Nearly one in five acres of Maryland farmland has enough phosphorus in its soil to potentially threaten local waterways and the Chesapeake Bay, according to new state data released Monday. 

Soil sampling results collected since last summer by the Department of Agriculture show that about 18 percent of all fields statewide have elevated phosphorus levels. And on the lower Eastern Shore — in the heart of the state’s poultry industry, where phosphorus-rich chicken manure is widely used as fertilizer— data indicate that two out of every three farmed acres have high enough levels of the plant nutrient to pose a risk to water quality.

While more analysis is needed, the phosphorus concentrations in those farm soils are such that at least some of the plant nutrient could be seeping or running off the land and feeding the Bay’s algae blooms and oxygen-starved dead zones.

But the problem apparently is not as extensive or severe as earlier estimates made it out to be, state officials said. The sampling shows that 82 percent of farm soils statewide are low in phosphorus, they noted, and there is ample farmland even on the Eastern Shore where manure could safely be spread.

“Assumptions were made that phosphorus was higher than it is,” said Hans Schmidt, an assistant agriculture secretary and a mid-Shore grain farmer himself.

Spurred by warnings about elevated phosphorus levels in Bay tributaries, former Gov. Martin O’Malley had proposed new regulations that would restrict farmers’ use of animal manure as fertilizer on soils with elevated phosphorus levels.

O’Malley’s proposed rules imposing the new “phosphorus management tool” sparked fierce outcry in the poultry industry and among Shore farmers, who feared widespread disruption to their operations if chicken manure could no longer be routinely used as a cheap fertilizer for their crops.

The tool analyzes areas with excess phosphorus in the soil and identifies where the nutrient is likely to run off and affect water quality. New applications of phosphorus would be restricted or even forbidden in those fields.

Based on limited field sampling, scientists at the University of Maryland had estimated that 81 percent of lower Shore fields and 41 percent of upper Shore croplands had elevated phosphorus levels, making it problematic to keep fertilizing them with manure. As a result, state officials said that as much as 228,000 tons of poultry waste may no longer be safely spread on Shore farm fields. 

Gov. Larry Hogan, who had vowed to block the rules while running for election, promptly pulled them when he took office in early 2015. Under pressure from lawmakers and federal regulators, though, Hogan ultimately imposed similar regulations, albeit with a longer phase-in and assurances to farmers that their livelihoods wouldn’t be ruined.

The rules took effect last June, with an immediate ban on additional phosphorus applications to soils with the highest levels, and restrictions on other high-level soils phased in over the next six to eight years.

But the new data collected since last summer shows high phosphorus levels on 67 percent of lower Shore fields, on 23 percent of mid-Shore fields and just 10 percent of upper Shore croplands. The figures show that, 1 percent of all croplands statewide, and 11 percent on the lower Shore, have phosphorus levels high enough to warrant an immediate prohibition on additional manure applications under the new regulations.

State officials say the new soil sampling data will help them track farmers’ compliance with the phosphorus regulation and provide them with adequate financial and technical support.

“I think we can take a breather and say, ‘Yay! At least the problem’s not as big as we thought,’” said Valerie Connelly, executive director of the Maryland Farm Bureau. “That’s the best-case scenario for all of us, if the problem’s not as crazy as anticipated.”

Environmentalists stressed that soil test data has yet to be reported for 30 percent of the state’s croplands, including half of those on the lower Shore.

“It’s not surprising that the fields where it’s most concerning have reported the least,” said Alison Prost, Maryland director for the Chesapeake Bay Foundation.

“But even the preliminary results to me confirm that we do have a phosphorus problem,” she added, “and we’re going to need to figure out where these pounds are going to end up.”

The phosphorus data were released as lawmakers weigh legislation pushed by environmentalists that would require poultry companies to take responsibility for manure produced by the birds grown under contract to them.

As it is now, contract growers are left with the manure, and many either use it on their fields or make some money by selling it to another farmer. But the stock of nearby land where manure can safely be applied was expected to shrink with the advent of the phosphorus regulation, and environmentalists sought to put the onus on the industry to take any poultry “litter” — mixture of animal waste and wood shavings — that farmers can no longer use.

The Bay Foundation, Food & Water Watch and the Maryland Clean Agriculture Coalition contended in a statement Monday that the soil phosphorus data support the need for the legislation.

“The Poultry Litter Management Act would go a long way toward protecting clean water by making sure excess chicken manure is utilized or managed properly,” they asserted.

But many growers, poultry industry representatives and state agriculture officials oppose the bill as unwarranted and at least premature. They contend that until all the data are in on the extent of the soil phosphorus problem, it’s too soon to change the current setup, in which farmers can sell their manure directly or use a state-subsidized network to truck it to other parts of Maryland and even out of state.