Effect of Humic Substances on Cu bioavailabity in soils of cacao growing areas of Southwestern Nigeria.

摘要

Soils of cacao growing areas in Nigeria are exposed to annual spraying of Cu fungicides to curb black pod disease of cacao caused by phytophthora palmivora thus making accumulation of Cu in the soil inevitable. A study was carried out to evaluate the effect of humic substances on Cu bioavailabilty in soils of cacao growing areas of Southwestern Nigeria. Soil samples from 25 sites and their corresponding adjacent plots were randomly collected from major cacao producing states (Ondo, Ekiti and Osun States) of Southwestern Nigeria. Significant effect was observed in total humified carbon (HA + FA), % HA and available Cu. The FTIR result indicated that COOH and OH of HA from cacao plantation dominated the exchange site and this allows for chelation of Cu by humic substances thereby reducing the concentration of copper in soils under cacao plantations, thus, ensuring healthy environment.