A Simple Sequential Extraction Procedure for Evaluation of Zinc Behavior in Composts and Soil

Abstract

A simple sequential extraction was used for evaluation of the Zn behavior during twelve-week intensive composting and on compost application in two soils. The efficiency of Zn extraction from compost with 0.11 mol l⁻¹ acetic acid is higher than that with 0.01 mol l⁻¹ CaCl₂. Composting led to redistribution of exchangeable Zn jnto less available, mainly oxidizable and reducible fractions. The content of zinc extracted with 0.01 mol l⁻¹ CaCl₂ decreased in Fluvisol and Cambisol soils fertilized with compost. On the contrary, the zinc extracted with the acetic acid solution increased in a Fluvisol soil after compost application, despite the 70 % bonding of Zn in residual fraction. No significant change was found in compost-modified Cambisol.soil The results suggest that the sewage sludge compost can be safely used in soils containing zinc. The Zn content in compost and soil can be simply assessed by extraction.