中国食物链养分流动与管理研究

为寻求食物生产与消费系统中粮食安全、资源高效和环境友好的协调和农业绿色发展途径,研究团队构建了"土壤-作物-畜牧-家庭-环境"(简称食物链系统)研究体系,运用物质流动和养分代谢理论方法创立了养分流动模型,深入研究了该系统养分流动规律及调控机理,经过近十多年系统研究,获得结果如下:(1)提出食物链养分流动金字塔概念模型,创建了食物链系统养分流动模型。通过分析养分在"土壤-作物-畜牧-家庭-环境"系统的行为特征,发现养分从"土壤-作物-畜牧"向"家庭"的流动呈金字塔状,其形状决定了系统生产力、养分效率和环境效应。处于金字塔顶端的"家庭"消费驱动了系统养分流动,决定了养分效率;"土壤-作物-畜牧"位于金字塔底层,支撑顶层"家庭"消费,决定了系统养分通量,也是养分调控的核心。在此基础上,开发了食物系统养分流动模型——UFER,构建了参数体系,实现了国家和区域尺度食物链氮磷流量、利用效率和环境排放的定量分析。(2)揭示了食物链系统氮磷养分流量、利用效率及其资源环境代价的时空变化特征。阐明了我国土壤-作物系统、农牧系统和整个食物链系统氮磷养分流量、养分效率和环境排放的时空分异特征;明确了土壤作物、畜牧和家庭各子系统对整个食物链养分环境排放的贡献;提出了食物氮(磷)代价概念,发现我国食物生产和消费的资源环境代价增速很快,已远远超过发达国家。(3)明确了食物链系统养分流动的驱动因素,阐明了提高养分效率和降低环境排放的调控机理。明确了决定食物链系统养分效率的关键环节,发现城镇化、食物结构变化和畜牧业发展是食物链养分流动加速的主要驱动因子;阐明了增加粮食和饲料进口、优化膳食结构和改善农牧业养分管理技术等对食物链系统优化的效应及作用机制。发现农牧结合和粪尿资源化利用是大幅度减少化肥需求和环境排放的关键途径,是实现农业绿色发展和食物链养分优化管理的重要突破口。

Nutrient flow and management in the food chain in China

In order to explore food security, high resources use efficiency and environmental friendly pathway for the coordinated and green developed agriculture in the food production and food consumption system, we constructed the "soil-crop-livestock-family-environment" ("food chain system" in short) research system. Using the material flow and metabolism theories, a nutrient flow model had been developed, and was used to evaluate the nutrient flow and control mechanisms of food chain system. After more than ten years systematic studies, the research team obtained the following main results:(1) Develop the pyramid framework for nutrient flow of the food chain, and the food chain nutrient flow model. By analyzing nutrients behavior in the "Soil-Crop-Livestock-Household-Environment" system, we found that the nutrient flow from "Soil-Crop-Livestock" to "Household" sector was in the shape of pyramid. The shape of pyramid determined the productivity, nutrient efficiency and environmental effects of the food chain system. The "Household" consumption at the top of pyramid was the driving force of nutrient flow in the whole food system, meanwhile, determined the nutrient efficiency of whole system. "Soil-Crop-Livestock" was located at the bottom of pyramid, supporting the "Household" consumption sector at the top. It determined the total nutrients flux and acted as the core of nutrients management. Based on this, the NUFER (NUtrient flows in Food chains, Environment and Resources use) was developed, the parameter set was build and quantification of nitrogen (N) and phosphorus (P) flows, use efficiencies and environmental emissions at the national and regional scales had been done. (2) Spatial and temporal analysis of N and P flows, use efficiencies and environmental costs in the food chain system. We quantified the spatial and temporal characteristics of N and P flows, efficiencies and environmental emissions in crop and animal production sector, and the whole food chain in China. We identified the contribution of nutrient losses form soil-crop system, livestock and human consumption. We also developed the concept of food N (P) cost and found that the resource and environmental costs of food production and consumption in China had increased rapidly, far exceeding the developed countries. (3) Identifying the driving forces of nutrient flow in the food chain and the options to improve nutrient efficiency and reduce environmental losses. The key sector that determined nutrient efficiency had been identified. Urbanization, diet changes and development of livestock production were the main driving forces of the accelerated nutrient flow in food chain system. We also explained the effects and mechanisms of increasing imports of food and feed, optimizing dietary and improving the nutrient management in agriculture production on improving food chain systems. We also found that the coupling of crop and livestock production, improving utilization of livestock manure was the key to reducing chemical fertilizer use and environmental losses, and was also the key for achieving green development of agriculture and sustainable food systems.