稻田生态系统氮素转化经济价值研究

根据2002年上海奉贤县五四农场田间实验数据，结合相关研究结果对稻田氮素输入和输出进行研究，并运用生态经济学和环境经济学方法计算稻田生态系统氮素转化的经济价值.结果表明，当季不施氮肥的处理小区氮素收支出现赤字；而施加氮肥的处理小区氮素收支都出现盈余.不施氮处理小区单位面积稻田提供的氮素转化综合价值为正；而施加氮肥的小区其氮素转化的综合价值都为负.施氮处理小区氮素转化的负价值主要是由于过量氮肥导致田间氮素以氨挥发、渗漏和径流方式损失造成.

Economic values of nitrogen transformation in rice field ecosystems

Based on the 2002 field experimental results in the Wusi Farm of Fengxian County in Shanghai and related studies,and by the methods of ecological economy and environmental economy,this article examined and estimated the nitrogen input and output,and the economic values of nitrogen transformation in rice field ecosystems.The results indicated that the plot without N fertilization showed a deficit of nitrogen budget,while those with urea application showed a surplus.The economic value of the plot without urea amendment was evaluated to be positive,while that of the plots with urea application was calculated to be negative.The negative value of the plots with urea amendment resulted from the nitrogen losses through ammonia volatilization,nitrogen leaching and runoff,which had serious harmful impacts on environment and human society.Therefore,only when some measures were taken to encourage and facilitate farmers to improve the efficiency of urea application and to mitigate the environment problems from N losses in the process of food production,the advantages of nitrogen transformation in rice fields could be promoted,and the sustainability of agriculture would become reality.