Early season, The Bean Report

The Bean Report – April 28, 2020

April 28, 2020

  • Field pea seeding tips
  • Cold temperature considerations for pulses and soybeans
  • On-Farm Network sign-up information
  • Approaching soil fertility in spring 2020

Giving Your Peas a Good Launch

Seeding Date

  • Peas are a cool-season crop that can be seeded early for the best yield potential, from late April to early May when the top inch of soil reaches 5°C.
  • Peas thrive in drier soil conditions and are susceptible to root rot (most commonly Fusarium spp. or Aphanomyces euteiches) in wet soils.

Seeding Rate

  • Target 80-90 live plants/m2 (350-400,000 plants/ac or 8-9 plants/ft2).
  • Adjust your seeding rate (lbs/ac) based on expected seedling survival (typically 85%) and seed weight, which can vary widely among seed lots (from 125-300 g/1000 seeds).
  • Determine seedling survival by conducting a germination test, a soak test to calculate % seed coat slough and factoring in expected seed mortality based on planting conditions, damage from seeding equipment and annual plant stand assessments, if available.

Seeding Depth

  • Plant peas at 1.5 – 2 inches deep, ensuring seeds are in contact with moisture.

Other Considerations

  • Inoculate with Rhizobium leguminosarum, to facilitate successful N-fixation.
  • If applying starter phosphorus (P), the maximum safe rate of seed-placed P is 20 lbs P2O5/ac with seedbed utilization (SBU) of >15%. Place away from the seed row with lower SBU.
  • Peas are poor competitors against weeds early in the growing season. Pre-emerge herbicides help provide effective weed control. There are fewer post-emerge options and a risk of yield loss if they are not applied at the correct time in-crop.
  • If the risk of early-season insect or disease pest pressure is high, consider using seed treatment.
  • How you launch your peas will impact the crop’s potential for uniformity and influence late-season management decisions like desiccation or preharvest weed control.

Check out our Field Pea Production Guidelines fact sheet for more pea agronomy tips.

Cold Temperature Considerations

Pulse crops like peas and faba beans can be seeded early because their cotyledons remain below ground, protected from spring frost. If young pea or faba bean plants are damaged, they can regrow from below-ground nodes.

If you’re contemplating early soybean planting, the decision comes down to risk management. The planting window for soybeans is pretty wide in Manitoba – the month of May. But where you can work within that window depends on your individual situation:
  1. According to the soybean maturity zones map, are you in the very early-, early-, mid- or long-season zone? This dictates the number of frost-free days you will get in a growing season. Frost is the number one threat to early soybean planting. A good rule of thumb is to plant within two weeks of your last expected spring frost to ensure your soybeans emerge into a frost-free environment.
  2. Soil temperature is still top of mind in Manitoba. It’s true that soybean seeds are susceptible to imbibitional chilling injury during the first 48-hours after planting. This may be from cold, wet soil at the time of planting, or from cold rain or snowy weather immediately after planting. However, field research in Manitoba pushing soil temperatures as low as 6°C (at 10 AM at seed depth) on planting dates as early as April 27, has not shown any yield hit to soybeans.
  3. Other soybean planting date research has also shown earlier calendar dates (first three weeks in May) to produce the greatest yields. Early planting dates maximize yield potential by taking advantage of as much growing season time as possible. But if that early planting date puts your soybeans at risk of frost damage, wait to plant.
  4. How many soybean acres are you planting in total, and how many compared to other crops on your farm? If you want to experiment with early planting dates, try it with a few acres first. You may also have other crops that need to go in the ground first that can better handle the cool temperatures.
  5. Do you have known early-season insect or disease pressure (e.g., wireworms, root rot)? How early you plant and the weather conditions that follow impact how long it takes soybeans to emerge. If cold conditions persist and they are sitting in the ground for more than 2-3 weeks, seed treatment may be wearing off.

Details on soil temperature and calendar date research:
When to Plant Soybeans in Manitoba: Should Soil Temperature Be Your Guide?
Soybean Seeding Decisions – Seeding Window and Seeding Depth Trial Results from 2017 and 2018
Real Agriculture interview with Horst Bohner (OMAFRA) – The Risks and Rewards of Early-Planted Soybeans

On-Farm Network Sign-Up

The On-Farm Network is getting ready for multiple research trials this season aimed at maximizing productivity and profitability. There is still time to sign-up if you have a question that needs to be answered. Take a look at our trial protocols and contact Megan if interested: megan@manitobapulse.ca | 204-751-0439

Follow us on Twitter, Instagram or Facebook to stay up-to-date on research this season!

Approaching Soil Fertility in Spring 2020

At our Getting It Right Crop Production Meeting in January, John Heard (Soil Fertility Specialist, Manitoba Agriculture and Resource Development) presented on how to handle soil fertility and management under saturated soil conditions in 2020. Check out his presentation slides for information on prepping the seedbed of rutted fields, handling unharvested acres from Fall 2019 and more.

Additional Resources

Questions about your pulse and soybean crops? We’re here to help:

Cassandra Tkachuk
Production Specialist – East
(204) 293-4424
Laura Schmidt
Production Specialist – West
(204) 751-0538