Depthwise Distribution and Horizontal Movement of Cadmium and Nickel in Sewage-effluent-irrigated Soils and their Uptake by Vegetable Crops Grown Thereon Kumar Vipin*, Prasad R.K.1, Prasad B.2, Singh A.P. Department of Soil Science, Rajendra Agricultural University, Pusa, Samastipur, 848125, Bihar. *Corresponding author (Email: drvipinkumar@sify.com)
1Present address: Krishi Vigyan Kendra, Bikramganj, Rohtas, Bihar. 2C-13, Krishi Nagar, P.O.- Ashiana Nagar, Patna, Bihar. Abstract Continuous application of sewage-effluents on agricultural fields led to the accumulation of DTPA-Cd from 0.020 to 0.298 mg kg−1 and DTPA–Ni from 0.45 to 8.64 mg kg−1 in surface soil (0–15 cm). A very low amount of Cd and Ni was observed in 45–60 cm depth in comparison to surface soil (0–15 cm) in all the soils examined, indicating low mobility of these metals down the depth. The DTPA-extractable Cd and Ni contents of sewage-effluent-irrigated soils decreased with increasing soil depth and distance from sewage entry points. The soil organic carbon content in sewage-effluent-irrigated soils was positively and significantly correlated with DTPA-extractable-Cd (r=0.98**) and Ni (r=0.93**). Soil properties like pH, electrical conductivity (EC) and cation exchange capacity (CEC) exhibited positive relationship with DTPA-extractable Cd and Ni content in soil, while clay content showed negative impact on the extractability of these metals. The Cd and Ni contents in different crop species grown on sewage-irrigated soils were higher as compared to those grown on groundwater-irrigated soils. Continuous application of sewage effluents on to agricultural land increased Cd and Ni concentration in the soil which might have augmented the Cd (from 1.32 to 8.23 mg kg−1) and Ni content (from 8.16 to 35.03 mg kg−1) in different plant species. Although, vegetable crops grown on the sewage-effluents-irrigated soils around Patna city for many years in the past have elevated the contents of Cd and Ni in soil, no metal toxicity symptoms in plants were observed. Top Keywords Cadmium, movement, nickel, organic carbon, sewage effluents, vegetable crops. Top |