Cadmium and nutrient heavy metals uptake by rice, barley, and spinach as affected by four ammonium salts

This experiment was conducted to investigate the influence of ammonium salts on the uptake of cadmium (Cd) and nutritional heavy metals (copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe)) by rice, barley, and spinach. These plants were grown in Cd, Cu, and Zn contaminated entisol (ES) or andisol (AS). The following ammonium salts were used: ammonium nitrate (NH4NO3), ammonium sulfate ((NH4)(2)SO4), ammonium chloride (NH4Cl), and ammonium dihydrogen phosphate (NH4H2PO4). In ES, the Cd concentrations in three plant shoots were higher with NH4Cl than with the other salts. The concentrations of Cd in soil solutions collected from ES were higher with NH4CI. Thus, the increase of Cd uptake by three plants with NH4CI treatment would be caused by the increased concentration of Cd in the soil solution. In contrast, in AS, the concentrations of the heavy metals in the shoots of all plants were not different among NH4 applications, with one exception, the Mn concentration in rice increased with NH4Cl in both ES and AS.