GIS based evaluation of land suitability: A case study for major crops in Zanjan University region

The knowledge of land resources is an essential need, especially in developing countries, where resources are often scarce. To reduce the human influence on natural resources and to identify an appropriate land use, it is essential to carry out scientific land evaluations. A land suitability assessment was carried out in Zanjan University region for three major crops and apple orchards. In this area crops such as wheat, barley and maize take a special role in economical status of the area. For this study, a historical and a recent remote sensing-derived map was homogenized to increase accuracy. Also, GIS has been used to match the suitability for main crops based on the requirements of the crops and the quality and characteristics of land. Different land quality parameters, viz, soil texture, depth, erosion, slope, flooding and coarse fragments under various land units were evaluated for the crops. Only about 27% of the area was found to be highly suitable for wheat. The percentage of first class suitability of wheat was much higher than that of barley (13.9%). More than 90% of the total area was classified moderately suitable for maize. The present orchard area is not in accordance with the land qualities. Land units with severe limitations are due to organic matter (OM), gravel and carbonates. Implementation of this procedure should help achieve suitable use of land resources and prevent land degradation in the area. Hence, there is an urgent need for a good land suitability assessment so that the appropriate crops can be grown on these marginal areas of steep highlands. It was also found that with the help of GIS, it is easy to develop a framework for the optimum use of land area.