| This article systematically evaluates the input-output condition,work efficiency and environmental loading ratio of the Agro-ecosystem in the Northeast of China on the basis of energy theory.It is shown that large part of man-made energy flow such as chemical fertilizers have been inputted to the Agro-ecosystem.The index of sustainability of the three provinces Hei,Ji,Liao,are 1.31,0.94 and 0.70,respectively,indicating that the Agro-ecosystem in this area runs well and is sustainable with a higher energy yield ratio and lower environmental loading ratio.Because of the highest energy investment ratio and environmental loading ratio,Liaoning has the lowest sustainable index,while Heilongjiang has the highest.From the perspective of energy analysis,high quality energy investments such as science should be increased to improve the quality of the farm products and the people here should conserve their resource and utilize it efficiently to keep it sustainable. |