Modelling the toxicity of Cu and Zn salts to wheat in fourteen soils.

Abstract

There is mounting interest in developing and utilising soil-specific soil quality guidelines. This requires quantifying the effects that soil physicochemical properties have on various ecotoxicological endpoints including phytotoxicity. To this end, 14 agricultural soils from Australia with differing soil properties were spiked with copper (Cu) and zinc (Zn) salts and used to conduct 21 d plant growth inhibition tests using wheat (Triticum aestivum L.) in pot trials. The toxicity of Cu and Zn was similar with EC10 values ranging from 110 ? 945 and from 235 ? 965 mg kg-1 respectively, while the corresponding EC50 values ranged from 240 ? 1405 and 470 ? 1745 mg kg-1 respectively. Copper toxicity values (EC50, 20 and 10) were best modelled by logarithm of cation exchange capacity (CEC) and either soil pH or electrical conductivity. Zinc EC50 and 20 values were best modelled using the logarithm of CEC while the EC10 data was best modelled using soil pH and the logarithm of organic carbon. These models generally estimated toxicity within a factor of two of the measured values.