Fractionation and Distribution of Copper and Zinc in Calcareous Soils of Igarra, Nigeria

Abstract

The experiment was conducted to fractionate Cu and Zn into the exchangeable, carbonate, Fe- Mn Oxide, organic and residual fractions within 0-30, 30-60 and 60-90 cm soil depths of calcareous soils of Igarra. The results obtained indicated that mean concentration of copper was highest in the Fe/Mn oxide fraction (3.68 mg kg-1) followed by the carbonate (1.93 mg kg-1) and exchangeable fractions (1.28 mg kg-1) respectively. Hence, the distribution trend of Cu in the various fractions was in the order Fe/Mn oxide > carbonate > residual > organic. On the other hand, the amount of Zn increased with depth in the exchangeable fraction with a relatively high concentration of 9.13 mg Kg-1. However, the highest amount of Zn (12.15 mg Kg-1) was obtained in the Fe/Mn oxide fraction. Zn occurrence in other fractions decreased in the following order: Fe/Mn oxide fraction > organic > carbonate > exchangeable. The present assessment of the forms and distribution of Cu and Zn in the soil showed that higher concentration of these metals in the Fe/Mn oxide fraction suggest unavailability or low supply of these metals for possible plant uptake in the short term.