Harvest is arriving as the weather looks to return to warmer temperatures for the next seven days. Soybean fields impacted by the frost have opened the canopy a bit with the shriveled or cast damaged leaves and the warm temps will help further finish those crops not already reaching maturity naturally. I’d like to suggest a few last-minute things to consider as your soybean harvest begins.
Check your harvest equipment regularly for safety and efficiency. The little things are the easy ones to overlook and can also cost in threshing efficiency, actual yield and value at the gate. Be sure to check your combine adjustments, particularly cutter bar sickle sections and ledger plates. Missing sickle sections are easy to spot, but worn or damaged sections or ledger plates can be just as detrimental.
Any extra impact during the cutting process can lead to shattering loss and can be avoided by close inspection and repair if needed. If you have rocky soils, even if you have rolled your fields in the spring, check the cutter bar at the end of each day to make sure you are operating with optimum equipment for maximum harvest efficiency.
Harvest moisture is important in terms of storage, but also in terms of harvest efficiency. Optimum harvest moisture is 12 to 14 percent in respect to storage and keep in mind when checking fields that soybeans may be approaching optimum harvest moisture even though one or two leaves remain on the plant.
This leaf retention might be “normal” or a consequence of frost damage where they simply don’t senesce. Retained leaves should not be confused with green stem syndrome (GSS) – dry pods are present on the plant but stems remain green.
Several issues have been implicated as the cause of GSS from insect or disease stress to foliar fungicide use or low humidity and higher temps during maturation, but none seem proven unequivicably. In any case, the difficulty of harvesting fields with GSS can be alleviated with harvest aids (an added harvest expense) or by waiting for a killing frost before harvesting affected fields.
As the season progresses, harvesting at too low moisture is more likely a concern as soybeans continue to dry down in the field. The potential for shattering loss increases greatly as seed moisture drops below 10% and these field losses can be easily quantified with a small time investment.
As an example, four beans, or one to two pods per square foot on the ground, equate to about a one bushel per acre lost from yield. It is always a good idea to check for harvest loss and make sure combine settings are not the cause of loss vs. shattering under low-moisture conditions. At lower seed moistures, the potential for seed coat injury is also greater, resulting in splits or damaged seed from the combining/seed-handling process.
Early morning harvest may start at higher moisture and require a faster cylinder speed for efficient threshing. Monitor seed moisture levels and decrease cylinder speed as pods dry toward mid-day to reduce seed damage.
As harvest moves into full swing, continue your regimen of equipment checks regularly for safety and harvest efficiency to be sure to gather all of the crop possible and reduce injury potential on your farm operation.
Dr. Paul Meints is the Director of Research at Minnesota Soybean and has an MS in plant breeding and genetics and a PhD in Seed Physiology.