Effect of biosolids application on soil chemical properties and uptake of some heavy metals by Cercis siliquastrum

Abstract

The objective of this study is to investigate the effect of three kinds of biosolids usage on soil chemical properties and uptake of heavy metals by Cercis siliquastrum leaves. The experiment was carried out in a completely randomized block design with seven treatments including: no fertilizer as a control (C), sewage sludge (SW), cow manure (CM), municipal solid waste compost (MC), mixture of sewage sludge and cow manure (50% SW + 50% CM), mixture of sewage sludge and municipal solid waste compost (50% SW + 50% MC) and mixture of cow manure and municipal solid waste compost (50% CM + 50% MC) at three levels of 0, 2.5 and 5 kg/shrub and three replicates in calcareous sandy loam soil at the botanical garden of Mobarekeh steel company. After 180 days, soil samples were collected from 30 cm depth and leaves assemblage. Results showed that the treatments had significant effect (P < 0.05) on organic matter content, pH, electrical conductivity and cation exchange capacity of the soil. Total diethylen-triamine pent acetic acid (DTPA) extractable concentrations of Zn, Fe and Pb increased significantly (P < 0.05) in biosolid treatments. Between unwashed and washed metals concentrations of leaves, significant differences were shown, so it appeared that the source of metals on leaves was mainly airborn.

Key words: Biosolids, soil chemical properties, heavy metals, Cercis siliquastrum.