Land rolling is one method that can improve harvestability of soybean crops. Rolling evens the soil surface by pushing small and medium-sized rocks into the soil, and crushing soil clods. As these crops are harvested low to the ground due to low pod heights, the risk of rock and soil intake by the combine causing machinery damage is increased. Rolling is a necessity if there are a lot of rocks in the field or if the soil surface is very uneven.
The best time to roll is immediately after planting, or within two days of planting. However, post-emergent rolling is acceptable under certain conditions. Rolling immediately after planting can be an issue if the soil is wet. This may increase the risk of soil sealing or crusting.
Rolling dry soil immediately after seeding can also be a concern, as soil becomes pulverized making it more prone to wind and water erosion. In these cases, it is recommended to wait until the V1 or first trifoliate stage to roll soybeans and dry beans. The first trifoliate stage is recommended because all soybean plants should be past the hook (hypocotyl arch) or cotyledon stages. Soybeans and dry beans at these early stages are at risk of breakage from land rolling. Breakage from rolling can also occur if the hypocotyl arch is just below the soil surface, prior to emergence.
When soybean and dry bean plants are rolled at the unifoliate or V1 stages , they can bend and bounce back with much less damage. In comparison, the epicotyl is first to emerge with field peas and is more pliable and less susceptible to breakage than the hypocotyl of bean plants. Field peas may be rolled safely until the 2nd to 3rd node stages. Post-emergent rolling of pulse and soybean crops should be done on a warm day (~25°C) and avoided in the morning when plants could snap.
Soybean Rolling Research
Research conducted by the University of Minnesota examined soybean rolling at different stages: pre-plant, post-plant, 50% emergence, first trifoliate, and third trifoliate. No significant differences in plant stand, average yield and seed quality were found between treatments, including the comparison to no rolling. Soybeans in this study were safely rolled until the V3 or third trifoliate stage. However, rolling at the V3 stage is not recommended due to the increased risk of yield loss from breakage.
ADVANTAGES OF SOYBEAN ROLLING
- Smoother & firmer seed bed
- Easier harvest
- Faster combine speeds
- Reduced risk of equipment damage
- Cleaner seed at harvest (reduced dockage from stones & soil)
DISADVANTAGES OF SOYBEAN ROLLING
- Risk of soil sealing or crusting
- Potential increased risk of wind or water erosion
- Tractor tire damage to emerged plants
- Increased risk of disease and lodging, if plant damage occurs
- No yield increase