Producers have been pushed to accomplish as much planting possible in the little time given as calendar dates roll by in a late spring start. The goal has been to get the seed in the ground when fields are ready for equipment and between rain events. It has been common across the state in previous years for producers to ground roll fields within hours of planting soybeans. However, the push to plant between rain events and other delays this year has left many fields unrolled. The question is, "Can I still roll without causing significant damage to the plants or stand?"

To address the question, "When is the best time to roll soybeans?" University of Minnesota Extensionconducted a three-year research project (2008-2010) funded by the Minnesota Soybean Growers Association.

Understanding that the first two ground rolling windows have passed (pre-plant and immediate post plant), producers are now wondering about a new timing at pre-emergence. This option will be addressed following a summary of the research.

The research took place at 11 locations across western Minnesota over a span of three growing seasons and included multiple styles of land rollers. The rolling treatments consisted of pre-plant, post-plant, 50% emergence, first trifoliate stage (V1), third trifoliate (V3) and no rolling.

We collected data on the initial impacts that follow treatment, including plant population, percent plant damage and residue decomposition. Yield, test weight, seed protein, oil and moisture were determined at harvest.

Surprisingly, we did not find significant yield differences between treatment timings for each year when combined over locations. Also, no significant differences for plant populations, seed oil, protein, moisture or test weight were found. We did document significantly more plant damage with the V3 treatment in two of the four sites in 2010 but did not see significant, negative consequences on yield.

The research project concluded that, with good conditions, rolling can be performed out to the V3 stage. We do not have data on the impacts of rolling after the V3 stage and are reluctant to recommend it, but we recognize that for some fields it may be the only option.

Iowa State University researchers conducted a similar study where at one site in 2010 they evaluated rolling soybeans with 6 leaves. They reported no significant differences between V3 or earlier rolling, like the Minnesota studies. However,they did find a significant yield reductionwhen rolling at 6 leaves compared to all other treatments and a reduction of almost 9 bu./acre compared to not rolling at all.