 1 year, 3 years, 6 years, 8 years and 10 years, one 15-year grassland developed from an apple orchard, one 15-year grassland developed from farmland, one natural grassland and one 15-year locust. Results showed that restored vegetation had better soil aggregate stability, soil organic carbon (SOC), and nitrogen (N) than apple orchards, and the composition of soil particles with the best aggregate stability was clay 6%, silt 8%, and sand 86%. At a 0-10 cm soil depth, soil aggregate stability had a significant positive correlation with SOC and soil total nitrogen (STN), and a negative correlation with NO3- and NH4+. In addition, vegetation diversity and coverage only affected the soil aggregate stability of the 0-10 cm soil depth; however, soil pH, bulk density, and soil aggregate-associated inorganic nitrogen were the main influential factors that drove the soil aggregate stability of the 0-30 cm soil depth. Further research discovered that macro-aggregate associated NO3- and micro-aggregate associated NH4+ may be the key factors affecting the soil aggregate stability. Therefore, it is essential to further explore the effect of soil aggregate-associated inorganic nitrogen on soil aggregate stability.