Two experimental drainage sites provide invaluable information on nitrate removal
By Janet Kubat Willette
jkubat@agrinews.com
Date Modified: 04/01/2010 9:17 AM
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DODGE CENTER, Minn. — Two Dodge County farm fields are test sites for
innovative new drainage practices in Minnesota.
At the Ed Smith site in Ellington Township, a woodchip bioreactor was
installed in September 2007. A controlled drainage experiment began at the
John Kruger site in Hayfield Township in spring 2007.
Research at both sites was discussed at a meeting earlier this month at
the Dodge County USDA Service Center in Dodge Center.
At the Smith site, the woodchip bioreactor is four feet deep and 270 feet
long. The trench is 10 feet long for every acre they are trying to treat,
said Jim Hruska, Dodge County Soil and Water Conservation District
technician. They are trying to treat 26 to 28 acres.
A tile line comes into the trench for 10 feet to 15 feet on both ends,
Hruska said. There is no tile in the middle of the bioreactor. The wood
chips are four to five feet deep with dirt on top.
If there is too much water, it bypasses the bioreactor and goes through
existing tile, Hruska said.
From March til mid-July 2009, two thirds of the water was treated and
one-third bypassed the bioreactor, said Andry Ranaivoson, a research
associate in the University of Minnesota Department of Soil, Water and
Climate. The water that went through the bioreactor had reduced levels of
ortho phosphorus, nitrate, nitrite and total phosphorus, Ranaivoson said.
It cost $19,900 to install the bioreactor, Hruska said. It was funded by
the Zumbro River Watershed.
The Smith site is in the Milliken Creek Watershed of the Zumbro River
Watershed.
Additional funding was provided by a Conservation Innovation Grant,
Legislative Citizens Commission on Minnesota Resources and most recently
by funds from the 3/8ths amendment passed by voters, said Mark Dittrich,
Minnesota Department of Agriculture senior planner in conservation
drainage. Ellingson Companies provided in-kind support as did Prinsco.
The project has funding to continue through the 2011 growing season, Dittrich said.
Customers are curious about controlled drainage, said Mike Tveten,
southeast Minnesota survey manager for Ellingson Companies. They want to
know if they can use it to get more from the land they own. Ellingson
installed the bioreactor at the Smith site and the controlled drainage
structure at the Kruger site.
It was tough to install the bioreactor at the Smith site, Tveten said, but
he's been impressed with how it's working.
Both practices are in the research phase and Ellingson is involved to stay
on top of what is coming in drainage, Tveten said. ADMC, MDA and the U of
M are doing an excellent job of educating farmers about what they are
doing in the area of drainage research, he said.
They have several research sites across the state where data is being
collected. The results from the Smith site have resulted in more research
there. This year, Ranaivoson will put bugs into the bioreactor to see if
they eat atrazine and acetochlor. The bioreactor is similar to those used
to control odor from hog barns.
Ranaivoson is breaking ground in both the physical and biological analysis
for bioreactors, Dittrich said.
Hanging over the research is a statement made by an individual from
Washington, D.C., at a Agricultural Drainage Management System Task Force
meeting in St. Louis earlier this month.
The individual said that under the Clean Water Act there is a likelihood
that the Environmental Protection Agency might classify agricultural
drainage as a point source of pollution, said Leonard Binstock of the
Agricultural Drainage Management Coalition. Currently, any point source discharge requires a permit to discharge into an impaired watershed, he said. Tile outlets are now considered
non-point sources of pollution.
The discussion that followed afterward was how do members of the task
force move forward, Dittrich said. Many said the research of today will
help if the country moves to the point where tile outlets are classified
as point sources of pollution. The statement was an eye opener, he said.
But it doesn't change what he, Binstock and others are trying to do in
Minnesota. They want to better manage water that leaves the soil to not
only lower nitrate levels, but also increase yields. In the end, the goal
is to clean up or at least shrink, the hypoxic zone in the Gulf of Mexico.
The hypoxic zone is formed when algae dies and deprives the water of
oxygen. The size of the hypoxic zone in the Gulf of Mexico varies from
year-to-year, Binstock said. Eighty percent of the land mass that the
water in the Gulf comes from is under agricultural production, he said.
Binstock said that farmers need to think twice before they install new
tile. It may be more important to pay a little extra upfront than to come
in later and try to retrofit the system.
Drainage water management won't fit everybody, he said, that's why
researchers are evaluating bioreactors, saturated buffers and ponds, any
way to treat or reserve water on the landscape for a time before releasing
it.
Farmers in the Corn Belt are spoiled, Binstock said, and they don't
realize how valuable water is. In other states, farmers pay for water.