By Liz Stahl and Debalin Sarangi
Crop progress, weed control, and what effect variability in precipitation was having on the crop were topics of discussion on the June 10 Strategic Farming: Field Notes episode. Drs. Seth Naeve, Extension Soybean Agronomist, and Debalin Sarangi, Extension Weed Specialist, were joined by moderator Dave Nicolai, Extension Educator - Crops to discuss these issues and more.
Overview of soybean progress and replant questions
Precipitation has been variable across the state, with some areas having very heavy rainfall over a short period of time, while other parts of the state are still quite dry. Naeve notes that dry springs seem to benefit MN farmers as this helps conditions at planting as long as we get timely rains.
We are in the middle of the time period where drastic yield reductions occur if soybean planting/replanting would be needed. Up until May 31, yield potential averages around 87% of maximum. By the time we get to July 1, however, yield potential is about half what we would expect compared to an optimal planting date of May 1. This means we lose about 45% of our yield potential over a month, or a point and a half per day. Soybean populations would have to be considerably reduced to make replanting worth it at this time, just due to the reduction in yield potential from a later planting date.
Another part of the replanting equation is plant stand distribution. Large gaps mean more potential for weed emergence and growth, so this needs to also be considered if one is faced with reductions in stand at this point in the season. Useful resources to help with this decision include the When and how to plant soybean and the When and how to plant soybean on-line resources.
Source : umn.edu