Tallgrass Prairie in Central Washington: Establishing Warm-Season Perennial Grasses on Irrigated Pasture

Warm-season perennial grasses (WSG) native to the American tallgrass prairie have tremendous production potential under irrigation. Central Washington irrigated pastures occupied by cool-season grasses exhibit dramatically slower growth during meteorological summer. Grazing land is a scarce resource in Washington State for which there is high demand. Further, many ranchers’ business growth is limited by unavailability of pasture. Warm-season grasses grown for pasture (Indiangrass, Eastern gamagrass, little bluestem, switchgrass) have the potential to address all three limiting factors to livestock production in the Pacific Northwest. Further, the potential for longer duration high temperatures in spring and summer predicted under most modeled climate change scenarios increases the desirability and adaptability of WSG, and, in some locations potentially preferable to cool-season grasses. Hudson, Llewellyn, and Fransen propose field trials to grow WSG under irrigation at the field scale instead of plot scale in order to evaluate the economic feasibility of this novel forage base for Pacific Northwest ranchers. We will measure timing of growth and forage yield under grazing and without grazing, evaluate winter survival, and measure forage quality using in situ digestibility analysis methods through Bar Diamond Labs of Parma, Idaho. The success of warm-season grasses as a viable crop depends on proper grazing control and stand management to a greater degree than cool-season grasses; therefore, the project will focus outreach on grazing practices for optimal forage yield and animal nutrition on both warm-season and cool-season grasses in addition to instruction on growing tallgrass prairie in Washington State.