Planting structure optimization based on agricultural non-point source pollution control in Three Gorges Reservoir Region

Abstract: Agricultural non-point source pollution has gradually become a major pollution source of lake eutrophication and deterioration of water quality in recent years. The Three Gorges Reservoir Region is both an important sensitive eco-economy area and a typical poverty-stricken mountain area. However, its unique geographical location, its irrational agricultural structure and its increasing serious agricultural non-point source pollution problems challenge the environment in this region. Hence, it is a necessity to take controlling agricultural non-point source pollution from the source as one of the most effective approaches. In current research, agricultural non-point source pollution control excessively depends on engineering and technology. Anyhow, the roles of agricultural planting structure adjustment and agricultural cleaner production which can reduce non-point source pollution should not be ignored. Promoting the adjustment of planting structure, reducing the use of chemical fertilizers and pesticides, and adopting agricultural cleaner production technologies not only help improve the land production capacity and agricultural products quality, but also effectively reduce the agricultural non-point source pollution. By these important measures for energy saving and emission reduction can be realized in Three Gorges Reservoir Region. Based on the dual goals of the optimal agricultural economic benefits and non-point source pollution emission reduction, the linear programming model was used to optimize the planting structure and clean agricultural production in the Three Gorges Reservoir Region. The optimization results showed that the optimal paths to maximize the crop net income were as follows: The land area for grain production should cover 119.16×104 hm2 but cleaner production area of rice-wheat, corn, soybean and tuber crops needs 31.91×104, 18.69×104, 6.79×104 and 19.55×104 hm2; the land area for vegetables planting should be 33.25×104 hm2 and its cleaner production area was 18.26×104 hm2; the total land area for tobacco, fruits and tea planting should be 17.05×104 hm2 and the cleaner production area was 2.65×104, 10.28×104 and 0.95×104 hm2. In the premise of stable grain production, the conventionally grown grain, corn and soybean planting area can be gradually reduced. Otherwise, the planting areas of tobacco, vegetables, fruits and tea can be appropriately increased. In the process of crops production, according to the present ecological agriculture construction, the clean production can be vigorously promoted. The soil testing and formulated fertilization areas for food production in rice, wheat, oil crops, corn and soybean must be expanded. The organic vegetable planting can be increased positively. If the construction of the vegetable greenhouse is strengthened, the farmers' household farming pattern will be affected, regulated, or transferred. Therefore, the losses of nitrogen and phosphorus in agricultural non-point source runoff can be decreased. The local government should encourage farmers to develop the sustainable agriculture and make them realize that if the agriculture nonpoint pollution can be mitigated, the greatest social welfare will be got in the Three Gorges Reservoir Region, which are the bilateral-won benefits. By this means, both the non-point source pollution can be controlled and the sustainable development of agricultural economy can be realized. Therefore, the optimization of various crops is important to control agricultural non-point source pollution. Space layout has played a decisive role in the process of the entire agricultural land system optimization. The economic and environmental comparative advantage of agricultural land can be achieved. The goal of total emission control of agricultural non-point can be achieved by reasonable structure adjustment and regional distribution of planting industry. Further research will be required to achieve the targets of controlling the total pollution emission.