Tile drainage installation is on the upswing in Manitoba, but producers need to take a hard look at their operations and evaluate beneficial management practices before making the plunge.
“Addressing excess moisture is definitely a worthy pursuit,” Mitchell Timmerman told producers gathered for St. Jean Baptist Farm Days last week. “In this province, we know that excess moisture is one of agriculture’s major limitations.”
According to Manitoba Agricultural Services Corporation data, 54 per cent of all crop losses between 2005 and 2014 were the result of excess moisture.
But not every year is a year of excess moisture and not every area that experiences excess moisture one year will see it the next, adds Timmerman, an agri-ecosystem specialist with Manitoba Agriculture.
“So the biggest question here is whether or not farmers should be managing for the extremes or for something more towards the typical,” he said.
Ultimately, the decision has to take into account an operation’s location, historic weather events and averages, yield and profitability, soil type, crops grown in the affected areas and the larger drainage system.
“There are going to be lots of variations, depending on the field, depending on the soil, the local hydrology, so there is really not a single answer for every situation and that’s the challenge to make it work properly for you,” said production adviser Ingrid Kristjanson.
Producers also need to consider the possibility of future water shortages.
“It’s preparing for a day that’s often hard to imagine. We don’t often have not enough water around these parts,” Timmerman said. “But it’s something we definitely have to encourage farmers to keep thinking about, because it definitely wasn’t always too wet.”
Water retention for tile drainage systems isn’t mandatory in Manitoba, but it may be something producers want to consider. Timmerman notes that retaining the excess water removed by tile drainage systems keeps it available for future use and can also provide an opportunity for nutrient management.
One method of nitrogen management in a tile system is a simple and easy-to-build wood chip bioreactor — essentially wood chip-filled trenches, lined with waterproof membranes. Here the carbon in the wood chips allows nitrogen to be converted into nitrogen gas before being released into the atmosphere by the organic matter.
Vegetative filters or riparian areas have been used in other regions to help control nutrient flow, but proved ineffective in Manitoba where winter temperatures and spring snowmelt process resulted in them actually releasing additional phosphorus.
Control structures, tile spacing, filters and depth are also factors that affect both the price and efficacy of drainage systems, said Timmerman, stressing the unique situation on every farm makes it crucial for producers to look at all factors, both short and long term.
“There really are a lot of numbers here to play with, which is why we are encouraging farmers to learn as much as they can, which is what they would for any of their other practices,” Timmerman said. “And also to challenge installers, or any other service providers to explain the principles and some of the details like drainage coefficient, as opposed to a cookie-cutter approach. Even if 50-foot spacing generally works we’re encouraging site-specific management.”
Beyond the nuts and bolts of production, cost and yield, farmers also need to consider issues of social licence when taking water off their lands.
“Will my brother fixing the extreme on his farm send the extreme downstream to me or someone else? Anything water related with this province is contentious as you know,” he said, adding producers in general could see the finger of blame point in their direction if things go badly during subsequent high-water events.
In Manitoba, drainage works require the approval of both the province and the rural municipality in which the work is located.