ISU Studies Continue to Address Livestock Air-quality Issues

June 30th, 2002

AMES, Iowa — Air-quality research at Iowa State University continues to address questions about the impact of livestock confinement facilities on the environment and people who live and work nearby.

Dwaine Bundy and Steven Hoff, researchers in the Iowa State University agricultural and biosystems engineering department, are leading three on-going projects.

The projects are important because they will provide actual emissions data from a variety of livestock production facilities and under a mix of weather conditions, Bundy said. "Taking a scientific approach to measuring odors and gases is vital before technologies to control odors and gases can be developed and evaluated," he said.

There is a gap in research data linking the actual emissions from livestock operations to downwind concentrations of gases and particulates. Projects are being initiated at Iowa State University to fill these gaps for both swine and poultry operations.

One of the projects is a six-state, $2.2 million air-quality study funded by the USDA Initiative for Future Agriculture and Food Systems grants program. The project will evaluate odor and gas emissions from swine and poultry facilities.

State-of-the-art monitoring equipment has been purchased for this project, and is being calibrated. Mobile laboratories will be set up at various production facilities to continuously record gas and particulate levels. Odor emissions will be evaluated at regular intervals using a dynamic dilution olfactometer at each of the six participating universities. Emissions sampling will begin in September and continue for two years.

Baseline emission rates will be established to determine starting points for studying changes in emissions. Then the researchers will evaluate differences in emissions due to geographical region, season of the year, time of day, building design, growth cycle of the animals and building management.

"This research will provide producers, consultants, regulators and the public with accurate information on emission levels," Bundy said. "The ultimate goal of this project is to develop technologies that will be effective at reducing odors, gases and particles emitted from animal facilities."

Premium Standard Farms is funding research to address environmental problems at its site near Princeton, Mo. Bundy and Hoff are working on a study that involves taking air emission samples from both buildings and manure storage lagoons, then evaluating odor and emission control reduction strategies. Testing is being done to see if lagoon additives, permeable lagoon covers, aeration of wastewater and other technologies can reduce emissions.

The project began last August and will continue for two years. "This research should provide information to other livestock producers about technologies and management techniques they can use to reduce odor and gas emissions from their production facilities," Hoff said.

Bundy and Hoff also are developing a computer model that can help determine how far gases from livestock production facilities will travel under a variety of atmospheric conditions. "This odor dispersion model could be used to guide the site selection process for swine facilities in Iowa," Hoff said.

The model makes predictions based on historic weather patterns, the type and size of the facility, the number of animals and the kind of ventilation system. The model will predict how frequently and how intensely neighbors in a community can expect to smell odors from a livestock production facility.

The computer model is designed to incorporate the combined effects of multiple odor sources at multiple locations. That theory will be field-tested this summer. Odor data will be gathered from a pit under a confinement swine finishing unit, as well as from downwind locations under a variety of climatic conditions. This data will be compared to what the computer model predicts will happen. The researchers hope to have results this fall.

Initial funding for the modeling project came from the Iowa Pork Producers Association. The Iowa Farm Bureau Federation has provided $36,000 to allow calibration data to be collected so the model can be refined.


Dwaine Bundy, Agricultural and Biosystems Engineering, (515) 294-1450

Steven Hoff, Agricultural and Biosystems Engineering, (515) 294-6180

Susan Thompson, Agriculture Communications, (515) 294-0705