April 14, 2022
- Field Selection for Soybeans and Pulses
- Herbicide Carryover Risk
- Consider an On-Farm Trial to Evaluate Inputs this Season
- Planning for Soybeans and Pulses with Soils Testing High in Nitrates
- In case you missed it:
Field Selection for Soybeans and Pulses
Soybeans thrive in warm summers with sufficient moisture, while peas are more suited to relatively dry conditions where root rots are not as frequent. Dry beans prefer more moderate conditions, while faba beans thrive in cool, wet environments.
Selecting fields for growing soybeans and pulses should consider the water holding characteristics of the field, each crops water demand and salinity tolerance.
Soybeans and pulses are very sensitive to salinity, where 10% yield loss may typically be expected when soil salinity reaches 1.0 mmho/cm (dS/m). Yield losses of 25% may be expected when electrical conductivity (EC) reaches 1.8 mmho/cm for soybeans, peas and faba beans. For dry beans, 25% yield loss may be expected at lower EC levels of 1.3 mmho/cm and profitable dry bean yields are unlikely at ECs greater than 1.5 mmho/cm. More information about crop tolerance to salinity is available here.
According to AGVISE data from soil samples collected in fall of 2021, less than 19% of soil samples (0-6″) in Manitoba have EC greater than 1.0 mmho/cm. However, salinity occurs in zones in the field and composite soil samples may not provide an accurate measure of troublesome areas. To assess salinity in a field, take soil samples from affected areas and adjacent non-affected area.
Managing salinity boils down to managing water. Plant salt-tolerant crop species or perennial forages in affected saline areas instead of salt-sensitive soybeans and pulses. Having something growing in those saline areas of the field throughout the growing season will prevent the salinity from moving further into the field. Consider improving drainage in those areas to leach soluble salts.
Soybeans: Evaluate IDC risk and choose tolerant varieties
Iron deficiency chlorosis (IDC) is most commonly observed in soybean crops, but dry beans, faba beans and field peas can also be sensitive to IDC. Despite the abundance of iron in Manitoba soils, factors such as excess calcium carbonates, soil moisture, soluble salts and/or high nitrate levels can impede iron uptake into the plant and increase the risk of IDC.
The risk of IDC development can be predicted based on the combination of soil test calcium carbonate and soluble salt levels. For example, a combination of high soluble salt (>1.0 mmhos/cm) and carbonate (>5.0%) concentrations in the soil indicate an extreme risk of IDC.
The best management method is prevention. Choosing an IDC-tolerant soybean variety is the primary management tool. IDC tolerance ratings are available in MPSG’s Soybean Variety Guide, where 1 is most tolerant and 5 is susceptible. Other management options include heavier seeding rates or wider rows, improved drainage, and practices that reduce soil N levels like cover cropping, companion cropping with a cereal and N management in other crops.
Iron chelate products are also on the market for IDC prevention. Research from North Dakota State University has shown that in-furrow iron chelate products, such as Soygreen (2-3 lb/ac of FeEDDHA) can offer some protection. However, significant yield loss can still occur when varieties that are susceptible to IDC are planted. Foliar sprays haven been shown to be ineffective. Read more here.
Herbicide Carryover Risk
Many of our residual herbicides are broken down by microbial activity. This requires adequate soil moisture and warm temperatures. If less than normal precipitation occurs, residual herbicides may remain in the soil longer, increasing the risk of injury to sensitive crops like pulses and soybeans. As a result, the risk of greater than expected herbicide carryover may be interpreted from precipitation maps during the previous growing season (June to August and mid-June to mid-September). Refer to the current Guide to Field Crop Protection and the product label for recropping information.
Note that rainfall events in 2021 were sporadic and localized. While there may have been an adequate amount of rainfall over the entire season, much of the moisture came in early June and late August. Many areas had little or no rainfall for the majority of the summer, and microbial activity required to breakdown residual herbicides would be greatly reduced during this period. Use rainfall data (timing and amount) specific to your fields to help determine the risk of herbicide carryover and adjust your cropping plans accordingly.
In-season, if you have herbicides with residual carryover, you will see injury pop up after a rain, which releases herbicides from soil particles and into the soil solution to be taken up by crop roots.
Consider an On-Farm Trial to Evaluate Inputs this Season
To say that it will be an interesting year is an understatement. It will be an educational year for Leanne, as she dives into her new role as the On-Farm Network (OFN) Agronomist. It will be a year of change for the industry, as the word sustainability evolves from a buzzword to a comprehensive strategy. And it will be an unpredictable year for farmers as we pull out of a drought year and face rising input costs.
Uncertainty is not a new feeling for farmers. But what is certain, is that the OFN can clarify your production questions as we face the ever-evolving landscape of the ag industry. Perhaps the increasing demand for plant proteins have you thinking about ideal pea seeding rates for your farm. Maybe rising input prices have you questioning optimal fertilizer rates. Wondering, could you save money by reducing your seeding rate without sacrificing yield, or does that biological you’ve had your eye on, really work? These are all questions that the OFN can help you answer through on-farm trials in your fields.
What would you like to fine-tune on your farm this season? We’re here to help. Contact Leanne at 204-751-0439 or firstname.lastname@example.org to set up a trial on your farm. Check out previous year’s results in the database here.
Planning for Soybeans and Pulses with Soils Testing High in Nitrates
Drought conditions across Manitoba in 2021 have resulted in high residual nitrate levels due to less crop uptake and removal from lower yields, early termination of some crops and fewer losses to leaching and denitrification. For high N-use crops this can be an asset in a time of high fertilizer pricing, but for N-fixing legumes this is an added challenge.
How will N-fixing pulses and soybeans respond to soils testing high in nitrates? This article is a summary of what we know so far, based on field observations.
Keep it Clean: 2022 Product Advisory Webinar
Join Keep it Clean on April 19 at 11:00 a.m. for a webinar offering timely information about crop protection products that may create market risk in 2022 and how your crop protection decisions can support market access for all. Registration and details available here.
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