Arsenic Mobility in Karnak Soils after Multi-Year Application of Poultry Litter Containing Roxarsone

An agricultural area in western Kentucky with compromised corn yields and a Karnak silty clay soil type was examined for the presence and mobility of arsenic in land-applied poultry wastes containing roxarsone. The soil was analyzed for metals, anions, pH, particle size, zeta potential, and moisture content to identify any relationship between these analytes and arsenic mobility. The Karnak soil was less acidic than expected, but retained significant arsenic (7.52 +/- 0.58 mg kg(-1)) that demonstrated a moderate relationship to soil sulfate (R-2 = 0.6641) and a strong relationship to soil manganese (R-2 = 0.9355). The Karnak soil arsenic was strongly bound to particles greater than 0.45 mu m size fractions and not readily leached with aqueous extractions. In comparison, litter arsenic (5.84 +/- 0.72 mg kg(-1)) leached 83.7% and 70.5% of the total arsenic available in a 24 hr extraction. Copper and zinc in the litter and soils were also readily leached with neutral water. Despite the apparent ease in mobilization of arsenic from chicken, there was relationship between the amount of arsenic-containing chicken litter applied and the concentration of arsenic in Karnak soil.