The influence of trigger events on bursts of soil microbial metabolism and N2O production and consumption

气候驱动土壤中发生的生物过程，但在农业氮管理中却很少被描述和考虑。这是由于土壤氮循环过程的数量和复杂性。在这一建议中，我们研究了气候触发因素（冻土融化和干土湿润）在刺激微生物活动爆发和造成土壤N损失中的作用。具体而言，本工作侧重于基质有效性对无机氮过程的影响，无机氮过程控制硝化和反硝化在产生N2O排放中的时间和相对重要性。我的假设是，环境事件通过微生物细胞裂解和土壤有机质的溶解而释放底物来触发微生物代谢。此外，受土壤温度和含水量影响的微生物代谢作用于这些基质的速率，以及碳和氮分布的结构，决定了反硝化的位置、强度和产物，从而决定了N2O的排放。

Climate drives the biological processes occurring in soil yet is a poorly described and seldom considered part of nitrogen management in agriculture. This is due to the number and complexity of processes involved in the soil N cycle. In this proposal we examine the role of climatic triggers (thawing of frozen soil and wetting of dry soil) in stimulating bursts of microbial activity and causing soil N losses. Specifically this work focuses on the influence substrate availability on inorganic nitrogen processes that control the timing and relative importance of nitrification and denitrification in producing N2O emissions. My hypothesis is that environmental events trigger microbial metabolism through the release of substrates as a result of microbial cell-lysis and solubilization of soil organic matter. Further, it is the rate at which microbial metabolism acts on these substrates, as influenced by soil temperature and water content, and the architecture of carbon and nitrogen distribution which determines the location, intensity, and products of denitrification and therefore N2O emissions.