Copper and zinc runoff from land application of composted poultry litter

Authors: DELAUNE, PAUL - Texas A&M University; Moore, Philip

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2016
Publication Date: 9/16/2016
Citation: Delaune, P.B., Moore Jr, P.A. 2016. Copper and zinc runoff from land application of composted poultry litter. Journal of Environmental Quality. 45(5):1565-1571.

Interpretive Summary: Elevated nutrient levels in soil pose a potential threat to regions with long-term animal manure applications. Most of the negative attention has focused on phosphorus, but concern of heavy metals such as copper and zinc also exist. Composting is a potential management practice that can reduce total manure mass and volume while creating a stabilized product with less odor and pathogens. However, composting animal manures can lead to high levels of ammonia emissions and nitrogen loss and increased concentrations of non-volatile nutrients. The objective of this study was to measure copper and zinc concentrations in runoff water from plots fertilized with composted and fresh poultry litter. Seven treatments were evaluated in the first year: 1) unfertilized control; 2) fresh poultry litter; 3) normal compost (no amendment); 4) composted litter with alum; 5) composted litter with phosphoric acid; 6) composted litter with a microbial mixture; and 7) composted litter with alum+microbial mixture. Six treatments were evaluated in the second year: 1) unfertilized control; 2) fresh poultry litter; 3) normal compost (no amendment); 4) composted litter with alum; 5) composted litter with phosphoric acid; and 6) composted litter with a microbial mixture. Concentrations of Cu and Zn were elevated in compost compared to fresh poultry litter. However, elevated metal concentrations in compost did not always result in higher metal concentrations in runoff water. Total Cu and Zn concentrations in runoff water did not differ between alum-amended compost and fresh poultry litter in each year.

Technical Abstract: Regions with long-term animal manure applications based upon nitrogen (N) requirements have concerns for elevated nutrient levels. Most attention has focused on phosphorus (P), but concern of heavy metal accumulation has received attention due to perceived environmental concerns. Some nutrient-dense regions have evaluated the potential to transport manure to nutrient-deficient areas. Composting is a potential management practice that can reduce total manure mass and volume while creating a stabilized product. However, composting animal manures can lead to high N loss and increased concentration of non-volatile nutrients. The objective of this study was to measure copper (Cu) and Zinc (Zn) concentrations in runoff water from plots fertilized with composted and fresh poultry litter. Seven treatments were evaluated in the first year: 1) unfertilized control; 2) fresh poultry litter; 3) normal compost (no amendment); 4) composted litter with alum; 5) composted litter with phosphoric acid (H3PO4); 6) composted litter with a microbial mixture; and 7) composted litter with alum+microbial mixture. Six treatments were evaluated in the second year: 1) unfertilized control; 2) fresh poultry litter; 3) normal compost (no amendment); 4) composted litter with alum; 5) composted litter with H3PO4; and 6) composted litter with a microbial mixture. Each treatment was replicated four times in a randomized complete block design. Rainfall simulators were used to produce a 5 cm hr-1 storm event sufficient in length to cause 30 minutes of continuous runoff. Concentrations of Cu and Zn were elevated in compost compared to fresh poultry litter. However, elevated metal concentrations in compost did not always result in higher metal concentrations in runoff water. Total Cu and Zn concentrations in runoff water did not differ between alum-amended compost and fresh poultry litter in each year.