Cadmium in Sugar Cane and Vegetable Systems of Northeast Australia

Abstract

Long‐term agricultural sustainability and food quality are threatened by a range of chemicals capable of persisting in the environment and entering the food chain at concentrations that can pose threats to human health. The heavy metal cadmium (Cd) is one of these, despite the existence of Cd food standard developed by Food Standards Australia New Zealand and standards for Cd in fertilizer. This article collates information from northeast Australia (mostly Queensland) by river catchment on historical inputs of Cd as an impurity in P fertilizers and on total concentrations in a broad selection of soils used primarily for sugar cane and vegetable production. How Cd partitions by soil depth and how it recycles in sugar cane production systems is explored in the context of sustainability. Actions by state governments to regulate the maximum permitted concentrations and encourage the fertilizer industry to lower Cd impurities in commercial products have helped reduce the quantity of Cd entering the two cropping systems. The study also reports briefly on the assessment of four soil chemical tests for Cd to assess the likelihood of edible vegetables grown on nonsaline soils from Queensland exceeding a concentration of 0.025 mg Cd kg−1 fresh weight. The order of accumulation of Cd (fresh weight basis) in the vegetables studied was as follows: leaf vegetables>roots and bulbs>vegetable stems and fruits>seed vegetables≈brassica. Silverbeet accumulated the most Cd, a finding in accord with international reports.