Effects of Soil Erosion on Nutrient Loss under Different Land Use Types in the Central Yunnan Plateau

Purpose To study the patterns of soil and water loss under different land use types in the central Yunnan Plateau, and to reveal the effects of soil erosion on nutrient loss under different land use types.

Methods Using the entropy weight method and TOPSIS method, data of soil and water loss and soil nutrients from forest land, orchard land, barren grassland, farmland, and bare land in the Dachun River watershed of Jinning District, Kunming City, Yunnan Province, from 2018 to 2020 were analyzed to determine the effects of soil erosion on nutrient loss under different land use types.

Results There were significant differences in sediment yield, runoff volume, runoff depth, and runoff coefficient among forest land, orchard land, farmland, and bare land (P<0.05). From July to September, surface runoff and sediment yield were high, with higher runoff volume, sediment yield, runoff depth, and runoff coefficient than in other months. The comprehensive ranking of land use types for water and soil conservation was orchard land, forest land, barren grassland, farmland, and bare land, with fit degree of 0.606 0, 0.533 0, 0.456 0, 0.370 0, and 0.368 0, respectively. Soil nutrient loss was minimal in orchard land and forest land, while bare land experienced the most severe soil and nutrient loss. Different land use types were extremely significantly correlated with organic matter, nitrate nitrogen, ammonium nitrogen, bulk density, moisture content, runoff volume, sediment yield, runoff depth, and runoff coefficient (P<0.01).

Conclusion Land use type and rainfall are the main factors affecting soil and water loss, with soil erosion being the primary factor influencing soil nutrient levels.