Gaseous Emissions from In-house Broiler Litter


Broiler litter is a valuable fertilizer but can also be a source of odorous and GHG emissions during production, storage, and land application. Impacts of these emissions are felt by local communities, posing respiratory health impacts and decreased quality of life, as well as increased deposition into soil and water systems. This study seeks to quantify the magnitude of emissions associated with in-house broiler litter and estimate variability across farms. Finally, the study evaluates litter parameters, such as litter age and chemical composition, for gas emission predictors.

What Did We Do?

A set of five active broiler houses in North Carolina were sampled to measure gaseous emissions (NH3, H2S, CH4, N2O, CO2, and VOCs) using headspace flux measurement gas samples. Headspace gas concentrations were measured at 1 hour and 3 hours after incubation at 30°C using a photoacoustic analyzer (Innova 1412) for NH3, CH4, N2O, and CO2 and Jerome 631-X was used to measure H2S, concentration. The headspace was also sampled to quantify VOCs associated with odorous emissions. After incubation, water extraction was used to quantify less volatile organic species that are associated with odorous emissions in the litter. Experimental setup is described in Figure 1. Statistical software, JMP, was utilized for analysis of litter composition on NH3, H2S, CH4, N2O, CO2, and VOC gaseous emissions.

Figure 1. Broiler emission experimental setup

What Have We Learned?

H2S emissions were very low (< 0.01 ppm) and did not produce statistically significant observations. There was a wide range of emissions from the litter samples for different gases as shown in Figure 2: 146-555 ppm NH3, 1.5-22 ppm N2O, 4,077-50,835 ppm CO2, and 9.1-43.3 ppm CH4. The differences between farms accounted for 86%, 81%, 76%, and 84% of the variability in NH3, N2O, CO2, CH4 observations, respectively. This could be attributed to differences in integrator and management strategies. Moisture content and age of the litter were the primary contributing factors to increased gaseous emissions from all samples. More specifically, NH3 was largely impacted by pH (p < 0.01), while N2O, CO2, and CH4 were largely impacted by C:N (p < 0.01). Quantitative VOC analysis was difficult due to the number of gases detected by the GC-MS (20+), however the most common species present in the litter samples were a variety of volatile fatty acids, alcohols, phenol, as well as a few amines, ketols, and terpenes.

Figure 2. Photoacoustic flux measurements of litter samples at 1 and 3 hour intervals.

Future Plans

These results will serve as baseline emission readings for odor and emission control strategies. We are currently developing Miscanthus-derived biochar as a poultry litter amendment for emission mitigation in poultry houses. This dataset will inform our decision making to help target gaseous species of top concern in NC broiler litter by methods of physical and chemical biochar modification.


Presenting author

Carly Graves, Graduate Research Assistant, North Carolina State University

Corresponding author

Dr. Mahmoud Sharara, Assistant Professor & Waste Management Extension Specialist, North Carolina State University

Corresponding author email address


Funding for this project is through Bioenergy Research Initiative (BRI)- NC Department of Agriculture and Consumer Services (NCDA&CS): Miscanthus Biochar Potential as A Poultry Litter Amendment

Performance of Mitigation Measures in the Dairy Sector under Future Climate Change


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Climate change is an economic, environmental and social threat, and worthy of scientific study. Immediate action must be taken to reduce greenhouse gas emissions and mitigate negative impacts of future climate change. Proposed action can start at the farm level and has the potential of making a contribution to mitigation of climate change. Dairy farmers are able to significantly reduce their emissions by implementing better management practices, primarily through feed production, enteric fermentation, and manure management. We model the corresponding changes in emissions from proposed mitigation efforts to understand their impact on global climate change.

What did we do?

Best Management Practices (BMPs) for dairy systems have been identified and simulated using the Integrated Farm System Model (IFSM). Simulations representative of a large New York farm (1500 cows) and a small Wisconsin farm (150 cows) estimated the emission of greenhouse gases for a whole farm system. Percent reductions were calculated by comparing a baseline scenario without any implemented mitigation, to scenarios that included the identified BMPs. Refer to Table 1 for emission and percent reduction estimates for the simulated BMPs.Table 1. Emissions and percent reductions from baseline for simulated mitigation strategies

Percent reduction estimates were then applied to a projected “business as usual” emission scenario. This scenario prescribes anthropogenic emissions through 2100 and excludes any climate action or policy after 2015. Taking 2020 as a reference year and 2050 as a target year, we applied the estimated percent reductions to the projected global agricultural emissions. Emission reductions were decreased linearly from 2020 to 2050, and held constant between 2050 and 2100 (Figure 1). This assumes that all farms globally can reduce emissions despite increases in production. To compare the performance of the mitigation measures under future climate change, we employed a fully coupled earth system model of intermediate complexity – the Integrated Global System Model (IGSM). The model includes an interactive carbon-cycle capable of addressing important feedbacks between the climate and terrestrial biosphere.

Figure 1. Global agricultural emissions for mitigation strategiesWhat have we learned?

