Early season, The Bean Report

The Bean Report – May 25, 2022

MAY 25, 2022

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New! AgriInsurance Seeding Deadline for Soybeans Extended

MASC has announced a permanent extension of the AgriInsurance seeding deadlines for soybeans starting in 2022. Full coverage deadlines for soybeans are now June 8 for Soybean Area 1 and June 4 in Soybean Areas 2 and 3. No change for Soybean Area 4.

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These changes were made in consultation between MPSG, MASC and Manitoba Agriculture after a review of available data and agronomic considerations. Find more information about this change at MASC News.

Below, find MASC data from 2010 to 2021 exploring average relative soybean yield by seeding date through the month of May into June for Crop Areas 1, 2, 3 and 4. Soybean varieties adapted to Manitoba were more readily available from 2010 onwards.

Soybean Seeding Date x Relative Yield (2010-2021) Zone 1 Chart. MASC
Soybean Seeding Date x Relative Yield (2010-2021) Zone 2 Chart. MASC
Soybean Seeding Date x Relative Yield (2010-2021) Zone 3 Chart. MASC
Soybean Seeding Date x Relative Yield (2010-2021) Zone 4 Chart. MASC

Seeding Update

Find the latest Manitoba Crop Report at https://www.gov.mb.ca/agriculture/crops/seasonal-reports/crop-report-archive/
  • Wet conditions persist across much of Manitoba. Conditions vary widely across the province with some areas still flooded.
  • Thankfully this May long cleared after Friday for many areas of the province, with weather conditions looking promising during the week for farmers to get back out into the field or start seeding. The Manitoba Crop Report indicates that seeding progress is at roughly 10% completion as of Tuesday, May 24.
  • Check out Manitoba Agriculture’s weekly region specific Crop Report and Weather Reports Crop Weather.

Residual Nitrate: Spring vs. Fall

John Heard, Manitoba Agriculture, has collected preliminary data comparing fall and spring soil test-N levels. These fields were mostly clay soils, ranging from Fannystelle to Winkler, Sperling and Homewood areas. These fields were wet, but not waterlogged.

In the fall, these fields had very high nitrate-N, with much concentrated in the top 6″. This spring, that N has moved into the 6-24″ depth. Overall range of N loss is between 20 to 60 lbs N/ac, but levels still remain high. These losses are expected to be due to leaching , not denitrification, since soils were very cool until recently and these fields were not waterlogged or flooded. Now that soils have warmed up, if soils are currently waterlogged denitrification processes will have started back up and losses of 4 lbs of nitrate-N/ac/day may be expected.

On one field with sandy loam soil more N was ‘lost’ deeper in the soil profile. At that field in the fall, there was 192 lbs N/ac in the 0-24″ (0-6″: 53 lbs N/ac and 6-24″: 139 lbs N/ac). This spring, there is 103 lbs N/ac in the 0-24″ (0-6″: 7 lbs N/ac and 6-24″: 96 lbs N/ac). Sampling deeper this spring, 80 lbs N/ac were found at the 24-36″ depth and 60 lbs N/ac at the 36-48″ depth.

Nodulation

Lower N levels in the 0-6″ layer is promising for soybean and pulse crops to develop sufficient nodules early in the season. For soybeans, nodulation may still be slightly affected, but if the field has had a history of soybeans, the crop can be expected to nodulate. In research conducted on the prairies, 75% of pea roots exist above 40 cm (15 .75″) soil depths, with the majority occurring in the top 0-20 cm (0-7.87″) of the soil profile. Pea nodules begin to form as early as 14 days after emergence. A double inoculation strategy is recommended due to challenging spring conditions to ensure that rhizobia effective at fixing N is present to colonize root nodules.

