Air Quality & Emissions Management Category Guide
Part of Water, Environment, and Climate
Understanding Dairy Air Emissions
Dairy farms emit various gases and particulates that affect local air quality and contribute to broader atmospheric concerns. Primary emissions include ammonia (from manure and fertilizer), particulate matter (dust), volatile organic compounds (VOCs), and greenhouse gases (methane and nitrous oxide). Understanding these emissions helps farmers manage environmental impact and prepare for potential regulations.
Key Emission Types
Ammonia (NH3)
Ammonia is released from manure, urine, and fertilizer applications. It contributes to particulate formation, nitrogen deposition, and can affect respiratory health. Major emission points include barns, manure storage, and field application.
Particulate Matter
Dust from feed handling, bedding, animal movement, and roads creates particulate emissions. Fine particles (PM2.5 and PM10) are health concerns, while larger particles affect visibility and nuisance conditions.
Volatile Organic Compounds
VOCs from silage, manure, and fermentation processes contribute to ozone formation. Silage piles and feed bunks are significant sources during fermentation periods.
Methane (CH4)
A potent greenhouse gas produced by enteric fermentation (cow digestion) and anaerobic manure decomposition. Dairy cattle are significant methane sources, with enteric emissions from the cow itself and additional emissions from manure.
Nitrous Oxide (N2O)
Released from manure management and fertilized soils. A powerful greenhouse gas with 298 times the warming potential of CO2 over 100 years.
Management Strategies
Ammonia Reduction
- Dietary protein management—reducing excess protein lowers nitrogen excretion
- Rapid manure collection and removal from barns
- Covered or enclosed manure storage
- Low-emission application techniques (injection, rapid incorporation)
- Additives to inhibit ammonia volatilization
Particulate Control
- Paved and properly maintained roads
- Speed limits in dusty areas
- Vegetation screens around facilities
- Feed handling practices that minimize dust
- Bedding management to reduce dust generation
VOC Management
- Silage management to optimize fermentation
- Covering silage faces promptly
- Feed bunk management to minimize spoilage
Methane Reduction
- Feed additives (3-NOP and others) that reduce enteric methane
- Dietary changes that improve feed efficiency
- Anaerobic digesters to capture and use manure methane
- Covered lagoons with methane capture
- Manure management changes that reduce anaerobic conditions
Nitrous Oxide Reduction
- Improved nitrogen management in feed and fertilizer
- Precision nutrient application
- Cover crops and practices that improve nitrogen cycling
Regulatory Landscape
Current Requirements
Large dairy operations (CAFOs) may be subject to Clean Air Act permitting for particulates and other criteria pollutants. EPCRA reporting requirements apply to ammonia emissions above thresholds. California has specific dairy methane regulations.
Emerging Regulations
Climate-focused policies are increasing attention on agricultural greenhouse gas emissions. Several states are developing or implementing agricultural emissions programs. Federal climate legislation may eventually include agricultural provisions.
Voluntary Programs
Many dairies participate in voluntary emissions reduction programs that provide recognition, premiums, or credits for implementing mitigation practices. These programs help demonstrate the industry's commitment to environmental improvement.
Monitoring and Verification
Emissions quantification is challenging for agricultural sources. Methods range from simple emission factors to complex modeling and direct measurement. Verification requirements for emissions credits or regulatory compliance may require more sophisticated approaches.
Economic Considerations
Some emissions reduction strategies provide economic benefits—improved feed efficiency, energy generation from digesters, fertilizer value of captured nutrients. Other measures involve net costs that may be offset by regulatory compliance, market access, or voluntary program payments. Carbon and methane markets are emerging that may provide revenue for verified emissions reductions.
Resources
- Extension services provide emissions management guidance
- State environmental agencies explain regulatory requirements
- EPA provides emissions estimation tools and guidance
- Industry organizations track regulatory developments
- USDA programs may support emissions reduction practices