Comparative analysis of soil physicochemical properties and chromium content in sewage and tubewell water-irrigated fields: A study in Malerkotla and Mandi Gobindgarh, Punjab

Surface (0-15 cm) and sub-surface (15-30 cm) soil samples were collected from fields irrigated with sewage water and tube well water at ten sites each in Malerkotla and Mandi Gobindgarh towns of Punjab. The samples were analyzed for physicochemical properties, DTPA-Cr, and total Cr contents. In Malerkotla, the pH of sewage water-irrigated fields was lower (mean value of 8.14 in the surface and 8.12 in the sub-surface layer) compared to tube well water-irrigated fields (mean value of 8.18 in the surface and 8.29 in the sub-surface layer). In Mandi Gobindgarh, the pH of sewage water-irrigated fields was even lower, with mean values of 7.99 in the surface and 8.08 in the sub-surface soil, while the mean pH of tube well water-irrigated surface soil was 8.17 and 8.29 in the sub-surface soil, decreasing with depth. The electrical conductivity and organic carbon content of sewage water-irrigated soils were observed to be higher in Mandi Gobindgarh compared to Malerkotla. The calcium carbonate content was 1.04% higher in tube well-irrigated soils of Malerkotla compared to Mandi Gobindgarh. The cation exchange capacity of Mandi Gobindgarh was 1.69 times higher than that of Malerkotla. The mean DTPA-Cr in both soils was higher in Malerkotla compared to Mandi Gobindgarh, but the total Cr content was 1.14% higher in Malerkotla. Correlation coefficients of DTPA-Cr and total Cr contents with soil properties showed that organic carbon, pH, calcium carbonate, and clay contents were significantly correlated with DTPA-Cr. Partial regression analysis revealed that pH, organic carbon, cation exchange capacity, silt, and calcium carbonate content significantly explained the variability in DTPA-Cr and total Cr contents.