Sequential cropping of fly ash-amended soils: Effects on soil chemical properties and yield and elemental composition of plants

Abstract

Fly ash from a western U.S. coal source was added to a calcareous soil and an acid soil at rates ranging up to and including 8% by weight. The treated soils were cropped to a native desert plant species followed by barley under greenhouse conditions, with the objective to monitor long-term effects of fly ash on soil and plant composition and plant productivity. Application of fly ash increased pH, EC, Ca, Mg, Na, B, and SO 4 in soil. The increase in soil pH of the calcareous soil was completely buffered following the first crop. Boron and SO 4 showed relatively low initial release but increased substantially upon cropping. Dry weight of shoots of the desert species and yield of barley grain were significantly improved upon addition of fly ash to soil. Data on analysis of plants showed positive response to S and Mo from fly ash, whereas the increase in Ca, B, and Na varied among soils and plants. The availability of P, Zn, Fe, and Mn to plants appeared to be diminished by fly ash. Low Cu:Mo ratios were found in the plants, suggesting potential problems of fly ash-treated crops intended for animal use. Although data on soil and plant analysis indicate substantial removal of fly ash-derived elements by plants, a long-term effect of the by-product on their chemical composition was evident.