Approximately nine million dairy cows, 90 million beef cattle, 60 million swine and billions of poultry in the U.S. produce more than 100 times more organic waste (and nutrients) than humans. But, where human waste makes its way to a septic tank or sewage treatment plant, livestock manure is usually spread on the ground for its fertilizer value, where much of it runs off. USEPA calls nutrient runoff one of the greatest water quality problems in the U.S. today; in many watersheds, runoff from livestock manure is among the largest sources.
Concentrated Animal Feeding Operations (CAFOs) account for most U.S. livestock production. Their large scale keeps food costs down, but spreading all that manure as crop fertilizer creates air and water pollution problems. The industry has tried to limit the impacts, but nutrient runoff, methane and ammonia emissions, and other issues have CAFOs under a microscope by regulatory agencies, advocacy groups, industry investors, and consumers.
Many in the dairy industry now use digesters to capture methane to produce Renewable Natural Gas – RNG. This process increases the ammonia problem dramatically. In California, agencies and the industry are considering how to manage dairy ammonia emissions due to their impact on PM2.5 and groundwater nitrates. The industry and it’s impacts on water quality and climate change are under scrutiny for a wide range of impacts.
Air Emissions
- Ammonia from livestock waste contributes to the formation of PM2.5 – small inhalable particulate matter that poses a significant health risk – especially in dry western climates
- Hydrogen sulfide (H2S), volatile organic compounds (VOCs), odors
Climate Change
- Impacts come from both enteric fermentation and manure waste and handling
- Methane, CO2, and nitrous oxide (N2O) produced
- Livestock account for 4.2% of U.S. greenhouse gas emissions (USEPA) and 14.5% globally (UNFAO)
- Impacts on climate change are a large focus of anti-livestock advocacy groups and industry competitors
Nutrients/Runoff
- Livestock production is one of the largest sources of excess nutrients (nitrogen & phosphorus) in many major U.S. watersheds
- Highly mobile and volatile N from ammonia (from animal waste) becomes airborne and deposits N elsewhere. It is difficult and expensive to control (UNEP: What is Nitrogen Pollution?; NOAA website)
- N&P fuel harmful algae blooms (HABs – EPA website) in fresh, estuary and coastal salt waters that are increasingly toxic
- HABs lead to dead zones in the Gulf of Mexico, Chesapeake Bay, and other large waterbodies (NOAA National Ocean Service website)
- Nitrates from manure leach down to contaminate groundwater (EPA website)
- Increasing P concentrations in agricultural soils reduce productivity
Pathogens
- Studies show increased pathogen levels near waste spray fields and that those pathogens demonstrate antibiotic resistance
- Pathogens in manure used as fertilizer lead to foodborne illnesses