Sustainable Utilization of Agricultural Land in Chengdu Metropolitan Area Based on Emergy Analysis

[Objectives] This study aimed to analyze the sustainable use of agricultural land in the Chengdu metropolitan area from 2006 to 2016. [Methods] Using Odum's emergy theory, an index system was constructed to evaluate the sustainable use of agricultural land, including total emergy input-output ratio, industrial emergy input-output ratio, environmental load index and sustainable use index of agricultural land based on emergy, to reflect the sustainable use of agricultural land in the Chengdu metropolitan area. The data base was a unified standard that was converted from various types of energy stored and flowing in the agricultural land system of the Chengdu metropolitan area, that is, emergy. [Results] From 2006 to 2016, the total emergy input-output ratio of agricultural land in the metropolitan area fluctuated and decreased, lower than the national average. The industrial emergy input-output ratio was generally in a fluctuating downward trend. The environmental load index of agricultural land in the metropolitan area was lower than the national average. However, it has been on the rise since 2012. During the corresponding period, the sustainable use index of the region also showed a downward trend. [Conclusions] The utilization rate of emergy in this area was low. The dependence of industrial emergy input-output ratio on industrial subsidiary energy and the degree of agricultural mechanization are constantly improving. The environmental resources in this area still have room for accommodation and have not been fully utilized. The sustainable use of agricultural land has been declining.