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Got Cover Crops?

As more growers in the Northwest become interested in using cover crops to enhance the productivity and profitability of their operations, USDA-NRCS Plant Materials Centers (PMCs) are working to provide the technical information growers need to get the right plant in the right place at the right time. Cover cropping can provide a variety of benefits to an operation, from increased soil organic matter and water holding capacity for drought resilience, to nitrogen production from legumes that can lower fertilizer costs, but maximizing these benefits requires selection of species or varieties that are adapted to the soil and climate conditions of the farm, as well as proper seeding techniques and termination timing.

For producers in the Pacific Northwest, species selection can start with the Pacific Northwest Cover Crop Selection Tool created by the Oregon, Washington, and Idaho Plant Materials staff. This interactive database allows users to generate a list of species adapted to their farm, and provides recommendations on planting depth and seeding rates. Cover Crops for the Intermountain West, a new technical note from the Aberdeen, Idaho PMC, provides more detailed descriptions, photos, and seeding rate recommendations for many commonly used cover crop species. And the Pullman, Washington PMC’s Green Manure and Cover Crops for the Pacific Northwest poster is a great reference that conservation planners can hang on their wall as a simple summary of some key attributes of 21 commonly used cover crop species.

But beyond just species selection, choosing an appropriate variety or cultivar can make a big difference in terms of winter survival, bloom time, disease and insect resistance, and biomass production. A current nation-wide, two-year study at Plant Materials Centers is evaluating the adaptation of 60 varieties of eight common cool-season cover crops (cereal rye, black oat, hairy vetch, Austrian winter pea, daikon radish, crimson clover, red clover, and Balansa clover). Preliminary results from the Corvallis, Oregon trial are now available, and final results from the trial nationally will be compiled and used to update regional cover crop variety recommendations.

Particular cropping systems or rotations often require specialized cover crops. Recent studies at the Bridger, Montana PMC have evaluated the potential of several cow pea, small-seeded fava bean, and mung bean varieties for use in cover crop mixtures in dryland cropping systems in Montana and Wyoming. The Bridger PMC is also evaluating the Impact of Legume Seed Rate in Cover Crop Mix on Legume Presence and Production. Studies from the Pullman, Washington PMC have investigated cover crop planting dates for Irrigated Rotations in Central Washington and Dryland Rotations in Eastern Washington, as well as Legume Cover Crops for Washington Apple Orchards. And recent studies at the Corvallis, Oregon PMC have looked at the adaptation of dryland and Irrigated Warm Season Cover Crops for Western Oregon, as well as Seeding Rates for Legume-Grain Cover Crop Mixes.

PMCs are also developing tools to help with the procurement and installation of cover crops. Once a grower has decided which cover crops to use, figuring out where to purchase seed is the next challenge. To help in this search, Plant Materials staff from eight western states recently released a list of Cover Crop Seed Vendors for Western States. The Aberdeen, Idaho Plant Materials Center’s new technical note provides step-by-step instructions on the process of Calibrating a seed drill for cover crop mixtures.

Northwestern PMCs are looking ahead in an attempt to anticipate the needs of field office staff as well as land owners to help make cover cropping a success and improve soil health in the region. If you have questions about cover crops, please feel free to contact the Plant Materials staff in your region.

Photo of six-way cover crop mix in bloom at the Corvallis, Oregon Plant Materials Center in May 2016.
Six-way mix of crimson clover, common vetch, fava, winter barley, phacelia, and
Balansa clover in a cover crop mix trial at the Corvallis, Oregon Plant Materials Center.
Photo of six-way cover crop mix in bloom at the Corvallis, Oregon Plant Materials Center in May 2016.
Cow pea and mung bean varietal study, Bridger Plant Materials Center, Bridger, MT
Photo of six-way cover crop mix in bloom at the Corvallis, Oregon Plant Materials Center in May 2016.
Three-way mix of triticale, Austrian winter pea, and purple top turnip for grazing cattle in an 8-10 inch precip. zone in Douglas County, north-central Washington.