Soybean School: The Return of Wide Rows

OMAFRA soybean specialist Horst Bohner estimates 40% of Ontario’s soybean crop has been planted.

Wide row soybeans are poised to make a comeback in Ontario, says OMAFRA soybean specialist Horst Bohner.

Whether it happens will likely depend on how farmers evaluate the importance of four key factors. Speaking at the recent SouthWest Agricultural Conference at Ridgetown College, Bohner explained that equipment is the first thing to consider. “We have big corn planters that are so much more efficient.” With 30-inch soys that corn planter can do double duty and you don’t need an extra piece of equipment.

Wide rows also require less seed, notes Bohner.“Every year seed costs are growing and it’s now our biggest per-acre cost, excluding land.” Disease is also part of the equation, and wide rows can play a key role in managing yield-robbing white mould, which has gained a foothold in many fields across Ontario.

But for many farmers it comes down to yield. In Ontario, there’s typically about a four-bushel yield difference between 30-inch rows and 7.5 or 15-inch rows, says Bohner. “ The first thing you have to do is wrap your head around the fact that (four bushels) is not a big number compared to the overall perspective.”

Bohner believes management can help growers close that yield gap. Early planting will help maximize sunlight and close the row quickly. Strip tillage, higher fertilizer rates and foliar fungicides can also play a role. Bohner tested his theory last year in trials at the Elora Research Station. He compared 15-inch no-till row-unit-planted soybeans to 30-inch strip till soybeans and both systems delivered the same yields. The 30-inch strip tilled rows actually out-yielded the narrow rows when extra inputs (higher P and K, foliar fungicides) were added to the wide rows.

However, Bohner does not want growers to get the idea that only wide row soybeans respond to extra inputs. “The perception is that if you grow wide row soybeans you can get more out of inputs – individual plants will bush more and you’ll get more of a response to inputs,” he says. “But so far we have not seen that…we can get the same kind of bump with inputs in narrow rows.”

Bohner recommends that farmers who want to plant wide rows consider some form of tillage. “No-till is a real stressful environment for the plant. You’ve got to get those rows clean, as a minimum, and for a lot of growers that means straight tillage.”

For farmers who have a white mould problem, Bohner says there’s nothing wrong with going with wide rows. “Even if you take a bit of a yield hit in a dry year, you will pick up far more than that in a white mould year. If you grow tall, bushy crops of soybeans, wide rows are a viable option.”

Check out more Soybean Schools here.

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