微润灌溉水肥管理对土壤N2O排放的影响机制研究

Water significantly affect soil nitrous oxide (N2O) emission by influencing soil nitrogen transformation, microbial activity, nitrification and denitrification process. Moistube irrigation, usually lead to a constant stability sate in time process and a non-uniform variation in spatial distribution of soil moisture dynamic, which determine that the N2O emissions should be greatly different from the traditional irrigation. In view of the characteristics of moistube irrigation, we hope to reveal the response of soil N2O emission to water dynamics and the difference among different spatial zones, by observing soil N2O emissions in different sub-regions under non-uniform wetting conditions of moistube irrigation, and combine with irrigation and fertilization, to research the temporal and spatial variation of soil N2O emission under different water and fertilizer management conditions, to reveal the influence mechanism of the regulation of water and fertilizer on soil water and nitrogen dynamics and N2O emission, to explore the water and fertilizer management strategy that with the potential of high efficient, emission reduction, high yield and high quality. The results will have an important theoretical significance for revealing farmland ecological effect of moistube irrigation and exploring the reduction of greenhouse gas emissions from the perspective of the regulation of irrigation and fertilization.

水分通过影响土壤氮素转化、微生物活性、硝化反硝化过程，显著影响土壤氧化亚氮（N2O）排放。“时间上近乎稳定、空间上非均匀分布”的微润灌溉土壤水分动态特征决定了其N2O排放与传统灌溉应该有着极大差别。针对微润灌溉这一特点，通过观测微润灌溉非均匀湿润条件下不同分区内土壤N2O排放变化，揭示土壤N2O排放对水分动态的响应及其不同空间分区间的差异，并结合灌溉施肥研究不同水肥管理条件下土壤N2O排放时空变化规律，揭示微润灌溉水肥调控对土壤水氮动态及N2O排放的作用机理，探求高效减排--高产优质的水肥管理策略。其研究结果对于揭示微润灌溉的温室气体排放效应，从灌溉施肥调控角度探索土壤温室气体减排具有重要的指导意义。

微润灌溉是随着近年来材料技术的革新而发展起来的一种局部灌溉技术，具有节水、节能、增产、改善作物品质与土壤环境等优势，是一种极具发展潜力的新型节水灌溉技术。但针对微润灌溉开展土壤N2O排放及其影响机制等方面的研究还鲜有报道。因此，本项目以负压微润灌溉“时间上近乎恒定、空间上非均匀分布”的水氮变化特征为切入点，从不同含水率的土壤分区内揭示了土壤N2O排放过程对水氮动态的响应，结合灌溉施肥研究了负压微润灌溉不同水肥管理条件下土壤N2O时空排放差异，并从土壤水氮动态--N2O排放响应关系角度阐明了负压微润灌溉水肥管理对土壤N2O排放的作用机制。研究结果对于从水肥调控角度探索负压微润灌溉的土壤温室气体减排具有重要的指导意义。