Nearly two out of every 10 acres of Maryland farm soil contains excessive phosphorus, a nutrient blamed for the Chesapeake Bay’s poor health, according to preliminary data the state agriculture department revealed Monday.
The report is a significant step by the state to detail the pollution that washes into waterways from farmland, the single largest source of Chesapeake Bay pollution.
Phosphorus, along with nitrogen and other nutrients used to fertilize crops, is a detriment to the bay's health because it helps create algae blooms that block sunlight and suck oxygen from the water when they decompose.
The report found the heaviest phosphorus loads at farms in Wicomico, Worcester and Somerset counties on the lower Eastern Shore, where slightly more than half of farmland has levels considered excessive. Phosphorus levels are so high on 11 percent of the land there that farmers are banned from applying any more.
Statewide, 18 percent of farmland has high levels of phosphorus, including 1 percent that is subject to immediate ban of phosphorus treatment.
The Maryland Department of Agriculture released the data because new regulations require farmers and the consultants they hire to report soil nutrient levels to the state.
The data is incomplete, however. Officials have received information on about 70 percent of Maryland’s 1.3 million acres of farmland. The data is least complete on the lower Eastern Shore, where phosphorus loads are highest. Information for only about half the farmland there has been reported to the state.
In a statement, a coalition of environmental groups said they were pleased the state released the data but that the figures raise concerns about the impact of chicken manure on the environment. The groups — the Chesapeake Bay Foundation, Food and Water Watch and the Maryland Clean Agriculture Coalition — said the data support their arguments in favor of a bill in Annapolis that would make poultry companies responsible for removal of chicken waste.
An official with Delmarva Poultry Industry Inc., a nonprofit group representing chicken farmers, could not be reached for comment.
The state is using the data to determine which farmers must use a new method to calculate how much phosphorus they can use, said Hans Schmidt, assistant secretary for resource conservation at the state agriculture department. All farmers must test their soil and use the data to determine how much fertilizer they can use, but under new regulations, they must use a new calculation tool if their soil hits a phosphorus benchmark that indicates high levels.
The new tool takes into account information on croplands' sub-surface drainage and distance to bodies of water, in addition to the soil phosphorus levels, to guide fertilizer usage.
The data shows that 82 percent of farmland has levels low enough that it is not subject to the new method, state agriculture officials said.