In years such as this one, when frost might outpace soybean maturity because of late planting, harvesting the crop as silage or hay becomes a viable alternative.
Extension specialists at Michigan State University (MSU) recently offered some suggestions for harvesting soybeans as forage and also acknowledged some pitfalls with the practice.
Before pulling into the field with the mower to cut soybeans, there are some preharvest checks that need to be made.
“Communicate closely with your crop insurance agent before harvesting a field for forage that was originally intended for grain production or as a delayed planting cover crop,” notes Michael Staton, a soybean educator with MSU Extension. “Failure to communicate with your agent prior to harvest may lead to misunderstandings, resulting in a loss of indemnity payments. Also, contact your local Farm Service Agency office to determine how harvesting a field for forage that was originally intended for grain production will affect USDA program eligibility,” he adds.
A final bit of information to obtain before harvest relates to previous pesticide usage. Check product labels to ensure that a forage harvest is legal and that all defined intervals between application and harvest are being met.
Hit the right growth stage
As with most forage crops, there are some yield and quality tradeoffs with soybeans depending on when they are harvested. The Michigan State specialists suggest targeting the R3 to R5 growth stages. At the R3 stage, one of the four top nodes with a fully developed leaf has a 3/16-inch pod length. Harvesting at R3 or R4 growth stages will result in the highest quality forage.
Harvesting soybeans at later stages, for example R6 or R7, will result in higher yields, but the crop will contain higher concentrations of oil, be more difficult to ferment, and is less palatable. Pod and seed shatter may also be a problem during mowing and raking.
“As with alfalfa, wilt soybeans in the field to 65 percent moisture before chopping,” Staton says. “Determining the whole-plant moisture content is critical to achieving proper fermentation.”
When chopping soybeans for silage, adjust the harvester for a 3/8-inch theoretical cut length. This will help ensure a proper packing density.
Good soybean silage has a feeding value that’s similar to alfalfa; however, it’s less palatable than haylage or corn silage. For this reason, soybean silage is often fed in a total mixed ration (TMR) at levels of less than 20 percent of the dairy ration.
Hay is a challenge
Drying soybean plants in the field during the fall can be challenging, if not impossible, with shorter days and cooler temperatures. For this reason, trying to make dry hay out of soybeans is a less attractive alternative to silage. When making hay, it’s more important to cut when the crop is in a growth stage of R3 to R4 to reduce pod shatter.
“Use a roller-type mower-conditioner set to lay the hay in a wide swath, leaving about 4 inches of stubble,” Staton says. “When dry, slowly and gently rake the swath into a windrow in the morning when humidity levels are higher to avoid leaf loss; then invert the windrows after several hours of good drying conditions, and bale in the early evening to avoid further leaf loss,” he suggests.
Late-planted soybeans, harvested as a forage, can help to bolster forage inventories, but attention must be paid to harvest maturity and whole-plant moisture to optimize feed quality and preservation.