Urbanization Impact on Soil Quality Assessment in Semi-Arid Region: Bangalore Metropolitan City, India

Soil quality degradation is a recent concern of climate change effects in semi-arid regions of India. Soil degradation is a major threat in developing cities; hence the assessment of soil quality plays a key role in evaluating urbanization's impact on soil quality. Thus, a study was carried out to address the selection of the most suitable soil quality indicators to determine the current status of soil quality in Bangalore. Around 248 geo-referenced surface soil samples were collected from rural, peri-urban, and urban areas and exposed to several physical, chemical, and biological properties to assess the soil quality. Selective parameters were subjected to principal component analysis (PCA), which screened out the three principal components (PCs), with an eigenvalue of > 1, and explained 57.2% of the variance in the data set using varimax rotation. The results indicated that a soil quality index (SQI) was computed using four key indicators, viz. pH, dehydrogenase activity (DHA), available potassium (K2O), and electrical conductivity (EC). In rural, peri-urban, and urban soils, dehydrogenase activity contributed the most to soil quality (59.69, 51.71, & 47.88%) > pH (20.41, 21.87, & 29.30%) > available K2O (14.93, 15.86, & 14.72%) > EC (4.97, 10.56, & 8.11%). The soil quality index recorded in rural soil was very high (0.61), moderate in peri-urban soil (0.52), and low in urban soil (0.44). The results revealed that the evaluation of the soil quality index is the best to understand the soil quality for sustainable agriculture practices.