Organic no-till soybean production: is it possible in Ontario? (updated with 2020 data)

strong soybean stand with rye mulch below

In this article, we will take a look at using a roller crimper for organic no-till soybean production and the results of on-farm trials in Ontario.

Why organic no-till?

Organic soybean production relies on a significant amount of tillage. When done well, yields can rival conventional production. There are drawbacks, however, including a high labour demand in the spring and the potential for soil degradation over time. Cover crop-based organic no-till soybean production techniques have been developed in recent years and proven to work in parts of the US. The question is: will they work under Ontario’s climate and soils?

Cover crop-based organic no-till soybean production uses a roller crimper, a drum with chevron-shaped blades (Figure 1) that crimps rye (or another suitable plant) once it’s flowering and kills it. Soybeans are seeded into the mulch. If it’s thick enough, the mulch provides season-long weed suppression. The cover crop-based organic no-till system offers advantages in terms of labour savings and soil health improvements but comes with additional risk.

Ontario trial

On-farm experiences with organic no-till soybean production in Ontario over the past decade have yielded mixed results. As part of a two-season OSCIA Tier 2 trial, Heartland Soil and Crop Improvement Association evaluated cover crop-based organic no-till soybean production using best practices. The goals were to evaluate performance, identify barriers to success and develop Ontario-specific recommendations.

Figure 1. A front-mounted roller crimper being used to terminate cereal rye at anthesis, June 2019.

Seven replicated and randomized strip-trials were used to compare cover crop-based organic no-till soybeans to standard production practices in 2019 and 2020. Nine observational field sites were also monitored. At all sites, rye was seeded on an angle (> 20 degrees) relative to the direction of roller crimping and soybean seeding. Common cereal rye was drilled in September or early October across the sites and seeded at a rate of 3 bushels/acre (168 lbs/acre) for the strip-trial sites.

Seeding rye early is key 

The most consistent observation made across project sites was the importance of early rye seeding. Rye was seeded following early-harvested crops such as small grains, sweet corn and corn silage. All trial sites seeded before September 22nd achieved more than 5,500 lbs/acre dry matter, while those seeded after were consistently below that threshold (Figure 2). A thick, competitive stand of rye is critical for the cover crop-based organic no-till system to work. In nearby New York state, achieving >6,000 lbs/acre of rye biomass has been identified as critical for successful weed suppression1. Below average spring temperatures in 2019 and a late frost in 2020 may have contributed to slightly reduced rye biomass across all sites.

graph showing rye biomass on vertical axis and julian date on x axis
Figure 2. Cereal rye biomass at crimping vs. rye seeding date.

Vigorous spring growth is also important for competition with weeds. The Drayton-2020 site, which had high fertility and was seeded on September 20th, had good early season canopy coverage (Figure 3) and reasonable biomass (5,700 lbs/ac). As a result, it provided excellent season-long weed control (Figure 4).

overhead view of thick cereal rye stand
Figure 3. Thick cereal rye stand at the Drayton site on April 18, 2020.
soybeans yellowing, no weeds
Figure 4. Organic no-till strip at the Drayton site on September 3rd, 2020. The rye mulch provided effective season-long weed suppression.

The Elora site (Figure 5), which was lower fertility and seeded on October 2nd, provided only 4,400 lbs/ac of biomass and its mulch was not able to hold back strong witchgrass pressure (Figure 6).

overhead view of thin cereal rye stand
Figure 5. Thin cereal rye stand at the Elora plot on April 8, 2020.
view of grassy weeds and soybeans
Figure 6. Organic no-till strip (left-hand side) at the Elora site on September 3rd, 2020. The thin stand of rye did not provide adequate weed suppression.

