Search
Ed Twidwell, LSU AgCenter Extension Forage Specialist and David Moseley, LSU AgCenter Extension Soybean Specialist
Soybeans have been used as a forage crop since they were originally brought to the United States. Their use as a forage declined in the 1940’s as producers adopted other forages that had higher yields. So, although soybeans today are most commonly grown as a grain crop, they can be harvested as a forage crop under certain situations, such as drought.
Consult your crop insurance agent. Consult your crop insurance agent prior to taking any action regarding the harvest of your soybean crop as forage. Failure to do so may result in the loss of indemnity payments.
Consult with USDA Farm Service Agency. Consult with your local Farm Service Agency representative to make sure that any actions that you take including harvesting drought-stressed soybeans as a forage will not preclude you from receiving disaster relief payments or participating in subsequent farm programs.
Consider harvest restrictions for pesticides used. Many pesticides labeled for soybean use do NOT allow for harvest as hay or baleage. Always consult pesticide labels prior to harvesting as hay or baleage.
Harvest for forage before leaves yellow and fall off. It is essential to harvest soybeans when the leaves are still green. If harvested prior to leaf loss, drought-stressed soybeans can potentially have 12-15% crude protein and 55-60% total digestible nutrients (TDN). After leaf loss, these nutritive values are significantly reduced.
Baling soybean residue is NOT recommended. In most cases, soybean residue is poor in nutritional value. Typical composition of soybean residue is 4% crude protein and 35-40% TDN. The palatability of the residue is not readily palatable for livestock consumption.
Soybeans harvested for forage can either be made into dry hay or baleage. For dry hay, the major issue is leaf loss during the haymaking process. The leaves contain the highest level of nutrients in the plant, so care should be taken to retain as much amount of leaf material as possible. It is a good idea to mow early in the day, as this will maximize drying time. It is advisable to use a mower-conditioner for cutting if possible. This piece of equipment will crush the stems, and allow moisture to escape. The leaves will dry quickly, but the stems will take more time to dry. It is advisable to leave the widest possible swath. This will allow for maximum surface area to be exposed to solar radiation from the sun. This will also shorten curing time and result in more uniform drying. Raking should be done when the moisture content is still above 40%. Raking at levels below 40% will result in high levels of leaf loss. Tedding soybean hay is generally not recommended as it will result in high levels of leaf loss. It is better to gently turn windrows over with a side delivery rake. The soybean hay should be baled at about 16-18% moisture. Baling at higher levels will result in mold growth, heating of the hay, and reduction in nutritive value. If the hay becomes too dry, wait to bale. Soybean hay that becomes excessively dry can experience very high levels of leaf loss during baling. Once baled, the soybean hay should be stored under some type of storage structure, such as a barn or storage shed. Soybean hay tends to be more susceptible to weathering losses than does grass hay. The stems and leaves of soybeans do not shed water as readily as grass hay.
Harvesting soybeans as baleage reduces leaf shatter and normally results in a higher quality forage product than dry hay. Baleage is the ensilage of high-moisture forage. This process involves making high-moisture large round bales, and then wrapping the bales with plastic soon after harvest. Wrapping the bales excludes oxygen, which leads to fermentation. The cutting and raking process is the same as described previously for dry hay. However, for baleage, the moisture content at baling needs to be between 40 and 60%. Since the bales will be heavier than traditional dry hay bales, make sure you use a baler than can handle the added weight. When baling, use a slow ground speed to allow for the formation of dense bales that ensile well. Wrap bales immediately after balling. Delaying wrapping allows undesirable microbial growth and delays the start of fermentation. Rapidly excluding oxygen from the forage is essential for fast and complete fermentation. Use at least 4-6 layers of high-quality silage wrap. This is NOT the place to save money, as not applying enough layers or using poor quality wrap will result in poor fermentation, lower nutritive value and higher dry matter losses. Allow bales to ferment for about 4 weeks to ensure a good fermentation has occurred. The soybean baleage can then be fed to livestock.
It is advisable to have the soybean tested for nutrient content. Soybean hay and baleage can have good forage quality. However, excessive leaf loss during harvesting, heating, or poor fermentation can significantly alter the nutritional value of the forage. Samples can be analyzed for forage quality measurements such as crude protein, TDN and fiber content. In droughtstressed conditions, soybeans can accumulate high levels of nitrates. This can be an issue if high-nitrate forage is fed to livestock. Symptoms of nitrate poisoning in cattle include rapid breathing, muscle tremors and staggering. Samples of soybean forage can be analyzed for both forage quality and nitrates through the LSU AgCenter Forage Quality Lab. For more information about sample submission and testing procedures, contact the lab at http://www.lsuagcenter.com/foragequalitylab.
For additional information concerning the use of drought-stressed soybeans for forage, contact Dr. Ed Twidwell at etwidwell@agcenter.lsu.edu or 225-281-9448.
