长期保护性耕作对黄绵土有机质组分及土壤质量的影响机制

土壤有机质是评价土壤质量的重要指标。土壤有机质包括诸多物理组分、生物化学组分和生物学组分，不同组分对有机质和土壤质量的贡献各异。然而，在长期保护性耕作对黄绵土有机质组分的影响及机制还不够清楚，不同组分对土壤质量的影响也有待深入研究。为此，本研究拟在黄土高原丘陵沟壑区借助2001年建立的不同耕作措施（传统耕作、免耕秸秆覆盖、免耕、传统耕作秸秆翻埋）长期定位试验，采用大田试验、室内分析、多元分析相结合的方法，通过历年保存土样和本项目执行期土样各种有机质组分的分析，结合历年作物、土壤等方面的数据积累，研究（1）长期不同耕作措施下黄绵土有机质组分的演变规律；（2）耕作措施影响有机质变化的物理保护机制、土壤生物化学机制及生物学机制；（3）有机质组分对土壤质量的影响。以期从有机质组分角度探明黄土高原丘陵沟壑区长期保护性耕作影响黄绵土有机质和土壤质量变化的主要机制，为该区保护性耕作的推广应用提供理论依据

Soil organic matter is a very important soil quality indicator, it includes lots of physical, biochemical and biological fractions, different fractions contribute to soil organic matter and soil quality differenttly. However, long-term conservation tillage effects on soil organic matter fractions and its underline mechanisms is not clear, different fractions effect on soil quality remains a mystery. To this end, based on a long-term field experiment on different tillage practices (conventional tillage, no-tillage with stubble retention, no-tillage, conventional tillage with stubble incorporated) commenced in 2001 in hilly and gully areas on the Loess Plateau, using the integrated methods of field experiment, lab analysis and multivariate analysis, this project will analyse different soil organic matter fractions of historical soil samples and fresh samples within the project research, integrated with historical soil and crop data of the long-term experiment, to explore (1) evolution of soil organic matter fractions responses to long-term conservation tillage practices,(2)physical protect mechanisms, biochemical mechanisms and biological mechanisms of long-term conservation tillage practices effects on soil organic matter, and (3)soil organic matter fractions effect on soil quality. Aim to ascertain the main mechanisms of long-term conservation tillage effects on soil organic matter and quality of Loess soil in hilly and gully areas on the Loess Plateau from perspective of organic matter fractions, and thereby to provide theoritical base for the extention and adoption of conservation tillage in the research area.