Action taken globally in the agricultural sector to reduce greenhouse gas emissions over the first half of the 21st century is likely to have an impact in mitigating global warming. Following a “business as usual” emission scenario without any climate policy or action beyond 2015, an increase in global mean surface temperature by the end of the 21st century (2081-2100) relative to pre-industrial (1961-1990) levels is projected to be 2.8 C to 3.5 C (Figure 2). This exceeds the 2 C temperature target described as the maximum warming allowed to avoid dangerous and irreversible climate change. An associated net radiative

forcing for the “business as usual” scenario is projected to be 7.4 W/m^2 by 2100 (Figure 3). Adopting the identified BMPs in the dairy sector and decreasing global agricultural emissions by 2050 is projected to decrease global mean surface temperatures for 2100 by 0.2 C and net radiative forcing by 0.4 W/! m^2 on av erage. In summary, this modeled experiment demonstrates that ongoing efforts to decrease greenhouse gas emissions in the dairy and agricultural sector are effective at reducing the overall warming of climate change.

Figure 2. Projected global mean surface temperature and changes for mitigation scenarios

Figure 3. Projected radiative forcing for mitigation scenarios over the 21st century

Future Plans

Future work will look further into the evolution of regional temperature and rainfall profiles for the mitigation scenarios. Then, ecological risk assessment methodologies will be applied to determine the probable impacts of climate change by each scenario on agricultural production.

Corresponding author, title, and affiliation

Kristina Rolph – Graduate Student, The Pennsylvania State University.

Corresponding author email

Other authors

Chris Forest – Associate Professor of Climate Dynamics, The Pennsylvania State University.

Rob Nicholas – Research Associate, Earth & Environmental Systems Institute.

Additional information

  1. The Sustainable Dairy Project, funded by the USDA, researches alternative management practices in the dairy industry.
  2. The Integrated Farm System Model simulates all major farm components to represent the many biological and physical processes on a farm.
  3. The MIT Integrated Global System Model is a fully coupled earth system model of intermediate complexity designed to analyze interactions between human activities and the Earth system.


This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2013-68002-20525. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

Reducing or Mitigating Greenhouse Gas Emissions In Animal Agriculture

Animal agriculture has dramatically increased its production efficiency over time, as it continues to produce more products with fewer resources. Although its overall carbon footprint is relatively small compared to other sectors of the economy such as energy and transportation, it is often called upon to defend its impact on the environment. Recent commitments made by livestock and poultry industry groups to reduce greenhouse gas emissions shows that animal agriculture is willing to do its part as good stewards of shared natural resources and to protect the environment.

Factsheet: Mitigation of Greenhouse Gas Emissions in Animal Agriculture (look below the fact sheet and title for a “download” link)

Measures to mitigate or reduce greenhouse gas emissions must be weighed on a farm by farm basis, as types of animal production among species and geographic locations are extremely diverse. There is no magic bullet or one size fits all solution to reduce greenhouse gas emissions among animal agriculture.

There are four main approaches to mitigation greenhouse gas emissions in livestock and poultry systems.

(1) Production efficiency – producing more output of meat, milk and eggs per unit input (water, feed, fertilizer, etc.)

(2) Manure management – applying manure collection, storage, and disposal practices that not only reduce greenhouse gas emissions, but at the same time address water and air quality concerns.

(3) Energy efficiency – as we continue the trend toward more controlled environments within animal production, there is a growing need to be more energy efficient in our lighting, heating and cooling systems.

(4) Carbon capture (also called carbon sequestration) – capturing and storing carbon in the soil by maintaining cover crops, or by planting trees or other perennial vegetation increases organic matter content and also retains carbon that would have otherwise been released as carbon dioxide into the atmosphere.

All Species

  • Increase conception and pregnancy rate
  • Improve animal health
  • Reduce animal stress
  • Lower mortality (death) rates
  • Use feed analysis/precision feeding – match dietary requirements and nutritional needs
  • Practice genetic selection for increased production efficiency and/or reduced maintenance energy requirements

Beef Cattle

  • Increase weight gain through concentrates, improved pastures and dietary supplements
  • Increase digestibility of feed/forage
  • Encourage earlier weaning
  • Use proper stocking rates & rotational grazing
  • Move to low input production
  • Breed for better heat tolerance and pest resistance

Dairy Cattle

  • Increase milk production per head
  • Encourage earlier weaning
  • Improve energy efficiency of exhaust fans, lighting, generators, and incinerators
  • Improve cow comfort through improved cooling systems and bedding material


Also see a related project on pork production and environmental footprint.

  • Reduce crude protein content in diet and supplement with amino acids
  • Switch from dry feed to wet/dry feeders
  • Improve bedding materials
  • Improve energy efficiency of exhaust fans, lighting, and generators


  • Use insulated curtains in houses without walls
  • Insulate walls in houses with walls
  • Install circulatory fans to prevent temperature stratification inside barns
  • Improve energy efficiency of exhaust fans, lighting, generators, and incinerators

Manure Management Strategies

  •  Anaerobic digestion captures methane (a greenhouse gas) and destroys it or utilizes it for energy generation.
  • Composting manure – can reduce greenhouse gases by avoiding methane production that would be seen if the feedstock was landfilled or stored in an open air anaerobic system (such as a lagoon)  [1]
  • Covered manure storage – can capture methane and either destroy it (flare) or utilize it for energy generation
  • Frequent removal of manure from confined facilities
  • Separating manure liquids from solid

Educator Materials

If you would like to use the video, slides, or factsheet for educational programs, please visit the curriculum page for download links for this and other climate change topics.

