Soil N dynamics as affected by different land use in Western and Southern China

该研究项目的目的是量化中国西部和南部土壤氮素的储量和周转，这取决于土壤结构和土地利用。在具有区域具体土地利用和退化状况的代表性地点确定关键土壤特性。调查将遵循天然林、耕地和牧场土壤的土地利用梯度，后者考虑不同的退化和恢复状况。实际和潜在的土壤氮周转将横向量化，并与土壤结构和土地利用的影响。除矿物氮外，还将检测使用物理和化学提取的初步有机氮化合物。调查的参数是，除了总C和N库存和分布，总和净N矿化，硝化作用，微生物生物量C和N和微生物呼吸和土壤N周转指标，如活性N库和有机质的轻组分。在最后阶段，将确定土壤微生物群落的结构，并将其与氮状况和效率的指标相关联。研究活动将与杨凌大学水土保持研究所（黄土）和中国科学院南京土壤研究所（红壤）密切合作。

The aim of the research project is to quantify the stocks and turnover of soil nitrogen in Western and Southern China as dependent from soil structure and land use. Key soil characteristics are determined at representative sites with regional specific land use and degradation status. The investigations will follow a land use gradient of natural forests, arable and pasture soils, the latter ones considering different degradation and rehabilitation status. The actual and potential soil nitrogen turnover will be horizon-wise quantified and related to soil structure and land use impacts. Beside mineral nitrogen, also preliminary organic N compounds using physical and chemical extraction will be detected. Parameters for the investigations are, beside total C and N stocks and distribution, gross and net N mineralization, nitrification, microbial biomass C and N and microbial respiration and indicators for soil N turnover like active N pools and light fraction of organic matter. In the last phase the structure of the soil microbial microbial community will be determined and related to indicators of nitrogen status and efficiency. The research activities will be carried out in close co-operation with the Institute for Soil and Water Conservation/ Yangling University at loess soils and the Nanjing Institute for Soil Science/ Chinese Academy for Science in Nanjing at red soil sites.