By Mike Staton
Some soybean producers may be considering harvesting severely drought-stressed soybean fields for forage this summer. This is not an easy decision and producers should consider the value of the soybean grain compared to the value of the soybean forage. Other considerations include impacts on crop insurance payments, federal disaster aid and feeding restrictions for all pesticides applied to the soybeans.
Value of soybean grain versus value of soybean forage
Estimating the potential grain yield of drought-stressed soybeans is very difficult. This is because plants that have retained more than 50% of their leaves have the potential to produce a good grain yield as long as significant rain occurs before they stop producing flowers (early August). Be patient and assess the grain yield potential in mid-August. At this time, if more than 50% of the leaves have been lost, the plants have stopped producing flowers and few pods are present, grain yield will be very low.
A reasonable estimate of the dry matter yield for drought-stressed soybean forage would be 1.5 tons per acre. Values will change with the development stage of the crop.
Harvesting for hay
Harvesting soybean forage for silage is preferred over baling it as dry hay because ensiling retains more dry matter during harvest and storage. However, it is possible to make high quality hay from soybeans in the R3 to R5 growth stages. There are lots of leaves at these stages and the pods are less likely to shatter during mowing and raking operations. Use a roller-type mower conditioner set to lay the hay in a wide swath and leave about 4 inches of stubble.
Harvesting for silage
The crop can be harvested from R3 to R6. Soybeans harvested at R3 to R5 will produce high quality forage and have lower oil content than those harvested at R6. The higher oil content may cause fermentation problems. However, soybeans harvested at R6 will produce more dry matter. Mow the crop with a mower conditioner equipped with roller crimpers. Experience from Wisconsin indicated that flail conditioners cause more damage and dry matter loss than roller conditioners. As with alfalfa, soybeans should be allowed to wilt in the field to 65% moisture before chopping.
Feeding soybean hay
Soybean hay has a tendency to cause bloat in cattle, so it should be fed carefully. Mix the soybean hay with grass hay or fill the cattle up on grass hay prior to feeding soybean hay. Horses can safely consume soybean hay if it is baled and stored properly.
Feeding soybean silage
Feed quality of soybean silage is equivalent to alfalfa haylage. Soybean silage is less palatable than haylage or corn silage. However, it can make up 15 to 20% of a dairy ration without impeding animal intake or milk production. The exception is when the soybeans are harvested after the R6 stage is reached as more seed (higher oil content) is present, which can affect fermentation and palatability.
Staton writes for Michigan State University Extension