Agricultural management-driven soil inorganic carbon dynamics: Evidence from Chinese field experiments

Abstract

Soil inorganic carbon (SIC) is a crucial component of soil carbon pool, impacting climate change and ecosystem functions. SIC is affected by drastic changes in agricultural practices, while its response remains uncertain. We synthesized 54 field studies in China to assess the impact of agricultural practices on soil carbon stock, focusing on SIC and its responses to environmental factors. Overall, agricultural practices significantly reduced SIC stock (3.37 %) while increasing soil organic carbon (SOC) stock (15.41 %) and total carbon stock (6.80 %). Carbon pool changes could be categorized as follows: synergistic increases in SIC and SOC; trade-offs between SOC increases and SIC decreases; and individual effects on either SOC or SIC. SIC varied significantly across practices and regions, driven by climate, field management, and soil properties. Mineral fertilizer and straw return caused SIC losses, particularly under low-temperatures (MAT < 10 ℃), high-rainfall (MAP > 400 mm), and after 30 years. Severe SIC losses were observed in Northeast and East China. Combining organic and mineral fertilizers optimized the balance between SIC and crop yield, especially in arid regions. Key factors affecting SIC stock included soil depth, nitrogen addition, and experimental duration. Furthermore, our meta-analysis revealed that the distinct responses of SIC and SOC to agricultural practices underscored the necessity of integrated management strategies that effectively balanced SOC sequestration with SIC conservation. This study enhances understanding of SIC cycle and provides scientific evidence for sustainable agricultural practices.