A lesser-known crop management practice is making some waves in the row crop business. More growers in the Midwest are using soybean rolling as a best practice on their farm. We’ve heard from a handful of growers recently questioning the practice and its effect on yields in soybean crops. Soybean rolling is becoming increasingly popular in areas like South Dakota, North Dakota, Minnesota and Iowa to help manage rocky soils. Here’s what we know about the practice.
What is it?
According to the University of Minnesota Extension, rolling soybeans is when “large rolling drums are pulled across the soil.” These drums are said to exert a force of three pounds per square inch. The rollers are typically used before planting or after emergence between the V1 and V3 trifoliate stages in soybeans for a few reasons, including:
- Harvestability. The practice pushes troublesome rocks below the surface so that when harvest comes around, growers can place the combine head at a lower level to ensure more pods are captured. This practice also helps prevent rock-related combine damage and downtime caused by equipment breakdown. It can also help crush other elements in the soil, such as corn rootballs or soil clods, to help smooth the seedbed for harvest.
- Plant development. Rollers are increasingly being used to encourage additional node and pod sets. When the roller runs through a field after emergence, its impact puts extra stress on the soybean plants, which may seem like a negative outcome, but some believe it actually encourages the plant to produce additional nodes, which in turn produce additional pods. According to the Illinois Soy Advisor, “On a soybean plant, the growing point is at the top of the plant. This growing point exerts apical dominance over the plant and limits node set and branching. Break the growing point and you sever apical dominance, perhaps resulting in more nodes and pods.”
Farm Journal explored this strategy in a multi-year study. One thing the study noted is that for this strategy to work, the plants needs to break above the cotyledons to ensure the plant survives, branches and creates additional growing points. They note, “Your ultimate window of opportunity to use a roller to stress soybean plants for potential yield gains is between V1 and V3 growth stages…At this stage, the plant is more pliable, you can roll it or push it over and it still has the ability to bounce back.”
Disadvantages
Disadvantages of this practice center around injury to the soybean plants. Once you get to the later stages of plant development, the plants become less flexible, making them more susceptible to damage. Other disadvantages include negative effects on the soil, such as erosion and runoff, and water infiltration caused by the moisture setting into the areas where the rollers compact the soil.
Is it worth the investment?
After you rent/purchase the equipment and factor in fuel and labor, some experts say that the costs associated with the practice outweigh the small yield advantages that growers may experience. In fact, a three-year, multi-site study conducted by the University of Minnesota Extension found that rolling soybeans at or before the V3 stage produced no significant yield or seed quality advantages to offset the cost of the operation.
If you’re considering soybean rolling on your farm, consult a local extension office before you take the next step. There are a number of best practices that need to be followed to ensure that plants survive soybean rolling and that soil structure isn’t compromised.