Reducing phosphorus runoff and improving poultry production with alum

This is a review paper on the effects of aluminum sulfate (alum) on ammonia volatilization and P runoff from poultry litter. Initially, laboratory stu dies were conducted that showed P solubility could be reduced in poultry li tter with Al, Ca, and Fe amendments, indicating that these amendments may r educe P runoff. These results were confirmed in small plot studies in which alum applications to litter were shown to decrease P concentrations in run off by as much as 87%, while improving tall fescue yields. Leaf tissue anal yses indicated that the yield improvements were due to increased N availabi lity, which we hypothesized was due to reduced NH3 volatilization. This res ult was confirmed in laboratory studies that showed that alum was one of th e most effective. (and cost-effective) compounds for reducing NH3 volatiliz ation. Field trials conducted at commercial broiler farms in conjunction wi th the Environmental Protection Agency showed that alum additions to poultr y litter lowered litter PII, particularly during the first 3 to 4 wk of eac h growout, which resulted in less NH3 volatilization and lower atmospheric NH3. Ammonia volatilization rates were reduced by 97% for the first 4 wk of the growout, Broilers grown on alum-treated litter were heavier than the c ontrols (1.73 vs 1.66 kg) and had lower mortality (3.9 vs 4.2%) and better feed efficiency (1.98 vs 2.04). Electricity and propane use were lower for alum-h eat ed houses. As a result of these economic benefits to the integra tor and grower, the benefit :cost ratio of alum addition was 1.96. Phosphor us concentrations in runoff from small watersheds were 75% lower from alum- treated Litter than normal litter over a 3-yr period. Long-term small plot studies on alum use have shown that alum-treated litter results in lower so il test P levels than normal litter and does not increase Al availability i n soils or uptake by plants.