GHGMP Project Reports by Region

Low disturbance opener wins the challenge

When moisture is a limiting factor, selecting the proper seed drill opener can play an important role in achieving top yields, while benefiting the environment

Minimize soil disturbance and maximize crop production.

That's not necessarily a radical statement, especially for supporters of conservation farming practices on the Prairies. But, a four-year study in the Dry Brown Soil Zone confirms that a lower amount of soil disturbance at seeding will produce a higher yielding, higher returning crop, says a Saskatchewan soil conservation specialist.

A comparison of four different drill openers showed seeding with an angle disc opener produced the highest yields and lowest weed populations, says Eric Oliver, an agrologist with the Saskatchewan Soil Conservation Association (SSCA) in Swift Current.

"Some people believe the broader weed control provided by sweep openers will improve yields over other types of openers," says Oliver. "But that's not the case. This study showed that any advantage of the high disturbance opener is generally short-lived."

$$$ advantage

The study showed as much as a 30 to 40 percent lower weed count with the disc opener compared to high disturbance openers, for example. That translated into a two to four bushel per acre yield increase, depending on the crop. The economics of the day showed nearly a $40 per acre advantage using angle disc openers compared to sweep openers.

The research near Aneroid in the Dry Brown Soil Zone compared an angle disc (Barton-type opener), a 0.75-inch wide knife opener, a 2.25-inch spoon opener and a 12-inch wide sweep opener. Conducted over four growing seasons from the late '90s through the early 2000s, conditions included two dry years and two seasons with higher moisture.

Crops seeded with low disturbance disc and knife openers showed considerably improved production and fewer weeds over crops produced with the higher disturbance openers, Oliver notes. The low disturbance openers minimize germination of weed seeds and also help conserve soil moisture. A pre-seeding burn off with a broad spectrum herbicide such as glyphosate was also an important factor in achieving improved weed control with the low disturbance systems.

While Oliver says longer term studies are needed, "the overall trend showed that with the higher level of soil disturbance, the higher the weed densities, while conversely lower yields were experienced with openers using higher levels of soil disturbance."

Reduced greenhouse gas

Along with improving production, low disturbance openers also benefit the environment, says Oliver. Reduced soil disturbance reduces the risk of carbon stored in the soil being lost to the atmosphere and improved soil moisture lessens the risk of nitrogen being lost to the atmosphere through volatilization.

The research fits with the objectives of the national Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP), which has been working since 2003 with SCCA and other organizations across the country to research and demonstrate a wide range of farming practices that can reduce greenhouse gas emissions.

In the SCCA, four different crops were seeded with the different openers attached to a Flexicoil air seeder. That included desi chickpeas, field peas, durum and malt barley.

The benefits of reduced weed counts and improved yields due to reduced disturbance were obvious in the first year with the disc opener, says Oliver. "The advantages occurred immediately with the angle disc opener," he says. "Although the knife opener eventually produced lower weed densities and higher yields than the spoon or sweep, these improvements didn't occur until the third year of the study. The advantages of the spoon and sweep were relatively short-lived, producing consistently higher weed densities and lower yields on all crops, especially in the last two years of the study."

Not perfect

However, the disc opener isn't a perfect solution, he notes. The opener restricts the amount of fertilizer than can be applied at time of seeding, and some producers say in dry conditions and on stony ground the drill depth can be difficult to control. Also, under higher soil moisture conditions, crop residue can get caught under the disc or "hairpin," resulting in uneven seed placement.

"The angle disc may not work under all conditions," says Oliver. "But it has tremendous potential for the Dry Brown, Brown and likely the drier parts of the Dark Brown Soil zones.

"High disturbance openers are often the first choice of producers who switch from conventional farming practices into single pass seeding systems," he adds. "While the goal is to control weeds to improve yields, the study showed particularly under dry conditions, crop establishment with high disturbance systems is significantly reduced due to drying down of the seedbed."


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