Perennial Wheat and Intermediate Wheatgrass As Dual-Purpose, Forage/Grain Crops Under Organic Management.

Perennial wheat and intermediate wheatgrass as dual-purpose, forage/grain crops under organic management K.A. Cassida, S.S. Snapp, and S.G. Tinsley The adoption of perennial grain crops, such as perennial wheat (PW; Triticum aestivum x Thinopyrum elongatum) and intermediate wheatgrass (IWG; Thinopyrum intermedium), presents farmers with environmental and economic risks that may be reduced if perennial grains can also be used as forage crops. To evaluate potential of these novel perennial grain species for dual-purpose forage-grain use, we compared robustness of primary growth and regrowth, grain quality, and forage quality for PW and IWG under two harvest regimes: grain harvest only or a spring forage harvest followed by grain harvest from the regrowth. Spring forage harvests were taken when plants were still in vegetative growth stage. Total yearly forage production was measured as spring forage cutting plus straw from grain harvest. The trial was conducted under organic management in southwest Michigan at the Kellogg Biological Station. Perennial grain crops were planted in 2010 and harvested in 2011 and 2012. The PW produced more grain than IWG (239 vs 104 g/m2/yr, respectively), but was less able to initiate late season regrowth after the grain harvest (59 vs. 100% of plants exhibiting regrowth), and thus less able to maintain perenniality. Total forage yields did not differ between crops in year one, but PW produced less forage than IWG in year 2 (391 vs 956 g/m2/yr). Neutral detergent fiber was greater for PW than for IWG, indicating reduced nutritive value for PW. The spring forage harvest did not consistently reduce grain yields for either crop, suggesting that dual grain/forage use is feasible for these crops. Choice of perennial grain crop depends on farm cropping priorities, with PW more advantageous when grain is the primary goal and IWG when forage is more important.