Use appropriate seeding equipment 

Another major finding was the importance of appropriate soybean seeding equipment for the high-residue conditions of this system. We had success using a planter set up for no-till conditions with sufficient down-pressure, sharp openers and appropriate closing wheels (Figure 7). Although no-till drills were generally successful as well, one site had a patchy stand because the drill could not effectively cut through the mulch (Figure 8). Planters are more likely to be effective in high rye biomass conditions and when the rye is crimped before soybean seeding.

strong soybean stand with rye mulch below
Figure 7. A strong stand of soybeans in rye mulch at one of the sites seeded using a no-till planter (Woodstock, July 14th, 2020).
rye mulch interfering with soybean seeding
Figure 8. An example of where the no-till drill was unable to cut through rye residue and place the seed into soil at the Blyth site in 2019.

Soybean seeding rates for the organic no-till strip-trials were 200-250,000 seeds/acre in 2019. In 2020, they were increased to 300,000 seeds per acre. Higher rates in the organic no-till system help to ensure a competitive stand, compete with weeds and provide yield improvements according to some research2. On average in 2020, final plant populations in the roller crimped plots were 195,000 compared to 248,000 plants/acre in the no-rye controls (both treatments seeded at the same rate).

Rye mulch delays soybean growth and development

Roller crimped rye creates a cooler, darker environment at the soil surface that reduces weed seed germination. Those same conditions also slow the early growth and development of soybeans in the organic no-till system. Soybeans were slow to emerge from the mulch.

At the strip-trial sites, soybeans planted into roller crimped rye typically lagged one growth stage behind the no-rye control throughout the season. The difference is shown at the Drayton-2019 site in July (Figure 9). By mid-to-late August in 2019, the roller crimped soybeans at all sites came on strong and canopied fully, though they remained shorter than the no-rye beans.

Organic soybeans. Taller, bigger beans where tilled; shorter, smaller beans where no-tilled into rye mulch.
Figure 9. Boundary between a no rye control strip with 30” soybeans and drilled, 7.5” no-till organic soybeans at Drayton-2019 site on July 22nd (left) August 20th (right).

In 2020, due to dry conditions made worse by rye transpiration before crimping, moisture-limited soybeans in the crimped plots remained stunted relative to their no-rye counterparts. This difference remained through to the end of the season (Figure 10). The stands at most sites were only half to two-thirds as tall right up until harvest. This contributed to significant yield reductions.

thin soybeans stand with rye mulch below
Figure 10. Soybeans in a roller crimped strip at the Drayton-2020 site on August 12th. Given a May 24th planting date and narrow spacing, these beans should have canopied well before this date.

Yield results

Strip trial sites

The average yield across strip trial sites in 2019 and 2020 for soybeans in the roller crimped system was 29.2 bushels/acre, which was 21.7 bu/ac less than the no-rye control yield of 50.9 bu/ac (Table 1). The difference in yield was greater in 2020 (25.8 bu/ac) than in 2019 (11.5 bu/ac), despite several improvements made to the organic no-till system between seasons. Note that only the Drayton sites were managed organically for the no rye (control) treatment; all other control treatments were managed using herbicides.

While insufficient mulch and weed pressure, as well as soybean stand damage from crimping, were factors at a couple of sites, they did not fully explain the yield difference. The Drayton and Seaforth sites in 2020, for example, had acceptable weed suppression, but both yielded below 25 bu/ac. It’s believed that dry soil conditions due to below average precipitation in May, June and July were exacerbated by the cover crop-based organic no-till system. This, in turn, severely stunted vegetative growth, root development and limited yield potential.

Soybeans in roller crimped treatments in 2020 had a 30% lower pod count of those in the no rye treatment. Slightly smaller seed size likely further contributed to reduced yields.

Observational sites

The yield data showed similar trends at observational sites from 2019 to 2020. Cover-based organic no-till yields ranged from unharvestable to 47 bu/acre (Table 1). Sharp openers, increased down-pressure and a higher soybean seeding rate may have helped in overcoming some of these barriers at the unharvestable Blyth site. At the St. Marys M site in 2019 and all St. Marys sites in 2020, narrow row spacing at a high soybean seeding rate enabled the grower to achieve reasonable weed suppression despite low rye biomass. As with the strip-trial sites, it’s believed that soil moisture depletion by the rye contributed to the yield reduction in 2020.

