Geostatistical assessment and mapping of soil spatial variability in Sirumugai, Western Ghats

This study examines the spatial variability of soil properties and classifies the soil in the Sirumugai Reserved Forest range, located in the Western Ghats, India. A systematic soil survey and profile studies were conducted, using landforms as the basis for investigation within the study area. Horizon-wise soil samples were analysed for key soil parameters, including pH, electrical conductivity (EC), soil organic carbon, phosphorus, and potassium. The results revealed significant variations in soil properties across different locations, primarily influenced by elevation. The coefficient of variation for phosphorus was 0.87, while for potassium, it was 0.48. The analysis also encompassed assessments of skewness and kurtosis. pH (0.15) and phosphorus (0.75) exhibited kurtosis values close to 1, indicating relatively normal and flatter distributions. Conversely, sodium (27.10), elevation (3.91), and calcium demonstrated high kurtosis. Most soil properties were found to be right-skewed, while bulk density (0.09) was left-skewed. Geostatistical analysis in the Sirumugai Reserved Forest revealed considerable spatial variability in soil properties, particularly in EC and organic carbon. Elevation emerged as a strong influencing factor for soil properties, coupled with soil depth and nutrient leaching, which were prominent at higher altitudes. Ordinary kriging provided accurate spatial predictions, offering valuable insights for land management and conservation strategies tailored to the region.