Heavy rains throughout southern Minnesota on June 12, 13 and 14 have prompted many questions about the effect of saturated soils on soybean production. We all recognize that soybeans that were submerged cannot survive. But what about those soybeans that were in saturated soils for three days or more? Results of research conducted by faculty at the University of Arkansas may help us understand the damage that can take place in flooded conditions.

In the research, soybeans were flooded for seven consecutive days when at the V1, V4 and R2 growth stages. The soil, at this time, was saturated, but the soybeans were not submerged. The flooded treatments were compared to a control where adequate water was applied without causing saturated soils. The soil used for this study had a high clay content and temporary flooding was common in most years.

Compared to the well-watered control, yields were reduced by 12%, 17% and 56.5% when the excessive water was applied at the V1, V4, and R2 stages respectively. Again, these yield reductions were measured when the soil was saturated for 7 days, but the soybeans were not submerged.

This study does not suggest a management practice other than tile drainage that can be used to overcome the saturated soils. It does, however provide some indications of yield loss that might be expected. Yield loss projections might be helpful in making marketing and/or storage decisions this fall.