The Chesapeake Bay Program estimates the Bay can tolerate 175 million pounds of nitrogen and 14.1 million pounds of phosphorus each year and still meet water-quality standards, but in 2008, it received 311 million and 19 million pounds of nitrogen and phosphorus, respectively.
Although the scientific community has extensively studied nutrient loads through the use of chemical fertilizer and manure in the agricultural industry, it is just now looking at the impact of atmospheric deposition associated with agricultural sources.
The Chesapeake Bay Program estimates agricultural atmospheric deposition of nitrogen to be 7 percent of the total nitrogen load entering the Bay.
“To reduce the agricultural atmospheric deposition to the Bay, we must find ways to reduce the ammonia emitted into the atmosphere,” says Jactone Arogo Ogejo, assistant professor of biological systems engineering at Virginia Tech.
Ogejo leads a multi-part, four-year research project on agricultural air quality that involves a partnership with the University of Illinois. The first part involves the development and evaluation of biodegradable litter amendment to mitigate ammonia emissions in broiler and turkey houses where the birds are raised on litter to reduce ammonia emissions.
“Ammonia lost in the atmosphere is a loss of the fertilizer value of nitrogen in manure or poultry litter,” Ogejo says. “It can also react with some acid compounds in the atmosphere to form particulate that can pose health issues, reduce visibility in the form of a haze, and cause odor problems. We are developing and evaluating a biodegradable poultry litter amendment material from locally available agricultural residues, such as corncobs, cotton-gin waste, peanut hulls, and wood. Right now, we are conducting production-level pilot studies on the effectiveness of several new products on reducing ammonia volatilization from poultry litter.”
Foster Agblevor, associate professor of biological systems engineering, is developing and evaluating the new poultry-litter-amendment material production technology. Dr. F. William Pierson, director of the veterinary teaching hospital and associate professor of biosecurity and infection control at the Virginia-Maryland Regional College of Veterinary Medicine, is testing the safety of the litter amendment relative to poultry health. Kurt Stephenson, professor of agricultural and applied economics, is working with farmers to identify the barriers to put best management practices into action. He hopes this collaboration will lead to an evaluative protocol to assist farmers, researchers, and decision makers in the selection of best management practices to mitigate ammonia emissions.
The project also involves the creation of a comprehensive agricultural air-quality program within Virginia Cooperative Extension. “We plan to develop a sustainable, science-based agricultural Extension air-quality program covering the basic concepts of agricultural air pollutants, including their formation, measurement, and control,” Ogejo adds.
Nancy Franz, professor of agricultural and Extension education, is facilitating listening sessions modeled after town hall meetings in four communities across the state to gather diverse views on agricultural air quality and ensure that the Extension program aligns with community needs.
Another air-quality project involves a study on the effects of dietary nitrogen manipulation on ammonia emissions from housing and manure storage facilities for dairy cattle.
“We found you can reduce the amount of ammonia emissions through dietary changes without adversely affecting animal nutrition or milk quality,” says Mark Hanigan, associate professor of dairy science. “The rumen microbes in dairy cattle have a lower nitrogen requirement than we previously thought.”
Hanigan and Ogejo are working with Lindsay Marr, associate professor of civil and environmental engineering, and Katharine Knowlton, associate professor of dairy science, on this project.
Other air quality research under Ogejo’s purview involves characterizing the sources of pollutants to understand the mechanisms of their release and developing process-based models to predict their release — for example, ammonia from poultry litter to the occupied zone or ammonia emissions from liquid storage and land-applied manure to the atmosphere. The multi-state air quality research, which includes Richard Gates, professor of biological systems engineering at the University of Illinois, is funded by the U.S. Department of Agriculture.