绿洲农田长期施用绿肥的土壤C、N过程及机制

Application of green manure is one of important components for sustainable agricultural operation. Green manure application can improve soil fertility, reduce soil pollution, accelerate soil nitrogen cycling and carbon storage capacity, and thus, improve crop quality. A deep understanding concerning the impact of green manure application on soil carbon and nitrogen processes is of importance for sustainable agriculture development. In this study, we use a long-term fertilization experiment established in an oasis farmland in Hexi Corridor region in 1988 to analysis soil carbon and nitrogen dynamics and processes including input ,transformation and use under different fertilization measures( green manure alone, chemical fertilizer, and green manure+chemical fertilizer). In addition, the project is to discuss soil organic carbon transformation and stability through analysis soil microbiological biomass C and N, particle organic C,light organic C fractions under green manure application, and to identify the impact of green manure application on soil aggregation stability and its physical protection to organic C and N. Furthermore, The project is to reveal the biological mechanisms of soil C and N retention under long-term green manure application through analysis soil enzyme activities and microbial population changes.The objective of this project is to identify soil C and N dynaimcs and soil quliaty evolution under long-term green manure application and, in turn,to provide scientific basis for soil management of soil fertilty retention and inprovement in oasis farmland ecological system.

施用绿肥可提高土壤肥力和农作物质量，减轻环境污染，促进土壤氮素循环和碳的储存，是生态农业的重要组成。深入研究长期施用绿肥的土壤C、N过程及机制对可持续农业发展具有重要意义。本项目利用1988年在河西绿洲农田设置的长期肥料定位试验，研究绿洲灌漠土长期施用绿肥、化肥和施用绿肥减少化肥投入下，土壤C、N的输入、转化、吸收、利用过程及动态变化规律；通过分析土壤微生物生物量C、N及不同年限土壤颗粒有机C、轻组有机C等活性组分揭示长期施用绿肥和化肥下碳库的转化和有机C稳定性；分析长期施用绿肥对土壤团聚体形成和稳定性的作用及其对有机C和N的物理保护机制；并通过土壤酶活性和微生物群落特征的研究解析长期施用绿肥对土壤C、N影响的生物学机制。从长期不同施肥措施对土壤有机碳、氮素的动态演变过程及维持和积累机制方面揭示绿洲高产农田的土壤质量演变，为绿洲农田生态系统土壤肥力维持和提升的土壤管理提供依据。