作物-生猪生产系统氮素养分流动特征和调控机制研究

Nitrogen (N) is an essential element to the growth of plant and animal, but is also associated with considerable environmental pollution. The total amount of N excreted by livestock in China is estimated to be 80% of chemical N fertilizer consumption. However, less than 40% of livestock N excretion is recycled to agricultural land, and the remaining fraction is lost during manure storage, handling and application to field, leading to a number of environmental problems. There is lack of understanding about the effects of manure management practices on flows and utilization of N in the crop-livestock system in China, and also lack of effective mitigation measures. This has hampered the development of programs to reduce livestock-related environmental problems and to increase the efficiency of N use in agricultural systems in China. The objectives of this research project are to evaluate flows and losses of N on pig farms with contrasting management practices, and to analyze the impacts of application methods on the use and losses N of different types of manure on agricultural land, based on experimental studies and modeling analysis. Moreover, a farm-scale model is aimed to be developed for analyzing the N flows in the crop-pig production systems, and consequently to explore the possible solutions to increase the N recycling and use efficiency and to lower manure N losses to the environment. The results from the project are essential to achieve the optimization of N management in the crop-pig production systems in China and to guide the future research in other crop-livestock systems.

氮素是动植物必需的营养元素，也是重要的环境污染因子。目前，我国畜禽氮排泄总量相当于化肥氮总量的80%，但还田利用率不足40%，其在粪尿管理和施用环节损失严重，引起一系列环境问题。由于我国在畜禽粪尿管理对农田-畜牧系统氮素循环与利用规律方面仍缺乏实证研究，更加没有形成系统有效的减排方案，直接阻碍了我国畜牧业环境污染治理和农牧系统养分高效利用目标的实现。因此，本研究以作物-生猪生产体系为例，通过跟踪监测、饲喂与田间试验和模型分析等手段，揭示不同管理水平下生猪养殖场的氮素流动特征；探明不同粪尿管理和施肥方式对猪粪肥农田氮素循环与利用规律的影响机理；在此基础上，构建具有我国作物-生猪生产体系特点的氮素流动模型，以此为技术手段，探索提高氮素养分循环与利用率、降低环境排放的实现途径。研究结果不仅对于我国作物-生猪生产体系氮优化管理具有重要理论和实践意义，也为其他农牧体系的研究提供重要的理论与方法。

氮素是动植物必需的营养元素，也是重要的环境污染因子。我国畜禽氮排泄总量相当于化肥氮总量的80%，但粪尿管理和施用环节损失严重，引起一系列环境问题。我国在畜禽粪尿管理对农田-畜牧系统氮素循环与利用规律方面仍缺乏实证研究，尚未形成系统有效的减排方案，阻碍了我国农牧系统养分高效利用目标的实现。因此，本研究以作物-生猪生产体系为例，定量了不同生长阶段生猪氮素吸收与氮排泄量，揭示了低蛋白日粮、高纤维日粮等饲喂调控技术对生猪氮素吸收、氮排泄与氨挥发的影响机制；解析了规模化猪场粪污储藏与处理方式（沼气发酵，固液分离，生物脱氮等）对粪尿氮素含量以及氮素循环的影响，定量了不同类型猪粪肥、不同有机无机配比下作物氮素利用效率与氨挥发特征；构建了农场尺度作物-生猪氮素流动评价模型与本地化模型参数库，发现了华北典型生猪养殖场之间氮素利用效率与氮平衡存在较大差异，揭示了饲料蛋白水平、粪尿储存方式、粪肥外售比例是影响农场氮平衡的关键因素，分析了低蛋白饲喂、粪尿覆盖储存与农田氮素平衡施肥等综合优化策略的氮素减排潜力，初步探索了不同管理策略情景下主要养殖规模生猪养殖氮足迹特征及其影响机制，上述研究为未来我国畜牧业粪污资源化利用和氮素环境减排策略制定提供了理论与技术指导。