How Soybean Architecture Plays into Planting Populations | AgriGold

How Soybean Architecture Plays into Planting Populations

How Soybean Architecture Plays into Planting Populations

Key Takeaways:

  • Soybean varieties exhibit diverse growth habits. Some branch extensively to produce pod-filled plants, while others grow upright with minimal branching, impacting crop potential.
  • Through multi-season studies, AgriGold discovered that soybean varieties show varied branching patterns and pod production at different planting populations, influencing optimal planting strategies.
  • Based on field observations, soybeans were classified into categories reflecting their branching characteristics. This aids farmers in choosing varieties that align with their planting population goals to maximize yield.

Every season, agronomists from all over the country walk fields — and sooner or later will find that one random plant by itself, with big branch architecture. It’s a beautiful plant, loaded to the gills with pods. It’s the kind of plant farmers wish they had 100,000 of in the field. 

AgriGold agronomists know that soybean varieties all grow differently. While some branch out, others grow straight up with little branching. While some branches are full of pods and blossoms, others have full main stems, with the branches just serving as vines. 

“A common assumption in agronomy has always suggested that if soybeans have more room to branch, they will – turning into that gorgeous, 10/10 pod-filled beauty. But do they?” asks Nick Frederking, AgriGold agronomist in southern Illinois. “Our team at AgriGold has looked into this question over the past several seasons and is continuing to dive deeper into how soybean architecture impacts yield results.” 

Exploring Branchability

Certain characteristics are table stakes when it comes to scouting soybeans. Any agronomist should observe color, height, stands, time to canopy or herbicide damage. While all of that’s good information to have, it doesn’t always tell the full story. 

“When you pull back that canopy and really look at how the soybean is growing, there is more to say about why a variety may be the right fit for farmer A and not farmer B,” says Frederking. “The end goal is always the same: get the best yields out of each soybean variety planted.”

Recently, farmers have been dropping planting populations lower. AgriGold agronomists want to ensure they recommend the right variety to match the farmer’s planting population strategy. 

“We started with a pilot in southern Illinois testing 10 AgriGold soybean varieties with the latest genetics and traits, including Xtendflex and E3 soybeans,” explains Frederking. “Each variety was planted in low and high planting populations: 80,000 and 160,000, respectively”

Although planting populations vary by farm, the average planting population in this area of Illinois is 140,000.  

The study’s purpose was to observe each variety’s branching and pods at differing plant populations. Frederking kept all other management decisions standard for the region, including row spacing, planting dates and herbicide programs.

Expanding Beyond One Maturity Zone

In the second year of this experiment, locations were selected across the Midwest and MidSouth, highlighting the variety of the maturity zones in the portfolio. The northernmost varieties were planted at 0.5 maturity, while the southernmost varieties were at 5.25 maturity.

Similar to the pilot year, the trials adjusted based on the region’s standard protocols. Right away, the differences in how the soybeans grew was noticeable. Every variety – as expected – has limited branching in higher populations. But when given all the room to grow, some varieties do not branch even in lower populations. 

Categorizing Soybeans

“Coming out of these trials, each variety was given a category for branching based on field observations,” says Frederking. 

The categorization was: 

Category 1:

Regardless of plant population or spacing, the variety demonstrates minimal branching in various trials. 

Category 2:

At reduced populations or increased spacing between plants, these varieties would branch with longer petioles and more branches off the main stem. However, that rarely resulted in more podding on the plant, and the varieties looked more like vines out in the field. 

Category 3:

At reduced planting populations and increased space, these varieties resulted in excessive branching and increased podding locations on those branches. Ultimately, the varieties not only use the resources to grow more branches but to add grain as well.

Putting It to Use

A variety’s branching potential is another data point for farmers when making decisions. Choosing the right varieties expands beyond the status quo to encompass the placement and management of the soybeans in each field. 

A grower looking to plant into moderate to high planting populations should lean toward a Category 1 or Category 2 soybean, where the pods emerge on the main stem. Category 3 soybeans are most likely to branch, making them well-suited for lower populations. 

“There is no right or wrong answer on the categories for planting. All three categories can yield within varying conditions,” says Frederking.  “But farmers planting in low populations who choose a Category 1 or Category 2 would have tougher choices when it comes to replant. While Category 3 soybeans can be forgiving in low populations looking toward a replant, Category 1 and Category 2 may not compensate, and a replant should be strongly considered.” 

By using the category system, AgriGold district sales managers can give farmers the best recommendations based on additional details beyond yield. 

Reach out to your local AgriGold agronomist for support in choosing the best varieties for your fields.