小麦蚕豆间作体系的土壤氮矿化特征——地下部的贡献

根系及根际淀积与土壤氮矿化过程密切相关。小麦蚕豆间作能改变地下部根系及根际过程、提高土壤氮有效性。但地下部根系及根际淀积对间作土壤氮矿化过程的影响、贡献及作用机制有待明确。基于间作田间定位试验，研究以地下部根系和根际淀积为主线，将田间原位培养、田间根系埋袋、15N田间标记-室内培养相结合，利用Illumina HiSeq和13C—NMR技术，1）研究单间作根系的还田量、分解特性及根际氮淀积量，定量间作体系地下部对土壤氮库的贡献；2）分析单间作土壤氮库的差异及有机氮矿化的周年动态、探究根系及根际淀积下的土壤氮矿化差异，揭示间作体系根系及根际淀积对土壤氮矿化过程的调控作用；3）探明单间作条件下根际微生态环境（微生物群落结构、碳库特征、胞外酶活性）的差异，解析间作体系根土互作驱动土壤氮矿化的机制。研究对全面理解豆科禾本科间作节约氮肥、调控土壤养分循环、提高土壤地力具有重要的理论和现实意义。

Root and rhizodeposition are closely related to soil nitrogen (N) mineralization process. Wheat and faba bean intercropping could change root biomass, root architecture and rhizodeposition, which induced increased soil N availability. However, the effects of root and rhizodeposition on intercropping soil N mineralization have not been well understood. Additionally, the belowground contribution to intercropping enhanced soil N availability and its underline mechanism are unknown. Hence, based on the several years field experiments of wheat and faba bean intercropping, the present study would be focus on below-ground root and rhizodeposition in intercropping through several experiments involving in situ field inoculation, root barrier in field and labeling with 15N in situ field-laboratory inoculation, and some key methods and techniques including Illumina HiSeq and solid 13C—NMR would be used. The mainly targets of present study are, 1), to study the amounts of root litter returned to field, the characteristic of root litter decomposition, and the N rhizodeposition under mono- and intercropping system. The contrition of root and rhizodeposition to soil N pool will be identified. 2), to analyze the difference of soil N pool between mono- and intercropped system and dynamic soil N mineralization. The regulation role of root litter and rhizodeposition on soil N mineralization will be measured. 3), to discuss the rhizosphere micro-ecological difference including rhizosphere microbial community, carbon (C) pool, and soil extracellular enzyme activity between mono- and intercropped system, and the mechanism of root-soil interaction in modulating soil N mineralization in wheat and faba bean intercropping will be revealed. The research is of scientific and practical importance not only for comprehensive understands cereal and legume intercropping saving N fertilizer, but also for intercropping regulating soil nutrients cycle and enhancing soil fertility.