Soil and P Fertilizer Effects On Plant-Available Cadmium.

Field studies were conducted between 2002 and 2009 at 7 locations across the Canadian prairies to determine the effects of addition of Cd in monoammonium phosphate fertilizer on plant-available Cd, as affected by soil characteristics. Durum wheat (Triticum turgidum L.) and flax (Linum usitatissimum L.) were used as indictor crops to assess the plant-availability of Cd at the various locations. Cadmium concentration in the seed of both crops increased with application of P fertilizer even when the fertilizer contained only trace concentrations of Cd, indicating that P fertilization directly influenced Cd concentration of crops apart from the effect of Cd addition.  Seed Cd concentration was higher when the fertilizer contained greater Cd concentrations, particularly when rate of fertilizer application was also high.  Cadmium concentration in crops was directly proportional to the total amount of Cd applied over time, but the effect of fertilizer application varied with soil characteristics.  Availability of Cd in fertilizers decreased with increasing soil pH and cation exchange capacity. Risk of transfer of Cd into the food chain will be affected by fertilizer rate and Cd concentration as well as by soil characteristics.