| Danjiangkou Reservoir area is the water source of the Middle Route of South-to-North Water Transfer Project. Keeping water quality and quantity is strong safeguard for sustainable development of social economy of Beijing, Tianjin and north China area. According to the ecosystem service appraisal theory, the paper takes six counties' farmland that locate in Danjiangkou Reservoir surrounding as the objects of the study, uses methods of ecological economics, remote sensing, geographical information system and spot investigation, comprehensive evaluates positive and negative value of farmland ecosystem service in Danjiangkou Reservoir surrounding in 2008, and studies influence factors that lead to negative value of farmland ecosystem service. And the paper predicts the change of farmland ecosystem service value of Danjiangkou Reservoir surrounding in 2015 by scenario analysis on the basis of control suggestions of agriculture non-point pollution.Evaluation results on farmland ecosystem service value in 2008:(1) The positive and negative value of farmland ecosystem service in the study area are 4.722 billion RMB and 1.755 billion RMB respectively. The total value is 2.96 billion RMB that is positive value. The ratio of positive and negative value is 2.7:1. It indicates that losses of environment pollution are considerable figure by incorrect management and cultivation practices. People's benefit from farmland ecosystem is seriously threatened. (2) For the positive value of farmland ecosystem service in research region, contribution ratios of service value of product and raw material, carbon fixation and absorbing SO2, nutrient cycling and soil conservation are 81.9%,6.6%,5.2% and 3.3% respectively. The service value of decomposition dung and maintaining soil moisture is much low. It indicates that product economical value of farmland ecosystem is higher, but ecological value is lower. (3) For the negative value of farmland ecosystem service in research region, influence ratios of economic losing of livestock and poultry, fertilizer, soil erosion and greenhouse gases are 44.6%,26.8%,17.6% and 8.1% respectively. The economic losing of plastic film and pesticide are much low. It indicates that the main pollution factors for local environment are excretion quantity of livestock and poultry, application rate of fertilizer and soil erosion.Evaluation results on farmland ecosystem service value in 2015:(1) The results of comparison three agriculture production modes show that current agricultural production mode has a great destructive effect for environment protection, eco-agriculture production mode is able to keep economic development of local agriculture and reduce the risk of environment pollution to a certain extent. And the total value of farmland ecosystem service by organic agriculture management is biggest because negative value has been maximum reduced. Organic agriculture production mode is most beneficial to environment protection but there is limit economic losses for local agricultural benefit for several years. The paper considers that it is suitable for protecting water source with organic agricultural production mode. (2) Estimation on contribution value and economic loss for local agricultural development and environment protection with organic agriculture production mode:If the change of farmland area is not considered, economic value is decreased by 1.764 billion RMB in short-term, but ecological and water protection value of farmland ecosystem service are increased by 283 million RMB and 1.494 billion RMB respectively from 2015 to 2008. If decreasing farmland area is considered and farmers whose farmland has been inundated have been settled to other place, the loss of economic is 384 million RMB by organic agriculture production mode, and ecological and water protection value are increased by 358 million RMB and 1.323 billion RMB respectively. (3)The results of comparison value trends of every county show that farmland area is not a decisive factor for contribution ratio of service value. Xichuan county need to optimize agriculture planting structure and improve management mode. And its task is urgent in control of agriculture non-point pollution.Farmers'cognition and behavior and influence factors of agriculture non-point pollution in Danjiangkou Reservoir surrounding:(1) Agriculture non-point pollution in research region is mainly come from planting industry, breeding industry and rural life waste.The main pollution source is synthetic fertilizer, pesticide, excretion of livestock and poultry and rural life waste. Under the current agriculture production, problems appear that application rate of synthetic fertilizer and pesticide is higher, the ratio of residue film is higher, farmers rely on synthetic fertilizer and pesticide to have a security yield, most scale livestock and poultry directly discharge excretion because of lacking of matching treatment establishment, producing and living waste stack, and wastewater discharge. Influencing factors of agriculture non-point pollution are mainly related with local social development background, farmers' production management level and market management in production means. (2)Based on logistic regression analysis on influencing factors of individual characteristics and family characteristics to farmers' cognition degree on non-point pollution, results show that education level and political status of farmers are significantly positive correlation with cognition degree. Increasing education level and recruiting rural party members are beneficial to improve farmers' cognition degree on non-point pollution. There is disagreement comparing planting behavior at present between farmers with certain cognition and lower cognition. It indicated that farmers' consciousness and behavior are disjointed. Farmers' attention-degree for negative influence of large using of production means on agriculture production is higher that it on environment pollution capital. (3) The mode with source control and comprehensive management is effective for agriculture non-point pollution. Decreasing runoff and leaching of Nitrogen and Phosphorus from farmland and rural area must be a feasible way for pollution control by making limit agricultural production technology standard and organic production mode instead of extensive production mode during the water source protection area.
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