根际激发效应与农田黑土团聚体周转过程的关系

The rhizosphere priming effect is one of the key mechanisms in plant-soil interactions, which has the potential to drive both rhizosphere processes and SOM dynamics. Results from laboratory experiments have clearly indicated that the rhizosphere priming effect has the potential to substantially control and influence transformations and cycles of soil carbon and nitrogen. The rhizosphere priming effect is also influenced by soil factors. It has been hypothesized that soil aggregate turnover regulates the rhizosphere priming effect by stabilizing or activating SOM in the rhizosphere. However, understanding and quantifying the rhizosphere priming effect under field conditions remains difficult and methodologically challenging. What is the actual magnitude of aggregates turnover and the priming effect under field conditions? What is the relationship between aggregate turnover and the rhizosphere priming effect? These are the key questions that this project aims to address. We will be the first to systematically investigate soil aggregates turnover and the rhizosphere priming effect in field ecosystems. We plan to quantify the rhizosphere priming effect and aggregates turnover by combining a unique natural 13C tracer method with a rare earth oxides tracer method. The results of these experiments will allow us to develop empirical equations that describe the quantitative relationships between the rhizosphere priming effect and soil aggregates turnover rate. We anticipate to make major progresses in mechanistic understanding of rhizosphere processes and to provide relevant information for properly managing the black soil resource.

根际激发效应是植物与土壤相互作用的一个关键机理，既是根际过程和土壤有机质动态的关键组分和驱动力，又可以大幅度控制和影响土壤碳氮的转化与循环。土壤是影响根际激发效应的重要因素。部分结果推测，土壤团聚体周转通过调控土壤有机质的固持和释放来影响根际激发效应的方向和强度。然而，目前仍不清楚野外条件下团聚体周转与根际激发效应的幅度分别是多大？二者的定量化关系怎样？这严重束缚了我们对根际激发效应影响机制及其重要性的认识。为回答上述问题，本项目分别采用稀土氧化物示踪法和天然13C同位素示踪法来量化农田黑土团聚体周转和根际激发效应，探明野外条件下根际激发效应对农田黑土碳释放的影响，解析根际激发效应与团聚体周转及微生物活性和胞外酶活性等因子的关系。预期结果将为土壤碳氮循环模型提供参数，为农田黑土的有效管理提供科学依据。