绿肥提升稻田土壤有机碳的作用机制

As rice production from the south China accounts for 80% of the country. Green manure application partially replaced chemical fertilizer has become the main approach for no increasing in chemical fertilizer and pesticide application, ensuring grain safety and soil fertility improvement. This study was carried out on a 8-year experiment in Yujiang County on paddy soil under double rice cropping system. In order to explore the mechanism of soil organic improvement with Chinese milk vetch application, the differences of soil organic carbon fractions variation, activities of carbon metabolic related soil enzymes, and the succession of functional micro-organism community of fallow-double rice and Chinese milk vetch-rice treatments with equal fertilizer application will be studied..Isotopic tracing technique will be used to trace the sequential order of 13C in different soil organic carbon fractions, and the abundance of 13C in aggregates with different size at different time. The research result is expected to identify the process of re-allocation of carbon derived from Chinese milk vetch and the regulating mechanism of microbial community composition and richness on soil organic carbon accumulation, which is of great significance in usage reduction of chemical fertilizer in rice field, energy-saving and emission-reduction, sustainable production in China.

我国南方稻田稻米产量占全国稻米总产量的80%以上。绿肥替代部分化肥还田已成为我国实现化肥农药零增长、保障我国粮食安全、提升稻田肥力水平的必由之路。本项拟前期8年定位试验的基础上，研究紫云英替代80%化肥条件下，冬闲-稻-稻和紫云英-稻-稻处理之间土壤有机碳周转过程中不同有机碳组分、土壤碳代谢相关酶活性、同期土壤微生物优势群落组成和数量的更替的差异，以期揭示紫云英碳提升土壤有机质的微生物学调控机制。同时，结合13C同位素示踪技术，监测13C在土壤各有机碳组分中出现的先后顺序及不同时期各粒径团聚体中13C丰度的变化，探明紫云英碳在土壤有机碳库中的周转过程，及其能够长期稳定存在并逐步积累的物理、生物学保护机制。试验结果有望揭示紫云英碳在稻田中的周转过程及在此过程中微生物的群落结构和多样性对稻田有机碳累积的调控机制。这对于我国稻田的化肥减量、节能减排及可持续生产意义重大。

南方稻区的稻米产量占全国的80%，是我国水稻的主产区。长期单一的种植模式和过量化学肥料施用引起的稻田土壤酸化、有机质含量下降、土壤可持续生产能力降低等问题已经成为南方稻田作物生长的主要限制因子。土壤有机碳是土壤肥力的核心和可持续农业的基础，提升稻田土壤有机碳含量，不仅可以提高稻田土壤pH和酸碱缓冲容量、提升稻田的养分供应能力，而且在保障粮食安全和减缓气候变化方面也具有重要意义。绿肥-双季稻/单季稻模式已成为我国南方稻区实现化肥零增长、兼顾粮食安全和土壤肥力提升的重要种植模式。本项目采用13C同位素示踪结合高通量测序技术，研究了绿肥-双季稻模式下绿肥碳在土壤中的周转过程，探明了绿肥腐解过程中土壤碳氮代谢关键酶、土壤团聚体组分、土壤微生物功能、结构和遗传多样性随时间的动态变化过程，最终揭示了绿肥碳在土壤中的再固定以及提升稻田土壤有机碳的作用机制。研究结果将为我国稻田土壤肥力提升，实现藏粮于地和藏粮于技战略提供理论依据。