Assessment the soil fertility classes for common bean (Phaseolus Vulgaris L.) production using fuzzy-analytic hierarchy process (AHP) method

This study was carried out to evaluate the capability of a combined fuzzy-analytic hierarchy process (AHP) method for soil fertility evaluation of common bean in Shiraz, Iran. A set of membership functions was constructed to represent the soil fertility classes, which were derived from 50 field samples collected through a purposive sampling approach. Seven soil parameters including phosphorus (P), potassium (K), iron (Fe), zinc (Zn), manganese (Mn) copper (Cu) and organic content (OC), of the soil were chosen for soil fertility analysis using inverse distance weighting (IDW) method and then fuzzy and AHP method were employed. The IDW showed that the south of the study area had the more P amount compared to the other area (Fig. a). In contrast, the Fe value was between 1.40 to 14.98 (mg/kg) where only some parts of northwest and southwest had the medium Fe value (about 8 mg/kg). The OC value of the study area was between 0.18 to 1.64% which all of the study area with OC more than 1% was suitable for bean production except the some parts of north and south. Fuzzy map showed that except the parts of northwest, all of the area was suitable for K that had the value close to 1. AHP model showed that the most important factor in soil fertility were P and OC of the soil with weights of 0.39 and 0.37, respectively. Fuzzy-AHP model showed that 52.38% of the study area had medium fertility for bean production and this method was a useful tool for prediction of soil fertility status in each case study. Received 4 Oct 2016; Revised 13 Oct 2016; Accepted 15 Feb 2017.