Farmers, scientists struggle with Red River phosphorus

Collection pond
This small pond collects runoff from an animal feedlot. The water is treated with an experimental filter to remove ammonia, phosphorus and nitrogen before the water leaves the farm near Miami, Manitoba.
MPR Photo/Dan Gunderson

Blane Benedict farms with his brothers near Moorhead, on the flat bottom of the Red River valley that covers parts of three states and two countries.

Benedict knows runoff from his land contributes to phosphorus pollution in Lake Winnipeg 250 miles to the north. He tests his soil to determine how much fertilizer he needs for the corn, soybeans, wheat and sugar beets he grows and he agrees that applying too much is foolish economics and bad stewardship.

View a slideshow of researchers working to track the damage pollution has done to Lake Winnipeg.

But he's not sure what he can do about pollution when the region sees the flooding that has occurred in the past two years.

"When you get excess amounts, there's a lot of that that's out of our hands," he said. "Everybody is aware of the challenges with the environment. We're all sensitive to that. And I think we all try to do the best we can to manage that."

Hoping to preserve water quality in the world's 10th largest freshwater lake, farmers and scientists in both Canada and the United States are trying to figure out ways to cut the amount of phosphorus that flows north from the valley.

"This is sort of the heart of the problem," said University of Manitoba soil scientist Don Flaten as he looks out over a field flooded by a heavy June rain. "If we can control phosphorus loss in the Red River Valley that will go a long ways to improving the health of Lake Winnipeg."

Researchers estimate agricultural runoff from fertilizer, decomposing plants and animal manure accounts for about 35 percent of the phosphorus causing massive algae blooms in Lake Winnipeg.

Algae bloom
This satellite photo shows a massive algae bloom on the north basin of Lake Winnipeg. The late summer and early fall blooms are caused by excess phosphorus in the water.
Courtesy Greg McCullough

Another 15 percent comes from urban sources like sewage treatment plants and lawn fertilizer. About half of the phosphorus is considered natural, from the nutrient-rich Red River valley soil.

Don Flaten said there's likely always been lots of natural phosphorus from native grasses and soil along the Red River.

"What we now call the LaSalle River used to be called the stinking river ... We have a natural problem, but we've made our stinking river even stinkier and our dirty lake even dirtier."

Manitoba researchers are intensely monitoring a small watershed on the western edge of the Red River Valley near the small community of Miami. The land is hilly and rainfall quickly fills small streams. The most common crops here are oil seeds like canola and flax.

Monitoring stations track water quality, and farmers carefully record all of their farming practices.

Deerwood Watershed board President and farmer Les McEwan said solving this problem will require a different, more sustainable perspective.

Flooded fields
A heavy summer rain floods farm fields in the flat Red River Valley near Brunkild, Manitoba, south of Winnipeg. Researchers say floodwater carries high levels of damaging nutrients like phosphorus.
MPR Photo/Dan Gunderson

"Do we look at the nutrients coming out of here as waste or do we look at them as an opportunity?"

Dozens of small earthen dams hold back water to ease downstream flooding, and some farmers use the water for irrigation. The phosphorus in that water is then absorbed by plants instead of flowing downstream with runoff.

Some of the animal feedlots nearby have small ponds to catch nutrient-rich runoff. That water is used for irrigation or is treated to remove phosphorus and nitrogen.

McEwan thinks what's being learned on the Manitoba landscape could be useful to American researchers. Researchers found 80 percent of farm field runoff happens during spring snow melt. The ground is frozen, vegetation is dormant and phosphorus can easily move from fields to streams.

That means some of the traditional techniques used to help improve water quality may not be effective. Grass buffer strips along streams are commonly used to filter farm runoff. But during spring snowmelt when most runoff happens, the buffers don't slow phosphorus runoff.

And they've found that zero tillage, where crop residue is left on the field after harvest to slow erosion, can actually increase the amount of phosphorus runoff from fields. More decomposing plant material left in the field releases more phosphorus, especially during spring runoff.

Water monitoring station
Automated water monitoring stations collect water as it enters and leaves a farm near Miami, Manitoba. This project is studying which farming practices best reduce nutrient runoff.
MPR Photo/Dan Gunderson

After seven years of intense monitoring and experimentation in this watershed along the Red River, researchers are just starting to understand the complicated exchange of nutrients between land and water. In the meantime, the pollution in Lake Winnipeg continues to worsen.

Gordon Orchard farms near the Manitoba research site and said good research is critical to sound public policy and regulation. "If you design a regulatory policy or law based on a false perception or knowledge of what the problem is you can do more damage to agriculture or an industry than actually cure it," Orchard said. "You could spin your wheels for 15 years regulating something and it's the wrong way to go."

In Minnesota, near Benedict's farm, Minnesota Pollution Control Agency researchers are starting to gather data about nutrients in the water. The Buffalo River, which flows into the Red River is the site of one of two pilot projects aimed at pinpointing phosphorous sources.

Jim Zeigler, PCA Red River Watershed unit supervisor, said all of the tributaries to the Red River should be studied in the next 10 years. He said the state is also developing new standards for nutrients in rivers.

But Zeigler said reversing the pollution that threatens Lake Winnipeg won't be easy or quick.

Read part one of this series, which investigates pollution's effect on Lake Winnipeg.

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