Consider impact on rotation when switching from corn to soybeans at planting


Planting across Ontario is nearing completion in many regions, but excessive rain continues to stall progress in some areas, leaving farmers to contemplate switching intended corn acres to soybeans.

It’s a decision that has significant cropping implications, says RealAgriculture agronomist Peter Johnson, and he wants growers to look at all the potential impacts before making the move to soybeans. “The immediate switch to soybeans should not be the first choice,” he stresses.

At an Ag Business Breakfast Meeting at Ridgetown, Ont. on Tuesday, agronomists and ag business reps provided planting progress and rainfall updates, which included rain gauges catching up to seven inches in areas of Middlesex and surrounding counties over the past week.

All the moisture means planters will be parked for days and many farmers will likely switch to soybeans when planting resumes. Johnson says he’s trying hard to keep growers on corn to limit the impact more soybeans can have on crop rotations. He’s recommending growers take a hard look at shorter-season hybrids before turning to soys, noting that 85-day corn still has up to 200 bu/acre yield potential.

Johnson agrees that growers in short season areas have limited corn switching options, “but when you switch from 105 days to 95 days you can still grow 250 bushels per acre. We have some really good hybrids out there.” Seed company representatives attending the meeting confirmed there is good supply of shorter season corn hybrids as companies have been successful in moving seed around the province in recent weeks.

Johnson says Ontario growers already have too many soybeans in their rotation and adding more will make it more difficult to manage diseases like soybean cyst nematode (SCN) and sudden death syndrome (SDS).

Ontario Ministry of Agriculture, Food and Rural Affairs plant pathologist Albert Tenuta echoes Johnson’s comments on disease management. He says an extra cycle of soybeans in the rotation can certainly give pests a leg up. “One of the things to consider when switching is all the benefits staying in rotation has done to maintain or lower your SCN and SDS,” says Tenuta. “You can blow that all with one year [of soybeans].”

AGRIS C0-operative agronomy strategy manager Dale Cowan understands the concerns of farmers who would rather make the switch to soybeans and drive on. “The thing that farmers are fearful of is low testweight, high moisture corn at harvest. It’s not a yield issue,” says Cowan.

But in areas like Essex County, which often get in excess of 4,000 heat units, Cowan says “even if you don’t plant corn until the first week of June, chances are that you’ll have enough heat to mature a full-season hybrid.”

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