Alfalfa Seed Growing and Harvesting Practices in Walla Walla County, Washington

By Shannon Pierce (’02)


Alfalfa, Medicago sativa, family Leguminosae

            Alfalfa is grown generally for baling, providing feed hay with valuable nutrients for cattle and other livestock.  Alfalfa is the fourth or fifth largest crop produced in the United States.  It is also grown for pasture and for cover, to minimize erosion, and as a rotational crop to provide the soil with nutrients.  In Walla Walla County, however, alfalfa is grown primarily for seed that is harvested and then sold to various regions worldwide.  The lead seed-producing states in the United States are California, Washington and Idaho.  California produces about 33 million pounds of seed every year, while Washington and Idaho each produce approximately 14 million pounds annually.

            Alfalfa is a perennial herbaceous legume, part of the pea family.  In dry regions, it must be replanted every ten years, and, in humid areas, new plants need to be seeded after five to seven years.  The stems of the plant, lined with leaves and clusters of between ten and 100 purple, white or green florets, can reach a height of up to three feet.  The stems mature in just six weeks, after which the alfalfa leaves and stem can be cut  for hay in order to make livestock feed.  When alfalfa is grown as a seed crop, the flower is allowed to bloom and produce many seeds after pollination occurs.  Alfalfa seed producers must keep bees in order to insure pollination of the plants' flowers.  The seed is then sold to seed houses and farmers to grow alfalfa for hay at their own farms.  As a seed crop, alfalfa requires sunny days, cool nights and dry weather for harvesting.  Moisture or precipitation will destroy the crop by causing the plant to wilt and therefore making it impossible to cut and process the seed.  Conversely, in conditions where temperatures are too high near harvesting time, the buds of the alfalfa plant can burst from the heat pressure, releasing the seeds into the air and onto the soil, and thus preventing seed harvesting. The alfalfa plant has a deep tap root system that enables the plant to survive extreme heat and drought conditions by allowing it to extract water and nutrients from deep within the soil.  Bacteria and fungi are common problems for the plant, and several insects have been identified as detrimental pests, including alfalfa weevil larvae, potato leafhoppers and spider mites.


Alfalfa in Walla Walla County: Seed production

            Alfalfa is a one of the major crops grown here in the Walla Walla Valley.  In 2001, a total of 20,712.2 acres were reported as used for the production of alfalfa - both for hay and for seed - in Walla Walla County (Farm Service Agency [FSA] Office, 2001 Acreage Report).  A total of 8,209.8 acres (about 40 percent) of the total production of alfalfa went toward alfalfa seed.  One alfalfa grower estimates that fewer than 20 farmers grow alfalfa in Walla Walla County, and that only six of these grow alfalfa as their primary crop.  The alfalfa market has suffered declines recently, and several farms have gone out of business, including one major seed house in Touchet. 

            In Walla Walla County, the harvest of alfalfa (for seed) takes place in late August or early September and must happen before the first rain.  The dry alfalfa is cut using a combine, leaving a dry residue of cut alfalfa plants that is very expensive and not cost-efficient to gather and bail.  As winter approaches, any new green alfalfa shoots die, and the plant goes dormant after the first frost of the season.  From November to March, the alfalfa root is dormant.  Under ideal burning conditions (as set by Washington’s Dept. of Ecology) in January and February, fields can be burned to eliminate the dead alfalfa and other residue, in order to prepare for the growing season. The six- to eight- inch mat of residue, if not removed, will inhibit the growth of the alfalfa when it begins to sprout in the first months of the following spring.  Thus, field burning is a common practice among farmers when preparing for the next season’s crop.  The plant then begins to grow in the spring.  For hay, the alfalfa is cut first around the middle of May, and consecutive cuttings occur until the weather gets colder and precipitation begins.  Seed farmers, on the other hand, keep their alfalfa uncut in order to bloom from about the 1st of June until mid-July. 

            Pollination occurs in July and August. Alfalfa produces large amounts of nectar, which attracts the bees.  The two bees used to pollinate alfalfa in the Walla Walla Valley are leafcutter bees and alkali bees.  Both bees have a preference for alfalfa pollen. Leafcutter bees (Megachile spp.) are indigenous to Europe and must be bought and imported to eastern Washington.  These bees are non-aggressive and nest above ground.  Alkali bees (Nomia spp.), on the other hand, are native to this region, and nest underground in the Touchet area.  Alkali bees live in areas with highly alkaline (non-acidic) conditions with little or no plant growth, and flooding (sometimes a problem in the Walla Walla Valley) can destroy their nests.

