Cadmium uptake by barley as affected by Cd sources and pH levels

Abstract

A field experiment in the central part of Norway was conducted for four cropping seasons on a silt loam soil adjusted to pH 5.5 and 6.5 to study the Cd uptake by barley. Cadmium was applied as NPK fertilizers (at three rates equivalent to 0.03, 2.7 and 12.0 g ha −1), CdCl 2 (12.0 g) and phosphate rock (12.0 g). The concentration of Cd in barley tended to increase with increased Cd applied through CdCl 2 in the last two years. Other sources of Cd did not show any consistent effect on Cd concentration in barley. Cadmium concentration in barley increased from the first to the fourth year in all the treatments. In the first three years, Cd concentration in barley was higher at higher pH but the reverse was the case in the fourth year. Both NH 4NO 3- and DTPA-extractable Cd in the soil increased with increasing rate of Cd through different sources but the concentration of extractable Cd in the soil decreased with increased pH. The effect of soil pH was more pronounced on NH 4NO 3-extractable Cd than on DTPA-extractable Cd. No significant correlation between extractable Cd and plant Cd was observed. The results suggest that the concentration of Cd in barley grain was not affected significantly by the Cd applied through different sources in any of the years under study. Plant Cd did not show any significant correlation with the extractable Cd in the soil. A minor tendency of plant Cd to increase with increased soil pH was observed.