...From the pages of Agricultural Research magazine
Don't Waste This Stuff!
Alum-based drinking water
treatment residuals have a
high ability to bind
phosphorus because they
contain high concentrations
of aluminum oxide and
ARS studies have found that residue
from water-treatment processesoften discarded as waste into landfillsmay
make good soil treatments for preventing phosphorus loss in runoff from
At ARS's Coastal Plains Soil, Water, and Plant Research Center in Florence,
South Carolina, soil scientist Jeffrey M. Novak is studying an alum-based
water-treatment residual that increases soil's capacity to adsorb (bond)
phosphorus, a vital plant nutrient. Increased adsorption of phosphorus
would curb its runoff, which can lower the oxygen content of water bodies
and spoil the taste of drinking water.
Manure is laden with phosphorus, making agricultural facilities such
as large livestock production operations potential sources of phosphorus
pollution. Farmers commonly spread manure on their lands, a practice
that often results in excess phosphorus being applied. But transporting
the manure off site is cost-prohibitive.
Novak says the studiesbeing done in collaboration with Ray Bryant, research leader at ARS's Pasture Systems and Watershed Management Research Unit in University Park, Pennsylvaniamay benefit states along the nation's mid- to southern Atlantic seaboard. "This region has sandy soils that generally adsorb less phosphorus than finer-textured soils," says Novak.
High Phosphorus-Binding Capacity
Novak says chemically binding phosphorus into water-insoluble complexes
by using water-treatment residuals containing iron-oxide, aluminum-oxide,
and hydroxide may become an important management practice. "The
alum-based water-treatment residual this research focuses on has a high
Separate researchconducted on wheat by agronomist Eton Codling
at ARS's Animal Manure and Byproducts Laboratory in Beltsville, Marylandhas
found that the treatment has no negative effect on plant absorption
of phosphorus once plant roots grow beyond a 6-inch-deep layer the treatment
creates in soil.
In previous independent studies, phosphorus runoff was reduced through
direct application of the alum-based residual onto fields recently treated
with manure. "But we set out to actually bind more of the phosphorus
in soils that, like sandy coastal plain soil, have a low adsorption
capacity," says Novak.
The lab tests "produced striking results," he says. "We
were able to increase phosphorus-binding potential four- to fivefold,
as compared to untreated sandy soil. This suggests that incorporating
the residuals into sandy soils has great potential as a chemical-based,
best-management practice to reduce off-site phosphorus transport."
The lab studies will be repeated and additional research done in the
field over the next 2 years. If successful, this use for waste from
the water-treatment process not only could get rid of the waste, but
would also hold phosphorus on the land until a crop can use it.By
Agricultural Research Service Information Staff.
This research is part of Water Quality and Management (#201) and
Soil Resource Management (#202), two ARS National Programs described
on the World Wide Web at www.nps.ars.usda.gov.
Jeffrey M. Novak
is with the USDA-ARS Coastal
Plains Soil, Water, and Plant Research Center, 2611 West Lucas St.,
Florence, SC 29501-1242; phone (843) 669-5203, ext. 110, fax (843) 669-6970.
"Don't Waste This Stuff! Water-Treatment Residue May Help Ease an Environmental Concern" was published in the July 2004 issue of Agricultural Research magazine.