Rolling right after planting has become a common practice on soybean fields in Western Canada over the last decade, but there are some good reasons to consider delaying the timing of rolling until after the crop is up.
Rolling right behind the planter or drill improves seed-to-soil contact and is definitely less unnerving than rolling a green field for the first time.
That being said, under the right (or wrong?) conditions, pre-emerge rolling can also result in a compressed top layer or crust that hurts emergence, or a powdery and flat soil surface susceptible to blowing as some growers in Manitoba have experienced this spring, notes Bryce Rampton, seed agronomist with Syngenta in this Soybean School episode.
“I think a lot of growers are taking the opportunity (this year) to step back and ask ‘was that the right thing to do? Can I plan to start doing a post-emerge roll if I know it’s going to compact? Or I have a light sandy soil, maybe I should just leave the ridges from the furrows and have a little more plant growth where it won’t blow quite as much,'” he says.
Research in Ontario has also shown a 1.5 to 2 bushel/acre yield benefit to rolling soybeans at the first trifoliate stage on a hot afternoon, as discussed in previous episodes here and here.
“Bringing this to Western Canada, it’s nice to know there’s not a real negative effect to doing it after emergence. So if we run into those situations pre-emerge where we can’t get it done well or are going to make a mess, we can wait and expect it to be as good as a pre-emerge roll,” says Rampton, standing in a soybean field near Morden, Man.
Rolling in-crop should be done between the first and third trifoliate (V1-V3) stages — ideally in the first trifoliate stage, as the plant’s stem become stiffer as it grows. “Typically you do lose some, especially behind the tractor tires, but if you have a field like this, losing one to two thousand isn’t a big deal,” he notes.
That being said, if you’re dealing with rocks or seeding equipment that leaves large ridges, rolling is critical for harvesting those bottom pods at the end of the growing season.
“We have a lot more air seeders here in Western Canada, so we get a lot more ridges. If you’re at that high risk of loss if we don’t get it rolled, I like to say don’t waste a good day to roll,” says Rampton. “If we have really good conditions where we’re not going to get compaction or soil erosion, just get it done.”
Watch/listen as Syngenta’s Bryce Rampton discusses the pros and cons of the different timing windows for rolling soybeans in Western Canada:
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