U of M extension

Production Notes: Keep Harvest Losses in Check

It’s been a long summer, and for many, their soybean crop has required more attention and management than ever. Despite good to excellent growing conditions across most of the state, controlling weeds and aphids has been unusually challenging this year. Fortunately, almost all farmers should see above average yields in return for their efforts. Many are likely to see record yields.

NaeveBecause yields have largely been determined by now, we are just waiting to harvest as much of that yield as possible. But, there is still an opportunity to lose overall yields due to pre-harvest and harvest losses.

Pre-harvest losses could come from late season hail and wind events or from natural shattering in the field. Modern varieties are extremely shatter resistant; however, if harvest were to be significantly delayed due to rain events, shattering losses could become significant. Shattering is generally exacerbated by prolonged and repeated wet/dry cycles. Reoccurring rainfall events or even many heavy dews tends to exacerbate shattering.

I would also consider excessive dry-down of soybeans in the field as a pre-harvest loss. While we adjust yields to a 13 percent moisture basis, we are not paid that way. Selling 8 percent moisture soybeans results in a yield hit of 5 percent off the top. And, while it’s quite easy to suggest that farmers harvest soybeans at moisture levels as close to 13 percent as possible, the on-the-ground reality is a bit more difficult.

Under normal Minnesota conditions, soybeans tend to dry-down very rapidly once they reach R8. Thereafter, they are simply on a daily cycle related to relative humidity. Once dry, it’s possible to catch soybeans at ideal moisture in the morning or late at night, but the sweet spot that combines ideal moisture level and good harvestablity is often fleeting. My only suggestion is to try to catch as many of these normal moisture beans as possible to layer or blend with much larger quantities of much drier beans harvested throughout the day.

Most harvest losses occur at the header, but it’s important to carefully monitor both combine and header losses throughout the day and throughout the harvest. A large portion of these losses can be reduced through careful and continual combine and header adjustment.

Overly dry or wet beans exacerbate these losses. Because header losses are large and not monitored by combine electronics, it’s important to pay special attention to the header. Keep in mind – four soybeans per square foot equals one bushel of lost yield.

Pay close attention to clipped pods. Results from our field research studies indicate that clipped pods are often a direct result of high yield. If you are seeing clipped pods and cannot lower your header height, please make a note for your records. Note the yield, variety, and planting date, and make an estimate of your final plant stands where clipped pods are a problem.

Our research indicates that low podding height can be managed by planting at higher seeding rates and choosing longer-season varieties that tend to be taller. Rolling soybeans is another obvious technique for managing clipped pods. A more thorough summary of research on this topic will be provided in Production Notes this winter.

Seth L. Naeve is a University of Minnesota Extension Soybean Agronomist and Associate Professor of Agronomy and Plant Genetics. Reach Seth at 612-625-4298 or email him at naeve002@umn.edu.