Restoring the nation's largest estuary

While many scientists track nitrogen and phosphorus pollution levels to determine the condition of the nation’s largest estuary, the Chesapeake Bay Foundation has also identified blue crab populations as one of a dozen indicators of the bay’s health. In 2007, the foundation reported that the blue crab catch had been approximately 30 percent below average for the past eight years.

How agriculture fits into the equation

When Capt. John Smith and his crew began their historic expedition to the Chesapeake Bay 400 years ago, they encountered a pristine inlet teeming with life and largely free of pollution. Today, urbanization and agriculture have fundamentally changed the situation.

   

John Ignosh demonstrates a nutrient-removal reactor John Ignosh demonstrates an on-farm nutrient-removal reactor at a test site in Dayton, Va. The cone-shaped reactor developed by Jactone Arogo captures the phosphorus in dairy manure and converts it into a phosphate-rich crystal.

“The Shenandoah Valley in Virginia is a major part of the Chesapeake Bay Watershed and contributes large amounts of excess nutrients because of the amount of agricultural production in the region,” says Saied Mostaghimi, professor and head of Virginia Tech's Department of Biological Systems Engineering and member of the Scientific and Technical Advisory Committee for the Chesapeake Bay Program. “Over the years, producers in the region have been applying phosphorus and nitrogen to the soil, but now the soil is no longer able to absorb all of the excess nutrients.”

Two Virginia Tech College of Agriculture and Life Sciences researchers are working with farmers to prevent this problem at the onset. Foster Agblevor, associate professor of biological systems engineering, developed a transportable pyrolysis unit to convert poultry litter into bio-oil, producer gas, and fertilizer.

“Past research has tried to find a technological solution to the problem, but we are treating the poultry litter as a resource, not a problem,” says Agblevor, who adds that his pyrolysis unit can remove 5.8 million pounds of phosphorus and 5 million tons of nitrogen each year from the Shenandoah Valley.

Jactone Arogo, assistant professor of biological systems engineering and waste management specialist for Virginia Cooperative Extension, is applying the same idea to the valley’s dairy industry. His innovative, cone-shaped reactor captures phosphorus from dairy manure and transforms it into struvite, a phosphate-rich crystal that can be used as a slow-release fertilizer, a raw material for the phosphate industry, and a binding material in cements. Struvite is also a compound in manufactured cleaning products and fire-resistant panels.

“Struvite is much easier to carry and transport over long distances than dairy manure,” Arogo says. “We can send the struvite to areas that are deficient in phosphorus, and because struvite has less volume than the alternative, transportation is cheaper.”

   

A handful of struvite Jactone Arogo's nutrient-removal reactor turns dairy manure into struvite (pictured here), a salt formed when equal molar concentrations of magnesium, ammonium, and phosphate ions in a solution react. The crystals have a variety of uses, including a slow-release fertilizer and a raw material for fire-resistant panels.

With the help of Extension personnel in the field, both Arogo and Agblevor have established small pilot plants in Virginia to test their nutrient-management techniques. John Ignosh, an Extension agri-based by-product utilization specialist, is working with Shenandoah Valley producers to bring the pilot plants to their farms. This effort demonstrates the value of these new technologies both to farmers using the reactors and to others in the agricultural industry who have seen the work in action.

These projects are part of an umbrella research project that evolved from the Waste Solutions Forum, a grassroots stakeholder group that addresses nutrient challenges for animal agriculture, particularly in the Shenandoah Valley. Katharine Knowlton, associate professor of dairy science, oversees this effort funded by the National Fish and Wildlife Foundation, and researchers involved in the foundation’s projects have received more than $5 million from government agencies and nonprofit groups for research opportunities identified at the forum.

Focusing on water quality

For decades, Virginia Tech faculty members have looked for ways to improve water quality in the Chesapeake Bay after excess nutrients have entered the waters. Jim Pease, professor of agricultural and applied economics and Extension farm business management specialist, has shown that many farmers would not lose money by improving water quality because they would more effectively utilize costly nitrogen.

“It is a win-win situation for farmers, offering both positive environmental effects and positive economic benefits,” says Pease, who is also a member of the Chesapeake Bay Program’s Scientific and Technical Advisory Committee.

But for now, the Chesapeake Bay is nowhere near the water-quality level that government officials hoped to reach by 2010, and species like the blue crab are among those taking the hit. Many expect the Environmental Protection Agency to mandate a total maximum daily load (TMDL) for the entire bay, which would determine the amount of specific pollutants the estuary could absorb without violating government standards. “This means that even small watersheds on the Chesapeake Bay basin must produce their own pollution-reduction plan with the hope that, collectively, these small changes will lead to overall improvements in the bay’s health,” Mostaghimi says.

Brian Benham, associate professor of biological systems engineering and director of the Center for Watershed Studies at Virginia Tech, explains that a bay-wide TMDL and watershed-improvement plan would be an enormous undertaking. Virginia Tech, however, has a considerable amount of experience dealing with water quality, such as the university's interdisciplinary project to reduce nutrient loads in the Opequon Creek Watershed that flows into the bay. Benham adds that the center “is well positioned to use its TMDL-related watershed modeling and watershed-management planning research and outreach expertise to contribute to the development of a bay-wide TMDL.”

Agblevor's pyrolysis unit

   

Foster Agblevor's pyrolysis unit Foster Agblevor’s transportable pyrolysis unit -- which converts poultry litter into biofuel and other by-products -- can be moved from farm to farm on the back of a large truck.

Other Chesapeake Bay research

   

Native Chesapeake Bay oyster At one of Kurt Stephenson’s project sites in Maryland, this native Chesapeake Bay oyster (Crassostrea virginica) is ready to harvest. These oysters grow from microscopic-sized seeds to three or four inches in an average of 18 months, about half the time that such growth requires in the wild. The disease mortality rate is lower in an aquaculture setting, and healthier oysters mean more water filtration.

Podcasts

Listen to Katherine Knowlton, professor in the College of Agriculture and Life Sciences, speak with reporter Gabrielle Minnich on efforts to protect the Chesapeake Bay.

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