Soil fertility specialist Les Lanyon talks with Brent Harner, owner of B & J Pork Production, about the challenges producers face. Keeping phosphorus in place is just one.

During the late 1800s, manure was so valuable a source of nutrients for 'worn out' soils that the Pennsylvania Supreme Court made it part of the property of a farm. While the British gleaned the battlefields of Europe to recover phosphorus from the bones of dead soldiers, U.S. fertilizer companies attempted to recapture phosphorus and other nutrients from waste streams, such as slaughterhouses. Today, the situation is reversed: excesses of nutrients, particularly nitrogen and phosphorus, threaten water quality in many areas.

"In today's global marketplace, Pennsylvania agricultural operators are challenged to produce commodities competitively," says Doug Goodlander, director of nutrient management for Pennsylvania's State Conservation Commission. "We're seeing more and more intensive farms out there every year. As operators raise more animals on smaller acreages, they're challenged to find an appropriate location to use excess manure. It's also a challenge to assure communities that they can co-exist with these types of operations -- especially in areas where people aren't accustomed to intensive animal agriculture."

In 1993, Pennsylvania passed the Nutrient Management Act, the first state law that requires concentrated animal operations -- those with more than 2,000 pounds of animal per acre -- to develop and implement nutrient management plans. The act is overseen by the State Conservation Commission. These plans focus on applying manure to manage nitrogen, while phosphorus is addressed through soil conservation practices. But in areas with increased concentrations of livestock or poultry, phosphorus is becoming more of a concern.

Agronomist Doug Beegle, one of the Penn State scientists working on the phosphorus issue, believes a clean environment will not come without a price.

"Phosphorus pollution has always been a concern," explains agronomist Doug Beegle, "but we worried more about nitrogen because of the direct health effects of high nitrates in water. Also, nitrogen is a lot harder to manage. Nitrogen leaches, it runs off -- it can even go up in the air as a gas and come back down someplace else. Phosphorus, on the other hand, binds tightly to the soil. We figured if we stopped runoff and erosion, phosphorus would pretty much stay in place. But we've since learned that when phosphorus builds up to very high levels in the soil, it can wash off, too."

When excess phosphorus enters surface waters, it accelerates eutrophication -- the natural aging of waters. The phosphorus stimulates blooms of algae and undesirable weeds. When those plants die, their decomposition decreases the oxygen available for fish and other creatures. In a natural setting, eutrophication should take hundreds of years. With phosphorus pollution, it can take place in decades. "The Environmental Protection Agency considers eutrophication from phosphorus to be the major problem in surface waters in this country," says Beegle.

Recently, because of the possible link between outbreaks of the toxic algae Pfiesteria piscicida and fish kills in the eastern U.S. -- particularly in the Chesapeake Bay tributaries -- phosphorus runoff is getting more public attention. Also, people exposed to a volatile toxin from Pfiesteria can suffer neurological damage, such as memory loss and confusion. In response, Maryland passed legislation that requires phosphorus-based nutrient management plans. The federal government also recently set national standards for nutrients, the USDA-EPA Unified National Strategy for Animal Feeding Operations. Farmers will need to control manure application by balancing nutrients from all sources -- soil, manure, biosolids, and fertilizers -- for the planned crops, emphasizing phosphorus as well as nitrogen.

"We know much more about phosphorus today than we knew just five years ago, says Karl Brown, executive secretary for the State Conservation Commission. "The science is evolving. With soil scientist Andrew Sharpley of the USDA-Agricultural Research Service, Doug Beegle, and others at Penn State, the state is revisiting phosphorus so that we can look at it intelligently and, if need be, make a decision about where to go from here."

In 1988, Lancaster County, with the highest dairy cow population per square mile in the United States, produced enough manure to spread 27 tons on every acre of cropland in the county. "When you get out of Lancaster County, to the other side of the state, farmers have to buy fertilizer," says soil scientist Andrew Sharpley. "Manure isn't moving more than 20 or 30 miles from where the animals are reared. It's just too costly to transport."

Currently, farmers apply manure to croplands based on the amount of nitrogen the crop needs. Planning for phosphorus complicates the issue because the ratio of phosphorus to nitrogen in manure doesn't match the ratio of nutrients needed by crops. When farmers calculate nutrient management plans based on nitrogen, they end up applying up to four times too much phosphorus. "In an ideal world, we'd calculate how much manure to spread on cropland based on how much phosphorus the crop will use -- then add nitrogen fertilizer," says Beegle. "But this has many practical problems."

Right now, phosphorus is a concern in localized areas, but the problem will spread if manure continues to accumulate. "Where once we had two or three poultry farms in the Delmarva peninsula, we now see literally hundreds," says Sharpley. "These farms generate more manure than the available acreage can handle. And where you have the farms, you get the feed mills, processing plants, and market distribution infrastructure, which attracts even more farms. It's economically cheaper to be near the center of the industry. So farms concentrate, and phosphorus accumulates.

"Ultimately, we'll need to make manure into a product or find some way to move it from areas like the Delmarva peninsula, or areas where there are a lot of pig farms, like southeast Pennsylvania or northwest Arkansas, and get it to places where farms need phosphorus to grow their crops. Meanwhile, we're working on ways to minimize the impact.