Ontario farmers test subsurface drip irrigation

Buried beneath the soil | Systems are already used in arid regions of the United States

DRESDEN, Ont. — Subsurface drip irrigation is catching on in Ontario.

Al Kominek, a farmer and sales representative with Heartnut Grove Inc., said several systems have been installed on former tobacco farms in the province’s drought-prone Norfolk Sand Plain.

“I’m the only one putting one in west of London, that I know of,” Kominek said, speaking at his family’s farm outside Dresden.

“They’ve been doing this for a while in the southern states. Number one, the moisture stays in the ground. If you do topical drip on top of the soil, there is more evapotranspiration.”

Kominek expects to get at least 15 years out of his system. He’s using it as a nine-acre demonstration site, where he plants corn, soybeans and wheat.

He sees it paying for itself quickly because of the strong commodity prices but said the system may be best suited to vegetables with root systems that are deep enough to reach subsurface moisture.

Kominek used a Rain Flo SDI machine to lay drip tape into his sandy-loam field. Later in the season, he’ll determine the timing of irrigation events using a tensiometer, which is a probe that measures soil moisture levels.

There’s also the option of adding supplementary fertilizer to the irrigation water, he said.

The three-shank machine Kominek co-owns with Heartnut requires a 150 horsepower tractor. He placed his drip tape 14 inches deep and 40 inches apart. The emitters on the tape are spaced at 20-inch internals.

According to the manufacturer, depth placement can be adjusted from four to 14 inches and the row centres from 36 to 68 inches. Depth is controlled by a set of adjustable wheels. Shear bolts prevent damage on stony ground.

Crop roots will reach for the moisture, so there’s no need to plant directly over the tape. Kominek said it’s suited to a variety of crops, including many vegetables.

Kominek’s system employs a header and a vented sub-header, both buried at 40 inches at either end of the system. He used a small wheel tile machine for their installation.

Risers connect the headers to the drip tape.

Other components include a water pump, pressure regulators, a filter and an injection pump for fertilizer.

The system should be periodically flushed using an acid solution to dissolve particulates.

Per acre pricing has yet to be worked out, but Kominek said there are advantages to the system that affect costs. Once in place, less time is needed for maintenance and the tape does not need to be replaced annually as with most on-the-surface systems.

“It’s a lot more applicable for vegetables,” he said.

“I’d say you should be able to pay for the system in three years. The guys on the old tobacco farms, some of them are using it for corn and soybeans.”

There is a machine available to retrieve the buried drip tape, although the old tape could also be left and new tape added.

Dan Powers, a sales representative with Southern Irrigation in Chilliwack, B.C., said subsurface irrigation is standard practice in British Columbia’s Fraser Valley, which is home to one of the world’s largest raspberry production areas.

In this case, the tape is placed directly beneath the cane rows, often using home-built equipment.

Powers said SDI is also used widely in Alberta for potato and alfalfa production. Systems are often installed in the corners of fields where overhead, centre-pivot irrigation systems will not reach.

It’s also used for sports fields and municipal turf applications in Alberta and British Columbia.

According to the Colorado State University’s extension service, SDI has been around since the 1960s and has become increasing popular in the United States over the past two decades. It’s a described as a highly efficient system that could involve a higher initial investment.

Along with meeting irrigation needs, the system may also reduce weed and disease pressure.

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