Uptake by Wheat of Cadmium and Other Heavy Metal Contaminants in Phosphate Fertilizers

Abstract

AbstractA field experiment was conducted to determine uptake of Cd and other heavy metals by winter wheat (Triticum aestivum L.) from three diammoniuni phosphate (DAP) fertilizers containing 2, 74, and 153 µg Cd/g. A phosphorus‐deficient Paden silt loam (Glossic Fragiudult, pH 4.7) was limed at two rates and treated with the DAP sources at a rate of 50 kg of P/ha (100 lb of P2O5/acre). Grain yields were higher at pH 5.9 than at pH 5.1, were significantly increased by P applications, and results were similar using all DAP sources.Concentrations of Cd in both grain and straw were significantly increased only with application of high‐Cd DAP to the low‐lime soil. Cadmium concentrations in grain increased from 0.028 to 0.086 µg/g, and those in straw increased from 0.067 to 0.118 µg/g (dry weight basis) with application of low‐Cd DAP and high‐Cd DAP, respectively, and were lower on the high‐lime soil. Concentrations of Cu, Mn, Ni, and Zn in both grain and straw were not significantly affected by DAP source. Results for a second year on the same plots limed to pH 5.8 and 7.0 and treated again with the same DAP sources were similar to those for the first year, except that heavy metal uptake was generally lower. Results suggest that Cd concentrations in wheat products are not significantly changed by the phosphate fertilization and crop production practices in general use in the United States at this time.