Trouble is, the use of poultry litter has come under intense scrutiny amid environmental concerns. Not surprisingly, nutrient management was a major topic of discussion during the American Forage and Grassland Council’s (AFGC) national tour in northwest Arkansas in May.

By utilizing waste from the poultry industry, farmers in the region have been able to grow hay on marginal land that would otherwise produce little, if anything, else.

“Poultry litter has allowed us to grow grass on a rock,” Nathan Slaton, a University of Arkansas (UA) professor of soil fertility, remarked during the tour.

For many hay growers, poultry litter is an affordable alternative to commercial fertilizer. But in the 1980s, its use started to raise some red flags.

Downstream in Oklahoma, state and local governments identified phosphorus pollution as a threat to domestic water supplies and scenic rivers. Poultry operations and municipal wastewater treatment plants in northwest Arkansas became the target of lawsuits.

“Our downstream neighbors came to us and said, ‘Hold on, you’re leaking,’” Johnny Gunsaulis, UA extension agent for Washington County, told producers attending the tour. “We had to make a few adjustments.”

Today, all poultry farms in Arkansas must have a nutrient management plan.

Poultry litter is still used, but not as much. It has virtually been eliminated in some sensitive watersheds.

In the past, application rates for poultry litter have been based largely on the forage crop’s nitrogen needs – but that had a tendency to result in an overapplication of phosphorus.

While intensive hay production can reduce levels of soil nitrogen and potassium, phosphorus removal is primarily impacted by forage yield and phosphorus concentrations, said Robert Seay, UA extension agent for Benton County. Consequently, soil phosphorus levels continue to increase with poultry litter applications.

Alfalfa can help reduce soil phosphorus levels, Seay said. Unfortunately, there isn’t much of it grown in northwest Arkansas because of its deep rooting requirements. Fescue and bermudagrass are the top forage crops.

One local hay producer established alfalfa on land surrounding a municipal wastewater facility near Rogers, Arkansas, where biosolids applications had been made for years. (Editor’s note: Read more about this project in an upcoming issue).

After five crop years, soil phosphorus levels were reduced by 800 pounds per acre, Seay reported.

Farmers, regulators and researchers all want to get a better handle on exactly how much runoff of phosphorus and other nutrients is occurring in the region.

There have been reports of the Environmental Protection Agency collecting water samples on some farms without permission.

The University of Arkansas, on the other hand, is working directly with a select group of farmers to compile some hard data.

Poultry and cattle producer Jeff Marley volunteered to participate in the Arkansas “Discovery Farm” program.

The 540-acre river bottom farm near Elkins was one of the last stops on the AFGC tour.

Most of the litter removed from Marley’s 10 chicken houses each winter is sold as fertilizer and hauled off to farms in Kansas and Oklahoma. He keeps a small portion to fertilize about 350 acres of pasture and hay ground.

Marley allowed the university to install three flumes just below his chicken houses to collect runoff. Researchers plan to analyze the runoff and examine how farm ponds can collect and store nutrients.

They’ll also look at how grass filter strips might be used to reduce sediment and nutrients from entering nearby streams.

“I’ve got two miles of riverfront and am very conscious about promoting a positive image in the cattle and poultry industries,” Marley told visitors in May.

The Discovery Farm program wouldn’t work without the cooperation of progressive farmers like Marley, UA researchers said.

The purpose of the program is to empower producers with real data. If the data reveals a problem, producers can take steps to correct it. If there’s not a problem, they’ll have concrete numbers to counter any accusations that they’re doing something wrong.

“If there isn’t a problem, that’s good information in and of itself,” said Andrew Sharpley, professor of soils and water quality. “We don’t go in expecting a problem.”

Regulators tend to depend too much on computer models, he said.

Computer modeling can be a useful tool for analyzing watershed runoff if used properly, but it’s no substitute for collecting hard data, Sharpley said.

“I think people tend to use models beyond what they were intended for,” he said. “We need to use them, but use them sensibly.”  FG

Wilkins is a freelance writer based in Twin Falls, Idaho.

Study eyes biomass yield, nutrient removal
Poultry litter has the potential to fertilize more than just hay fields. Researchers at the University of Arkansas used poultry litter to fertilize switchgrass and sorghum – two potential feedstocks for advanced biofuel refineries.

The main objective of the study, now in its final year, is to determine how poultry litter applications affect biomass yield and soil nutrient removal.

In research trials at Fayetteville, Arkansas, and Haskell, Oklahoma, scientists found that switchgrass did not remove large amounts of macronutrients and usually exhibited only intermediate biomass yields.

Biomass sorghum, on the other hand, showed very high potential for both biomass yield and macronutrient removal.

“In Fayetteville, sorghum was much better able to extract nutrients from the soil than was switchgrass,” said Charles West, a former UA professor who now teaches at Texas Tech.

“We think the litter makes more sense on the sorghum because it responds to it and takes up more phosphorous,” he said.

While sorghum may remove more nutrients from the soil, switchgrass has more potential as a biofuels feedstock, he said.

Perennial grasses have two big advantages over sorghum: They’re cheaper to produce because they don’t have to be established every year, and they have lower water content at harvest.

Still, it’s unlikely that a biorefinery will ever be built in northwest Arkansas, West said. There just isn’t a high enough concentration of arable land.

“It’s too hilly and rocky to support large-scale row crop production,” he said.