DECREASING METAL RUNOFF FROM POULTRY LITTER WITH ALUMINUM SULFATE

Aluminum sulfate [Al-2(SO4)(3) . 14H(2)O] applications to poultry litt er can greatly reduce P concentrations in runoff from fields fertilize d with poultry litter, as well as decrease NH, volatilization. The obj ective of this study was to evaluate metal runoff from plots fertilize d with varying rates of alum-treated and untreated (normal) poultry li tter. Alum-treated (10% alum by weight) and untreated litter was broad cast applied to small plots in tall fescue (Festuca arundinacea Schreb ,), Litter application rates were 0, 2.24, 4.49, 6.73, and 8.98 Mg ha( -1) (0, 1, 2, 3, and 4 tons acre(-1)). Rainfall simulators were used t o produce two runoff events, immediately after litter application and 7 d later. Both concentrations and loads of water-soluble metals incre ased linearly with litter application rates, regardless of litter type . Alum treatment reduced concentrations of As, Cu, Fe, and Zn, relativ e to untreated litter, whereas it increased Ca and Mg, Copper concentr ations in runoff water from untreated litter mere extremely high (up t o 1 mg Cu L-1), indicating a potential water quality problem. Soluble Al, K, and Na concentrations were not significantly affected by the ty pe of litter. Reductions in trace metal runoff due to alum appeared to be related to the concentration of soluble organic C (SOC), as well a s the affinity of SOC for trace metals. Metal runoff from alum-treated litter is less likely to cause environmental problems than untreated litter, since threats to the aquatic environment by Ca and Mg are far less than those posed by As, Cu, and Zn.