奶牛粪尿储藏过程氨和甲烷协同减排调控机制

Manure storage was one the main emission source of ammonia and methane from livestock production, and halted the sustainable development of livestock production. Previous studies showed that, the diet manipulation of energy and protein content, covering storage were the promising ammonia mitigation options, and there were very small variations between different studies. However, the impacts on methane emission mitigation were small, with large variations and methane emission greatly increased. There were not many studies has revealed how the diet energy and protein manipulation and different cover storage system impacts both on the ammonia and methane emission, and why there were huge variations of ammonia and methane mitigation efficiency between different studies. This leads to a unbalance mitigation of ammonia and methane during manure storage. Here we use dairy cattle manure as an example to explore possible mechanisms to reduce the ammonia and methane simultaneously during the manure storage. Based on the indoor incubation experiment, the emission of ammonia and methane, the manure pH, oxygen content and micro-organisms will be measured by in situ and high accuracy greenhouse gases analyzer, pH and oxygen sensor and Real –time quantitative PCR. The dynamic emission of ammonia and methane will be identified under different diet manipulation, different type of manure and different type cover storage. The key parameters, such as pH, oxygen content and carbon and nitrogen compositions will be used to investigate the involved environmental and microbial driving mechanisms during ammonia and methane emission. The results will provide theoretical bases for reduction of ammonia and methane emission simultaneously during manure storage.

畜禽粪尿储藏过程是畜牧业氨和甲烷主要排放过程之一，制约了畜牧业可持续发展。研究表明，日粮粗蛋白水平调控及粪尿覆盖储藏等均可大幅度降低氨排放，且变异区间较小；但对甲烷减排效果较弱，且变异系数大，往往增加了甲烷排放。但是目前对日粮能氮水平调控和覆盖模式如何影响氨及甲烷排放，尤其是在不同形态粪尿和覆盖储藏模式下两者排放差异产生机制缺乏系统研究，难以实现两者协同减排。本项目以奶牛为例，以阐明粪尿储藏过程氨和甲烷协同减排调控机制为目标，依托室内模拟试验，运用高精度温室气体在线分析仪、pH及氧浓度探头和定量PCR等方法，动态测定粪尿储藏过程中氨和甲烷排放特征、畜禽理化性质和微生物群落结构变化，明确日粮能氮水平调控、粪尿形态变化、粪尿覆盖酸化类型对储藏过程氨和甲烷动态排放差异，应用粪尿理化性质和微生物群落结构变化阐明这些差异产生的机制，探明其中的环境调控与微生物驱动机制，探索氨和甲烷协同减排途径。

畜禽养殖及粪尿管理是我国重要的氨、氧化亚氮和甲烷等温室气体排放源，制约了畜牧业的可持续发展并影响碳中和目标的实现。关于氨和甲烷在圈舍、储藏和处理过程中的协同减排技术途径和机制目前还不清楚。本项目以畜禽粪尿管理过程为研究对象，以阐明氨、氧化亚氮和甲烷协同减排途径和机制为目标，重点研究了酸化、覆盖和低蛋白日粮等技术的综合减排效果及潜在影响机制，同时通过建模分析了技术应用的综合减排效果及成本效益，取得了以下结果：.1）揭示了圈舍-储藏链条氨减排措施对氨和甲烷排放的影响及机制，发现粪污储藏过程覆盖蛭石能同时降低氨挥发和甲烷排放，但增加了氧化亚氮排放；圈舍环节粪尿表面酸化叠加蛭石覆盖可进一步降低奶牛粪尿储藏期间氨挥发和甲烷排放。.2）弄清了酸化程度对粪尿处理过程氨、氧化亚氮及甲烷排放的影响及机制。酸化物料至pH6和pH5时，可减少堆肥过程29-68%氨挥发，并减少20%的甲烷排放。其影响机制主要在于影响了堆肥过程的温度变化、物料降解程度和对NH4+的硝化抑制作用，同时影响了产甲烷细菌的活性。.3）明确了奶牛养殖体系氨减排措施的成本效益，评估了我国奶牛养殖体系氨减排潜力。低蛋白日粮和圈舍表层酸化可分别减少106和144Gg氨排放，蛭石或乳酸酸化蛭石覆盖可减排65Gg氨排放。不同措施的减排成本范围为1-45 $/kg氨，其中以乳酸酸化蛭石覆盖粪尿混合物的成本最高。.4）评估了我国反刍动物体系甲烷减排潜力及气候中性发展路径。未来如果我国采用均衡膳食结构，并且针对反刍动物采用提高饲料消化率，降低精料比例或者添加植物油，以及在饲料中添加甲烷抑制剂、替代电子受体等技术，将甲烷排放减少约55%，可以促进畜禽养殖系统实现气候中性（零增温）目标。.项目执行期内在Nature Food、Innovation、ES&T、EP等环境科学领域发表标注论文9篇，其中SCI论文5篇，完成项目预期目标。项目负责人在执行期内晋升青年研究员并获批国家自然基金委优秀青年基金项目。