District-Level Assessment of Agricultural Land Suitability in Erzurum Using the GIS-AHP Approach

This study evaluates biophysical agricultural land suitability across the twenty districts of Erzurum, the fourth-largest province of Türkiye by surface area, by integrating Geographic Information Systems (GIS) and the Analytic Hierarchy Process (AHP). Six environmental criteria were considered: land capability classification, slope, elevation, growing-season mean temperature, growing-season total precipitation, and distance to the stream network. To account for the province's complex topography, temperature was modeled using elevation-based regression, while precipitation was interpolated using the Inverse Distance Weighting (IDW) method. Criterion weights were derived from the aggregated judgments of twenty agricultural engineers, one from each district, and applied in a common province-wide weighted overlay model. The resulting suitability index was classified into five relative biophysical suitability classes using FAO (1976) terminology. The analysis classified 1.9% of Erzurum's area as highly suitable (S1), 6.2% as moderately suitable (S2), 22.3% as marginally suitable (S3), 14.9% as low suitability (N1), and 54.7% as very low suitability (N2). Higher suitability was concentrated in the Erzurum, Pasinler, and Horasan plains, whereas mountainous and high-plateau areas generally exhibited lower suitability. District-level statistics were derived from the common provincial suitability map to compare spatial differences among districts. The assessment is limited to biophysical conditions and does not incorporate irrigation infrastructure, existing agricultural practices, landholding characteristics, market accessibility, or economic feasibility. Accordingly, the results provide a basis for comparing potential biophysical suitability rather than a comprehensive assessment of agricultural investment or land-use decisions.