Using soil organic carbon isotope composition analysis to elucidate the carbon cycle of agroecosystems

Soil organic carbon is one of the most abundant and longest stored ecosystem carbon pools on the Earth’s surface. Improving soil organic carbon stability and enhancing soil carbon sink capacity have become a key scientific issue for sustainable strategies of carbon management in terrestrial ecosystems. There is an international consensus that agroecosystems are playing an increasingly important role in carbon sequestration and in the process of achieving carbon neutrality. Farmland management practices could disturb soil carbon cycle processes, and the carbon sink of agroecosystems can be enhanced by effective management practices. Currently, domestic studies have focused on the effects of tillage practices, fertilizer and irrigation levels, and straw incorporation on farm productivity, carbon sequestration rate, and greenhouse gas emissions; but the mechanisms of organic carbon stability in response to different farmland management practices and the relationship with soil carbon emissions have not been clearly understood. ¹³C isotope technology is a powerful tool for studying soil carbon cycling processes in agroecosystems. By measuring the isotopic abundance of different organic carbon components in soil carbon emissions, soil respiration components and sources can be accurately distinguished, which can better reveal the response mechanism of soil organic carbon stability to farmland management practices and provide a scientific basis for enhancing soil carbon sink effects and sustainable agricultural development. Most previous studies have focused on simulations and small-scale, short-term monitoring, with large discrepancies between results, which may overestimate or underestimate the actual values. Therefore, multi-point, long-term, and real-time in situ monitoring combined with ¹³C isotope technology should be adopted in future research on the soil carbon cycle to understand real-time decomposition of soil CO₂ emissions in agroecosystems, which can better reveal the mechanism of soil organic carbon stability.