Availability of cadmium for vegetable plants in allotment soils

Pot experiments with soils from allotments of Hamburg and different vegetables were carried out to determine the mobility and plant availability of cadmium. Total soil Cd-contents in combination with other soil properties as well as 0.1 M CaCl2 and 1 M NH4NO3 extractable Cd were tested with regard to forecasting the Cd-uptake by plants. A direct comparison of these methods and their suitability is given. Soil threshold values were derived, which possibly result in Cd-plant uptake and Cd-contents exceeding the actually valid limits in food. These threshold values were evaluated for three testing methods. Total soil Cd-content in combination with pH as well as 0,1 M CaCl2 and 1 M NH4NO3 extractable Cd.