Soil solution chemistry of a fly ash-, poultry litter-, and sewage sludge-amended soil

Mixing coal fly ash (FA) with organic wastes to provide balanced soil amendments offers a potential viable use of this industrial byproduct. When such materials are land-applied to supply nutrients for agronomic crops, trace element contaminant solubility must be evaluated. In this study, major and trace element soil solution concentrations arising from application of fly ash, organic wastes, and mixtures of the two were compared in a laboratory incubation. Two fly ashes, broiler poultry litter (PL), municipal sewage sludge (SS), and mixtures of FA with either PL or SS were mixed with a Cecil sandy loam:(fine, kaolinitic, thermic Typic Kanhapludult) at rates of 32.3, 8.1, and 16.1g kg(-1) soil for FA, FL, and SS, respectively. Treatments were incubated at 22 degrees C at 17% moisture content and soil solution was periodically extracted by centrifugation over 33 d. Initial soil solution concentrations of As, Mo, Se, and Cu were significantly greater in FA/PL treatments than the respective FA-only treatments. For Cu, increased solution concentrations were attributable to increased loading rates in FA/PL mixtures. Solution Cu concentrations were strongly correlated with dissolved C (R-2 > 0.96) in all PL treatments. Significant interactive effects for solution Mo and Se concentrations were observed for the FA/PL and may have resulted from the increased pH and competing anion concentrations of these treatments. Solution As concentrations showed a significant interactive effect for one FA/PL mixture. For the individual treatments, As was more soluble in the PL treatment than either FA treatment. Except for soluble Se from one FA/SS mixture, trace element solubility in the FA/SS mixtures was not significantly different than the respective FA-only treatment.