Its high yields and value as a hay or pasture crop during hot summer months have researchers looking at switchgrass as more than a renewable fuel source.
“Research has shown switchgrass can be grown successfully as both a biofuel feedstock and forage crop. There is no need, however, to grow it as only one or the other. There is the possibility of having switchgrass as a ‘dual-purpose’ crop,” write Gary Bates, University of Tennessee plant scientist and colleagues in an Extension publication called Using Switchgrass for Forage.
“The early growth of the forage, which is generally the highest quality, can be hayed or grazed. The later growth can be allowed to mature and harvested after frost as a biomass crop. Biomass production will be lower under this scenario, but, depending on the objectives and needs of the producer, this may be a useful strategy.”
Switchgrass produces its highest-quality hay early in the season, the publication points out, with crude protein levels ranging from 14 to 20%. Expect only 2 ton/acre yields, however, and don't wait for higher yields because that decreases quality. Waiting longer also hurts biomass yields, studies have shown. Leave a minimum residual height of 8” for quick plant recovery.
Although switchgrass hay works well for beef and dairy cattle, it isn't recommended for horses because of their possible phototoxic reaction – hair loss and possible sunburn.
Grazing switchgrass is another possibility, particularly if fencing and water are available. The grass can be grazed starting at 18-24” tall usually in mid-May in Tennessee and only for two to four weeks. It shouldn't be grazed too closely – just to 8-12” tall. Stocking rates of three to four steers per acre are advised.
For more detailed information, including fertilization recommendations, see the publication.