Growth and elemental composition of sorghum sudangrass grown on fly ash/organic waste‐amended soils

Abstract

Abstract A greenhouse study was conducted to evaluate the potential benefits of using fly ash/organic waste mixtures amended to soils for growth and composition of mineral elements by “sorgrass”; (Sorghum vulgaris var. sudanense Hitchc.) a sorghum‐sudangrass hybrid plant. This experiment was conducted using a 1:1 ratio of fly ash to either sewage sludge, poultry manure, or dairy manure at six application rates (0, 25, 50, 75, 100, and 125 tons/acre). Our three organic wastes when mixed with fly ash at varied rates of application resulted in elevated concentrations of NO3, P, K, Ca, Mg, Mn, Fe, B, Cu and Zn in both soil and plants. The data of this study indicated that the availability of elements to plants varied according to the organic source mixed with fly ash and the rate of application. The elements B and Zn were observed to be significantly greater in plant tissues exposed to fly ash/poultry manure or fly ash/dairy manure mixturers. Soils amended with fly ash/sewage sludge or poultry manure generally improved plant growth and enhanced yield when applied at rates of 25 tons/acre, and decreased thereafter. However, soils amended with fly ash/dairy manure improved plant growth and enhanced yield when applied at rates up to 50 tons/acre and decreased thereafter. The decreases in yield beyond these application rates were probably due to the accumulation of high levels of B and Zn which are phytotoxic and/or elevated levels of inorganic dissolved salts.