Recommended Reading on Reducing Emissions from Animal Production

All Livestock Species

Greenhouse Gas Mitigation Opportunities for Livestock Management in the United States (Duke University Nicholas Institute, 2012)
Mitigation of Greenhouse Gas Emissions in Livestock Production (FAO, 2013)
Livestock’s Long Shadow, FAO report

Beef Cattle

Dietary Mitigation of Enteric Methane from Cattle (Beauchemin, K. A. et al., 2009)

Dairy Cattle

DMI Sustainability Website
Sustainability in Practice-A Collection of Success Stories from the Dairy Industry
Greenhouse Gas Emissions from the Dairy Sector, FAO report


Swine Carbon Footprint Facts
Evaluating the Environmental Footprint of Pork Production


Carbon Footprint of Poultry Production Farms (C. Dunkley Webcast)
Global Warming: How Does it Relate to Poultry (C. Dunkley 2011, Factsheet)


Author: David Schmidt, University of Minnesota

This page was developed as part of a project “Animal Agriculture and Climate Change” an extension facilitation project to increase capacity for ag professionals. It was funded by USDA-NIFA under award # 2011-67003-30206.



Staying Ahead of the Curve: How Farmers and Industry Are Responding to the Issue of Climate Change

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Why Is This Topic Important?

Several farmers, ranchers, and industry groups are leading the way on the issue of climate change. 

What Will Be Learned In This Presentation?

These panelists will share how their farm or industry is responding to climate change, what factors are driving their decision to make changes, and the impact of climate change on long-term planning. This moderated session will encourage audience questions and facilitate exchange of ideas on how the agriculture industry can meet this challenge.


David Smith, Southwest Region Coordinator Animal Agriculture and Climate Change Project, Texas A&M University and Liz Whitefield, Western Region Coordinator, Washington State University

  • Jamie Burr –  Tyson Foods, Chair National Pork Board Environment Committee
  • Abe Collins – cattle grazier, Cimarron Farm, Regenerative Farmscaping consultant, Board Member Soil Carbon Coalition
  • Paul Helgeson – Sustainability Director with Gold’n Plump Chicken
  • Bryan Weech, Director Livestock & MTI Commodity Lead, World Wildlife Fund
  • Andy Werkoven – dairyman and anaerobic digester co-owner, Werkhoven Dairy Inc., 2012 winner of US Dairy Sustainability Award


Vegetative Environmental Buffers (VEBs) for Mitigating Air Emissions from Livestock Facilities: A Review

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Air emissions from livestock facilities are receiving increasing attention because of concerns related to nuisance, health and upcoming air quality regulations. Vegetative buffers have been proposed as a potential cost effective mitigation strategy to reduce dust, odor and other air pollutants from farm and can be an important part of air quality management plan. However, the effectiveness of vegetative buffers in mitigating air emissions seems to be site specific and can be affected by many factors. This study aims to provide a thorough literature review on the performance of vegetative buffers in mitigating air emissions, to investigate critical factors, and to identify research gaps. The results will be used as basis for planning future wind tunnel and field studies. The ultimate objective is to develop general guidance for vegetative buffer design and to demonstrate the variety and effectiveness of vegetative buffers for mitigating air emissions from livestock facilities.

Why Study Trees As a Potential Odor Management Strategy?

Vegetative environmental buffers (VEBs) have been proposed as a mitigation strategy for air emissions from livestock facilities. Survey indicated producers are interested in using VEBs for odor management. But lack of information on performance, cost and technical guidelines are barriers to adoption of VEBs.

What Did We Do?

Review published research on effectiveness of VEBs for mitigating air emissions from livestock facilities.

What Have We Learned?

VEBs have been examined primarily in swine and poultry farms. Iowa, Pennsylvania and Delaware are actively involved in research and implementation of VEBs for livestock farms. VEBs are potential cost effective strategy for reducing dust (by up to 56%), odor (by up to 68%), NH3 (by up to 54%) and H2S (by up to 85%) from farms, although effectiveness and costs are highly variable and depend on site specific design. Most effective reduction occurs just beyond the VEBs. Wind tunnel simulation on barriers at roadside showed that percentage reduction of pollutants decreasing with downwind distance, and they are generally below 50% beyond 15 barrier height.

Mitigation Mechanisms of VEBs

Future Plans

Measure the concentrations of multiple air emission constituents at various distance from a swine facility with and without the presence of a VEB under various weather conditions; determine the effectiveness of the VEB under various design parameters (height and depth) and evaluate how height and depth of the VEB will affect the mitigation effectiveness; develop design suggestions and best management procedures to utilize a VEB in order to maximize effectiveness with limited costs. 


Zifei Liu, Assistant Professor, Kansas State University.

Ronaldo Maghirang, Pat Murphy, Kansas State University

Additional Information


The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.