Tile systems do more than drain excess water

Gloria Hafemeister
Drain tiles help prevent soil erosion by reducing surface runoff of excess water.  As farmers learn more about tiling systems they are also looking at preventing the movement of nitrogen through the tiles.

PIGEON FALLS – Draining water from fields through a tiling system is nothing new. It dates back to the early 1800’s when Scottish farms used tiles to drain otherwise unproductive farmland.  Drain tiles started appearing on U.S. farms as early as the 1820’s when the goal was simply to get rid of excess water to allow crops to grow better.

During a recent virtual Discovery Farms conference, Tim Radatz, Minnesota’s Discovery Farms coordinator who also specializes in making tile systems work told the 150 participants, “Now in the twenty-first century the concern is more about water quality issues and what actually drains through those tiles.”

Radatz explains that soil and phosphorus losses occur with surface runoff.  Tiled fields with the greatest concentrations of soil loss are those that had older concrete or clay tile systems where tile blow-outs occurred.

“Blow-outs provide a direct conduit for nutrient loss,” he says.

He says the best way to prevent phosphorus movement is to avoid over-fertilizing.  Nitrogen losses are dependent on the amount of water flow. The more water that moves through the tiles the more nitrogen can go out.

While climate and soil conditions have a big influence on nutrient losses through runoff and tile flow, that is something beyond the farmer’s control. What farms can control, however, is the amount and the type of product they put on for fertilizer.  It needs to be applied at the right time and the right rate.

Joining Radatz in the presentation were two farmers who shared what they have learned about drainage and nutrient losses over the years.

Wisconsin dairy farmer Shawn Wagner and his family manage 1400 acres of land near Oconto Falls and 600 of those acres are tiled.  

He says, “We learned a lot about the iron ochre in our system and how that affects the tiles. Iron ochre plugs the tile system so we made some management changes, including cover crops.”

Wagner says covers help maintain the soil and hold the nutrients so they won’t leave the field through the tile or runoff.  This is been our most successful strategy.”

Corn and soybean farmer Roger Toquam who also runs a custom hog finishing operation in southeast Minnesota says his family began tiling their land many years ago.

“Drain tiles were the most important investment we have made on our land. Without tile we would lose nutrients and soil through runoff,” the fifth generation farmer said. “Wind is also a big issue here and if we do too much tillage or leave any bare ground we would have a lot of erosion.”

Toquam says the soils on his family's farm are heavy and black and do not naturally drain very well.

"In order for our farm to reach its full potential, our land was pattern tiled with wheel machines and most recently tile plows were used. Tile is an essential part of why the land in my part of the world is as productive as it is,” he said.

Drain tiles started appearing on U.S. farms as early as the 1820’s when the goal was simply to get rid of excess water to allow crops to grow better. They also prevent soil erosion by reducing surface runoff of excess water.

Monitoring project

Toquam is working with the Discovery Farm tile monitoring project to continue to learn as much as he can about their farm soils and how their farming practices effect any nutrients or sediment that may be discharged from the tile. 

His family has not used a moldboard plow since 1966. Toquam says they now use a ridge till system, created grass waterways, and have established conservation reserve fields and wildlife plots. The Toquams side dress nitrogen in summer next to the corn.

The family also tests their soil and the manure for nutrient content, applying it in fall according to the rates the corn will use.

Asked why he applies the manure in fall rather than in spring, Toquam explained that the heavy soils on their farm mean more potential for compaction.

Toquam described the saturated wood chip bioreactor filter strip that they established last year on their farm.

Bioreactors are subsurface trenches filled with a carbon source, mainly wood chips, through which water is allowed to flow just before leaving the drain to enter a surface water body. The carbon source in the trench serves as a substrate for bacteria that break down the nitrate through denitrification or other biochemical processes.

How it works

Organisms from the soil colonize the woodchips. Some of them break down the woodchips into smaller organic particles. Others “eat” the carbon produced by the woodchips, and “breathe” the nitrate from the water. Just as humans breathe in oxygen and breathe out carbon dioxide, these microorganisms breathe in nitrate and breathe out nitrogen gas, which exits the bioreactor into the atmosphere. Through this mechanism, nitrate is removed from the tile water before it can enter surface waters.

He believes bioreactors can greatly reduce nitrate loads from tile drainage systems, with the amount depending on residence time and the proportion of drain flow that flows through the bioreactor.

Toquam says it is too early to know exactly how much the bioreactor will help on their farm.

“We will test the water going in and coming out but since we only did this one year we don’t have any results yet,” he says.