It can sometimes be comforting for an organic farmer if the view of their field from the roadway shows an absence of green growth between the rows of corn or soybeans.
But according to the presenter of a recent Guelph Organic Conference session entitled “Avoiding Field Crop Disasters,” this illusion can often hide the troubling reality of a crop struggling to thrive.
Why it matters: Organic production can be challenging and staying on top of weed control is critical.
Greg Dineen described how he began the transition to organic six years ago, after coming back to his family’s Kenilworth-area farm following a stint in engineering in Alberta’s oilfields. By then, what had been a 340-acre dairy farm had been converted to chickens and was being farmed with almost no owned equipment.
“I feel like I’ve had more than an average number of absolute disasters,” he began.
Dineen says he suggested the “Field Crop Disasters” workshop to organic conference organizers last year, after perceiving a shortage of practical content for larger-scale farmers in the 2019 program.
Perhaps among the worst of his disasters was a corn field that eventually yielded 31 bushels to the acre. From a photo it was a challenge to make out the corn plants through the weeds. That was followed by a photo of twin-row soybeans from which weeds had recently been taken out of the inter-row areas by a scuffler, but a healthy stand of lamb’s quarters remained tight against the beans.
“Especially when you really put on that manure because you think it might help the crop get established quickly, you can get some really robust weeds,” Dineen said. “There’s really only so much you can do with a scuffler at that point.”
With a caution that other weeding implements – such as a tine weeder – may be preferable on soils different from the loam he farms in Kenilworth, Dineen says a rotary hoe works best for him.
The most important rotary hoe passes are two-to-three days prior to crop emergence, followed by another at two-to-three days post-emergence. Watch the weather forecast carefully, he stresses, to either time those passes correctly or adjust the timing if necessary to avoid completely missing the opportunity due to rain.
Best of all is if you can expose the loosened-up weeds to the stresses of sunlight and wind immediately after hoeing. “Any time you can knock the soil off the roots of the weeds, you’re making progress.”
Dineen uses real-time kinematic (RTK) navigation for all field operations, and has developed a strong sense of ease when driving at speed through recently-planted or recently-emerged row crops. “As fragile as those plants might look, we’ve actually seen very few losses, so far, with this pass,” he said, referring to the three-days post-emergence hoeing of soybeans.
He added this pass is typically done when 80 per cent of the beans are past the hook stage. But if the weather turns and it looks like rain, he has also completed a post-emergence pass one or even two days earlier. In these cases, it’s possible to lose as much as 30 per cent of the crop. But when you consider the possibility of $1,000 per tonne payment for food-grade organic soys or $800 per tonne for feed-grade, the cost of increasing the seeding rate to 250,000 per acre to account for this potential loss begins to make financial sense.
Dineen typically rotary hoes soybeans two or three more times as the crop grows, then switches to scuffling once weeds get well-established in the between-row spaces. If the beans are high enough, he adjusts the scuffler to roll dirt inwards into the row.
After first showing his photo evidence of weed-infested fields, he then showed examples of organically grown soybeans, black beans, rye and wheat that he feels represented success. He also described a corn field that looked like it had some mustard in it – contrasting, he smiled, with a previous crop that looked more like a field of mustard with some corn in it.
“I would say the sow thistle is decreasing year after year, so we’ve turned a corner there. And the same thing with mustard.” When it comes to twitchgrass, he said, “We’re at a standstill but I expect a turnaround there soon too.”
Beside mechanical weed control, the timing of tillage and planting are also crucial. Through his years of transition, Dineen turned sharply away from aiming to get onto the fields early to “get ahead of the weeds.” Now, by contrast, he’ll work the soil in the spring to stimulate the weeds, then put everything into park.
“The hardest part is to just wait,” he said, relating an instance of his father commenting in the spring, well after conventional neighbours had been churning up the dust and planting crops, that a field was starting to “look pretty bad” from the road. This, Dineen said, was the time when he first considered moving in for a second tillage pass.
“At the very least, wait until the first flush of annuals come,” he said, and you’re confident you’ll be able to plant into well-prepared soil during a solid weather window. “Because you have to remember: Once you’re done the tillage, that’s when the clock starts ticking for the weeds.”
In tandem with delayed planting should be researching for varieties that have been grown successfully under organic management in your region.
At harvest time, combining soybeans straight can be a challenge due to the green stems of weeds. For the organic wheat crop that often follows, however, early planting is crucial. Dineen is a bit of an expert in grain drying from his time in Alberta, so he aims for harvesting the beans at 18 per cent and drying them down. And if that means swathing the crop and letting the weeds dry for a few days, he’s happy to put the pickup header on his combine and go that route.
He’s lucky to have a couple of custom swather operators in his area, he says, but you have to be willing to pay more for the soybean job than you might for a spring grain crop because they’ll need to go slower and adjust their machine to cut closer to the ground.