Gross nitrogen cycling processes and nitrous oxide emissions in cultivated and non-cultivated hummocky soil landscapes

为了确定加拿大大草原农业景观长期管理的最佳策略，我们需要提高我们对氮循环过程和控制它们的因素的理解。拟议的研究计划将探讨土地管理措施和农业和环境意义的N-循环过程之间的关系。重点将放在那些产生无机氮的过程上（即，矿化和硝化作用）和排放一氧化二氮的那些（即，反硝化和硝化）。一氧化二氮是一种温室气体，其全球变暖潜力是二氧化碳的300倍，在加拿大，农业占人类引起的一氧化二氮排放量的70%。特别需要提高对总氮生产过程的理解，总氮生产过程是指在给定的时间段内从有机氮库中产生的无机氮的总量，以及这些过程与氮排放过程的关系。到目前为止，已经有一些研究考虑总氮生产在景观尺度和未知的加拿大大草原。为了解决这一差距，氮循环知识，拟议的研究计划将比较氮的生产和一氧化二氮的排放量在萨斯喀彻温省的棕色，深棕色和黑色土壤区的耕地和非耕地利用。稳定的15 N同位素技术将用于（1）量化管理对总矿化和硝化速率的影响，在丘状耕作景观和（2）估计硝化和反硝化的相对重要性，一氧化二氮排放量。

To determine the best strategy for long-term management of agricultural landscapes in the Canadian Prairies, we need to improve our understanding of N-cycling processes and those factors controlling them. The proposed research program will examine the relationship between land management practices and N-cycling processes of agricultural and environmental significance. The emphasis will be on those processes that produce inorganic N (i.e., mineralization and nitrification) and those that emit nitrous oxide (i.e., denitrification and nitrification). Nitrous oxide is a greenhouse gas that has 300 times the global warming potential of carbon dioxide and in Canada, agriculture accounts for up to 70% of human-induced nitrous oxide emissions. There is particular need for improved understanding of gross N-producing processes, which refers to the total amount of inorganic N produced from the organic N pool in a given time period, and how these relate to N-emitting processes. To date there have been few studies considering gross N production at the landscape scale and none known of in the Canadian Prairies. To address this gap in N-cycling knowledge, the proposed research program will compare N production and nitrous oxide emissions under cultivated and non-cultivated land uses in the Brown, Dark Brown, and Black soil zones of Saskatchewan. Stable 15N isotope techniques will be used to (1) quantify management effects on gross mineralization and nitrification rates in hummocky till landscapes and (2) estimate the relative significance of nitrification and denitrification to nitrous oxide emissions.