The use of a hybrid fuzzy-AHP system on the evaluation and mapping of soil fertility

Determination of soil fertility is very important to measure fertilization. Regardless of the level of soil fertility، the improper use of chemical fertilizers، not only the quantity and quality of agricultural products would not rise up، but also it makes imposed additional costs، disturb the balance of nutrients in the soil and environmental issues are also raised. Therefore، the assessment and mapping of soil fertility is essential. In this research، the fuzzy technique and the Analytic Hierarchy Process (AHP) were used for mapping soil fertility into Geographic Information System (GIS). The amount of available soil phosphorus and potassium، total nitrogen، soil organic carbon، pH and cation exchange capacity (CEC) obtained form 77 surface soil samples were used as the input data. In the first stage، the interpolation of data was done by Inverse Distance Weighting (IDW) model into GIS. Then a fuzzy membership function was defined for each factor according to Sys guideline. Finally، the map of soil fertility was prepared by using AHP technique into Expert Choice software with an inconsistency ratio of 0. 07. The results showed that soil organic carbon has the greatest impact on the soil fertility in the study area and for wheat cultivation، most area were classified into group of moderate suitable.