Spatial Variability of Soil Quality Under Diverse Land Use Systems in Tropical Coastal Environments: A Case Study from India

Abstract Soil quality is a key determinant of ecosystem functions and land sustainability in rapidly changing coastal regions. This study evaluated spatial variation in soil quality across five land-use types (agriculture, urban green spaces, built-up areas, mangroves, and barren land) in the Puducherry region of India. A total of 225 surface soil samples (0-20 cm) were collected and analyzed for fifteen physicochemical parameters. Principal component analysis (PCA) identified four key indicators: electrical conductivity (EC), organic carbon (OC), available nitrogen (Av. N), and manganese (Av. Mn). A weighted linear scoring system was used to compute the Soil Quality Index (SQI), and spatial interpolation was performed using ordinary kriging. SQI values ranged from 0.45 in built-up areas to 0.60 in mangroves, showing the order: mangroves > urban green spaces > agriculture > barren > built-up areas. Mangrove soils showed higher SQI due to greater organic carbon and nutrient content, while inland and built-up areas reflected lower quality linked to soil disturbance and reduced fertility. These findings highlight spatial patterns of soil degradation and provide a practical framework for improving land management in tropical coastal environments.