Given the dry weather across much of Missouri, many farmers are considering harvesting drought-damaged soybean for hay or silage. Soybean is a good alternative or emergency source of livestock feed if a managed correctly. A few tips on how to handle soybean for forage are offered below.
Ideally, soybean hay or silage should be harvested when 50% of the pods have immature beans. Under severe drought conditions, the pods may never develop or develop erratically. Fortunately, soybean makes decent quality hay or silage at any stage before the beans fully develop. Quality of soybean hay is quite variable but typically contains 16 to 19% crude protein and 50 to 55% TDN if harvested when 50% of the pods have immature beans. Once leaf-drop starts, forage quality drops rapidly and soybean probably should not be harvested for forage after this point.
A common problem with soybean hay is that the immature beans dry slowly in the pods and often mold inside the hay. Crimping the hay with a mower conditioner will make the drying more even, but the pods are still the slowest drying part of the plant. Waiting to bale until the pods dry fully reduces this problem, although more leaves will be lost. Chopping soybean for traditional silage or making them into baleage (bale silage) will minimize this problem. If making soybean into silage, the ideal moisture content for storage is 55%.
Another problem with soybean hay is that it does not weather well when stored outside. Large round bales of soybean hay left unprotected from the rain deteriorate much more rapidly than grass hay. It is common to lose 50% of the forage to weathering if the hay is left unprotected. Storing soybean hay in a well-drained and covered stack or in a barn is imperative. Net wrap helps keep the bales in better shape for feeding than does twine.
Often, soybean hay is stemmy and may be refused by livestock. Typically, 10-20% of soybean hay is wasted during feeding due to the coarse stems. If soybean is harvested for silage, or if soybean hay is chopped in a tub grinder, cattle will eat almost all of it. However, the stem contains high levels of fiber and low amounts of digestible nutrients. It may be more economical to simply feed more hay and let the cows leave the stems.
A word of caution: soybean treated with many herbicides can NOT be used for livestock feed. If in doubt, READ THE LABEL! A recent ICPM newsletter article by Kevin Bradley outlines the label restrictions for many commonly used herbicides https://ipm.missouri.edu/cropPest/2012/7/Considering-Your-Grazing-Haying-and-Silage-Options-for-Herbicide-treated-Corn-and-Soybean/
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REVISED: July 20, 2012