Soybean Seeding Tips

The optimal time to seed soybeans will vary each year by region and with spring conditions. Below are some considerations to keep in mind as you prepare to seed soybeans:

  • Ensure soil temperatures at seed depth are at least 8°C and that there is no cold rain or snow in the forecast for the first 24 – 48 hours after planting.
  • A benefit with later seeding is warmer soils, this will aid in quicker emergence and reduce the risk of chilling injury. Soybeans will emerge within 24 – 35 days when seeded into 6 – 12 °C and 4 – 16 days when seeded into 14 – 22 °C  soils (based on soil temperature at a 5 cm depth at 10:00 a.m. for two consecutive days). See the provincial soil temperature data here: MB Ag, 14 Day Soil Temperature,  MB Current Soil Temperatures.
  • Soybeans are a large seed and it is recommended to target a depth of 1/2″ into moisture. In wetter spring conditions, consider the recommended seeding depths of 0.75 to 1.75″ and avoid seeding on the deep end of this range to aid in quicker emergence.
  • Target 140 – 160,000 live plants/ac, taking into account expected germination and survivability. Use the Bean App Seeding Rate Calculator to determine an economical seeding rate for your farm.
  • The maximum safe rate of seed-placed phosphorus is 20 lbs P2O5/ac in narrow rows with good soil moisture and 10 lbs P2O5/ac in wide rows.
  • If considering utilizing a seed treatment, it is best applied if you expect significant pressure from early-season insects and disease. Check out MPSG’s Soybean Seed Treatment Assessment Guide to help you determine if a seed treatment is required.
  • Double inoculate first-time soybean fields. Consider single inoculation if the field has met the below four criteria:
    • The field has had at least two previous soybean crops,
    • previous soybean crops have nodulated well,
    • most recent soybean crop within the past four years, and
    • no significant flooding or drought.

Soybean Seeding Timing and Maturity

Given current spring conditions, many farmers are wondering how late you can plant soybeans in Manitoba, with previous years leaving us questioning how early they can be seeded. Research has shown that soybean seeding dates are quite flexible during the month of May, while delayed seeding into June may reduce yield potential. Reviewing data with MASC, relative soybean yields are maintained fairly well up until crop insurance seeding deadlines.

With current seeding conditions, there is still an opportunity to establish a successful soybean crop that will mature before your average fall frost. Select a soybean variety suited to your region’s maturity zone, which is the average frost free period of a given region in Manitoba. With soybean seeding being delayed in many parts of the province, check to ensure that your variety is likely to mature before your region’s average first fall frost.

Research conducted by the Soybean and Pulse Agronomy Lab has shown soybean yields to be statistically similar when planted from April 28 to May 24. Yield was reduced by 15% when seeding was delayed to the first week of June.

A second study investigated yield and maturity of late-seeded soybeans in Manitoba. In that study, soybeans grown at Portage and Morden demonstrated good yield potential and little risk when seeding as late as June 9 to 12. At Arborg on the other hand, seeding between May 31 and June 6 reduced yield potential and increased the risk of not reaching maturity due to fall frosts. View the full research results here.

Find more information about late soybean seeding here.

Rolling Soybeans

Land rolling is one method that can improve harvestability of soybean crops. Rolling evens the soil surface by pushing down rocks, soil clods and crop residue. As soybeans are harvested close to the ground due to low pod heights, there is a risk of machinery damage. Rolling is a necessity if there are a lot of rocks or corn root balls in the field, or if the soil surface is very uneven, posing a risk of substantial earth tag at harvest.

Timing

Rolling can be done immediately after planting, up to two days after planting, or post-emergence. If the soil is wet, rolling immediately after planting can be an issue, as it can cause soil sealing or crusting that can inhibit emergence. Under these conditions, post-emergent rolling is a better option. For timing, target the V1 (first trifoliate) stage on a warm day, during the warmest part of the day (~25°C). Plants are most sysceptible to stem breakage at the hook stage (VE) and after V3.  Read more about soybean rolling here.

Soybean and Pulse Herbicide Options 2022

Soybean Herbicide Options 2022
Pea Herbicide Options 2022
Dry Bean Herbicide Options 2022

Dry Bean Seeding Tips

  • Plant dry beans from late May to early June once soils have warmed to 15°C.
  • Plant at 0.75 – 1.5” seed depth, placing seeds 0.5″ into moisture.
  • Dry beans can successfully be planted in narrow (<15”) or wide rows (>15”), with black, navy and pinto bean types typically being better suited to narrow-row production. Research has indicated a yield advantage (90% yield increase) to planting these bean types in narrow rows (7.5”), targeting plant stands of 80 – 120,000 plants/ac.
  • Target plant populations vary with market class, seed size and, in some cases, row width.
    • Dry beans are susceptible to damage from seed handling – whether you’re cleaning seed, treating seed, or running it through equipment. Soak tests reveal if the seed coat has been cracked or damaged, and you can use them as a tool to adjust your seeding rates before planting.

