OSGOODE — Irrigation of any sort is rare enough in the corn and soybean fields of Eastern Ontario — let alone an underground drip irrigation system.
Employees at Osgoode Farms, south of urban Ottawa, showcased the system Aug. 22 during the Ottawa Carleton Soil and Crop summer field day tour. The site features 120 acres of corn whose roots are irrigated by thousands of feet of flexible plastic tubes buried 14 inches below the soil surface. They’ve been expanding the system in phases over the last four years, with the intention of eventually hitting 200 acres irrigated from below. They use a diesel pump to pull the water from a tributary of the Rideau River, sending it through the so-called “subsurface” irrigation system at what used to be the Manderley Sod Farm.
Employee Mark Ruiter explained that the property was a strong candidate for irrigation because the farm’s topsoil rests on a thick layer of sand that otherwise allows the land to dry out quickly.
Prior to the system’s installation, corn yields averaged about 100 bu/ac. Last year, with subsurface irrigation, they hit 185 bu/ac, he said.
Six hours of pumping adds the equivalent of one inch of rain to the fields, he said. “It really allows us when it’s dry to top up our yields, to make corn without the stress.”
Yes, the water really does saturate the soil above the tubing, despite the tubing being 14 inches deep in the ground. The water comes out of holes — or emitters — on the top side of the tubing. The water does flow downward, too, but it percolates upward once the soil’s saturation point — also known as the soil’s available “bucket” — is reached at the lower depths and is then maintained. “It’s like a wick. The wick will draw up, even though gravity draws down,” Al Saunders, Eastern Ontario representative with vendor Vanden Bussche Irrigation, explained.
One of the weaknesses of the system is that freshly planted seed still requires rain to germinate. However, a strength is that the system uses about 15 % less water because of lower evaporative losses when compared with broadcast sprinklers and overhead pivot systems.
But the true benefit of subsurface irrigation is the ability to incorporate liquid nutrients with the water, delivering “point source” fertilizer right at the plant roots, says Vanden Bussche’s Yuriy Gudz, designer of the Osgoode Farms system. “This is the key benefit of the technology.”
Developed in Israel, the systems do cost about 40 % to 50 % more than overhead irrigation, Gudz says. While underground irrigating is rare — Osgoode Farms is believed to be the first in Eastern Ontario — the technology has been making gradual inroads in Southwestern Ontario and is even more common in places like Kansas, Nebraska and Alberta. During last year’s parched conditions, a Southwestern Ontario client’s corn yielded 286 bu/ac in a particularly dry area, on a crop that might have otherwise gone straight to the silage chopper, he says.
Wire worms have posed one unusual challenge for the installation at Osgoode Farms. Known for eating seed corn, the worms have also developed an appetite for the underground tubes. The critters chew holes through the plastic in places, requiring repairs each spring. The operators find the holes by locating puddles in the field after running water through the system before planting. They fix the identified damaged sections by digging down with a shovel and fixing the tube with a special tape, Ruiter said during his presentation to the tour group. The system is billed as having a 20-year lifespan.