| In the past 30 years, high intensive agricultural land use pattern has improved the land income and ensured the food security in China, while also causing serious environmental problems, making the high intensive agricultural area a high environmental risk area. In the next decade, the high intensive agricultural land use pattern will face with the increasing demands of grain production in China, as well as the challenges caused by gradual deterioration of ecological environment. It has been one of the main topics to discuss how to reduce excess investment and environmental risks under the condition of high input and output in the field of modern agricultural development and sustainable land utilization.From the perspective of land-use system, this study resolved the characteristics and migration of input-output in the process of intensive agricultural land use as well as the environmental problems. On this basis, this study built a theoretical framework of the sustainable land use system design, attempting to establish a sustainable land use model with less inputs, benign cycle and lower environmental risks, taking Qingpu district, Shanghai as a case study. The main conclusions are as follows:(1) Based on the theory of material flow tentatively, this study proposed a theoretical framework of the agricultural land use system. Taking dematerialization and low environmental risk as purpose, this study applied the material flow analysis (MFA) theory to build a material flow comprehensive regulation and design theory, illustrating the connotation of the theory, design principles, design content, design guidelines, design patterns, general graphs styles and design methods in details. The results indicate that it can be meet requirements, which need of lower input, a virtuous cycle system and low environmental risk, based on the theory of the material flow control and design.(2) Agricultural land use system analysis and the effect evaluationThis study conducted a comprehensive analysis of agricultural land use system in Qingpu District. First, the influence of various input factors to the agricultural output growth and the potential environmental hazard was analyzed. Then, the input-output efficiency of the agricultural land use processes and the environmental effects were assessed, from the aspects of Nitrogen footprints, grey water footprints, land use efficiency and environmental efficiency. On this basis, this study assessed the potentiality of dematerialization and reduction of environmental risk.The results indicate that: â‘ The order of agricultural output and input factors of Gray Correlation degree is:sowing area> fertilizer use> machinery gross power> pesticide input> labor input. The sowing area and fertilizer have a significant impact on agricultural output. Raising the efficiency of land use has become an important and main way to alleviate the shortage of arable land resources in Qingpu.â‘¡ Analysis of Nitrogen footprint and gray water footprint shows that there are significant spatio-temportal differences between the discharge of reactive nitrogen (Nr) and gray water footprint in Qingpu district. The agricultural land use pattern with high-level fertilizer has serious influence on the agricultural environment quality. The key to optimize and adjust the agricultural land use system in Qingpu includes optimization of land use structure, scientific models of nitrogen fertilizer and increasing investment in technology.â‘¢ According to the results of classic data envelopment analysis (DEA), the key aspects to promote the integrated efficiency of agricultural land use in Qingpu are the spatial variation and the fluctuation trend over time of land use integrated efficiency, the land use technical efficiency, the pure technical efficiency. While maintaining and pushing steadily forward the moderate scale management, Qingpu need to enhance the level of agricultural land use management, introduce and popularize agricultural measures, adopt new technology and strictly control the extensive and inefficient use of land to improve the pure technical efficiency.â‘£Combined with nitrogen footprint, Grey water footprint and the expected output of a slacks-based measure(SBM) model window analysis methods, this study built the dematerialization potentials and the reduction potentials of pollutant emission as well as the potential shrink size of the material and pollutant model. From 2006 to 2013, the annual average dematerialization potentials of labor, fertilizer and mechanical power are 32.21%,25.70%, and 38.21% respectively. Meanwhile, the annual reduction potential of grey water footprint and nitrogen pollution footprint are 32.18% and 12.32%. The annual average amount of potential reduction in labor is 8,104 people, fertilizer 4,501.59 tons, and mechanical power 27,928.44kw respectively. The potential total emission of grey water footprint is 520, 468,800 m3 and nitrogen pollution footprint 381.04 tons.(3) Optimization of household land use patternThis study, taking typical rice and wheat planting model as examples, applied TechnoGIN model to evaluate the economic and environmental effects of current household land use situation. By building the indicator system of Nitrogen efficiency and land use integrated benefits, this study determined the optimization plan and matching policies and management measures.Results show that proper scale managed land use system which applying site-specific nutrient management (SSNM) is a sustainable land use pattern in household scale with invest reduction and low environmental risk. Agricultural policy needs to increase subsidies for farmers with appropriate scales, in order to compensate for the high cost input of labor and resources.(4) Optimization of land use structure and space partition prevention-controlâ‘ In order to protect water resources and control non-point source pollution, a grey liner programming model was applied to optimize the land use structure of study area. The economic benefits of the comprehensive land use structure optimized scheme will be 46.13 billion yuan in 2020. The economic benefit will increase by 28.12%, at the same time the output of TN and TN will reduce by 169.08 t/a and 79.83 t/a, at a drop of 10.96%,41.33%, which effectively reduces the risk of a non-point source pollution compared to 2012. â‘¡Using minimum cumulative resistance (MCR) model, the regional space partition protection model was built. On the basis of the ecosystem service values and non-point source pollution output load of each land use type, this study constructed the resistance coefficients of different land use types. Then, this study put forward a series of measures such as delimiting water conservation areas, key protection area of water resources, the general non-point source pollution control area, medium non-point source pollution control area, and the core non-point source pollution control area. On the other hand, targeted measures were put forward based on different partitions, including land use quantity structure and space dimensions for the design and control of land-use system. It shows that regional zoning regulation mechanism based on water resource protection and non-point source pollution resistance control is one of the effective ways to deal with non-point source pollution migration and water resource protection.(5) Coupled integrating of sustainable agricultural land use mode in high intensive agricultural areaDynamics model of intensive agriculture ecology coupling system was established by using the material flow theory and system dynamics method. This study analyzed the material flow of grain, livestock and aquatic process quantitatively, and took nitrogen as an example to predict the future evolution of the trend, and further formulate the optimization control scheme by simulating natural, economic and social effects of nitrogen. In the baseline scenario, the agricultural productive capacity of Qingpu will fail to meet the needs of the local population for Nitrogen in the form of meat and aquatic products in 2020. In the optimized scenario, fertilizer Nitrogen inputs will decrease by 53.75%, and Nitrogen production can meet the consumption need of the local resident population while Nitrogen imports will fall by 2245.16 tons. In the optimized scenario, the integrated nitrogen cycle efficiency of system will increase to 25.54%. Furthermore, leaching and runoff analysis shows that the influence of land use system on aquatic environment will decrease. The coupled optimized scheme can better protect the ecology and environment from the impact of intensive agricultural production and guarantee of agricultural production at the same time. |
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