| Based on the theory of emergy analysis, this article investigates quantitatively the emergy flow of agricultural eco-economic systems in Jinghe river valley on Loess Plateau. The results indicate that the solar emergy input, the solar emergy output, the primary productivity and the un-renewable emergy are 3.36×1019sej, 3.07×1020sej, 5.04×1019sej and 6.35×1019sej, respectively. This region is now in the stage of transformation from traditional agriculture to modern agriculture. The agricultural eco-economic systems face some severe problems, such as low emergy input and emergy transformation efficiency, increased environmental loading ratio and production cost, and reduced emergy sustainability index, etc. Suitable measures should be taken to improve the productivity of agricultural eco-economic systems and to lessen the stress of ecological environment in Jinghe river valley. |