Competition for N in forest soils: stabilization of organic N in recalcitrant pools

本项目的总体目标是阐明土壤有机氮（SON）的主要竞争性稳定和不稳定过程。我们之前的研究结果表明，有机矿物化合物的结合是研究小组所研究的土壤中N稳定的主要过程。这将通过参加在图特林根东北和西南斜坡进行的短期和长期小型渗湿仪实验以及正在进行的15N凋落物标记实验来实现。定量数据将产生的氮转移到非微生物，顽固的有机物质池，因此，主要的长期稳定过程的相关性，通过有机结合的形成。同时，试验提供了气候变化条件对原位SON稳定过程的响应信息。物理土壤分馏方案将对有机-矿物组合中稳定的氮量提供定量评价。总的来说，我们将通过考虑土壤中顽固性有机氮库的形成和缓慢周转，特别是有机矿物氮，提供植物，微生物和土壤之间对氮的竞争信息。

The overall objective of this project is to elucidate the major competitive stabilization and destabilization processes of soil organic nitrogen (SON). Our results from the previous research show that the association in organo-mineral compounds is the major process for N stabilization in Rendzina soils investigated by the research group. This will be achieved by participating in the joined short- and long-term mini-lysimeter experiments at the NE and SW slope of Tuttlingen as well as the ongoing 15N litter labelling experiment. Quantitative data will be generated on the N transferred to non-microbial, recalcitrant organic matter pools and thus, the relevance of major long-term stabilization processes via formation of organomineral associations. At the same time, the experiments provide information on responses of climate change conditions on in situ SON stabilization processes. The physical soil fractionation scheme will provide a quantitative evaluation of the amount of N stabilized in organo-mineral associations. Overall, we will provide information on the competition for N between plants, microorganisms and soil by taking into account the formation and slow turnover of recalcitrant organic N pools, especially the organo-mineral N in soil.