Designing the Best Possible Conservation
Buffers By Sharon Durham
December 1, 2003
Restored riparian wetland buffers retained or removed at least
60 percent of the nitrogen and 65 percent of the phosphorus that entered from
an adjacent site where manure was applied, according to results of a nine-year
study by Agricultural Research Service
scientists in Tifton, Ga., and cooperators at the University of Georgia.
This is the first time that a study of a restored riparian
buffer has shown that the retention of phosphorus was as high or higher than
nitrogen retention. Riparian buffer zones are areas of vegetation that act like
sponges, soaking up water and nutrients from the soil. Buffer zones also help
reduce soil erosion along downward slopes due to rain or irrigation, both of
which can cause surface runoff.
Ecologist Richard Lowrance of the ARS
Southeast Watershed Research
Unit, and engineer George Vellidis of the University of Georgia, found that
a particular type of buffercalled a restored zone 3 conservation
bufferis especially effective in removing excess nutrients from water
that runs off of agricultural fields where manure has been applied as a
fertilizer. A zone 3 buffer is a grassy edge that sits next to the field.
During the study, the amount of water and concentrations of
nutrients (nitrogen and phosphorus) in water entering and leaving the riparian
wetland were monitored. The stream flow concentrations of nitrogen and
phosphorus leaving the conservation wetland buffer were one-half (for nitrogen)
and one-quarter (for phosphorus) of the incoming concentrations in surface
runoff from adjacent fields.
Other Tifton scientists are conducting various conservation
buffer research studies that examine several different scenarios farmers
encounter. Ultimately, this research should help growers develop a way to lower
nutrients that make it to streams and waterways.
about this research in the December issue of Agricultural Research
ARS is the U.S. Department of
Agriculture's chief scientific research agency.