Scientists Develop Phosphorus Index to Control Pasture Runoff
By Jim Core
April 11, 2001
Agricultural Research Service scientists
have developed a Phosphorus Index (PI) to help curb runoff when farmers
fertilize pastures or crop lands with animal manure. The research is already
improving the way farmers fertilize their fields in Arkansas and may lead to
more advanced techniques across the nation. Arkansas, a leading
poultry-producing state, began using the index statewide in February.
Previous studies show that poultry litter applications to pastures often
result in excessive runoff into nearby water bodies, according to Philip A.
Moore, Jr., a soil scientist with the ARS Poultry Production and Products Safety
Research Unit, Fayetteville, Ark. Eutrophication occurs when nutrients from
animal manure--especially phosphorus--are carried by water runoff to waterways,
forming blue-green algae and undesirable aquatic plants that rob water of
One resulting problem is rising municipal water rates, due to the cost of
eliminating taste and odor problems caused by algae. The lack of oxygen in some
bodies of water has even led to the death of fish and other aquatic life,
according to Moore.
Phosphorus is a crucial nutrient in the nations pastures, but its
impact on the environment doesnt always stop there. Researchers recognize
a connection between increased soluble levels of phosphorus in water and higher
levels in a watershed's soil.
The index can be used to predict the risk of phosphorus runoff from pastures
fertilized with animal manure or commercial fertilizers, according to Moore.
Poultry litter, a mixture of chicken manure, feathers, spilled food and bedding
material, is an inexpensive and popular fertilizer for crop land because the
manure contains nitrogen and phosphorus, two important fertilizer ingredients.
Several states use a soil test to determine the threshold levels at which
animal manures may no longer be applied. However, the index developed by Moore,
Paul B. DeLaune, a doctoral candidate in the
Department of Crop,
Soil and Environmental Sciences at the University of Arkansas in Fayetteville, and
other researchers now provides farmers with a risk-assessment tool to prevent
over-fertilization and actually predict phosphorus runoff.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.
Scientific contact: Philip A. Moore, Jr., ARS Poultry Production and
Products Safety Research Unit, Fayetteville, Ark., phone (501) 575-5724, fax
(501) 575-7465, email@example.com.