By Connor Lynch
KEMPTVILLE — Soybeans are a stubborn crop. They tend not to respond to much, whether farmers throw nutrients and water at them or Mother Nature throws out weird weather. Yields have been on a slow but steady climb as hybrids continue to improve, but yields certainly aren’t ramping up like they are for corn.
So what’s the problem? OMAFRA’s soybean expert, Horst Bohner, was on hand at the Eastern Ontario crop conference in Kemptville last month to share the latest research. Right now farmers should make sure they have the basics down: Choosing the right variety for their field and ensuring that field has good background nutrients are the two most important factors in final yield.
For the farmer who’s nailed the basics and is looking to go beyond, foliar fungicides show promise, Bohner said. White mould is one of the main scourges of soybeans crops in Ontario, and dealing with it is a priority.
But even without obvious white mould problems in the field, foliar fungicides have yield-boosting potential. A 2-pass fungicide application between R1 (beginning bloom) and R2 (full flowering), when there’s one flower open on all the plants in the field, is worth it when you’re in the 50 bu/ac and higher yield range. Err on the side of R2, said Bohner, and definitely don’t mix the fungicide with the second pass of RoundUp. Without white mould pressure, the yield boost is right around 5 bushels/acre. In a field with white mould problems, that can climb as high as 20 bu/ac.
Bohner also cracked open an old chestnut. A story making the rounds is that rolling early-season soybeans stressed them out and helped with yields. There’s a kernel of truth in that. It looks like an early-season roll may in fact boost yields by as much as three bushels/acre.
The early roll comes with some caveats; best results are garnered with a roll at the first trifoliate (V1). After that, yield gains can go backwards, since the roller will snap the plant if it’s too tall. Make sure it’s a roller, not a packer, Bohner said. Definitely don’t roll twice. “Rolling twice is death.” The practice works better on no-till fields since the residue provides a bit of a cushion, and crusting can be an issue in either case.
While turbo-boosting yields is an elusive goal, Bohner said that researchers are noticing some promising trends. Namely, pod count. Bohner said that seems to be the fundamental factor when it comes to getting higher yields. “The more pods per plant, the higher the yield.”
Refreshing farmers’ memories, Bohner shared the fact of soybeans’ stubborn refusal to respond to starter. Beans prefer background P&K (phosphorus and potassium) and good stores of it in the soil are necessary for higher soybean yields, said Bohner.
Farmers can only do so much. Timing and availability of nutrients is important, but equally important is making sure that the soybean’s wimpy roots actually take up those nutrients at the right time. Bohner’s theory is that the weak roots of soybeans are part of what’s holding back bigger yield increases. “We’re going to have to do something about the roots.”
