Delayed soybean emergence and the seed costs for a lush cover crop of rye are the main reasons why one innovative approach to no-till farming might not make financial sense under conventional management.
But a new research trial being conducted at six sites across southern Ontario is showing promise that the method might be something to consider for organic farmers.
Why it matters: Farmers are looking for ways to keep living roots in the soil year round and planting into a live cover crop is one of those options.
Funded for three years as one-half of a “Tier 2” project of the Ontario Soil and Crop Improvement Association, and being supported with results analysis through the Farmer-Led Research program of the Ecological Farmers Association of Ontario (EFAO), the project is being led by Ontario Ministry of Agriculture, Food and Rural Affairs Soil Fertility Specialist Jake Munroe.
“On the conventional side of the project, I’m looking at cereal rye as a cover crop,” Munroe explained in a recent interview. Aspects being examined include the impact on the subsequent crop of rye seeding rate and the timing of termination in the spring. In his experience so far, he noted, “Generally, I’ve found the yield impact is fairly minimal” of using rye as a cover crop, but he hopes to determine if there are changes to the management approach through which more significant gains might be achieved in soil fertility or weed suppression.
On the organic side of the project, meanwhile, roller-crimping the rye prior to soybean seeding – as opposed to chemically terminating or harvesting as green feed – is an essential element of the approach, since it has the potential to create a thick mat of biomass through which the soybeans take more time to emerge, but also through which weeds may be significantly suppressed without chemicals.
The first year of the project included the purchase of two roller-crimpers – one 7 ½-foot and one 15 ½-foot – made by a pioneering company in Pennsylvania. Both are designed to be filled with water to optimize the weight available for crimping, and front-mounted on a three-point hitch to give the potential to roller-crimp and plant the subsequent crop all in one pass.
Munroe noted, however, that single-pass crimping plus planting generally happens only under ideal conditions . . . and the spring of 2019 in southern Ontario was far from ideal. So none of the six plots in the trial saw single-pass treatment this year.
Also in 2018, Thompsons donated the fall-planted rye seed. (Cribit Seeds is a contributor to the conventional half of the project.) At all six sites, rye was seeded no later than the end of September, at approximately three bushels per acre, at an angle of 20 degrees or more compared to the planned direction of crimping. Based on what Munroe described as “a decent number of studies in the United States,” it has been established that offsetting the angle of rye planting and crimping optimizes the amount of ground covered by the crimped rye.
Then came the spring of 2019 – the second year of the planned three-year project. Those U.S. studies call for a “threshold” of 8,000 pounds of biomass per acre to provide ample weed suppression in the subsequent soybean crop. And the best practice is to roller-crimp the rye as close as possible to full flowering, to prevent re-growing into the soybeans.
But this year, due to the compounding factors of unfavourable fall-planting soil conditions and the wet spring, the rye stand at one site was quite poor so it was instead harvested as green feed and that plot was abandoned for this year’s comparison. The growers recognized that weed suppression would be minimal as a result of the poor biomass coverage, so tillage would be necessary to give the organic soybeans a head start.
“It really illustrated that, if you’re dealing with soils with a little bit of topography and with a history of soil erosion, you’re kind of setting yourself up for a pretty tough time if you’re going to give this a try,” Munroe commented.
Also due to the cool spring, the rye hadn’t reached the appropriate maturity at two of the sites when it came time to plant soybeans. So the beans were seeded into a standing crop of rye. At one of these, crimping happened shortly thereafter, prior to emergence of the beans. But at the other site, the farmers missed that window, and ended up roller-crimping well after soybean emergence.
Munroe and the Drayton-area growers, however, didn’t give up on the method. At a field day on July 24 organized by EFAO at the farms of Morris and Jerry Van de Walle, Munroe showed slides of the Drayton farm’s side-by-side plots. The non-roller-crimped plot was definitely ahead, but the soybeans in both parts of the field looked promising.
And, on Aug. 28, Munroe and the Israel family were set to host another “informal” field day near Drayton to allow interested farmers to have a look at the late-season comparison.
One of the Van de Walle fields was the closest of all in the trial to achieve the 8,000-pound-per-acre threshold in the spring, but the cool weather meant it was still below the threshold. Plus, they had to wait over a week later than the previous year to get into the field and roller-crimp. But as participants in the July 24 field day saw, good weed control was still achieved.
“But there are definitely a couple of other sites that haven’t been as fortunate” with respect to weed suppression. That’s why, he suggests, growers considering this approach must get out into their field in the spring and assess whether or not the stand of rye will be sufficient to provide a mat of biomass once it has been crimped. If not, “it’s essential, I think, to have a Plan B” such as harvesting green for use as livestock feed.
For soybean planting, growers agreed to try a higher-than-normal rate of 225,000-250,000 seeds per acre – a fairly common approach in organic production. At all but one site, planting was with a no-till drill; a no-till planter was used in a plot at the Elora Research Station.
In the end for 2019, only two of the sites provided a full, side-by-side comparison of roller-crimping versus growing organic soybeans under the farm’s traditional tillage regimen. But Munroe notes that, given the challenging conditions this past spring, he’s happy to have even that level of comparison. And he has been spending time in the past few days arranging soil tests at the participating farms to determine the locations of next year’s final year of the project’s plots.
More than one visitor at the Van de Walle field tour said it’s difficult to financially justify roller-crimping a heavy crop of rye prior to soybean seeding under conventional management, given the cost of effective chemical weed control. But if you factor in the potential price premium for organic soybeans, and the fact chemicals are prohibited under organic regulations, it can make sense for organic growers.
Munroe agrees with that assessment. But farmers must start with a well-established stand of fall-seeded rye. For that reason, “field selection is really important,” as is testing soil fertility. Try this method on one of your best fields, he suggests, and in a field that is not seeing excess pressure from perennial weeds.
If perennials are problematic, consider other forms of weed control or expanding the rotation to include a few years of hay or pasture. “On the other hand, if your weed problems are mainly from annual species, this might be something to think about.”