USDA Has Designs for Baltimore Harbor's "Spoil-to-Soil" Recycling

BELTSVILLE, Md., Oct. 14--Poultry litter might be just the rich organic material the Maryland Port Authority needs to help turn harbor dredge spoils into a first-class soil substitute for land reclamation and other uses, says a U.S. Department of Agriculture scientist.

The Port Authority, through the Maryland Environmental Services Department, has signed an agreement with USDA's Agricultural Research Service to find new ways to recycle the 5 million cubic yards of dredge spoils removed each year from the Port of Baltimore and its estuarine tributaries.

"Dredge spoils have a head start on becoming soil substitutes," said microbiologist Patricia Millner in Beltsville, Md. "That's because the material originated as soil eroded from the land and deposited on lake, ocean, bay and river bottoms."

"But, over the years," Millner adds, "organic matter in this sediment is washed out." Millner heads the research team at ARS' Soil Microbial Systems Research Laboratory. The scientists are considering poultry litter as a potential ingredient in the soil substitute recipe. Maryland produces an estimated 339,000 tons of poultry litter a year.

The spoils have two other problems besides lacking organic matter. "They pick up salt from seawater that enters the estuaries. And the spoils become highly acid when removed from the water and exposed to air," Millner said.

To counteract the salinity, she said, scientists at the Beltsville lab will search for ways to leach out the salts so the spoils can be applied to land. To reduce the acidity, they will test gypsum, calcium-rich ash from electric power plants, and residues from concrete and lime manufacturing. "This would help Maryland turn another potential environmental problem into a valuable resource," Millner said.

The University of Maryland's Wye Institute will field-test recommendations expected to emerge from the spoil-to-soil experiments in the next two or three years.

Scientific contact: Patricia D. Millner, research leader, Soil Microbial Systems Laboratory, Agricultural Research Service, USDA, Beltsville, Md., (301) 504-8163, fax (301) 504-8370, pmillner@asrr.arsusda.gov.