Ecological zoning of agricultural lands in Gorgan for sunflower cultivation

Geographic information system (GIS) and analytical hierarchy process (AHP) were applied to ecological zoning of current agricultural lands in Gorgan for sunflower cultivation. For this purpose, agro-ecological requirements of sunflower firstly, identified according to scientific resources. Rating and thematic requirement maps were then provided. Studied environmental-components were: average, minimum and maximum temperatures, precipitation, slope percent, elevation, slope aspects and soil characteristics (OM, pH, EC, texture, nitrogen, phosphorus, potassium, calcium, iron and zinc). Each layer is classified into 4 classes. The analytical hierarchy process (AHP) was used to determine the weight of criteria by using the questionnaires analysis sheet. The digital environmental layers overlaid and integration in GIS media then zoning of lands carried out in 4 classes (high suitable, suitable, less suitable and non-suitable). The results showed that 71.38% and 13.85% of these areas were high suitable and suitable for sunflower cropping, respectively. These zones had enough rainfall (>400 mm) and high fertility. Also, about 14.76% of present agricultural lands of Gorgan were not suitable for this crop and these areas had at least one limitation in ecological resources. The less suitable and non-suitable regions were located in the south of Gorgan township. Moreover, results showed that the limitation factors were including: high slope and EC, deficient of some elements such as N, K and Ca.