MORDEN, Man. Ñ Manitoba soybean growers shouldn’t let last year’s experience dictate how they manage this year’s crop, says Manitoba Agriculture pulse crop specialist Bruce Brolley.
The soybean crop struggled last year in Manitoba, largely because of a difficult planting season followed by a cooler than normal summer that increased the risk of fall frost.
Brolley worries that this year soybean growers might opt to seed earlier with the hope the crop will mature sooner. During a recent bean symposium in Morden, he cautioned growers against doing that.
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“Let’s not make too many rash decisions for this upcoming year based upon what happened last year,” he said.
“Seeding dates are critical. I want to make sure that you don’t use last year as an example to determine what your seeding dates are going to be this year.”
A snowstorm swept across the province in May, which was followed by prolonged rainfall that made it difficult for growers in the Red River Valley to get their crops planted.
Brolley reminded producers that such a spring is not the norm, which is why they should not rush to plant their soybeans immediately after seeding cereals and oilseeds.
“Soybeans are a warm season crop. The seed will not start to germinate until the soil temperature at seeding depth is at least 10 C.”
Planting too early could leave the seed sitting idle in cool soil, where it could become a target for disease and insects.
Because seed carried over from last year likely will be of poorer quality, Brolley advised growers to consider holding off planting soybeans until soil temperatures are around 15 C. The warmer soil should help compensate for what is expected to be poorer germination and vigour in plants grown from poorer quality seed.
“Don’t try to seed the soybeans early just because you’re afraid of last year.”
In an average year, with good quality seed, May 15 would be a good time for planting soybeans, Brolley said. If the spring turns out to be warmer than average, planting could be advanced by a week. If the spring is cooler than normal, it would be better to push seeding back toward May 25, he said.
Because not all seed will be of premium quality, growers should consider increasing seeding rates to reach the desired plant density.
They must also prevent stands from becoming too thick because that could result in more lodging and disease problems. To help avoid this, Brolley advised against growing soybeans on fields where the crop was grown last year because volunteers could lead to a thicker-than-desired stand.
He also drew attention to how long it takes different varieties to mature. There have been a number of years with favourable fall weather, which has allowed growers to get away with growing soybean varieties that take longer to mature in the hope of tapping the higher-yield potential.
However, rather than banking on mild falls, Brolley said growers would be wise to study the history of heat units for their area and incorporate that information into their variety selection.
“The higher the number (of heat units needed), the more south you should be living before you grow that variety.”
