Spatial assessment of soil quality under different land use and land cover patterns in a micro-catchment of the Central Black Sea Region, Türkiye

Soil quality is a key indicator of sustainable land management because it reflects the capacity of soil to perform essential physical, chemical, and biological functions. This study aimed to evaluate the spatial variability of soil quality under different land use and land cover types within a micro-catchment located in Bafra District, Samsun Province, in the Central Black Sea Region of Türkiye. The study area includes forest, pasture, hazelnut orchards, and cultivated agricultural lands under semi-humid ecological conditions. A total of 27 soil indicators representing physical, chemical, biological, and fertility-related properties were used to assess soil quality. Surface soil samples (0–30 cm) were collected from 62 sampling points distributed across the study area. Soil quality indicators were grouped under four main criteria and weighted using the Analytic Hierarchy Process (AHP). Linear and non-linear Standard Scoring Functions (SSF) were then applied to normalize the indicator values and calculate linear and non-linear soil quality indices (L-SQI and NL-SQI). Spatial distribution maps of both indices were produced in a GIS environment using geostatistical interpolation methods. The results showed that the spatial patterns of L-SQI and NL-SQI were highly similar across the study area. Low soil quality values were mainly concentrated in the eastern parts of the micro-catchment, whereas relatively higher soil quality values were observed in the northern and southern parts. Forested areas generally exhibited higher soil quality, while hazelnut-dominated areas were associated with relatively lower soil quality values. The findings demonstrate that integrating AHP, SSF, geostatistics, and GIS provides an effective framework for evaluating and mapping soil quality under different land use systems and can support sustainable land management decisions in regions with similar ecological conditions.