Gorans Discovery Farm project is unique study of farm, city drainage
By Carol Stender
Date Modified: 05/14/2012 3:42 PM
WILLMAR, Minn. — The Gorans Discovery Farm project is a unique study of a farm and urban system.
More than 60 people recently heard the latest findings from the project. The information included an update on the woodchip bioreactor installed in 2010.
"The Willmar area study has become important," said Warren Formo, executive director of the Minnesota Agricultural Water Resource Center. "It is an example of how a community can come together — urban and rural."
Lake Wakanda receives water from farm fields and city streets.
Kim Gorans, president of Gorans Brothers Farm, was interested in what flows off the family's fields and welcomed the research project, said John Moncrief, University of Minnesota professor and Extension specialist.
The Gorans Brothers Farm study started in 2007 and was added to the Discovery Farm Program the next year.
Five monitoring sites were installed. One checks Willmar storm water, a west pump station, east pump station, a monitoring site on a small unamended control field and Lake Wakanda itself. Both surface water drainage and internal soil water drainage to pattern tile are measured. Measurements also are taken during snow melt, Moncrief said.
The Gorans Discovery Farm is the oldest and largest of Minnesota's Discovery Farm projects. About 150 acres of Gorans Brothers land are monitored and 1,700 acres are monitored within Willmar. Barr Engineering created a map for the project and characterized 175 small contributing watersheds within the city. On average, 59 percent of the area of the small watersheds is impervious resulting in 100 percent runoff.
Of the eight contaminants measured in the project, only nitrate was higher from the farm fields.
Drainage volume was higher, 73 percent, from storm water compared to 23 percent from farm fields over four years. The reason may seem obvious since the city has more impervious surface and fields have more holding capacity. The sediment loss in storm water was also 10 times greater than from farm fields.
In a study from 2007 to 2011, researchers found the cumulative total of nitrogen losses were seven times greater from farm fields compared to storm water. Ammonia losses were 12 times greater from storm water compared to farm fields.
The bioreactor started as a 350-foot long trench with a cross section area of 30 square feet. It has a liner to protect for leakage and to prevent groundwater penetration into the system. A large vertical pipe is the entry for the tile water into the bioreactor with a pumping station that lifts water from the patterned tile to either the bioreactor or to the creek flowing beside the property on the farm.
Researchers have noted a 92 percent reduction of nitrate in water coming out of the bioreactor and a reduction in phosphorus.
They will study the denitrification of both the bioreactor and a wetland. They hope to, at some point, improve the bioreactor's design.
Woodchips should remain viable for a good length of time, researchers said. One of the longest-working bioreactors in New Zealand has operated for 15 years.
Research on the Discovery Farms and the bioreactor will continue for the long term, Moncrief said.
"The reason you do these over a long period of time is, because right now, things are skewed to the wet side of time," he said. "This year I think we will get the dry year and maybe it will balance the research out. We just have to present this in a historical context."
Other Discovery Farms are located in Goodhue, Stearns, Chisago, Blue Earth, Wright and Renville counties. Blue Earth has two farms participating in the program. Researchers hope to add three to four new sites — including farms in northwest Minnesota — to expand the research.