Impact of various types of irrigation waters on carbon sequestration and accumulation of heavy metal in vegetables

One of the major addressable issues in modern agriculture is the environmental pollution and health security caused by city sewage water being used for irrigation. Untreated water coming from household as well as industries is used for growing vegetables mostly in the peri-urban areas. Present study aims to evaluate the impact of various types of irrigation water on carbon sequestration, heavy metal accumulation in soil as well as in vegetables. A field trial with three vegetables (carrot, pea and radish) irrigated with three types of water (canal, tube well and city sewage) was conducted in Sheikhupura under RCBD with split plot arrangement keeping vegetables in sub plot and water in main plot. Each treatment was replicated thrice. Physicochemical indices (bulk density, water infiltration. saturated hydraulic conductivity and soil organic carbon) with major crop nutrients (N, P and K) were analyzed using standard procedures. Results indicated higher bulk density in tube well water and canal water irrigated plots than sewage water. Water infiltration, saturated hydraulic conductivity and soil organic carbon were higher with sewage water and canal water but lower with the tube well water. The values of N, P and K under different depths 0-10 cm, 10-20 cm and 20-30 cm were recorded. The values of N and P were higher with sewage water and canal water but lower with tube well water. The values of K were higher with sewage water and with canal water but lower with the tube well water. Plant and soil samples were analyzed for Zn and Pb using DTPA method in soil and wet digestion method in plants. In soil the concentration of Zn and Pb was higher with sewage water and tube well water than with the canal water. In plants the concentration of Zn and Pb was higher with sewage water and canal water but lower with tube well water. Data was analyzed statistically using standard procedures and treatment means were compared using LSD at 5% level of significance.