Early season, The Bean Report

The Bean Report – May 24, 2023

MAY 24, 2023

Crop & Seeding Update

  • Seeding progress has varied with region, with areas that missed previous week’s rains in western Manitoba further along. View soil temperatures from local weather stations →
  • Soybean seeding is ongoing, with an expected increase in acres this year.
  • Field peas are emerging to V1, with some seeding still ongoing.
  • Dry bean seeding has begun and is progressing quickly with good soil conditions.
  • Faba bean seeding is nearing completion.
  • The majority of On-Farm Network seeding timing trials in soybeans and peas have been established, with dry bean inoculant and nitrogen trials going in this week.
    • Soybean trials are investigating seeding rates, row spacings and inoculation strategies. Pea trials this year are evaluating seed treatments and seeding rates.

      Seeding an On-Farm Network pea seeding rate trial comparing 160, 200 and 240 lbs/ac seeding rates.

Dry Bean Seeding Information

  • Plant dry beans from late May to early June, once soils have warmed to 15°C.
  • Plant at a depth of 0.75 – 1.5”, placing seeds 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 Bean Herbicide Options for 2023 →

Dry Bean Nitrogen Fertilization and Inoculant Research in Manitoba

Dry beans are relatively poor N-fixers, producing less than 45% of their N requirement. Nitrogen uptake rates in dry beans range from 3.9-4.7 lbs N/cwt of seed, meaning a 2000 lbs/ac dry bean crop would require 78-90 lbs N/ac. This nitrogen may come from a combination of residual soil N, biological N fixation and N fertilizer.

As nitrogen rate applied increases, nodulation decreases since plants become ‘lazy’ and rely on soil nitrogen alone. In 4 out of 5 on-farm trials to-date, good to excellent nodulation was found to occur when N rates applied were below 70 lbs N/ac. In small-plot trials, nodulation has generally been less than on-farm.

On-farm, yield response to nitrogen rate has been inconsistent. At three trials, there was no yield response to different N rates and at two trials there were opposite responses. At one, the highest rate of N (140 lbs N/ac applied) reduced yield, while at another, the highest rate of N applied (70 lbs N/ac) increased yield. In the first scenario, yield was reduced due to prolonged vegetative growth and delayed maturity. The second scenario occurred in a drought year, where the contribution of mineralized-N was expected to have played less of a role, meaning the crop relied more heavily on applied fertilizer-N.

In small-plot trials at Carman and Portage (2017-2019), yield was increased with the highest rate of N fertilizer (140 lbs N/ac applied). When considering the return on investment, it was statistically the same for all rates of N application, meaning the economic optimum rate was to not apply any N fertilizer at all.

In more recent small-plot trials at Brandon, Melita and Carberry (2021-2022) on narrow-row black and pinto beans, there was no response to different N fertilizer rates at 9 out of 10 site-years. Black bean yield tended to increase with increasing N rates, but only significantly with uninoculated beans at Melita in 2022. At Melita in 2022, black and pinto bean nodulation and yield (+390 lbs/ac) were improved with inoculant.

Small-plot research has also investigated dry bean inoculants at Carman and Melita from 2019-2021. Of product options available, N Charge improved yield and nodulation at Melita in 2020 and 2021.

Build a Bean Nitrogen Budget to Inform Your N Management Decisions:

  1. Set your yield goal (e.g., 2000 lbs)
  2. Calculate nitrogen uptake (multiply yield goal by 4.5 lbs/cwt = 90 lbs N)
  3. Account for soil residual N (0-24″) (e.g., soil N = 40 lbs N)
  4. Do you check nodulation in dry beans? (If no, skip to #6 and adopt as part of your scouting routine in 2023)
  5. Were your previous dry bean crops nodulated? (If yes, give a 40% N credit for biological N fixation by multiplying N uptake in #2 by 0.40 = 36 lbs N)
  6. Is your soil pH greater than 6.0? (If no, nodulation and N fixation capacity may be reduced and you should not rely on an N credit from #5)
  7. From N uptake (#2), subtract residual soil N (#3) and N credit (#5). This is your remaining N requirement (e.g., 90 – 40 – 36 = 14 lbs N/ac)
    1. If <20 lbs N/ac, N may be supplied through mineralization and deep N
    2. If >20 lbs N/ac, apply as fertilizer N
MacMillan 2023 Working Draft

In 2023, MPSG’s On-Farm Network has five trials planned to investigate dry bean nitrogen fertility on-farm. One black bean nitrogen trial near Deloraine is comparing 0, 35, 70 and 100 lbs N/ac fertilizer rates and four dry bean inoculant trials are planned in central and western Manitoba that will evaluate a liquid inoculant product vs. untreated dry beans. Stay tuned for effects on nodulation, lowest pod heights and yield!

Research conducted by Dr. Ramona Mohr, AAFC-Brandon (2021-2022), Kristen MacMillan, MPSG’s Agronomist-in-Residence, University of Manitoba (2017-2019) and the On-Farm Network (2019-2021).

Residue Management and Preceding Crop Ahead of Dry Beans

At Carman and Portage (2017-2020), pinto beans were grown following four crop residues (wheat, canola, corn, pinto beans) that had been split into tilled and direct seed/no-till treatments.

  • Previous crop did not affect pinto bean yield, but did influence grassy weed density and root rot severity. Grass weed density was lower when beans followed corn (13 plants/ft²) compared to beans following wheat (47 plants/ft²). Root rot severity was the greatest in pinto beans following pinto beans and lowest in beans following corn.
  • Residue management: In two out of six site-years direct-seeded (no-till) pintos yielded 10-17% greater than those seeded into tilled crop stubble. Pinto beans likely benefitted from some moisture conservation contributing to yield advantages. At other sites, pinto yields were the same regardless of tillage practice. Grass weed density in tilled treatments were double that of the direct-seeded beans.
  • Read more: Preceding Crop and Residue Management Effects on Dry Beans →

Research conducted by Kristen MacMillan, MPSG’s Agronomist-in-Residence, University of Manitoba (2017-2019).

Late Spring Frosts

Peas and faba beans have good frost tolerance, as their growing points are located below ground. If damaged, pea and faba bean plants can regrow from the seed below ground, or from the scale nodes if the main stem has been damaged. For crops with more advanced development, this can negatively influence crop uniformity.

Soybeans and dry beans are susceptible to frost damage because their growing points are located above ground. At this time, dry bean crops have not emerged yet and are safe from frost, but emerged soybean seedlings are at risk of damage. The level of damage incurred will depend on the severity and duration of freezing temperatures. Temperatures lower than -2°C are considered to be a hard or killing frost, and there is a risk of severe damage if these temperatures persist for more than 2 hours.

Scout your soybean fields 3-5 days after the frost event to assess the growing points and plant stand. Count the number of healthy plants and those that have green tissue and show signs of regrowth. If plant populations are very low (<80,000 plants/ac), re-seeding or topping up plant stands should be considered.

FACTORS THAT INFLUENCE FROST SEVERITY:

  • Duration of cool temperatures – longer duration of freezing temperatures can cause more damage.
  • Soil moisture – moisture in the soil will retain heat.
  • Wind speed – stronger wind can reduce the severity of frost.
  • Cloud cover – more nighttime cloud cover can reduce plant damage.

Assessing Early-Season Frost Damage →

Quick Links to Production Resources

Soybeans

Field Peas

Dry Beans

Faba Beans