Evaluation of Forage Soybeans

Tim was interested in experimenting with forage soybeans, which are still relatively new, and have been touted as a substitute for alfalfa on soils that for one reason or another are not suited to the latter. Tim planted the “Donegal” cultivar, at three densities—150,000, 180,000, and 210,000 seeds per acre—one acre of each. He no-till planted in 15” rows into wheat stubble, at a depth of 1½”. This was done during the summer of 1999, which was exceptionally hot and dry. Emergence was poor, because of the weather. Actual counts after emergence were, respectively, 86,000, 102,000, and 115,000 plants per acre.

Rains in late July and August produced respectable growth; by harvest time some of the plants stood five feet tall. Harvest yields (fresh weight, with moisture at approximately 50%) were 5.4 tons per acre for the low planting density, 5.2 for the intermediate, and 7.2 for the high.

A sample taken for nutrient analysis had crude protein of 19.8%, of which 43.1% was soluble protein. Acid detergent fiber registered 36.8%, neutral detergent fiber 49.2%, and total digestible nutrients 59.3%. Net energy of lactation was 0.61 MCal/lb (all figures expressed on a dry weight basis).

Steve Matthias, a dairy nutrition specialist who consulted on this project, describes this forage soya as having the properties of “a good grass alfalfa haylage mixture.” He believes the protein content might have been somewhat higher had it not been for the drought. He says further that he believes soya of this variety “will make an excellent forage for dairy cattle that have the ability to make a lot of milk.”