Effect of Manures and Vermicompost on Zinc Release Kinetics in a Calcareous Soil Grown Ocimum Basilicum L.

Abstract

Desorption of zinc (Zn) from soil is important to determine the bioavailability and toxicity Zn in soil. The objective of this study was to evaluate the effect of organic compounds [cow (CM) and sheep manures (SM) and vermicompost (V)] on Zn desorption from a cultivated calcareous soil and determine the best models for description of the Zn release. Zinc release (using DTPA for 20–1440 minute at 25 ± 2°C) in soil amended with 2% CM, SM, and V were investigated in a completely randomized design with three replications. Basil (Ocimum Basilicum L.) seeds were cultivated in each pot for 90 days. Seven kinetic models were evaluated to describe the rate of Zn desorption in soil after basil harvesting. Results showed that Zn release from soil samples increased with increasing of time. Zinc release was rapid at first and then became slower until equilibrium was approached. Cumulative Zn desorption in organic compounds amended soils especially vermicompost was higher than unamended soil and simple Elovich and two-constant rate were the best equations to description of Zn release from studied soils.