Relationship between soil test methods and uptake of copper and zinc by grasses on polluted soils

Abstract

A study was conducted to evaluate the suitability of selected analytical methods for correlating the uptake of copper (Cu) and zinc (Zn) by grasses on soils exposed to sewage and industrial effluents and automobile exhausts. Samples of soils and selected grasses, such as Cynodon dactylon and Cyperus rotundus growing on these polluted soils, were taken and analysed for their Cu and Zn contents by extraction. Four extractants, 4M HNO₃, DTPA‐CaCl₂(pH 7.3), 1N NH₄OAc (pH 4.8), and 0.001N HCl were used. The results revealed that for the extraction of Cu and Zn from these soils, the efficiency of extraction was in the order of 4M HNO₃ > 1N NH₄OAc > DTPA‐CaCl₂ > 0.001N HCl. Significant positive correlationns were found between all the extracting methods and the Cu and Zn uptake by the grasses. The DTPA‐CaCl₂and 0.001N HCl extractants were found to be most promising extractants for the determination of Cu and Zn in the polluted soil in view of their high statistical relationship with the uptake of these elements by the grasses.