Assessment of Soil Fertility for Sugar Beet Production Using Fuzzy AHP Approach and GIS in the Northeastern region of Iran

Abstract

Assessment of soil fertility seems to be a crucial step in appropriate site-specific management for crop production especially for sugar beet cultivation in the Northeastern region of Iran. For preparing the soil fertility zonation map for sugar beet production, the most important soil chemical parameters and nutrient elements affecting soil fertility in 0–30 cm soil depth were analyzed and mapped. Implementing fuzzy analytical hierarchy process (AHP) approach, the S-shaped fuzzy membership function was defined for each factor to fuzzify soil fertility parameters. The soil fertility map was prepared by weighing factor layers through AHP approach, the summation of factor layers, and subsequently inverse distance weighted interpolation function in geographic information system. The values of soil fertility in the scale of 0–1 ranged from 0.13 to 0.39, classified the study area in low (1205.41 km2) and very low fertility (1366.59 km2), which comprises 46.9 and 53.1% of the surface area, respectively. It was revealed that there is a high correlation (R2 = 0.98) between soil fertility values and sugar beet yield area, which validate the zonation mapping of soil fertility in the study. With respect to the findings obtained in our study, the fuzzy AHP approach may clearly apply in similar regions in estimating soil fertility index for a specific crop.