Effects of fly ash deposition on growth, metabolism and dry matter production of maize and soybean

Plants of maize Zea mays L. and soybean Glycine max L. were treated with fly ash, a waste product of coal-fired electric generating plants, at the rates of 2, 4 and 8 g m⁻² day⁻¹ for 30 consecutive days between 15 and 46 days of plant age. At the lower two rates, both crops showed an increase in plant height, metabolic rate, content of photosynthetic pigment and all dry weight fractions measured. This response was, in part, due to correction of boron deficiency by fly ash deposition. The highest dusting rates, however, caused reductions in pigment content and dry matter production. Reduction in plant growth at the highest dusting rate was attributed chiefly to the excessive uptake and accumulation of boron, and alkalinity caused by excessive soluble salts on the leaf surface.