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A report from the AgTech Centre

Wide row spacing takes heavy toll on yield

Seeding equipment set for wide row spacing may have some operational benefits for prairie crop producers, but the spacing could take a heavy toll on yield, says an Alberta agricultural engineer.

Drill shanks set at 12-inch spacing, for example, may do a better job of working through heavy crop residue, but the extra row width may mean anywhere from 20 to 40 percent yield reduction, says Lawrence Papworth with the AgTech Centre in Lethbridge.

"The wider spacing helps reduce the cost of iron in the field," he says. "But it's doubtful that savings would offset the yield penalty."

The results came from two years of field research evaluating different types of seed drill openers set at three row spacings. Papworth's research showed reduced yield in wheat and canola, over conventional narrower row spacing.

The research addressed producer concerns about row spacing, he says. Older seed drills commonly used six and seven-inch row spacing, and later, eight and nine-inch spacing became common.

"But, we had producers wondering about manufacturer recommendations to use 12 inch spacing," he says. "It's a benefit in fields with heavy crop residue. And with 33 percent fewer shanks on the drill, the wider spacing represents lower equipment costs too. However, yield is the issue."

In field research conducted at High River, Edmonton, Provost and Lethbridge, Papworth looked at the yield in grains and oilseeds seeded under different combinations of openers and row spacing. In one study, Barton double disk openers were set at eight, 10 and 12 inch spacings. In a second study, three spreader tips with mid row banders were used for fertilizer set at eight, 10 and 12-inch spacings. This resulted in greater seedbed utilization.

Currently, Papworth is evaluating both row spacing and seedbed utilization using different types of openers including, Flexi-coil Barton double shoot angle disk openers, Flexi-coil five inch single shoot spreader tip, the Flexi-coil Stealth sideband double shoot and Flexi-coil Stealth pair row double shoot type openers.

In the Barton opener research, Papworth found up to a 40 percent yield reduction in crops seeded at 12 inch spacing compared to crops seeded at eight inch row spacing.

The second project had similar results, but the differences were not as drastic, due to increased seedbed utilization. "Our thinking was that perhaps seed spread over a wider area of the seed row would compensate for the yield loss we saw under narrow seed placement systems," he says.

The seed spreaders helped, but didn't fully compensate for yield loss, says Papworth. "There was still a 10 to 20 percent yield difference between eight-inch and 12-inch row spacings," he says. "This suggests that even with seed spreaders, not enough of the seedbed is being utilized at the widest row spacing."

While more field research is needed, he says a mid-point setting that involves nine or 10 inch row spacing and a three-inch seed spreader might provide yield comparable with narrower row spacing.

"In particular, I would still recommend that disk drill systems be used at a narrow spacing," he says.

The AgTech Centre is part of Alberta Agriculture, Food and Rural Development's Technical Services Division and has a mandate to support all aspects of agricultural sustainability.

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