story to find out more.
An ARS soil
scientist collects bottom sediments from a constructed wetland. This wetland,
located alongside a crop field, removes nitrate and sediment from field
drainage water so they won't end up in streams. In dry years, water from the
wetlands can be recycled back onto fields to boost yields. Click the image
for more information about it.
Bringing Wetlands to the Farm
By Luis Pons
August 21, 2006
Most farmers and ranchers aren't near any wetlands, which are nature's
tool for filtering impurities out of waterwaysand would help keep excess
crop nutrients and livestock waste out of rivers and streams.
That's why scientists at the
Plains Soil, Water and Plant Research Center of the
Agricultural Research Service in
Florence, S.C., are exploring the use of constructed wetlands as a way to bring
these natural filters to farmers.
According to Florence research leader
Hunt, the constructed-wetlands studies are in keeping with the center's
mission to anticipate, identify and solve natural resource problems in
agriculture that are important to the United States in general, and to the
Southeast Coastal Plain in particular.
The Florence lab addresses a problem unique to its region: the fact
that soils in the Southeast Coastal Plain are very sandy and hold very little
water. This makes runoff from farms and livestock operations an especially big
problem that has grown over the past decade as animal production has
Constructed wetlands have been used for decades for municipal
wastewater treatment. They work on the principle of denitrification, a process
in which microorganisms convert nitrogen thats in plant-available form
into an inert gas. In studies, Hunt, soil scientist
Szogi, agricultural engineer Kenneth Stone and other Florence researchers
have found that constructed wetlands can remove about half of the total
suspended solids in water and about 60 percent of the nitrogen.
According to Hunt, the keys to constructed wetlands systems are marsh
plants, aeration and drainage. The wetlands system must have a sloped bottom
and shallow water at the entry point. The shallow water assures crucial
interaction with oxygen.
about this research and other ARS projects related to a healthy environment in
the August 2006 issue of Agricultural Research magazine.
ARS is the U.S. Department of
Agricultures chief scientific research agency.