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Paul Davidson, who did the research as a senior in agricultural
and biological engineering, won the Undergraduate Student Paper
Competition from the Water Environment Federation in Washington,
D.C., as well as the regional competition in Rochester, Minn. He
was also awarded first place in the 2005 Undergraduate Student
Poster Competition of the American Society of Agricultural and
Biological Engineers in Tampa, Fla. Earlier research from the
U of I had shown that a wood chip biofilter reduced the
concentration of nitrogen (nitrate-N) in water draining from
field tiles. Under normal conditions, bacteria in the soil
naturally break down nitrates. A biofilter provides an organic
carbon source, such as wood chips, which the bacteria feed upon.
This allows the bacteria population to grow. And more bacteria
break down more nitrates.
Davidson wanted to know if concentrations of herbicides, such
as atrazine and alachlor, were also reduced with the use of a
biofilter. So he placed the biofilter in a number of soil
columns, and over a six-week period he applied six different
combinations of the three chemicals, using different soil types
and placing the filters at different depths. Two soil columns
had no biofilter.
While there was little difference in the columns with no
biofilter, runoff from the columns with biofilters showed a
significant reduction in not only nitrate-N, but atrazine and
alachlor as well. Nitrate-N was reduced from 25 parts per
million to 0, atrazine went down from 25 parts per billion to
0.5, and alachlor went down from 25 parts per billion to 0.
"Depth made a slight difference but nothing significant,"
said Davidson, "so biofilters placed at any depth should have
satisfactory results." Reductions in the contaminants were
also consistent across soil types.
[to top of second column] |
 Davidson was also intrigued by some results of his study that he
feels should be reviewed and investigated further.
He found that when all three contaminants were mixed in
combination and applied in the presence of only the biofilter, the
nitrate-N still showed a significant reduction in concentration,
from 25 to 4.6 parts per million, and atrazine and alachlor both
reduced from approximately 25 parts per billion to 3.27 and 2.41
parts per billion, respectively.
This finding could affect the method of application for
agricultural chemicals.
"We need to run the tests again to confirm those results,"
Davidson said. "But if it's true that the nitrate-N concentration is
reduced in the presence of atrazine and alachlor, you'd want to wait
a length of time between applying your anhydrous and applying your
atrazine or alachlor. Otherwise, they would react with your
fertilizer and you would reduce the effectiveness of your
fertilizer."
Prasanta Kalita, a professor of ag and bio engineering, had high
praise for the young researcher.
"Paul worked night and day on this project," said Kalita. "We
like to encourage the brilliant students in this type of study. Not
everyone has the dedication to do research like this."
"I've never conducted research or written a research paper,"
Davidson said, "so this definitely helped me prepare for grad
school. It was a great experience."
[University
of Illinois College of Agricultural, Consumer and Environmental
Sciences news release] |
