液态粪肥注射施用对华北平原“粮—饲”轮作体系温室效应的影响机制

North China Plain is an important grain and livestock production area of China, with high application rate of mineral N fertilizer and low recycling rate of manure, which has led to serious environmental problems, such as large GHG emissions. Research on the mechanisms and regulation methods of GHG emissions in different “grain—feed” crop rotation systems under manure application has scientific significances for optimizing the grain and livestock production system, increasing manure recycling rate and improving environmental effects. The experiments will be conducted by a split-plot design, where, the main plots will consist of wheat/maize rotation, ryegrass/Gaodan grass rotation, while the subplots will include liquid manure injection, solid manure deep application, mineral N fertilizer deep application and no fertilization. The GHG emissions will be studied by adopting the static chamber method combined with gas chromatography. The carbon balance characteristics in soil—crop systems are identified, and a comprehensive assessment is conducted for the net greenhouse effects in the whole life cycle of "food-feed" rotation systems. The results are expected to reveal the mechanisms of GHG emissions in different rotation systems under liquid manure injection, clarify the key controlling periods and strategies. Therefore, it can be used to guide the coordinating production of grain and livestock and the mitigation of GHG emissions in North China Plain.

华北平原是我国农牧主产区，农田矿物氮肥施用量过高，畜禽粪肥资源化利用率低，温室气体排放量大，造成了严重的环境危害。研究该区畜禽粪肥施用下“粮—饲”轮作系统温室气体排放的过程机制和调控方法，对优化农牧生产方式、提高畜禽粪肥资源化利用和改善环境具有重要意义。本项目拟按照裂区设计设置不同“粮—饲”轮作方式（小麦/玉米、黑麦草/高丹草）和施肥方式（液态粪肥注射施用、固态粪肥深翻、矿物氮肥深施和不施肥）组合，利用静态箱−气相色谱法，研究土壤温室气体排放规律，分析“土壤—作物”系统碳平衡特征，并对“粮—饲”轮作系统全生命周期净温室效应进行综合评估。研究结果将揭示液态粪肥注射施用对“粮—饲”轮作系统温室气体排放的影响机制，探讨温室气体减排的关键调控时期和调控策略，为指导华北平原农牧协调生产、降低温室气体排放提供科学依据。

华北平原是中国农牧主产区，其主导种植体系—玉米-小麦轮作体系—的作物高产主要依赖于水肥的过量投入，然而其畜禽粪肥资源化利用率低。由于缺乏自给自足的饲料来源和不能及时处理的畜禽粪尿，该区农业生产与畜牧业生产不匹配，且面临严重着资源和环境问题等方面的巨大挑战。本项目在不同“粮-饲”轮作体系下探讨固液粪肥替代化肥对系统氮素表观平衡、温室气体排放和潜在环境危害的影响。结果表明：1）综合考虑作物产量、氮素利用和环境效应，猪场肥水替代25%和50%尿素注射施用是该区玉米-小麦轮作农田猪场肥水最佳施用方式；2）以养殖产生的固态和液态粪肥替代50%化肥条件下，甜高粱-黑麦草和高丹草-黑麦草轮作是氮肥偏生产力高、表观损失低的轮作方式；3）在玉米-小麦轮作体系，固液粪肥替代化肥，特别是液态粪肥替代50%化肥，可降低温室气体排放；4）在各“粮-饲”轮作体系中，固液粪肥替代化肥均可在一定程度上降低温室气体排放，且甜高粱-黑麦草轮作体系降幅最大，其次为高丹草-黑麦草轮作体系降幅最大；5）固液粪肥替代化肥，特别是液态粪肥替代50%化肥，可增加经济效益，减少环境危害，提高生态效率；6）采用“粮-饲”轮作体系，如甜高粱-黑麦草和苏丹草-黑麦草轮作体系取代玉米-小麦轮作体系，利于农牧区牧草生产和农牧业的可持续生产。本研究为畜禽废弃物资源化利用、“粮-饲”轮作设计和环境变化适应等方面均提供了有价值的见解，利于我国粮食安全和农牧业的可持续生产。