Dry Bean Nitrogen Fertilization and Inoculant Research in Manitoba

Dry beans are poor nitrogen (N) fixers (fixing <45% of their N-requirement), and to-date inoculant options have not been widely available. As a result, they are fertilized like a non-legume crop. Research has been ongoing through the soybean and pulse agronomy lab and the On-Farm Network (OFN) investigating N rates and inoculant products. Find a summary of that research here.

Nodulation Response to Applied N

In 4 of 5 on-farm trials investigating N rates, we have found good to excellent nodulation at N rates lower than 70 lbs N applied/ac. In OFN trials and small-plat trials, as N rate applied increased, nodulation decreased.

Yield Response to N Rate

In small-plot trials, yields were only increased at the highest rate of N applied (140 lbs/ac), while in on-farm trials, yield response was more variable. In three OFN trials, yield did not respond to N rate.

In one OFN trial in 2020, yield was decreased with the highest N rate (105 lbs N applied/ac; 139 lbs N/ac available as a combination of applied and residual). Yield was nearly 400 lbs/ac lower at the highest N rate due to prolonged vegetative growth and delayed maturity at that trial.

In another OFN trial in 2021, yield was increased at the highest N rate (70 lbs N applied/ac; 140 lbs N/ac available). Overall yield at this trial was lower due to the drought. Mineralized-N was expected to have played less of a role during 2021 due to dry conditions, resulting in the crop relying on fertilizer-N and N derived from biological fixation.

Emerging N Fertility Management Options from the Research:

  1. No supplemental N and no inoculant added.
    • Small-plot trials indicate to expect 86-93% of expected yield.
    • This was the economic optimum in the small-plot trials and at 4 of 5 on-farm trials.
  2. Apply supplemental N at 35 lbs N/ac or to reach 70 lbs total N/ac (combination of fertilizer-N and soil residual-N).
    • If skipping N fertilizer is too risky. This will achieve maximum yield without reducing nodulation.
  3. Inoculate
    • As product availability and testing increases.
  4. Inoculate and apply supplemental N?
    • Requires more research first!

Evaluating Root Rot Risks

Root rots are caused by a complex of diseases that infect the belowground portions of developing plants. These include Fusarium spp., Pythium sp., Rhizoctonia solani, Aphanomyces eutiches in peas and Phytophthora sojae in soybeans. They may be seed- or soil-borne and can infect plants at any stage, however, the seedling stages during plant establishment are most susceptible. Fusarium species are the most predominant, infecting every field at some level each year. Learn more about managing Fusarium root rot here.

Stress factors that delay germination and slow emergence or growth of plants contribute to an increased risk of root rot infection. Factors that can challenge early-season growth of soybeans and pulse crops include:

  • wet conditions,
  • cool temperatures,
  • short rotations,
  • heavy-textured soils,
  • compacted soils,
  • nutrient deficiency,
  • herbicide residues and
  • low seed vigour.

Management strategies:

  • Field selection: Choose lighter-textured soils with good drainage and minimal compaction for pulse and soybean crops.
  • Seed quality: in addition to germination testing, disease testing can be used to inform seed-borne disease levels.
  • Seed treatments: provide protection for 2-3 weeks after seeding. Consider a seed treatment if seeding into cool and/or wet soils or into fields with a known history of root rots.
  • Extended crop rotations: reduce the disease inoculum in the field.
    • If Aphanomyces is identified, pea rotations should be extended to 1-in-8 or 10 years to allow time for the spore loads to decrease. The exact number of years between susceptible crops is less important than what the severity was in the past, the environment during the years the crops were grown, and what has been on the field since. Read more here.
      • Manage Aphanomyces-susceptible weed species like chickweed, vetches and shepherd’s purse.
    • Due to the wide host range of Fusarium species, crop rotation alone is an ineffective strategy for Fusarium root rot. Peas planting in a 1-in-4 or 5-year rotation have still experienced severe root rot under the right environmental conditions.
  • Genetic resistance:
More Resources: