Enhancing soil organic carbon stabilization by coupling microbial-mineral carbon pumps in agroecosystem

Prioritizing the enhancement of soil organic carbon (SOC) stabilization is essential for increasing its stocks. Limited understanding of how SOC becomes stable makes it difficult to predict its changes under future climate conditions. The soil microbial carbon pump (MCP) and mineral carbon pump (MnCP) play critical roles in regulating the SOC stabilization process. Our study reveals that the coupling of MCP and MnCP, where both pumps work synergistically for SOC stabilization, dominates the processes of SOC stabilization, contributing between 10.3 % and 14.9 % to stable SOC pool. Soil total phosphorus and total potassium are key factors in improving MCP and MnCP efficacy, respectively. Soil viruses regulate the MCP efficacy by primarily altering microbial biomass and necromass through lysis, rather than by changing the microbial community structure. Maintaining lower levels of soil viruses is beneficial for enhancing SOC stabilization, as both excessively high and low viral loads accelerate the mineralization of organic carbon. The combination of no-tillage and straw mulch at medium nitrogen rate can enhance SOC stabilization by coupling MCP-MnCP. Our findings conclude that the key to enhancing soil organic carbon stabilization in agroecosystems is to facilitate the coupling of microbial and mineral carbon pumps. Key process and factor for enhancing soil organic carbon stabilization in agroecosystem. The green, blue, and peach lines indicate the processes contributing to the stable SOC pool by particulate organic carbon, MnCP, and MCP, respectively. Pathways marked with + are key processes to enhancing agricultural soil organic carbon stabilization. • The MCP-MnCP coupling dominates SOC stabilization (10.3–14.9 % contribution). • Soil total phosphorus and total potassium are key factors in improving MCP and MnCP efficacy. • Soil viruses modulate MCP efficacy via microbial biomass-necromass ratio shifts. • No-tillage combined with straw mulch at medium nitrogen rate enhances SOC stabilization.