Ground Rolling Timing Effect On Soybean Production.

Minnesota producers pull steel rollers (30’ to 60’ wide) across fields in the spring to push rocks into the soil, manage corn root balls, and assist in creating optimal seedbeds.  This practice also eases harvest and minimizes driver fatigue.  Rolled fields allow lower cutting heights while avoiding damaging rocks and minimizing the amount of soil entering the combine.  While a large percentage of fields are pre or post planting rolled, conditions occur in which rolling is delayed and questions arise as to the effect of rolling on emerged soybeans.  Research was established at nine locations over three years in Western Minnesota to study the agronomic effects of ground rolling and timing on soybean production.  Treatments included rolling: 1) before planting, 2) immediately after planting, 3) 50% soybean emergence, 4) first trifoliate (V1), 5) third trifoliate (V3); these were compared to 6) no rolling.  All sites were set up as an RCB design with three replications.  Measured variables were: plant population, plant injury, yield, moisture, oil, and protein.  Stand counts taken at each location did not differ statistically between treatments.  Rolling had a significant effect on whether damaged plants were observed and plant injury ranged from 0-20% across locations and treatments.  However, rolling did not significantly affect yield, except at one location.  At that location there was an increase in yield when rolling occurred near planting versus rolling when the plants were at V1, V3, or not rolled at all.  Protein, oil, and moisture content were not affected by rolling at any sites.  While we found little yield incentive to rolling soybean fields, the reduction in operator stress and fatigue along with less wear and tear on combines during harvest, weighs heavily in the absence of agronomic or economic returns.