By Sherri Roberts, Regional Crops Specialist, Weyburn
While soybeans prove to be a good cash crop their versatility makes them a crop to be considered in any producers’ rotation. Soybeans were originally introduced into several Provinces as a forage crop option. They can be grown for annual hay or as a pasture crop as well as for ensiling or as a green feed. In fact, if properly timed, the level of quality that they provide as a hay source is equal to alfalfa. The biggest hurdle in using them as a forage crop is planning because many herbicides used on soybeans have not been cleared for usage on forage crops.
Using the proper variety of soybean is key to successful harvests. While grain soybeans are often made into silage or hayed after a hail event as a means to salvage them, forage varieties have been especially bred for the ensiling, grazing and hay process. A study conducted in New Liskeard, Ontario examined the forage production from one adapted grain variety, one non-adapted grain variety and one forage type soybean. The results showed that forage yields of grain varieties were 30 per cent less than that of their forage counterparts.
Studies reported in the Journal of Agronomy on soybean hay note that the highest yield (six tonnes per acre) was achieved with 7.5 inch row spacing that provided a plant population of 113,300 plants per acre and was harvested at the R7 stage. The crude protein percentage was 19.2 per cent along with a neutral detergent fiber (NDF) of 40.7 per cent and an acid detergent fiber (ADF) of 29 per cent.
Soybeans used in silage can be harvested later than those used for hay. The optimum time for cutting is right before the pods are full. Delaying harvest until the plants reach full maturity will produce silage that is lower in digestibility; the higher oil content from mature seeds can lead to fermentation problems. Moisture content should be between 60 to 65 per cent. Soybean silage has a protein content of from 16 to 20 per cent while the NDF ranges from 38.3 to 48.3 per cent and the ADF is 27.3 to 37.3 per cent. Studies done on dairy cattle in Quebec show cows fed on soybean silage produced milk with greater milk fat and milk urea nitrogen concentrations.
According to University of Wisconsin Forage Professor Dan Undersander, soybeans harvested for silage should be harvested with a mower conditioner and dried to 65 to 70 per cent moisture for storage in a silo tube or bunker silo or dried to 60 to 65 per cent moisture for storage in an upright silo. He also states that palatability can be an issue, so mixing soybeans with a grass such as corn, sorghum or sudangrass at harvest is advisable.
If you’re interested in learning more about soybean hay and/or silage, Dan Undersander will be a featured speaker at the SE Saskatchewan Corn and Soybean Summit on December 9-10 in Estevan, Saskatchewan. For more information and to register, you can call the Weyburn Ministry of Agriculture office at 306-848-2857.