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A Look At RTK-Guided Inter-Row Seeding

Like other farmers and researchers, Brett Stimson of Coaldale, Alta., hasn’t made up his mind yet about whether inter-row crop seeding makes a difference.

Stimson, who farms north and east of Lethbridge, has been experimenting with inter-row seeding for the past three years. Being involved with the Rocky Mountain Case IH dealerships across Western Canada, he had access to the technology that makes inter-row seeding possible. But rather than just sell the equipment, he wanted to see if the practice of using field guidance technology to seed a new crop between rows of standing stubble does improve crop production or reduce input costs.

“We’ve looked at it for the past couple seasons but I really don’t know yet if it makes a difference or not,” says Stimson. “The fields look good. The technology allows you to go into a field and seed directly between rows of stubble. It is so accurate that sometimes you wonder afterwards if the field has been seeded, but I can’t really stay that I have seen production advantages.”

Stimson’s CASE IH tractor is outfitted with RTK guidance technology as he seeds wheat and canola with a Bourgault paralink air drill, with nine-and-a-half inch row spacing. He says the system achieves more than 90 per cent accuracy at inter-row seeding.

While he plans to continue with his own on-farm evaluation, the next step in testing inter-row seeding is to see if can be used

to shorten crop rotation. Stimson normally follows a three-year rotation with canola, but plans to shorten that to two years on plots in 2011, to see how inter-row seeding affects disease risk.

“That three to four year rotation is recommended to reduce build up of disease such as sclerotinia in the canola crop,” he says. “If we can use inter-row seeding and not contribute to increased disease pressure, then that shorter rotation could prove to be a real economic advantage to producers, especially when canola prices are strong.”

Stimson will also be watching the results of other on-going field research involving inter-row seeding.

RESEARCH TRIALS

Findings form the first-year of research trials in southern Alberta looking at the benefits of inter-row seeding didn’t produce any dazzling results, but it did generate enough information to suggest the topic needs more study, says the research manager.

Plot trials at Acme, north of Calgary and also near Lethbridge suggested there might be some benefit to attempting to seed a new crop between standing stubble rows (inter-row), says Ken Coles, with the Southern Applied Research Association (SARA). And even though results from the 2010 project were mixed, one year of a field trial isn’t enough to draw any firm conclusions.

“We produced enough results to learn this is something we need to look at further,” says Coles. “In plots where we attempted to seed between stubble rows, there was no dramatic or significant difference in plant counts, compared to other seeding operations, but there was some difference. In many respects this is a very difficult thing to measure.”

There has been considerable interest in the last two or three years about the potential benefits of inter-row seeding. Admittedly much of the “talk” has been fueled by suppliers of a highly accurate precision farming technology known as RTK. That stands for real-time kinematic networks. Most farmers are familiar with conventional global position systems (GPS) guidance, which can narrow accuracy of field operations around the six to 10 inch range. RTK is the Cadillac of guidance technology, which for an added subscription fee, can provide guidance of farm machinery to within an inch or less.

That accuracy certainly helps reduce the risk of overlapping field operations, but proponents also suggest farmers can realize measurable benefits — increased yields and perhaps lower costs — by seeding a new crop between the standing stubble rows of the previous crop. expensive or quite as accurate as RTK, but is more accurate than the WAAS network, which is commonly used by conventional GPS technology. (WAAS has accuracy within six to 10 inches, RTK is accurate to within an inch, and OmniSTAR HP has accuracy to within two to four inches). Omnistar and RTK systems require yearly subscriptions.

Coles says the challenge was to establish a realistic benchmark. “We want to determine if inter-row seeding produces any benefits, but the question is what do you compare inter-row seeding to?” For this first year of the study, plots were set up to compare inter-row seeding to cross-row seeding, although in 2011 Coles says he may eliminate the cross-row treatment and simply compare intentional inter-row seeding to standard same-direction seeding”

As part of the 2010 trials, Coles compared inter-row and cross-row seeding at both full and half seeding rates. And as a measure of the two seeding methods — inter-row versus cross-row — plant counts were made a few weeks after emergence.

At the Acme site there appeared to be no significant difference in wheat plant counts between the two seeding methods, however at the Lethbridge site they found a 22 per cent increase in canola plant numbers on the inter-row seeding treatment compared to the cross-row seeding treatment, at the full seeding rate. There was no difference in plant counts at the half-seeding rate.

“The figures from the canola trial, in reality, aren’t as significant as they sound, but it does suggest that inter-row seeding may make a difference and is worth looking at further,” says Coles.

In one other project, on a Lethbridge research plot, which may be more informative than the other trials, Coles seeded winter wheat into standing stubble. What was interesting in this trial, Coles says, that while the plan was to seed the new crop directly into the stubble row, between 70 and 85 per cent of plants actually ended up growing between stubble rows or inter-row.

This information suggests to Coles, even when farmers aren’t paying attention to inter-row seeding and are just seeding in the same direction as standing stubble, a high percentage of the crop may in fact end up being seeded inter-row.

“I think we have to look at whether you are trying or not that perhaps 70, 80 or 90 per cent of the crop plants end up being seeded inter-row anyways,” says Coles. Inter-row seeding alone may not justify the added cost of RTK technology. There would have to be other reasons.

He says it may be possible by using the “nudge” feature on conventional GPS guidance equipment, farmers are able to adjust the placement of seed row openers so the majority of seed is being placed in the inter-row space.

For the 2011 trials, Coles says he may drop the cross-row seeding treatment, since most farmers don’t usually seed cross-row, and focus more on comparing efforts to purposely achieve inter-row seeding, with the more common same-direction seeding practice.

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RTK-accuracy may not be necessary to

inter-row seed

About the author

Field Editor

Lee Hart

Lee Hart is editor of Cattleman’s Corner based in Calgary.

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