ST. PAUL, Minn. (2/14/2011) —The idea of using land rollers is somewhat novel to row-crop farmers, but alfalfa producers have been rolling fields for decades. Ground roller equipment sales have increased substantially in the past five years, with soybean producers as a major new customer.
To answer the question "When is the best time to roll soybeans?" University of Minnesota Extension carried out a three year (2008-2010) research project with grant funding from the Minnesota Soybean Research & Promotion Council.
We found that, while the rollers were designed to push rocks back into the ground, they were being used for many other reasons and in fields with little to no rocks. Some purposes included residue breakdown, field leveling, managing corn root balls, and decreasing operator fatigue by improving crop harvestability.
The research took place at 11 locations across western Minnesota over three growing seasons, and included multiple styles of land rollers. Our rolling treatments consisted of 1.) Pre-plant, 2.) Post-plant, 3.) 50-percent emergence, 4.) First trifoliate stage, 5.) Third trifoliate, and 6.) No rolling.
Following the treatments, we collected data on residue decomposition, plant population, percent plant damage, seed protein, oil, moisture, test weight and yield.
No significant differences for plant populations, seed oil, protein, moisture, or test weight were found. Surprisingly, we did not find significant yield differences based on timing of treatments for each year of combined locations.
We did document significantly more plant damage with the third-trifoliate treatment in two of the four sites in 2010 but did not see yield consequences. With good conditions, rolling can be done out to the third-trifoliate stage. Rolling at or after the third-trifoliate stage cannot be recommended.
If the field is subject to erosion, the best time for rolling is pre-plant or post-emergence. The easiest time and most common for farmers is immediately after planting. However, if conditions don't allow, a producer could roll post-emergence with careful attention to conditions and temperatures.
We uncovered no yield advantage or disadvantage with this study, but certain conditions have potential to hurt yield.
Advantages for rolling include harvestability, operator ease, residue control/breakdown, and cleaner seed at harvest.
Disadvantages include the time and fuel for an additional pass across field, expense of equipment, possible soil crusting/sealing, tractor track damage to emerged plants, susceptibility to wind and water erosion, and breakage of brittle plants.
For more educational information and tools, visit www.soybeans.umn.edu. The website is a cooperative effort among the University of Minnesota, University of Minnesota Extension, and the Minnesota Soybean Research and Promotion Council. More Extension information about other commodity crops can be found at www.extension.umn.edu/CommodityCrops.
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Doug Holen is a crops educator with University of Minnesota Extension.
Media Contact: Catherine Dehdashti, U of M Extension, (612) 625-0237, email@example.com