By Catherine Clabby

In a surprising conclusion, a new report finds North Carolina poultry farms generate far more nutrients in manure than do hog farms.

The report, produced by the state Department of Environmental Quality, concludes poultry growers produced 56.6 million pounds of nitrogen and 79.8 million pounds of phosphorus in 2014. That amount is three times the nitrogen and six times the phosphorus produced statewide by swine operations in the same year, the DEQ estimates.

Nitrogen and phosphorus are valuable fertilizers when well managed, but they become pollutants when they seap or wash into groundwater, streams or rivers.

But the extent to which that may be happening in North Carolina cannot be determined, the report stresses. That’s because the state Department of Environmental Quality does not monitor waste disposal at the vast majority of poultry farms across the state.

Poultry farms in North Carolina that raise more than 30,000 birds and produce dry litter are “deemed” permitted when it comes to manure disposal, as long as they follow rules that forbid over-applying the waste to farmland, among other things.

“[That] adds significant uncertainty to assessment of the loading contribution of poultry to the state’s nutrient-impaired water bodies,” says the report. It was presented Wednesday to the water quality committee of the state Environmental Management Commission by Heather Patt, a DEQ river basin water quality planner.

Managing nutrients in river basins

DEQ regulators work to limit how much nitrogen and phosphorous wash into state waterways because the federal government requires it. The nutrient management rules in North Carolina river basins are intended to help the state comply with the federal Clean Water Act.

map shows dense spots representing poultry farms in three major regions of the state: southeast, central piedmont and the Appalachian foothills.
Data & map courtesy: NC DEQ, NCDA&CS

Municipal sewage treatment systems, developers whose projects can create soil erosion and farmers are all expected to collaborate to reduce direct discharges of nutrients into waterways in river basins with elevated levels.

But poultry farms are not part of this process in North Carolina because state environmental regulators know so little about their operations in North Carolina river basins, including where most are located.

The new report uses federal county-level animal census data as well as manure production formulas to work up estimates to fill in the blanks in state regulators’  knowledge. It concludes that poultry operations in 2014 produced more nitrogen and phosphorous than swine statewide and in river basins with elevated nutrient levels.

chart showing many times the amount of nitrogen and phosphorus produced by poultry than swine in six river basins
PAN stands for plant-available nitrogen; P205 stands for phosphorous. Table courtesy: NC DEQ

Excessive nitrogen and phosphorus can promote algal growth, including the profusion of toxic algae, which can be harmful to people. Large algal blooms reduce or eliminate oxygen in water, sometimes killing large numbers of fish.

“[The report] gives the opportunity to put this waste in perspective,” said Steve Tedder, a former DEQ water quality official who sits on the water quality committee of the state Environmental Management Commission.

After the release of the DEQ report Wednesday, officials with the North Carolina Poultry Federation and the North Carolina Department of Agriculture and Consumer Services stressed that poultry farmers are obliged to follow rules regarding waste management and they do.

“Poultry farmers have a professional nutrient management plan that’s custom designed for land application of poultry manure/litter on their farm depending on amount of nutrients needed for crop or pasture production,” said Robert L. Ford, executive   director of the poultry federation.

Pressure on poultry

Poultry farmers are one link in what is now the largest agricultural industry in this state.

As the poultry industry has grown, North Carolina environmentalists have been pressuring state regulators for tighter monitoring and regulation of the disposal of waste from poultry  farms, something that is occurring in other Southeastern states with large poultry sectors.

Dry chicken manure frequently is disposed of by getting spread on fields as fertilizer. If applied above the levels where plants can use it, which state rules forbid, the manure and its nutrients can be blown or washed into waterways.

The DEQ report cites potential pollution from poultry waste.

“[N]utrient contributions from swine operations have remained fairly constant over the last several years,” the report states. “However, the shifts in both location and the type of poultry industry in NC is potentially adding to the current nutrient loading from nonpoint sources.”

“This adds to the concerns over environmental impacts of manure application on a limited land base.”

The new DEQ data are a good step to shedding more light on the intensity of manure productions in the state’s river basins, said Will Hendrick, an environmental attorney with Waterkeeper Alliance. But closer scrutiny of poultry manure impacts are needed, he said.

“DEQ’s effort is appreciated, but the lack of information available to the agency is more notable than the agency’s conclusions,” Hendrick said. “I’m glad they’re not turning a blind eye to this issue, but unfortunately they’re still wearing blinders.”

map shows different levels of poultry estimates for each river basin
The highest numbers of poultry since the 1990’s have been in the Yadkin-Pee Dee and Cape Fear basins. The Yadkin-Pee Dee Basin had the highest poultry population with bird inventories over 15 million in Union County and over 11 million in Wilkes County in 2014. Map, data courtesy: NC DEQ

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Catherine Clabby

Catherine Clabby (senior environmental reporter) is a writer and editor. A former senior editor at American Scientist magazine, Clabby won multiple awards reporting on science, medicine and higher education...