Assessing the health of agricultural land with emergy analysis and fuzzy logic in the major grain-producing region

Agricultural land is a complex system that combines natural ecology and social economy, and the health of agricultural land directly influences regional economic development and national food security. Emergy analysis is an effective method for value analysis of ecosystems, assessment of the health of ecosystems, which is based on principles of systems ecology and energy. And fuzzy logic is a generalization tools to operate with vaguely defined parameters or concepts, which has been extensively applied in the quality evaluation of soil and land. The health of agricultural land as an aggregate that takes into account the quality and productivity of land as well as the soil environment. This paper presents an integrated evaluation model based on emergy analysis and fuzzy logic and using the geographic information system (GIS) to evaluate the health of agricultural land. An evaluation system is developed, which includes quality, productivity and the soil environment. A major grain-producing region in the North China Plain, namely Luancheng County, was selected for the case study. Field survey, household inquiry, sampling, and experimental analysis were conducted in the study area. The health of agricultural land expressed as the emergy index ranged from 0.471 to 0.763; as the fuzzy index, from 0.603 to 0.878; and as a composite index, from 0.284 to 0.666. Based on the composite index, the agricultural land was divided into four classes, namely in perfect health (which accounted for 7.6% of the agricultural land), in normal health (54.3%), in sub-health (32.9%), and in poor health (5.2%). Overall, agricultural land in Luancheng County is healthy, although 89.00km² of the farmland – mainly in Douyu, Nangao, and Liulintun – is in sub-health and 14.22km² in Douyu is in poor health because of poor productivity and unfavorable soil environment.