Based-on Emergy Analysis Of Forewarning System Of Farmland In Xi'an

Land is the space and environment where the mankind survives and develops. As population increases and social economy develops rapidly, the use range expands, the use degree and intensity becomes deeper constantly. It is of significance to study the sustainability of land use and sustainability level in order to predict the developing direction and take measure to solve the problem between people and land.The emergy input-output and emergy-based indices of farmland in Xi'an from 1996 to 2006 are studied through the emergy analysis in order to dynamically evaluate and identity the farmland sustainability. Therefore, analyzing the driving factors affecting farmland use change and establishing forewarning system of Xi'an farmland with ARMA model are utilized to forewarn the land use.The stations of all factors comprehensively functioning and self-functioning are gained. Then the approaches to realizing the farm- land sustainability are presented.Based on the analysis above, the thesis gets the next several conclusions.(1)m this paper, by incorporating the emergy indicator system and indicator system of sustainable land use we develop some emergy - based indices and ratios from three aspects of economy, society and ecology such as emergy net profit, the net emergy yield ratio,environmental loading ratio,emergy density,emergy self-sufficiency and emergy-based sustainable index.(2)Analysis on the emergy of farmland sustainability in Xi'an shows that the emergy input of farmland is increasing. Industrial emergy input which is 70.3% in total emergy input such as chemical fertilizer is the most important for agriculture in Xi'an. Machine input takes 13.7%, while human power input takes 24.8%.It indicates that agriculture in xi'an is still belong to conventional agriculture frame. Stockfeeding in Xi'an develops slowly. Economic benefit of farmland in xi'an is increasing gradually,but resource using is some of close;The pattern of farmland use which deteriorate environment easily brings the huge environmental pressures. The farmland use in Xi'an is sustainable in the aspects of social acceptability and economical viability, but it is at the low level in the resource protection and ecological security.(3)In a short time, the main driving factors are population, economic development, policy,technology and urban level.Population growth is the direct reason for land resource use and exploitation.Economic advantage driving is the deep reason for farmland's rapid reducing.(4) Predicting results of xi'an farmland forewarning system show that, inner farmland use adjusting and ratio of farm to total agriculture output value keep decreasing. Farm will be in the condition of passive benefit and income difference between urban and country may expand.