Reducing Ammonia Emissions from Animal Production Systems

Animal Production

In animal production systems, ammonia emissions most often originate from urea-nitrogen in urine or feces. Most of that nitrogen enters the animal as feed protein, which producers want to convert to meat or milk. The best means of reducing ammonia emissions is to maximize the amount of protein utilized by the animal, thereby capturing the maximum value from the feed input and minimizing negative environmental consequences.

Even when rations are balanced to provide the optimal levels of crude protein in the most available forms, some portion (usually greater than 80% in cattle) of nitrogen fed will be passed through the animal. Some general management strategies for minimizing ammonia emissions from animal production systems include:

  • Feed Management
    • Manage protein intake and balance rations to maximize conversion of protein into meat or milk. This includes phase feeding by stage of growth or production and utilizing nutritionists to develop balanced rations. When possible, rations should be formulated based on “as-delivered” feed ingredient analyses and protein analyses should be based on “metabolizable protein” rather than “crude protein”.
    • Utilize technologies to improve the digestibility and/or conversion of protein to meat or milk.
    • Consult nutritionists and have feedstocks tested for protein and energy when utilizing non-traditional or alternative feedstocks in diet rations. Feeding dietary protein in excess of animal needs leads to increases in ammonia emissions.

  • Animal Housing
    • Maintain dry, well drained open lots with properly constructed mounds for animals to rest on. Dry pens produce less ammonia than wet pens. Sprinkling pens for dust control may also reduce ammonia emissions when ammonia is leached into the pen surface material.
    • Maintaining clean pen surfaces. Clean pen surfaces are characterized by lower emissions of dust, odor, and ammonia.
    • In enclosed housing, maintain good bedding conditions and minimize the floor area that is wetted or covered in manure. Separating manure and urine through use of slatted floors, drained sand bedding, or textured surfaces that channel away urine will reduce emissions.

  • Manure Management
    • For flush systems, ammonia emissions generally decrease as flush frequency increases.
    • For liquid manure management systems, ammonia emissions are generally lower when nitrogen levels in effluent and treatment structures are maintained below 5 lbs N/1,000 gallons. Separating solids from effluent streams can help reduce nitrogen loading.
    • Emissions from composting and solid manure storage are lower when carbon to nitrogen ratios are maintained above 3:1, which requires addition of carbon. Emissions from these sources can also be minimized by covering piles daily or with each manure addition and by preventing storm water and precipitation from wetting compost or solid manure piles.

  • Land Application
    • When land applying solids, stage piles as near the date of application as possible (preferably less than 3 days before spreading). Incorporate manure within 24 hours of application to reduce ammonia volatilization and capture the maximum amount of nitrogen fertilizer value.
    • When applying liquids, inject manure when possible or incorporate as soon as possible (within 24 hours). If applying via irrigation systems, drop-hose systems will reduce emissions over sprinklers. Avoid use of high-pressure sprinklers or guns.

When a warning is issued that an air mass in eastern Colorado is likely to move into RMNP and move nitrogen into the Park, some practices that may be employed to reduce emissions during a warning period include:

  • Delay disturbing manure by cleaning pens, turning compost piles, or loading out manure or compost until the warning period expires. These practices lead to large, short-term releases of ammonia.
  • Sprinkling pens with sufficient water to leach nitrogen away from the pen surface.
  • Delay aerating lagoons. Aeration leads to short-term bursts of ammonia emissions.
  • Add cover to compost, solid manure, or mortality disposal areas daily or with each addition of manure. Adding dry acids such as alum to compost and manure piles can significantly reduce emissions temporarily.
  • Increase the frequency with which alleyways are flushed to remove manure and urine.
  • Delay draining pull-plug waste systems, pumping or aerating open-air lagoon system, and applying manure to fields except by injection. If applications must be made, incorporate manure or effluent immediately.
  • Avoid land application of solid manure by spreader truck and application of lagoon effluent by sprinkler or spray truck.

For additional assistance identifying sources of air emissions at animal feeding operations and/ or means of reducing emissions, visit the National Air Quality Site Assessment Tool (NAQSAT) website and the following Extension Fact Sheets produced by Colorado State University: