| Considering the unsustainability of modern intensive agriculture for economic return in the price of resources and environment, this dissertation aimed at assessing physical impacts induced by intensive farming and at evaluating the externality loss of a regional agriculture. To achieve these objectives, a case study was done on a typical cereal high-yielding region, Huantai County, North China. The research targets were to make a calculation tool for cost-benefit analysis of agricultural techniques and policies, as well as to provide methodology for green GDP accounting of agricultural regions.This research was systematically designed with focus on analyzing the dynamic budgets of water, carbon and nitrogen in agro-ecosystem. Theoretical analysis, environmental monitoring and surveys together with model simulations were integrated in order to fulfill the calculation of the environmental cost of agriculture. Different approaches were compared for sieving suitable ones for evaluating specific agriculture related environmental problems. Finally, a universal procedure was summed up to estimate environment cost of agriculture in the investigated region.Based on a large amount of first-hand and statistical data, full and accurate case study, the important output of the studies were concluded as the followings:(1) The budgets and cycles of water, carbon and nitrogen in the agro-ecosystem are the material bases for determining the physical impacts of agriculture and for evaluating the corresponding environmental cost. For the purpose of externality evaluation, the external impacts were divided into two types, viz. resource degradation loss and environmental pollution loss. By employing the theories of resource economics and environmental economics, the value of the agriculture related externalities were estimated. A method named Scarcity Value Increment method, Human Capital Approach, C-D Production Function as well as Benefit Transfer methods were adopted to valuate the cost and/or benefit of groundwater resource depletion, non-point source pollution, soil fertility changes and green house gas emission from farmland.(2) In the case study, three basic supporting database consisting natural, social-economic and model parameters were summarized to complete an evaluation. These databases were supposed to be organized in a four-layer-structure GIS format. A general procedure for environment evaluation composed of five steps, namely farming pattern classification, impacts sieving, physical impact quantification, monetization and aggregation. Based on these results, a framework was established for modeling, programming and computerizing environmental valuation for regional agriculture in the future. They can also be used as the algorithmic basis for software development of agricultural environment evaluation.(3) Concerning the exhausting extractable groundwater as a consequence of intensive agriculture, aScarcity Increment model was set up to describe the dynamic depletion. The surface analysis techniques by GIS were used to analyze the regionally spatial distribution of nitrogen pollution in the groundwater. It was discovered that nitrate pollution was unevenly distributed. It was assumed that some areas might have gradually developed into source area with nitrate outflow, while the others into catching areas receiving nitrate out flowing from the former. The spatial consistence between nitrate pollution distribution and groundwater isoiines probably indicated that the groundwater flow might dominate the regional pollution differentiation. This conclusion strongly supports that countermeasures considering watershed as an ecological unit are necessary in order to control agricultural induced non-point pollution.(4) The externalities of agriculture in Huantai County were evaluated by several approaches. In 2002, the total net externality loss amounted to 30.893 ~ 47.787 million yuan/a, equivalent to 1101.5-1703.9 yuan/hm2 annually. Among the externalities, water resources accounts the majority, 26.088~...
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