Published Summer 2022
By: By Shayan Ghajar, Phd. OSU Organic Pasture & Forage Specialist
The increasing unpredictability of precipitation and temperature in spring and summer in Oregon has been an immense challenge to many farmers and ranchers in Oregon. By the end of August last year, about 27% of Oregon was classified in the most severe “Exceptional Drought” category by the United States Drought Monitoring Service. Conversely, this year much of western Oregon has had an exceptionally rainy, cool spring lasting into late June. These extremes reduce pasture and hay productivity, and cost producers money twice over with lower summer yields and increased costs of supplemental feed for livestock. A recent needs assessment of pasture and forage producers in Oregon confirmed what many of us already know from talking to friends and colleagues: climatic uncertainty is seen by producers as one of the primary challenges to pasture and forage-based operations in the state.
One potential avenue for mitigating the impacts of heat and drought on forage-based operations is expanding our options when it comes to forage species and varieties. For decades, the primary options for Oregon forage producers have been a few warm-season annual grasses such as sorghums, millets, sudan grass, or teff; these are useful forages, but a rather limited selection to choose from. Yet many regions of the world have dealt with extreme variation in precipitation and temperature—and dichotomies between wet seasons and dry seasons— for millennia. It’s possible some of the forage and crop species popular in these climate analogues would work in Oregon. To that end, the Center for Small Farms Organic Pasture & Forage program is New Warm-season Forage Research at Oregon State University By: By Shayan Ghajar, Phd. OSU Organic Pasture & Forage Specialist testing several annual and perennial forage species this summer to determine whether they might do well here and mitigate the “summer slump.” Species have been planted in plots at the USDA Plant Materials Center in Corvallis with the help of agronomist Ian Silvernail and farm manager Tyler Ross, as well as on several farms throughout western and southern Oregon.
The annual species being tested are (Vigna unguiculata), mung beans (Vigna radiata), lablab (Lablab purpureus), and a type of crabgrass developed specifically for forage production (Digitaria ciliaris). Cowpeas, mung beans, and lablab are all leguminous species, meaning they have symbiotic relationships with specific types of soil bacteria which colonize the plants’ root nodes and fix nitrogen for the plant to use. Leguminous species are a natural alternative to synthetic fertilizers for improving soil nitrogen and fertility. The legumes in this research have a long track record of drought resistance, productivity, and moderate-to-high grazing tolerance in regions with hot, dry summers. While many Oregonians think of crabgrass as a nuisance weed, forage cultivars may be a very useful asset for graziers. Forage-bred crabgrass varieties are popular in the Southeast and Great Plains as a fast-growing summer annual with decent yields, excellent nutritive value for livestock, and moderate drought tolerance.
The perennial forage species in the research trials originate a little closer to home: all are perennial warm-season (i.e. grow in summertime) grasses native to regions spanning from the Rockies to the Southeastern states. These grasses include switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), eastern gamagrass (Tripsacum dactyloides), and what we’ll call paisleygrass (Sorghastrum nutans; the common name is outdated and offensive to indigenous peoples). These species can tolerate a wide variety of soil conditions, have high water use efficiency, drought resistance, deep carbon-rich roots, and produce high forage yields with decent to good nutritive value. While it’s too soon to have concrete results from the testing so far, all species have germinated satisfactorily on the research plots at the Plant Materials Center and at many of the working farms participating in the research. The damp, shady conditions stalled their growth for a time, but now that the dry season is upon us, we’ll get a better idea of how they handle local conditions.
Stay tuned for further updates. If you have any questions about the research, or are interested in getting involved next year with on-farm trials, feel free to email Oregon State’s Organic Pasture & Forage Specialist, Dr. Shayan Ghajar, at [email protected].