农田作物同化碳输入与周转的生物地球化学过程

作物同化碳在“大气-植物-土壤”系统中流通的生物地球化学过程,显著影响全球陆地生态系统碳循环过程。作物同化碳是土壤有机碳的重要来源,与根际环境及作物生长发育有密切联系,但由于其复杂性和多变性,作物生长期内同化碳在土壤中的分配、转化与稳定的机理尚不十分清楚。因此,综述了作物同化碳向土壤碳库输入及其对土壤有机碳库的贡献,在土壤碳库中的分配与转化特征,在土壤中流通的微生物机制以及同化碳在土壤-微生物系统分配、稳定的微观机制。探讨同化碳在地上部-根际-土壤系统中的分配及调节机制,土壤界面同化碳流动过程与土壤微生物多样性形成的关系;提出了在不同生态系统尺度上加强作物同化碳在土壤-作物系统中分配过程的定量研究对于明确陆地生态碳循环过程的重要意义;指出了研究作物同化碳向土壤碳库迁移、分配定量过程与机制的重要性,以及应用显微镜成像技术与同位素示踪技术相结合的纳米二次离子质谱技术、和微生物分子与群落生态相偶联的技术是未来研究作物同化碳生物地球化学特性的有效手段。

Biogeochemical processes underlying the input and turnover of crop assimilative carbon in farmland ecosystems

Crop assimilative carbon, which is an important part of the carbon cycle of the "atmosphere-plant-soil" system and also an important source of soil organic carbon, is closely linked to the rhizosphere environment and crop growth. However, because crop assimilative carbon is both complex and variable, the fate of this part of the carbon cycle is still poorly understood. The biogeochemical processes involved in the distribution, transformation, and stability of assimilative carbon significantly affect the carbon cycle in terrestrial ecosystems globally. In this study, we accordingly summarize the distribution, transformation, and stabilization mechanisms of crop assimilative carbon and its contribution to soil organic carbon; discuss the distribution and adjustment system of assimilative carbon in the rhizosphere-aboveground soil system; analyze the characteristics of microbe-assimilative carbon interactions; and explain the relationship between assimilative carbon and the establishment of soil microbial diversity. We propose focusing on the quantitative study of crop assimilative carbon, including its distribution within the soil-crop system in different ecosystems and on improving the understanding of carbon cycling processes in terrestrial ecosystems. We also highlight the importance of the mechanism of assimilative carbon transfer and distribution to the soil carbon pool. Finally, we describe how nanometer secondary ion mass spectrometry technology, combined with microscope imaging and isotope tracer technology, and a combination of molecular microbiology and community ecology techniques, can be effective means for studying the biogeochemical characteristics of crop assimilative carbon.