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Elisabeth C. Miller Library

Keyword: Legumes

Cover crops for the Pacific Northwest

I have two raised garden beds (8 x 12 feet) in my back yard. Recently I read somewhere that having a cover crop during our wet winter months would help decrease the leaching of nutrients and would also help bind nitrogen in the soil.

Three suggested cover crops were crimson clover, Australian field peas (did they mean Austrian winter peas?), and vetch.

What would you suggest? Are these good recommendations? Which
might be the best?

Sustainable Horticulture: Today and Tomorrow (R. Poincelot, 2004, p.
372-377), says,

“Cover crops, when managed as green manures, can supply considerable nitrogen
for [vegetable] crops.”

Legumes, like the pea and vetch you mentioned are
good choices for increasing the nitrogen level in soils. (Hairy vetch, Vicia
villosa, and Austrian winter pea, Pisum arvense). Crimson clover (Trifolium
incarnatum) is almost as efficient at supplying nitrogen to the soil.

Hairy Vetch supplies 33-145 lb of nitrogen per acre/year to soil, Austrian
winter pea supplies 53-100 lb/acre/year, and Crimson clover supplies 19-114
lb/acre/year.

Another species you might consider as a cover crop is Fava bean (Vicia
faba), which supplies 25-105 lb/acre/year.

Additional information about growing cover crops in the Pacific Northwest
can be found on this information sheet from the Washington State University extension.

Territorial Seed Company, in Oregon, sells small quantities of cover
crop seed by mail order, including Hairy vetch, Crimson Clover, and Fava
Bean.

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removing sod and preparing soil for vegetable gardening

We plan to put in a vegetable garden next spring where we now have grass. It is a great sunny spot that we think would work well for this. The question is, after we cut out the sod this fall, someone has suggested we plant rye grass for the winter, is this a good solution? If not, what do we do to the soil this winter? (We plan to bring in some top soil after we take out the sod).

 

There are several approaches that you can use to get your new garden ready. One is from Growing Vegetables West of the Cascades by Steve Solomon. He
recommends removing the grass, covering it with no more than 1/2 inch of
completely rotted compost or 1 inch of raw ruminant manure, and spread
agricultural lime at 50 pounds per 1,000 square foot. Do this in early
October. Then scatter small-seeded fava bean seed at 6 to 8 pounds per
1,000 square feet. Rototill no more than 2 inches deep and relax until May.
In late May you rototill deeply and or spade in the overwintered garden
area. Then you can plant.

Another information source, Seattle Tilth’s Maritime Northwest Garden Guide,
recommends using an annual winter cover crop to improve the soil. It
suggests using 85% legume and 15% grain for maximum nitrogen fixation. For
the legume, you can use Field peas, Crimson clover, Fava beans or vetch. For
the grain you can use cereal rye, winter wheat, spelt or barley. Most of
these are applied at about 2 pounds per 1,000 square feet. Again you would
rototill or turn under the cover crop in late April or May.

Solomon’s method will provide a better total approach. You also should
consider having your soil tested to find out what is missing and what your
pH level is.