Forage yield and profitability of grain-type intermediate wheatgrass under different harvest schedules

Intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & Dewey] (IWG) is a perennial forage grass being domesticated to function as a perennial grain crop. Grain yield of improved, grain-type IWG cultivars decline by the third year of production and managing aging stands for forage production presents economic opportunities. Limited research is available on the response of second- and third-year grain-type IWG to different forage harvest schedules. We measured forage yield and nutritive value of grain-type IWG in the second and third year of production under nine forage harvest schedules varying in the timing of the first harvest (at boot, anthesis, or soft dough stage) and the number of fall harvests (none, one [Sept.], or two [Sept. and Nov.]). As timing of the first harvest was delayed and IWG maturity increased from boot to soft dough, yield increased from 2.4 to 3.7 Mg ha^–1 and relative feed value decreased from 113 to 82. Yield at subsequent September and November harvests averaged 30% and 12% of the initial harvest yield, respectively. Total annual forage yield was not affected by the timing of the first harvest but was predictably greater for two or three harvests compared with one harvest; however, additional harvests in September and November decreased net returns. Grain-type IWG stands harvested in the third year after peak grain production have potential to provide forage similar to common perennial cool season forage grasses. Tradeoffs between forage yield and nutritive value should be considered when selecting the timing of the initial spring forage harvest.