Land suitability evaluation for irrigating wheat by Geopedological approach and Geographic Information System: A case study of Qazvin plain, Iran

Land evaluation, using a scientific method, is essential to recognize the potential and limitation of a given land for specific use in terms of its suitability, and certifies its sustainable use. The soil is such a source that its renewal takes a long time, so effective use of soil and land resources requires a thorough understanding of the effective morphological processes of soil forming in different regions. The current study identified available soil in the area in terms of interpretation of aerial photographs and Geopedological approach. After mapping the geoform area, 61 profiles of the designated area were drilled and sampling was done for all diagnostic horizons. Then, the samples were transported to the laboratory for Physico-chemical analysis. By the end of the profile classification process, which was based on the Soil Survey Staff (2014) , the soil map, was prepared by integration of the soil data and the geoform map in ArcGIS software. There are several limiting factors for wheat in Qazvin plain, namely; electric conductivity (EC), gypsum, coarse fragment, soil depth, soil organic carbon (SOC), texture, calcium carbonate and climate. The map of the land units was prepared, and land requirements for the type of utility were calculated. Land suitability evaluation was performed according to FAO. The results showed that land unit’s number 17 and 18 were unsuitable (N1) for irrigating wheat with limiting factors such as; high levels of EC and gypsum in the studied profiles. Moreover, the land unit’s number 10, 20, and 23 are suitable (S 1 ) for the wheat production and have the highest rate of predicted yield.