Grainswest - Fall 2022

Fall 2022 grainswest.com 29 “If you lose all of your six inches of topsoil, it’s not productive land. Who’s going to want to buy it?” —Ken Coles Tonya Lwiwski is a riparian specialist with the Alberta Riparian Habitat Management Society, better known as Cows and Fish. In an erosion webinar presented in mid-March, she advised viewers on how to protect riparian areas such as streambanks and slow, naturally occurring water erosion. She understands why farmers express frustration over the presence on their land of these green zones that surround waterbodies. They’re inconvenient to work around, especially with a combine, and they can be dangerous for livestock. There are many benefits to retaining healthy riparian areas, though. They capture and store water, which helps to recharge groundwater reserves. They also trap and store sediments, which, with sufficient vegetation, protects banks and shorelines from erosion and provide habitat for fish and wildlife. From the farmer’s perspective, perhaps their most important benefit is how such areas slow the impact of snowmelt and heavy rain. Without adequate vegetation, runoff can move overland or create gullies, channels and slumping along watercourses. Cows and Fish circulates a factsheet that lists the plant species best suited to these buffer zones. Willows and sedges, for example, have deep, binding roots. “If you have vegetation, don’t remove it,” said Lwiwski. “And if you have the capacity to help it out by putting in perennial cover as a buffer, that will greatly help riparian health.” SHORT-TERM SOLUTIONS Perhaps no one is more familiar with erosion issues in Western Canada than retired federal soil conservation researcher Frank Larney. “And then erosion kind of disappeared off the radar,” he said. “Everybody thought they’d got it sorted, but now it’s coming back.” Most erosion in Alberta has to do with the surface cover or the lack thereof, said Larney. This is why irrigated land sees more erosion than dryland. “If 30 per cent of your soil surface is covered by residue, wind erosion risk is lowered,” he said. “But once you drop below 30 per cent, your risk increases dramatically.” One of the factors that makes conservation tillage possible is the use of herbicides for weed control. Conservation tillage really took off in the early 1990s in concurrence with the introduction and affordability of RoundUp. StatCan numbers support this claim. In 1991, 73 per cent of seeded acres in Alberta were under tillage practices that incorporated most crop residue into the soil. By 2016, that number had nearly inversed itself, with only three per cent under tillage while 69 per cent of seeded acres were under no-till production. “RoundUp is part and parcel of conservation tillage, and has been since its inception,” said Larney. “If you pull RoundUp out of the system, guys may have to go back to mechanical weed control and that wouldn’t be good.” While farmers have adopted no-till and minimum-till practices across much of the Prairies, on a drive from Lethbridge to Edmonton in 2019, Larney was surprised to see obvious renewed interest in tillage. “I couldn’t believe how bare the surface was due to vertical tillage,” he said. In wetter years, vertical tillage makes sense because it helps deal with heavy residue. But in dry years, it just leaves fields vulnerable. Providing cover, even with the availability of RoundUp, isn’t always possible. Under drought conditions, crops fail, and conditions come harvest aren’t always ideal for the establishment of cover crops. There are emergency options to help protect soil in the event of high winds, said Larney. Tillage with a deep ripper can provide some protection. Deep rippers bring large clods of earth to the soil surface and create a rough landscape that’s more difficult to erode. “The wind loves a flat surface and small aggregates,” said Larney. As well, spreading manure creates a protective carpet that temporarily keeps soil in place. ONE-TIME AMENDMENTS Should soil erosion occur, there are also several “treatments” that can repair the damage. In 1990, Larney began a study to measure the impacts of three one-time treatments. The study remains ongoing, and AAFC research scientist Charles Geddes and biologist Brendan Alexander are evaluating its three decades of yield data.