摘要
摘要:华北平原是我国重要粮食生产基地，农业生产中，片面追求高产，过量施肥现象普遍存在，由此造成了肥料利用率低下，氮素损失严重，对环境造成了巨大压力，影响到本区域农业经济和生态环境的可持续发展。本文对中国科学院栾城农业生态系统试验站建站以来有关农田氮素过程方面的研究成果进行了梳理，从相关长期定位试验介绍、氮素转化研究方法的创新集成、氮素过程通量与转化机制研究、氮素综合管理与调控等方面入手，全面汇总了有关华北平原农田生态系统氮素过程及其环境效应的研究进展。自建站以来先后建立了8组与氮素有关的长期定位试验，基于此开展了土壤培肥与高产高效、养分循环再利用、农田生态过程及其对人为干扰和环境变化响应和反馈效应等方面的试验研究。研究过程中不断对研究方法进行完善与创新，建立了N₂高背景浓度下原位土壤反硝化研究的方法体系，为土壤反硝化室内机理与原位无扰动反硝化脱氮总量及产物构成规律研究提供了新的方法；量化了乙炔抑制法测定反硝化的系统误差，为克服乙炔抑制法的误差提供了新的技术途径；建立了深层土壤剖面气体监测的技术体系，使N₂O的研究由单纯的农田排放通量测定扩展到深层土体N₂O的产生机制、扩散与还原过程研究，为定量深层土壤产生的N₂O对表层排放的贡献提供了技术支撑。通过对农田氮素转化机制、过程通量及其环境效应的综合研究，分析了该区域农田生态系统氮素平衡状况，定量评价了农田氮素不同损失途径的相对重要性，提出了阻控氮损失、提高肥料利用率的合理调控途径。
关键词:氮素过程/
反硝化/
氨挥发/
硝态氮淋失/
环境效应/
农田生态系统/
华北平原
Abstract:The North China Plain is one of the most important bases for grain production. In the present agricultural production, farmers apply excessive fertilizer for high yield. Therefore, fertilizer use efficiency has become very low and environmental pollution as a result of it has also become more and more serious. The sustainable development of local agricultural economy and ecological environment has been greatly threatened. This paper reported our research findings on nitrogen processes in agro-ecosystems based on long-term (since 1978) fertilizer field experiment in Luancheng Agro-Ecosystem Experimental Station of Chinese Academy of Sciences. Nitrogen processes and the related environmental effects on the agro-ecosystem in the North China Plain were analyzed. This included nitrogen transformation characteristics in soil-plant systems, nitrogen fluxes and their transformation mechanisms, comprehensive nitrogen management and regulation, etc. Eight long-term field experiments related to nitrogen addition to the soil were conducted since 1978. Based on the field experiments, improvements in soil fertility, high production and high efficiency, recycled nutrient applications, agro-ecological processes and response mechanisms and feedback to climate change were studied. The research methods for nitrogen processes were fairly improved and innovated. Based on in situ observation system of soil denitrification in high nitrogen background concentrations, the mechanisms of soil denitrification in indoor incubations, total quantity of nitrogen removal in situ denitrification and production compositions were also studied and quantified. Meanwhile, system errors of denitrification rate measured by acetylene inhibition method were quantified. Furthermore, soil gas determination techniques in deep soil profile were established. Therefore, the mechanisms of N₂O production/consumption at the soil-atmosphere interface were expanded into the deep soil profile. The depth-dependent contribution of N₂O flux in the soil profile to soil surface gas exchange was quantified based on studies on N₂O production mechanisms, diffusion and reduction processes in the subsoil. The state of nitrogen balance in agro-ecosystem in the region was estimated based on studies on nitrogen conversion mechanisms, nitrogen fluxes and the related environmental effects. Different ways of nitrogen loss in agro-ecosystem were compared and the prefer approaches for controlling nitrogen loss and increasing fertilizer use efficiency put forward.
Key words:Nitrogen process/
Denitrification/
Ammonia volatilization/
Nitrate leaching/
Environmental effect/
Agro-ecosystem/
North China Plain



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