Variable rate planting technology has been around a long time now. We have the technology to create planting zones and deliver seed based on these zones. Generally this technology has been used to change seeding rates of corn. However, less often this technology has been used on soybeans.

One of the concepts that has been thrown around for the past 15 years is not just changing seeding rate (that is relatively easy with today’s technology), but changing varieties on-the-go. That is a bit more difficult since your planter has to have two seed bins and independent flow units.

Becks has been test planting two different varieties in a field, as well as changing populations on-the-go. Jason Webster, Central Illinois PFR director with Becks explained that in their Multi-Variety Planting Study the goal is to not blend varieties together on-the-go but rather to place two varieties when they best fit in the field.

“Our approach to multi-variety soybean planting is different than our corn hybrid placement,” said Webster. “The goal is to identify low-yielding environments and place a stress-tolerant, tall and robust soybean variety at higher seeding rates. While in high-yield environments we place a shorter racehorse variety and reduce the population.”

Becks makes it relatively easy to select varieties because it classifies them by adaptation:

• Low Productivity – taller and defensive
• Medium Productivity – go anywhere
• High Productivity – shorter stature

The key to variety place is creating the right management zones in fields, and that is based on identifying offensive and defensive soils. Webster explained that in high-yielding environments it is common to see soybeans that concentrate on too much vegetative growth. “This leads to very tall soybeans with high potential for lodging. To combat this problem, we place a shorter, bush-type variety planted at lower seeding rates.”

Low-yield environments are described differently. “Defensive areas include hilltops, sidehills, low CEC and light timber soils,” said Webster. “High elevations, low organic matter with low water-holding capacity soils can inhibit the height of the soybean plants, thus limiting their ability close the row. This lack of canopy exposes the soil to more sunlight, causing higher soil temperatures and evaporation of soil moisture, creating more potential for stress.”

So what where the results? According to a report posted on Becks’ Practical Farm Research site, data compiled over 2012 to 2014 indicates that average yields increased by 3.2 bushels per acres and revenue increased by $38.48 per acre.

• Low Productivity Soils Defensive Variety, +3.0 bushels, +$40.21 per acre
• High Productivity Soils Offensive Variety, +3.4 bushels, +$36.75 per acre

Webster said to accomplish variable varietal placement they used a Kinze® 4900 planter. In addition, they have the opportunity to vary the population with a lower seed rate in offensive zones and a higher seed rate in defensive zones. For more information, visit the Practical Farm Research website http://www.beckshybrids.com/Research/Practical-Farm-Research, click on the link “2014 PFR Partners Results” and go to page 78.

Does carrying two varieties on a planter and placing them in their appropriate zones seem like a good strategy to increase yield?

Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at djdavidson@agwrite.com.