FIELD-STUDY - INFLUENCE OF FLY-ASH ON LEACHATE COMPOSITION IN AN EXCESSIVELY DRAINED SOIL

Alternatives to landfilling ny ash may be to use it as a soil amendmen t since it is fine textured and could alter soil texture and thus impr ove water retention. However, by ash contains elevated B, soluble salt s, and trace element concentrations that could adversely affect plant and soil quality. Objectives were to characterize leaching of soluble salts, plant nutrients, and trace elements in a sandy soil amended wit h a high rate of by ash (similar to 662 Mg ha(-1)). We established fie ld plots in an Evesboro loamy sand using typical agricultural equipmen t. Lysimeters were installed to a depth of 120 cm and used to collect leachate over a 9 mo period. We also used microplots (1.0 by 1.0 m) an d similar ash rates to characterize leaching under controlled conditio ns. Lysimeters were installed at four depths in each microplot (15, 30 , 60, and 120 cm) and water applied with a rainfall simulator. Boron a nd soluble salts were leached from the rooting zone after similar to 3 8 cm of natural rainfall or 42 cm of irrigation. Calcium and S were th e dominant plant macronutrients in leachates while Cu, Mn, and Zn were the only detectable micronutrients. Peak concentrations of these elem ents were detected after similar to 50 cm of rainfall or irrigation an d decreased to below or near initial concentrations by the conclusion of the study. Nickel was the only detectable trace element in leachate s, however, concentrations were variable and <0.15 mg L-1. Results sug gest that if ny ash incorporation is properly timed to allow for natur al leaching, adverse effects will be minimal.