Cadmium accumulation by forage species used in New Zealand livestock grazing systems

Abstract

© 2015 Elsevier B.V. All rights reserved. Cadmium (Cd) accumulation in 12 forage plant species was investigated in a glasshouse trial. Potted soil (total Cd 0.43 mg kg- 1) was fertilised with varying rates of superphosphate to manipulate phosphorus availability, plant growth rate and soil Cd availability. Mean tissue Cd concentration decreased in the order chicory > plantain > turnip > lucerne > sheep's burnet > strawberry clover > kale > perennial ryegrass > haresfoot trefoil > red clover > crimson clover > white clover. Chicory and plantain had significantly greater mean tissue Cd concentrations (1.639 and 0.734 mg kg- 1 DM, respectively) than all other species. Rate of superphosphate and plant yield had little influence on plant tissue Cd concentration. The correlation between soil total Cd and plant tissue Cd concentration was generally poor (R2 = 0.006-0.428) and was only significant for perennial ryegrass and red clover. Modelling of lamb kidney Cd accumulation indicated that food standard maximum levels may be exceeded in animals younger than the current meat industry 30 month offal discard age. With increased use of chicory and plantain as specialist forage crops in New Zealand, this information will be important for improving livestock Cd accumulation risk assessment models.