4. First trifoliate (V1) 5. Third trifoliate (V3) 6. No rolling Following the treatments the following data was collected: •Water infiltration and runoff •Plant population •Plant injury •Yield •Seed quality characteristics (protein, oil, moisture, test weight) During the three year study, there were no significant differences in stand, average yield, or seed quality among the treatments. The study also concluded that soybeans may be safely rolled up to the third trifoliate growth stage, or V3, when soybean plants are about 4-6 inches tall. Plant Damage and How Late Can You Roll One of the most practical questions for farmers is “How late soybeans can be rolled without cutting into yield?”. Rolling is usually done immediately before or after planting, but delays for wet weather or spring workload are common. In general, wheel tracks caused more plant damage to emerged soybeans than the rollers themselves. Soybeans rolled at V3 suffered significant plant damage at two of the four research sites in 2010 (Table 1, Figure 6). However, greater plant damage did not always reduce yields. Caution should be taken in wet years, where stem injuries caused by rolling could make plants more susceptible to soil-borne diseases. At two sites, rolling after V3 increased goose-necking and lodging. Table 1. Impact on plant population and injury when soybeans were rolled at different stages compared to non-rolled soybean in Minnesota. Effect of Rolling on Soybean Population and Plant Injury Treatment 2009 2010 2009 2010 --- Avg. Pop. 1,000 plants/acre --- --- % Plants Injured --- Pre-plant 158 160 -- --
After emergence, roll in the afternoon, during the heat of the day, when soybean plants are flexible. Control wheel damage by configuring tractor tires and roller width to minimize plant injury. Do not roll when the soil surface is moist to reduce the risk of crusting or sealing and soil sticking to the roller. Avoid rolling when plants are damp because they can stick to the roller and be pulled out of the soil. Avoid rolling when it’s windy because residue can be moved easily to ditches and neighboring fields. Don’t use rolling in an attempt to level soil ruts. ******** [Sidebar Box] Research Summary Multi-state research conducted over the past decade concluded that: •Rolling did not change yields, population or seed quality. •Later rolling induced more plant damage. •Residue protected plants from rolling. •Rolling can improve harvest conditions. [Sidebar Box] Advantages of Soybean Rolling •Smoother and firmer seed bed •Easier harvest •Faster combine speeds •Less operator fatigue •Less down time for equipment damage due to rocks, corn rootballs •Cleaner seed at harvest; decreased dockage for soil tags Disadvantages of Soybean Rolling •Additional time and expense •Risk of the soil sealing or crusting •Potential for increase in wind or water erosion •Tractor tire damage to emerged plants •Cracked stems that increase the risk of disease and lodging issues •No yield increase References Al-Kaisi, M., DeJong-Hughes, J., Holmes, J., Hanna, M. 2011. Land Roller Use: Challenges and Benefits. Iowa State University. Online at: Edwards, W., Johans, A., Chamra, A. 2012 Iowa Farm Custom Rate Survey. Iowa State University. Online at:
Holen, D. 2011. Consider advantages, disadvantages and timing of ground rolling in soybean production. Ag News Wire, University of Minnesota Extension. Online at: Rueber, D., Holmes, J. 2012. Water Infiltration following Land Rolling of Soybeans. Iowa State University 2011 Northern Research and Demonstration Farm Progress Report. Online at: Captions for Photos Figure 1. Rolling corn residue in a field ahead of planting soybeans. Figure 2. A Flexi-coil packer used at the Woodlake, Minnesota scale research locations. Figure 3. A Brillion notched roller used at the Canby, Minnesota scale research location. Figure 4. A smooth roller (like the Degelman pictured here) was used at 5 field-scale research locations in Minnesota. Figure 5. Locations of the field scale research plots in Western Minnesota. Figure 6. Broken stem from rolling a soybean plant at the 3rd trifoliate stage.