Managing Nutrients for a Better Environment

Nitrogen and phosphorus are essential to plant growth. Without them, we'd have no crops, flowers or trees. But when nutrient levels in the soil exceed what plants can absorb, environmental problems can develop.
Richard Neff Owner, Neffdale Farms, Lancaster County

Richard Neff Owner, Neffdale Farms, Lancaster County

"I've been able to use Penn State information to make a lot of environmental improvements on my farm. Now we're working together to design a wildlife habitat along the creek to help prevent erosion."

Animal manure is an excellent source of nitrogen and phosphorus, and many dairy, beef, poultry and hog farmers routinely apply it to their fields to provide crops with essential nutrients and build reserves in the soil. But if manure is applied to the same land too frequently, or over-supplemented with commercial fertilizers, more nutrients can accumulate in the soil than the plants can absorb. Unabsorbed nitrogen can leach down through soil and contaminate groundwater as nitrates, which may be harmful to young children and livestock. Excess phosphorus can run off into streams and rivers that feed resources such as the Chesapeake Bay.

To address environmental concerns, recently enacted state legislation and increased federal oversight require many farmers to develop and implement agency-approved nutrient management plans. Generating these plans requires special knowledge -- soil nutrient amounts can vary widely from farm to farm and field to field -- and implementing the plans can add production costs that often are not recovered in the value of agricultural products. Farm operations with heavy concentrations of animals, for example, face an expensive and difficult challenge finding ways to responsibly use, store or dispose of surplus manure.

Penn State's College of Agricultural Sciences research and extension specialists develop, evaluate and share new nutrient management techniques with the agricultural and environmental communities. New strategies also are being taught to undergraduate and graduate students through course work, internships and research projects.

The Payoff

Science-based legislation

As Pennsylvania was developing criteria for new nutrient management legislation, Penn State research demonstrated that the greatest challenges to water quality and best opportunities for environmental benefits could be achieved by focusing on animal operations where the manure produced is in excess of crop needs. The effect of the researchers' involvement was that state-certified nutrient management plans are required only from those operations with more than 2,000 pounds of live animal weight per acre, rather than from all Pennsylvania farms. Even so, many more farms voluntarily are developing and implementing nutrient management plans.

Management training and expertise partnerships

Penn State helps farmers meet nutrient management standards by developing tools -- from publications and fact sheets to computer models for managing nutrient applications -- and holding workshops to teach new management methods. Through a program supported by the National Pork Producers Council, for example, extension specialists have conducted educational audits of more than 130 Pennsylvania swine operations comprising more than 275 thousand hogs to help identify the strengths and weaknesses of environmental initiatives. The specialists found that nearly 90 percent of producers already met the environmental standards set but were anxious to learn about additional improvements that could be made. Extension programs also teach farmers and crop consultants how to write state-certified nutrient management plans. Other programs provide decision makers with the information they need to know to review and approve those plans. By the fall of 1998, 292 farmers, consultants and agency personnel had been trained and passed the state examinations required for certification.

A farmer-friendly phosphorus "score card"

Until recently, nitrogen was the primary nutrient of environmental concern. Now, because of a possible link between Pfiesteria and fish kills in Maryland and North Carolina, phosphorus is getting more public attention. Penn State's research and extension programs are educating people about phosphorus so that future nutrient management policy is based on sound science. Because most of the agricultural phosphorus that enters waterways comes from limited areas within watersheds, Penn State and USDA's Agricultural Research Service are developing a "phosphorus index" to help farmers identify hot spots with the highest potential for phosphorus loss. By focusing on these areas, farmers can maximize efforts to control phosphorus in a way that's practical and economically feasible.

What goes in, comes out

What farmers feed their animals affects what nutrients come out in manure. Nitrogen in poultry and swine manure can be reduced by feeding the animals a lower-protein diet. Phosphorus in manure may be reduced by adding an enzyme to feed that helps some animals utilize phosphorus more efficiently. Because an animal's environment also can affect the amount of nutrients it excretes, researchers are using a modified lighting program to prevent hens from drawing calcium from their bones when making eggshells -- a process that releases phosphorus into urine.

Field trials find answers. Penn State scientists continually conduct extensive field trials of different nutrient management methods to find those that can reduce nutrient use without reducing crop yields. One research project demonstrated that 40 percent less nitrogen could be applied to corn crops without reducing the harvest. Researchers also have developed soil and plant tests to determine whether or not plants are adequately supplied with the nitrogen they need.

Combining wastes. Sometimes the only fix is to move manure to another location where excess nutrients are not already present in the soil. Because manure is expensive to handle, agricultural specialists are exploring ways to make it more manageable. A project that combines manure with food waste from Penn State dining facilities and municipal leaf and yard waste produces a compost that can be recycled back into flower beds and gardens. This program demonstrates how farmers can work effectively with their urban neighbors to combine wastes and create a product that is desirable and environmentally friendly.

The College of Agricultural Sciences nutrient management programs are a collaborative initiative among the Departments of Agronomy, Agricultural and Biological Engineering, Agricultural Economics and Rural Sociology, Dairy and Animal Science, Horticulture, Plant Pathology, Poultry Science, and Veterinary Science; the School of Forest Resources; and Penn State Cooperative Extension. For more information, contact Dr. Steven Fales at (814) 865-6541.