GRAND FORKS – When cool weather lingers through spring and when it arrives in the fall, irrigation is the furthest thing from the minds of many growers.
That shouldn’t be the case, says irrigation designer Andrew Bennett.
“It’s been a cold April – nobody’s thinking about irrigation,” he says. “[But] start early, and make sure you’re going into winter moist.”
Bennett and Bruce Naka, both irrigation designers and consultants certified by the Irrigation Industry Association of BC, visited Windermere, Skookumchuk, Creston and Grand Forks from April 25-29 as part of a series of field days hosted by Kootenay and Boundary Farm Advisors
They toured a farm each morning to assess its irrigation system, then presented their findings and general advice to the farmers and guests in the afternoon.
“These field days are all about the fundamental principles: Apply the right amount of water at the right time, evenly to all the roots and microbes, and save yourself time while you’re doing it,” says Bennett, who has his own five-acre farm in Rossland. “This way, our crops are stress-free, grow to their greatest potential, and we don’t cause problems like nutrient leaching, soil erosion and working harder than we have to.”
“I enjoy going out and meeting people from the agriculture community, as well as learning their story about their farms and being able to, maybe in a small way, help them to improve their farm through irrigation system improvements,” says Naka, who started working for his father’s irrigation supply business in the mid-1970s.
Century-old licence
Their final stop on April 29 took them to the Mehmal Farm, a family operation east of Grand Forks that dates back to 1914, when Leanna Mehmal’s grandfather had the farm’s water licence transferred into his name.
“We’re the second people to farm the land,” she says.
The Mehmal family has 200 head of cattle and 200 irrigated acres dedicated to corn silage, alfalfa, barley and timothy. Naka and Bennett’s initial presentation and discussion took place on a nearby 16-acre parcel, later moving to their Kettle River intake on the main part of the farm.
The parcel is irrigated by wheel lines, with wheels set 120 feet apart and fed by four-inch pipe. The line, designed prior to the Mehmals operating on that land, has sprinkler heads spaced 38 feet apart instead of the usual 40 feet, possibly planned with the weather in mind — not surprising to the dozen or so onlookers gathered on a blustery day.
“Somebody was really sharp on this one,” says Naka. “If it was done for a reason, it might be because of the wind. … If there’s a strong wind, it impacts the ability of the head to throw.”
“Sprinklers water much more heavily near the head, so spreading them too wide leads to really wet and really dry patches,” says Bennett.
“Head-to-head” overlap creates more even irrigation, a method he also recommended during the April 28 visit to Creston’s Cartwheel Farm, a market garden.
At the outside edge of a wheel line, where there are no overlapping sprinklers, the application rate is lower, but the Mehmal farm’s line has a double head at the end, making up for the lower amount of water.
“‘Nozzle up’ on the ends,” says Naka.
The line did, however, have noticeable leaks, which could represent a loss of four or five gallons per minute, a challenge in a system that is typically 65% efficient. With no other farms running irrigation during the presentation, the line’s pressure was about 70 psi, when it should be in the 40-50 psi range – pressure that’s too high leads to water loss through misting, and pressure too low results in crop damage from heavy drops of water.
As he had at Skookumchuk’s B-E Ranch on April 26, Bennett recommended replacing brass impact sprinklers with plastic rotators, which offer more uniform distribution and have lower maintenance costs. They’re sturdy, too; one of his clients has cows that enjoyed rubbing on the old brass nozzles, but still appreciate plastic.
“They can rub on them all day,” the farmer told Bennett, although “they might not get as good a scratch.”
“The cows might not be as happy,” says Bennett, but “the worst that can happen is they unscrew them.”
On the main part of the farm, just east of the 16-acre parcel, the Mehmals also use irrigation guns, which, as with the wheel lines, are labour-intensive.
“We need technologies to automate water use on oddly-shaped Interior BC fields where centre pivots are impractical,” says Bennett. “Ideas range from basic automatic valves on wheel moves and hand lines to fancy GPS-guided systems.”
Accurate and sufficient watering is particularly important as farmers deal with the effects of climate change. Last year, many crops were already stressed going into the extreme heat that settled over the province at the end of June and into July.
“We’re looking at a hot year,” says Naka. “In the Okanagan [in 2021], we had three or four districts make commercial growers use 20% less water.”
“What we are going to see with climate change is that we need to water more frequently,” says Bennett. “Many people only have four or five days of decent water storage in the soil.”
Government soil surveys are a helpful tool, showing the type of soil – such as sand or loam – in a general area, which directly affects water storage. At each farm, Bennett tested soil at various depths, sifting through 4mm and 2mm screens.
“Anything that can’t go through the screen can’t hold water,” says Bennett. “It can’t count toward water storage.”
Soil moisture sensors work
At Noble Farms, a 14-acre commercial cherry orchard south of Creston visited April 27, trees were already in need of water, with dry soil 18 inches down – a problem that soil moisture sensors could help with.
“You want to, every single day, be adding enough to keep it at the top,” says Bennett.
Owned by retired engineer Dev Singh, the farm uses drip irrigation, which presents its own challenges, but can be 90% efficient under ideal conditions. This system, designed by a previous owner, is manual, which may lead to human error, a challenge they also found at Windermere’s Winderberry Farm on April 25.
“Automation saves time and waters plants better – for every farm, it’s almost always worth the investment,” says Bennett.
Most systems should also have air relief valves at high points, allowing lines to fill quicker and eliminating water hammer.
“As the valve shuts off, the water hammers back,” says Naka. “If you have 100 pounds [of water in the pipe], 244 pounds hammers back. If you have too small a pipe, there will be more breaks.”
The more flexible polyethylene pipe, rather than PVC, can help in that regard, one of the reasons Bennett uses only polyethylene hose with time-saving cam locks, rather than screw-type hose connectors, on his farm.
“Getting water and soil relationships right is fundamental to every farm, so I get charged helping people think about them in ways that are simple, accurate and, most importantly, practical,” says Bennett.
An expert isn’t required to determine a farm or garden’s soil composition and water depth, but the process isn’t a tidy one.
“There are no substitutes for digging holes, getting dirty and making an afternoon of it,” says Bennett.
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