Project probes benefit of damming field drains

Thursday, May 29, 2014

by BETTER FARMING STAFF

The launch of a controlled drainage project north of London marks a fresh step in the eventual commercialization of the technology, says one of those involved in the venture.

photo: controlled drain's interior

The project, which is taking place on two five-acre plots on the property of Middlesex farmer Henk Van Den Berg, marks the first time the technology has been used on a working farm in southwestern Ontario, says Brad Glasman, coordinator of conservation services of the Upper Thames River Conservation Authority. The authority is conducting the project in partnership with Van Den Berg, the Ontario ministries of Agriculture and Food and Rural Affairs, and Agriculture and Agri-Food Canada.

Glasman says it’s anticipated the technology, which enables farmers to dam water percolating through a farm field’s drainage system, will increase the two test areas’ corn yields this summer by 10 to 15 per cent. The damming process, he explains, enables nutrient-rich water to remain near a crop during dry summer months.

photo: controlled drain piping

The Middlesex County site is located at the headwaters feeding Medway Creek, which in turn drains into the Thames River. The drain structure, essentially tubing manufactured by a Blenheim, Ontario manufacturer, is installed vertically into the ground to intercept the drain tiling system’s header before it empties into an adjacent stream. The vertical tubing contains adjustable fittings called “stop logs” that allow the pipe to be divided vertically to different elevations. Water flows through the intake and then up and over the logs and out through the other side.

photo: Andrew Jamieson

Andrew Jamieson, senior water management engineer with Agriculture and Agri-Food Canada, says testing in the South Nation Conservation Authority’s area in eastern Ontario shows that the devices reduced the overall nitrogen loading in the watershed by 40 to 50 per cent. Reductions in phosphorus have also been found in some research but the “jury is still out” on how significant this is because of widely differing results between studies, he says.

Jamieson notes that the concept has been around for a long time and using tile drainage for below ground irrigation is gaining popularity as a way to counter increasingly frequent drought and variable weather associated with climate change. Currently, there is a push to adopt controlled drainage in the U.S. Midwest, he says.

Here in Canada, Chin Tan, a research scientist at Agriculture and Agri-Food Canada’s research centre in Harrow, has been evaluating the technology’s ability to control water levels and provide below ground irrigation of plots for several years.

Introducing it to a working farm, as it has been at the Middlesex site, is a next step in making the technology more broadly available to the farm community, says Jamieson.

“Ag Canada’s interest right now is taking a lot of the research that’s been done in Harrow, for example, and moving it out into the field and understanding the issues that come along with taking plot scale research out to the field,” he says. “There’s a lot of different logistics and challenges there.”

Other controlled drainage and sub irrigation initiatives are taking place elsewhere in Canada, he adds, noting that in Manitoba, the technology is being applied to a 300-acre potato farm. There are plans to try out the technology in the Holland Marsh, north of Toronto, for horticulture crops, he says.

Jamieson says a 2012 federal analysis of why the technology was not adapted by farmers, despite having been researched in Ontario for two decades, indicated the biggest challenge is a lack of guidelines or standards for contractors installing the drainage control devices.

photo: Adjusting the level of the dam in the controlled drain

Data from the Middlesex project, as well as others in Manitoba and Quebec will be used to help answer those questions.

Farmers also have questions about “the yield piece,” Jamieson adds. The idea of increased yields “is one of the selling points, but it’s not known as to how frequently it pays,” he explains. For instance, there might be a boost in yield on a dry year but not so much on a wet year. It’s hoped that testing the Middlesex site will help to resolve questions such as what water depth provides the best yield boost, he says.

At the Middlesex site, two flow controls were installed; each cost about $700. Additional upgrades to the field’s drainage system also took place, says Glasman, noting the field was previously only partially tiled. “If it was tiled systematically from the start, we wouldn’t have had to,” he explains. “So it could fit into a typical drainage system.”

The Ontario Ministry of the Environment funded this project.

Glasman says the drainage flow will be dammed the day the corn crop is planted.

The project will include water sampling to determine nutrient levels being released to the adjacent stream as well as within the field’s drainage system. Water flow will be measured as well.

The eventual goal is, says Jamieson, presenting controlled drainage as something any farm operation could do — “provided the landscape works.” BF