Prediction of Soil Infiltration Rate From Soil Color Parameters in a Brown Forest Soil of Transitional Climate Zone

Aim of the study: Forest vegetation exerts a significant influence on the physical and chemical characteristics of brown forest soils in transitional climate zones. Among soil physical properties, the infiltration rate (IR) is a key indicator of soil-water interactions, hydrological functioning, and ecosystem stability. However, direct measurement of IR across large spatial extents is labor-intensive and time-consuming, necessitating the development of reliable prediction approaches. This study aimed to quantify the relationship between soil infiltration rate and soil color parameters (L*: lightness, a*: redness, b*: yellowness) to evaluate whether color information can serve as a practical proxy for estimating IR Area of study: The research was conducted on brown forest soils located within the transitional climate zone of Tosya District, Kastamonu Province, Türkiye. Material and method: Field infiltration tests were carried out at 30 sampling points, and soil samples were collected from 90 GPS-referenced locations at a depth of 0-30 cm. The study area is predominantly covered by black pine (Pinus nigra) and oak (Quercus spp.) stands. Soil samples were analyzed for organic matter, particle-size distribution (sand, silt, and clay), electrical conductivity, pH, and CaCO₃ content. Infiltration rate and bulk density were measured on undisturbed soil cores, while soil color was determined using a chromameter in the CIE Lab* color system Main results: Multiple linear regression (MLR) analysis revealed that the a* and b* color parameters were strong predictors of soil infiltration rate, together explaining 92% of its total variation. The results indicate that numerical color parameters can be effectively utilized to estimate IR, with a* and b* values providing greater predictive reliability than L*. The Durbin-Watson test confirmed the absence of significant multicollinearity among variables Research highlights: The developed MLR model demonstrated a strong relationship between soil color parameters and infiltration rate, explaining 92% of the observed variability. These results suggest that soil color measurements may provide useful information for estimating infiltration characteristics and for identifying areas with contrasting infiltration behavior in forest soils.