Towards realistic assessment of cultivated land quality in an ecologically fragile environment: A satellite imagery-based approach

It is very difficult to realistically assess cultivated land quality (CLQ) because its contributing factors cannot be accurately quantified. This study aims at overcoming this difficulty by using information objectively derivable from ETM+ and SPOT images for Hengshan County, Northwest China. This objective approach is able to yield a comprehensive CLQ assessment using five proposed indicators. They are slope gradient, proportion of sandy land, water availability, soil fertility, and land use types organized into three indices of pressure resistance, land state, and land use response. Therefore, this assessment takes into consideration topographic setting, land degradation risk, moisture, vegetation growing condition, and land use response of farmers. The developed CLQ is found to be significantly correlated with the spatial distribution of water resources, suggesting that water availability is a decisive factor influencing land productivity. CLQ is also correlated closely with rural economic level, agricultural infrastructure investment, and the farming system. The whole County was further classified into three cultivated land use zones based on the calculated CLQ value. Each zone is best used for different purposes and requires different strategies of protection. Such assessment outcomes are essential for the prevention of land degradation and adjustment of agricultural structure to promote sustainable use of cultivated land. (C) 2009 Elsevier Ltd. All rights reserved.