Table 1. Summarized yield results from all sites. All values corrected to 13% moisture. ST = strip trial; O = observational site. Statistically significant differences are shown by different letters.

SiteYield (bu/acre)
No Rye
Yield (bu/acre)
Roller Crimped
2019
Blyth (O)-0*
Drayton-2019 (ST)45.4 A36.8** B
Elora-2019 (ST)48.8 A34.5 B
St. Marys J (O)-38
St. Marys M (O)-47
2019 Average
(strip-trial sites only)
47.135.6
2020
Bornholm (ST)60.7 A33.2 B
Drayton-2020 (ST)46.9 A22.9 B
Elora-2020 (ST)66.2 A19.3 B
Seaforth (ST)35.3*** A24.9 B
St. Marys D-2020 (O)-30
St. Marys H-2020 (O)-32
St. Marys J-2020 (O)-28
St. Marys M-2020 (O)-35
Woodstock (ST)53.0 A32.7 B
2020 Average
(strip-trial sites only)
52.426.6
2019 and 2020 Average
(strip-trial sites only)
50.929.2

*Soybeans at the Blyth site were unharvestable due to insufficient weed suppression, poor soybean growth and red clover re-growth.

**Approximately 18% of this yield is estimated to have come from rye seed

***Inadequate soybean stand

– No data

Lessons learned

Based on the yield results to date, the organic no-till system represents too much risk to recommend on a large scale. It is possible to grow a cover crop that can do a good job suppressing weeds, though this was not universally achieved. Early-planting and good base soil fertility to support tillering and aggressive rye growth are key. Also, use of appropriate soybean seeding equipment is critical.

The below-average precipitation in the spring and early summer of 2020 exposed a key vulnerability of the system – resulting in disappointing yields, even in cases where everything else was done properly.

Based on observations from the past two seasons, the following lessons were learned:

  1. Select fields with low perennial weed pressure and at least moderate background fertility (e.g. >15 ppm P (Olsen), >100 ppm K)
  2. Seed rye early – ideally mid-September – and thick to achieve sufficient rye biomass
  3. Use appropriate seeding equipment to ensure good cutting of the rye mulch, placement of soybeans, and closing of the seed trench
  4. Seed soybeans at a high rate (minimum of 250,000 up to 300,000+ seeds/acre)

“Success starts with planting your rye in the fall and carries through to the soybean crop. Good base fertility and planting the rye thick are key. Don’t go in with the assumption that it’s going to work the same way every year – be ready to alter your plans if needed.”

Morris Van De Walle, farmer cooperator

Next steps

Cereal rye was seeded in the fall of 2020 to evaluate cover crop-based organic no-till for another season at the Elora and Bornholm sites. It is important to assess the system for at least three seasons to better understand how it performs across different weather conditions.

To read the full, detailed project report click here to visit OSCIA’s Tier 2 Projects website.

Acknowledgements

This project was supported by OSCIA Tier 2 project funding. Donations of cereal rye seed were generously made by Cribit Seeds and The Andersons (formerly Thompsons Ltd.). Soils at Guelph supported the Woodstock strip-trial site in 2020. Thank you to Horst Bohner and Mike Cowbrough (OMAFRA) for key project support. Finally, thank you to the farmer cooperators who made the project possible.

References

  1. Personal communication with Dr. Matthew Ryan, Associate Professor of Sustainable Cropping Systems, Cornell University.
  2. Jeffrey A. Liebert and Matthew R. Ryan “High Planting Rates Improve Weed Suppression, Yield and Profitability in Organically-Managed, No-Till Planted Soybean,” Weed Technology 31(4), 536-549, (1 August 2017). https://doi.org/10.1017/wet.2017.35