FLUIDIZED-BED COMBUSTION BY-PRODUCT TREATMENT AND LEACHING OF ACID SOIL AFFECTS GROWTH AND BORON ACQUISITION OF MAIZE

Fluidized bed combustion bottom ash (FBCBA) from coal burning power pl ants often contain substances that detrimentally affect plant growth [ (e.g., boron (B))] when applied to soil. Leaf symptoms similar to B to xicity appeared when maize (Zea mays L.) was grown during Year-1 of a field experiment where FBCBA was incorporated (6,790 and 13,580 kg ha( -1)) in an acidic soil (Aquic Hapludult). Soil extractable B increased with increased levels of FBCBA in Year-1 and in Year-2. Although leve ls in Year-2 were lower than in Year-1 they were still sufficiently hi gh to raise concern about B toxicity. Acquisition of B in leaves of ma ize grown in Year-1 was relatively high at the 5-leaf stage of growth, and at a normal level in the ear leaf; ear leaf B in Year-1 was great er than ear leaf B in Year-2. Grain and fodder yields of plants grown with added FBCBA were reduced in Year-1, but not in Year-2. A greenhou se study was conducted to determine leachability of B through acidic s oil (Typic Hapludult) columns whose surface had been treated with FBCB A at 0, 6, and 12 g kg(-1) soil and leached with different amounts of water (25, 200, and 800 mm). Maize was also grown on the leached soil columns to determine effects of compounds leached from FBCBA on growth and B acquisition in leaves. The application of 800 mm of water reduc ed soil levels of B, and increased the amount of B leached from the co lumns. Maize shoot and root dry matter (DM) were enhanced with FBCBA. Increased DM associated with higher FBCBA levels may reflect increased soil pH in this acidic soil. Shoot B concentrations decreased with gr eater amounts of water used to leach columns. Shoot B concentrations w ere closely related to levels of B present in the 0-15 cm layer of soi l in the column and field experiments.