Keep that cadmium down! Zinc, lime, good counters

Farmers need to keep an eye on levels of the heavy metal cadmium in their wheat.

A recent concern is that cadmium in Australian food may exceed the maximum permissible concentration set by the National Food Authority (0.05 mg/kg).

Using lime to raise soil pH sometimes limits cadmium uptake if liming costs make this action viable. Also, South Australian trial on zinc-deficient soils indicate that zinc application can reduce grain cadmium concentration by up to half, giving extra value to treating zinc deficiency.

There are two ways of controlling cadmium: firstly, by slowing the build-up of cadmium in the soil; secondly, byreducing the amount taken up by the plant.

Cadmium in the soil can be increased by some phosphatic fertilisers, by atmospheric pollution or by using sewage sludge. Changing to a low cadmium fertiliser will slow the cadmium build-up from that source.

The CSIRO Division of Soils, with support from growers through the GRDC, and in collaboration with State primary industry departments, is researching these and other management practices aimed at keeping cadmium at bay.

Subprogram 2.11.03 Contact: Ms Danni Oliver 08 303 8434