Chemical Amendments and Process Controls To Reduce Ammonia Volatilization During In-House Composting

Abstract

Composting inside high-rise, caged layer facilities can produce atmospheric ammonia (NH3) concentrations exceeding standards for human and poultry health. Control measures that reduce NH3 volatilization are necessary for in-house composting to be sustainable. Due to differences specific to in-house composting — low carbon to nitrogen ratios of composting material, continuous manure addition, and frequent turning — it is not known whether NH3 control measures used previously for poultry manure will work. The objectives of this study were to evaluate various amendment and process controls on NH3 produced during simulated in-house composting in the lab, and to evaluate select chemical control measures during composting inside a high-rise layer facility. Ten amendments (aluminum sulfate; chloride salts of aluminum, calcium, magnesium, and potassium; gypsum; sodium bisulfate; zeolite (clinoptilolite); straw; and cellulose) and four process controls (moisture; temperature; turning frequency; and particle size) were evaluated in lab incubations in 1 L vessels wherein samples of poultry manure compost were incubated to simulate composting. Vials of boric acid solution were used to capture NH3 evolved during incubations. With the exception of zeolite and cellulose, all amendments reduced NH3 capture. Low moisture and temperature also reduced NH3 capture, although managing temperature and moisture to achieve low NHg would adversely impact microbial activity and other desired benefits of composting. When evaluated inhouse, aluminum sulfate, calcium chloride and magnesium chloride did not reduce NH evolution from compost measured on three different dates with a gas sensor. Spatial variability along treated segments of windrow apparently masked amendment effects. At the end of a six-week composting cycle, total nitrogen content was higher in compost treated with aluminum sulfate than control or chloride salt treatments. Aluminum sulfate and process controls such as moisture content, carbon source and particle size have potential to reduce NH3 loss from poultry manure composted inside high-rise layer structures. In-house compost management to reduce NH3 volatilization must consider the cost of amendments, effectiveness, and impacts on the composting process.