甘肃省典型农业生产系统温室气体排放评估及趋势预测

Ensuring food security and alleviating climate change have synchronously developed since western ecological civilization construction and ecological security mechanism in China were developed. Greenhouse gas emissions and mitigation strategies for regional agricultural production systems are not clear. The key factors for calculating greenhouse gas emissions from regional crops and livestock in Tibetan Plateau, Hexi Oasis, Loess Plateau and Longnan Hilly Area were collected from data and published literature based on the accumulated experience of applicant and team for 2-15 years in research site according to this important scientific propositions and urgent national needs. The model and factors of greenhouse gas emissions for crop and livestock products with typical agricultural production systems in Gansu Province is built by Greenhouse gas emissions measured from cropland soil about main local crops for typical agricultural production systems and methane emissions measured from main local livestock, life cycle carbon footprint, investigation from farmer, statistical yearbook, and IPCC. The temporal variations in recent 30 years on carbon emissions from regional crop production systems, livestock production systems and integrated crop-livestock production systems were studied. At the same time the study is to discover main factors of effecting carbon emissions from agricultural production, and the trend of greenhouse gas emissions from typical agricultural production systems in Gansu Province over the next 20 years. It provide the theoretical basis and technical guidance for evaluating the effect of carbon emissions from agricultural production systems in Western Province, the mechanism of ecological protection for developing and improving farmland, and food security.

我国西部开展生态文明建设和生态保护补助奖励机制以来，保障粮食安全和缓解气候变化同步发展，区域农业生产系统温室气体的排放量及发展趋势尚不清楚。本项目针对这一重要的科学命题和紧迫的地区需求，拟在青藏高原、河西走廊、黄土高原和陇南山地4个甘肃典型农业生态系统,利用申请者及学术集体在研究区2-15年工作积累，收集区域主要作物和家畜生产温室气体排放估算的关键参数,补充测定区域主要作物农田土壤温室气体排放和家畜胃肠道甲烷气体排放。运用生命周期碳足迹法，结合农户调查、统计年鉴和IPCC建立农畜产品温室气体排放估算模型，确定排放因子；揭示作物生产、家畜生产和作物-家畜综合生产系统近30年碳排放时空变化特征，探明影响区域农业生产碳排放的主要因素；预测未来20年甘肃省典型农业生产系统碳排放趋势。该研究为评估西部省份农业生产系统碳排放、发展和完善生态保护补助奖励机制、保障粮食安全等提供理论基础和技术参考。

本项目选择青藏高原、河西走廊、黄土高原和秦巴山区4个甘肃典型农业生产区域的主要作物和家畜为研究对象，结合项目研究内容和目标，全面完成了5个方面的工作：.（1）布点调查和持续跟踪了4个试验区30-50家农牧户作物和家畜生产情况，查阅和梳理国内外相似区域作物和家畜生产环节碳排放系数，运用碳足迹生命周期法建立了农产品、畜禽产品和作物-家畜综合农业生产系统碳排放估算模型，对甘肃省18种农产品6类畜禽产品温室气体排放因子进行了省域尺度的最新评估和差异性分析。.（2）基于农产品碳排放评估数据，研究表明在1991年至2016年期间，河西绿洲、陇东高原和秦巴山区的单位干物质土豆、油菜籽和玉米的温室气体排放有增加趋势，单位畜禽产品（含青藏高原畜禽产品）猪肉、牛肉、羊肉和单位价格农产品（作物+畜禽）温室气体排放有降低趋势。.（3）针对作物生产碳排放预测较为困难的实际问题，提出并建立了基于BP神经网络算法的作物生产碳排放预测模型，且BP神经网络算法预测性能要优于其它线性回归模型和非线性回归模型的预测性能。.（4）本研究开展了试验区主要农作物土壤温室气体排放日动态及月动态实测工作，且在河西灌区进行了春小麦、玉米和苜蓿3种作物的水氮耦合控制实验，研究发现生长季河西灌区作物地（春小麦、玉米、苜蓿）和陇东高原作物地（冬小麦、玉米、土豆）土壤均表现为CH4汇、CO2和N2O源，播种至收获期间，作物地土壤CH4吸收和CO2排放均呈现为先增加后降低的趋势，N2O排放先增加再降低，追施氮肥后，N2O排放升高，然后呈缓慢下降趋势。秦巴山区水稻地土壤CH4排放通量最大，小麦与玉米地土壤CH4呈现微弱吸收状态。.（5）本研究已取得反刍家畜胃肠道甲烷气体排放测定的初步成果。.本项目研究成果补充了IPCC数据库，为评估和预测干旱区农业生产温室气体排放量提供基础数据和重要参数。