Phototoxicity assessment of green amaranth (Amaranthus viridis Linn.) grown on soil amended with sewage sludge

Abstract

Sewage Sludge (SS) land application remains the best sustainable disposal method. The present study evaluated SS samples tested on Amaranthus viridis Linn for phytotoxic effects. The soil and SS samples were analysed for Organic Matter (OM), N, P and K contents; exchangeable cations: Na, Ca and Mg using standard methods. Application of the SS followed Nrequirement of the test plant in a completely randomised design with three replicates. Plant growth parameters measured for phytotoxicity test were germination, stem diameters, number of leaves and height. The shoot of the plant was analysed for Cr, Zn, Cu, Cd and Pb using Atomic Absorption Spectrophotometer (AAS). Data collected were analysed for simple descriptive and inferential statistics. Range of results for analysed parameters in SS samples before treatments were OM = 384.20 ± 12.40 to 576.50 ± 3.00 g kg-1, N = 9.10 ± 0.53 to 19.60 ± 0.53 g kg-1, P = 11.98 ± 0.95 to 22.74 ± 0.65 mg kg-1, K = 5.13 ± 1.39 to 10.26 ± 0.25 cmol kg-1. The plant had steady growth parameters. Most of the analysed metals were below detection limits in the shoot except for Zn that ranged from 1.43 ± 0.23 to 3.88 ± 0.30 mg kg-1. The SS amended soil exhibited no phytotoxic effects on plant growth.