            After pollination and maturation, the seeds are harvested at the end of August or beginning of September, and the alfalfa cycle begins again.  Common causes of the destruction of alfalfa crop in Walla Walla County include the alfalfa weevil, the spider mite and the chalcid fly. 

            In the Walla Walla Valley, the most abundantly grown type of alfalfa for seed is the winter hearty variety, which survives in colder climates.  Wisconsin and other Midwestern states make up the largest percentage of the market for this type of alfalfa.  Other states that buy the seed produced in this county include Ohio and New York.  A secondary type also grown in the Walla Walla Valley is non-hearty alfalfa.  This type of seed grows best in milder weather conditions in southern states such as California.  However, this type of seed is risky to sell, because if the winters get too cold where it is grown, the seed will be destroyed and the crop will not grow.  Internationally, the alfalfa seed harvested in the Walla Walla Valley is sold to countries in Europe, parts of South America and Saudi Arabia.  Alfalfa is sold to many seed houses throughout the country including major ones such as Cal West (California), Allied Seed (Idaho) and Dairyland Seed (Wisconsin).


Alfalfa as an ecological crop

            The soil is very deep in the Walla Walla Valley as a result of the Missoula floods in the geological history (link to: Margo Burton’s website).  As a result of this deep soil, alfalfa grows well in this area.  The soil stays wet, providing water to the deep root system of the plant.  Roots can extend from 10 to 20 feet below the ground surface.  Consequently, in the dry months in Walla Walla County (May until September), when the water is in short supply and rivers are low, no irrigation is needed for the crop because the extensive root system is able to absorb sufficient amounts of water from deep within the soil.  In other areas where alfalfa is grown, in contrast, irrigation is necessary the entire year.  In the spring, when the alfalfa plant is just beginning to grow and requiring more water, the crop is irrigated with water that is diverted from the rivers in the region.  The water level of the rivers is highest in the spring season, so water resources are not exhausted in the irrigation of the plant.  Thus alfalfa seed in Walla Walla County is, as one farmer calls it, an “ecologically sound crop.”

Field Burning

            Field burning is a controversial environmental issue because of its affect on air quality in the areas where it takes place. Farmers still burn fields before the growing season, as they have done traditionally,  for the following reasons:

-         To decrease the pests and insect population residing in the residue on the surface of the soil (the chalcid fly, for example, eats holes in the seed bloom, causing the seeds to fall from the plant)

-         To help eliminate residues so that the alfalfa isn’t blocked from sunlight and can grow, and so that nutrients do not remain trapped in the mulch

            In the Walla Walla Valley, burning will most likely take place sometime between the end of January and the 1st of March, when burning conditions are most ideal and can be met.  The alfalfa plant is still dormant within the soil and therefore is unaffected by the surface burning.  One alternative to field burning is to increase insecticide to reduce pest and insect populations that destroy the crop.  Aside from the environmental implications of pesticides and insecticides, these sprays also affect the good insects such as the bees pollinating the alfalfa seeds.  Another alternative to field burning is to use combines that leave less residue, but this kind of machinery is very expensive.  Additionally, farmers can bale the residue and mechanically remove it from their field; however, this can be expensive.  Other alternatives are being researched currently as concerns for air quality and smoke emissions rise.

            Recent regulations have been made as to what conditions must exist in order for field burning to take place.  These are outlined by the Washington Department of Ecology [Ch. 173-401 WAC, Ch. 173-430 WAC] ( 

(1) Agricultural burning is allowed when it is reasonably necessary to carry out the enterprise. A farmer can show it is reasonably necessary when it meets the criteria of the best management practices and no practical alternative is available.

(2) All agricultural burning requires a permit.

(3) All agricultural burning permits require a fee.

(4) All agricultural burning permits must be conditioned to minimize air pollution.
(For example, burning may be further limited depending on the current air pollution levels, and other conditions may apply, such as allowing the trading of permits within one year under certain conditions.)

(5) A farmer must obtain any local permits, licenses, or other approvals required by any other laws, regulations or ordinances. The farmer must also honor other agreements entered into with any federal, state or local agency.

            Further requirements for burning specify times when the burning must take place such as the hours of the day and the season of the year.  Burning in the fall months used to take place about 30 years ago, but today burning of the alfalfa crop generally must occur in the spring when all of the conditions for field burning set by the Washington Department of Ecology are ideal.  Burning in the spring rather than the fall reduces the amount of smoke that lingers in the valley, because localized winds disperse the smoke and ventilate the Walla Walla area.  Farmers must obtain permits (with advanced notice with the intent to burn), but also must consider best management practices (BMPs) for field burning.  This requires that farmers consider alternatives to burning first and maintain low residue without burning.  They must also submit an annual design, with the goal of reducing the farmers' dependence on burning to eliminate residue.