Assessing the effects of agricultural management practices and land-use changes on soil organic carbon stocks

Soil organic carbon (SOC) stocks have profound effects on climate change, sustainable agricultural development, and environmental management. Our objectives were to propose a conceptual framework and quantify the impact of land use change (LUC) and agricultural management practices (AMPs) on SOC stocks. By comparison, we choose the Kriging-based spatial prediction model to estimate SOC stocks based on the field sampled soil data (depth of 0-30 cm) in 2005 and 2019. Film mulching, drip irrigation, and fertilizer application were selected to represent the regional AMPs. Our results indicate that SOC stocks increased by 12.7% in the Sangong river basin from 2005 to 2019. From the proposed conceptual framework, we notice that the transition between different land-use types may cause both losses (e.g.,-9.49 Gg C caused by expansion of construction land) and gains (e.g., +3 Gg C caused by the conversion of cultivated land to grassland) of SOC storage. Benefiting from improved AMPs (e.g., film mulching, drip irrigation, and fertilizer application), the "stable cultivated land" category contributes the most (+36.0 Gg C) to the growth of SOC stocks.