Currently， cropland soils face the dual challenges of soil organic carbon （SOC） pool depletion and fertility decline under long-term intensive agricultural utilization. Accordingly， elucidating the functional mechanisms of soil biota and harnessing their biota-driven potential for carbon sequestration and fertility enhancement are of considerable practical significance for safeguarding food security and mitigating climate change.This paper first underscores the pivotal role of soil biological pathways in organic carbon accumulation， drawing on calibration studies of microbial necromass carbon conversion factors used in global-scale SOC pool assessments. Building on this， metagenomic analyses reveal that soil viruses-particularly lytic viruses rather than lysogenic viruses-make a pronounced contribution to soil multifunctionality by regulating key components of carbon cycling， including microbial necromass carbon， plant-derived carbon， microbial biomass carbon， and carbon use efficiency. Moreover， evidence from farmland management case studies indicates that the combined application of nitrogen fertilizer and straw can substantially promote SOC accumulation by reshaping viral and bacterial community structures and activating auxiliary metabolic genes， with bacteriophage-based bioregulation strategies showing promise as a novel route for enhancing carbon sequestration. With respect to biochar application， the paper further elucidates how biochar strengthens SOC sequestration by reconfiguring the trade-off between the “enzyme latch” and “iron gate” effects and by restructuring virus-bacteria interaction networks. Finally， integrating the above evidence， the paper explicitly proposes that “virus-bacteria interactions” constitute a key biological process for improving cropland fertility and achieving carbon sequestration， thereby identifying new directions for research on biologically driven SOC enhancement and fertility cultivation and opening broader prospects for the sustainable development of cultivated land.
