Effects of sodium fertiliser on the distribution of trace elements, toxic metals and water-soluble carbohydrates in grass and clover fractions

The distribution of trace elements, toxic metals and water-soluble carbohydrates was examined in the leaves, stems and inflorescences of perennial ryegrass and white clover, with and without sodium fertiliser. Copper and manganese were observed in both species to concentrate in the leaves and stems and iron and molybdenum in the leaves. In clover, nickel concentrated in the inflorescence. Differences in mineral concentrations between fractions were related to the mobility of the metal and its function in the plant. Sodium fertiliser approximately doubled the cadmium content of the leaves, stems and inflorescences of both species, reflecting cadmium mobilisation from the soil. The sodium fertiliser also reduced the zinc, copper, manganese and iron contents of grass but not clover and increased the molybdenum content of clover but not grass. Water-soluble carbohydrates were increased by sodium in grass but decreased in clover. Differences between the two species appeared to relate to nitrogen fixation by clover but not grass. (C) 1999 Society of Chemical Industry.