Chicken litter
Photo: Dodo-Bird 
Chickens might seem harmless, but their waste isn’t. Throughout much of the country, farmers nourish the birds with phosphorous-enriched chickenfeed. That, in turn, creates loads of phosphorous-rich manure, which is problematic because the nutrient eventually makes its way into waterways, polluting them.
But thanks to the efforts of a number of scientists and state officials, less phosphorus is ending up in lakes and streams in Delaware, one of the top 10 poultry-producing states in the country. The key to their success has been cutting the amount of phosphorus in the birds’ food.
Phosphorus from chickenfeed can’t be blamed for all of the excess nutrients that end up in Delaware’s waterways, but it does have an impact. The state produces more than 300,000 tons of manure, one-third of which researchers and state agencies consider excess based on how much is produced compared to how much grain farmers in the state require.
For decades farmers applied the waste directly to the land as fertilizer—a practice that over time caused excess nutrients to build up in the soil and run off into waterways. Once in the water, the nutrient spurs the growth of algae, an overabundance of which can deplete oxygen, creating a toxic environment for fish and other aquatic creatures.
“Agriculture has been looked at first and foremost as a source of these nutrients,” says William Saylor, a professor of animal and food sciences at the University of Delaware. Saylor also advises the Delaware nutrient management commission, a group of farmers and government employees who implement the state’s regulations on phosphorus and other nutrients.
Most chickenfeed contains phosphorus because poultry need it to grow strong bones. However, chickens can’t digest all phosphorus and about half of it goes right through the animal, ending up in litter.
“The dilemma is that phosphorus has a black eye because of the environmental implications, but phosphorus is required for all forms of life and in the diets of all animals,” says Saylor.
The 1999 Nutrient Management Law required Delaware officials to look for ways to reduce nutrients like phosphorus and nitrogen that end up in waterways. One solution they found was to add an enzyme called phytase to chickenfeed. The enzyme breaks down the compound that contains phosphorus, helping the animals absorb the nutrient instead of just expelling it.
As a result, farmers can reduce the amount of phosphorus they feed their chickens, saving some cash while lessening the impact of their livelihood on the environment.
Farmers first made the switch in 2000, and members of the commission say the water quality has already started to improve.
“We’re getting close to a balance,” says William Rohrer, Jr., administrator of the commission.
Reducing the phosphorus in chicken manure has made a difference, but the waterways won’t be completely healthy for years, according to Thomas Sims, the associate dean of the University of Delaware’s College of Agriculture and Natural Resources and a researcher who also works with the commission.
“Modifying the diets was a big step in the right direction,” he says, “but people need to be patient.”
The commission is taking several other steps to stem the flow of phosphorus and other nutrients into Delaware’s lakes and streams. These include sending manure to a plant that grinds up raw litter and molds it into pellets that look like rabbit food. The certified organic product is then sold as fertilizer. Manure is also trucked to commission-approved farms in Maryland, New Jersey, and Virginia that use the manure as a fertilizer. Delivering the nutrients to places that need them prevents one area from becoming oversaturated with phosphorus. Some even goes to mushroom farms in Pennsylvania.
So far, these programs have reduced the amount of poultry manure by 80,000 tons; the state’s goal is to cut the load by 100,000 tons by the end of 2007. Results will be in by next spring.
Despite their success, the researchers are looking for even more ways to decrease the impact of chicken waste on the environment.
“There are a lot of other opportunities in making changes to the way we feed the animal so that we have less phosphorus in the environment,” says Saylor. “Over the long haul we will see that there is less phosphorus in the waterways.”
Story by Susan Cosier. This article originally appeared in "Plenty" in August 2007.
Copyright Environ Press 2007
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