Discovery Farms adds locations to its water quality testing

Written by Jonathan Eisenthal

Just how much nitrogen and phosphorous are leaving the topsoil on our farms and heading through the Mississippi River system? A lot of people seem to have strong opinions based mostly on emotion and perception. But actual data documenting movement from the farm to the Mississippi are limited. George Rehm wants to change that.

A retired professor and nutrient management specialist, Rehm has been the director of a project designed to measure transport of nitrogen and phosphorous from farmland and into water courses since last August.

The latest developments include the addition this year of a farm east of the city of Goodhue that runs intensive feeder pig and cow-calf operations, and which applies all the manure to cropland used to produce oats and alfalfa to feed the animals. The farm utilizes conservation tillage practices. A team of researchers constructed a flume to collect runoff from ten acres and measure the movement in pounds-per-acre of suspended solids, sediment, total phosphorous, inorganic phosphorous, total nitrogen, ammonium nitrogen and nitrogen in the form of nitrates.

An additional three locations–one in Stearns County and two in Chisago County–will be set up this fall, so Rehm and his team will be ready to take measurements when the snow melts next Spring.

“The overall purpose is to monitor the movement of phosphorous and nitrogen under real world conditions and to do this under the diversity of types of farm enterprises we have in Minnesota,” said Rehm. “We want to know what is going on. We see people getting into a debate. With neither side really knowing what the facts are, you can’t do anything but debate. Once you have the facts, you can move forward.”

Rehm noted that the Minnesota Pollution Control Agency is currently undertaking a project, based on modeling, of what total daily maximum loads (TMDLs) of various nutrients and compounds should be, in order to consider a water course impaired, and how much lower must levels be in order to rehabilitate it.

“We will measure actual flows and see how that compares to predictions (PCA is making), said Rehm. “This information will help to either verify that PCA model accurate or inaccurate. It all goes back to the TMDL process, to hopefully put it on a hard scientific basis.”

The project began with a research site at Goran’s Farm in Willmar, Minnesota. U of M Professor Dr. John Moncrief has directly overseen the apparatus there, which has measured nitrogen and phosphorous, not only from the Goran place, but also from storm sewers that drain city sources near Willmar. What may surprise some is that the city effluent contributes a sizable quantity of these nutrients.

The new locations north of the Twin Cities include an intensive dairy operation in Stearns County, a corn and soybean crop farm in Chisago County that has utilized no-till cultivation since 1995, and another corn and soybean operation in Chisago County that uses conventional tillage near  the St. Croix River. All three sites have the same soil type and the same slope, making the comparison quite valuable.

Rehm plans to release data as it becomes available, and hopes to continue the project seven years if not longer. When the project is completed, he believes the picture of how nutrients end up in the watercourses may be quite different than the picture painted by current speculation.

“Minnesota Corn Research and Promotion Council and the other members of the Minnesota Ag Water Resources Coalition have come together to support this research and they’ve really gotten it off the ground,” Rehm noted. “At this point, Minnesota Department of Agriculture has stepped in and helped provided resources to hire some very smart people, and I think this project will expand rapidly. The more locations, the more valuable the data becomes. Part of what’s driving this is that everyone who is concerned about hypoxia in the Gulf likes this, they like getting the actual measurements. And the farmers are supporting this because they all want to know what is happening on their fields. And it’s not just farmers. Up in Stearns County, we have a guy who puts in tile lines for a living and he said, ‘We really need this.’ He is thumbs up on the project 100 percent.”


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