CARMAN, Man. – “You can’t change the weather but you sure can change the sails.” That’s a line from an old sailing song.
Had it been a farming song, it may have gone, “You can’t change the weather, but you sure can change the seeding date.”
That was the message Morris agricultural representative Ingrid Kristjanson left with students at the recent Crop Diagnostic School in Carman.
“No matter what crop you’re seeding, you always aim for a certain target population,” Kristjanson said. “For instance, in wheat you need 20-30 plants per sq. foot. That’s a big range, and it gives you a really wide seeding window, because the plants can do some tillering to compensate for things that might go wrong. Most crops are tolerant. They have the ability to compensate for less than ideal conditions.
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
“When you get to crops like soybeans, they do not tiller out and they have very little ability to compensate for less-than-ideal conditions. The soybean seeding window is very restricted.”
As part of the recent diagnostic school, Manitoba Agriculture staff seeded soybeans in three different containers under controlled conditions in a growth chamber.
Bin 1 is the scraggly looking bunch of plants in the left bin in the photo. Bin 1 was seeded at a soil temperature of 7 C and brought up to a soil temperature of 18 C over a couple of days. It had a 60 percent plant stand and was a full trifoliate behind Bin 3 during the July school.
Bin 2 is the adequate looking bunch of plants in the centre. It was seeded at a preferred soil temperature of 18 C but that soil temperature was dropped down to 7 C over a couple of days. It had a 95 percent stand due to the fact that the seeds went into warmer soil, but Bin 2 was a half-trifoliate behind Bin 3 during the school.
Bin 3 is the good looking bunch of plants on the right. The seeds went into soil that was 18 C and which was maintained at that temperature. Bin 3 still only has the same 95 percent stand as Bin 2, but the plants are fully developed for their specific stage of growth, and will outyield Bin 2 at harvest.
“What this little Bin 1 demo shows us is that if we were seeding early in the window and our soil temp was only 7 C, we’ve already done the damage to our crop, even if the soil temp shoots up to 18 C in a couple days. The moment the seed touches cold soil, we have already limited our production, no matter how well the growing season turns out from that day forward,” said Kristjanson.
The Bin 2 story is happier.
“If we wait until the soil warms up to 18 C, at least we know the seeds will get the best break and we’ll have a 95 percent stand. Then if we get an unexpected cold spell and the soil temperature drops to 7 C, crop damage is minimal.
“In Bin 2, the plants were a half trifoliate behind, but they were fighting hard to catch up to Bin 3.”
Kristjanson said accurate weather predictions cannot be made far in advance, but farmers can measure soil temperature and can study the calendar to figure out what is likely to happen.
“Let’s say it’s May 10 and your soil temperature is 7 C and the forecast is for three or four days of cool weather. You just know that soil will not warm up enough. I’d hold off seeding soybeans.
“Or, a different scenario. It’s a warm, early spring and in mid-April you’ve got 18 C soil temperature. That’s enough heat for the seeds, but look at the calendar. What are the chances that your soil will remain that warm? That could be a big risk in mid-April.
“The best scenario is mid-May with 18 C. Then you have very good odds that your seeds will have the heat they need.”
