GRASSLAND IN WESTERN WASHINGTON

E. J. Kreizinger, Alvin G. Law

WESTERN WASHINGTON, that area west of the summit of the Cascades between Canada and the Columbia River, was almost entirely covered with forest when the first settlers arrived. The trees, large and dense, indicated soils of high fertility and an abundance of rainfall. Now the agricultural land is made up of cleared river valleys, tide flats sweet enough to support crops, and a little level upland. Only small areas of potentially good agricultural land remain undeveloped.

The area is approximately 125 miles wide and 325 miles from north to south, embracing 15,894,000 acres; only 2,264,000 acres, or 14.3 percent of this area, is in farms, the average farm having 46 acres. Of the 770,000 acres of cropland, two-thirds is used for hay and pasture; 1,060,000 acres of other land grows pasture and hay. Thus, 67 percent of the land in farms and 67 percent of the cropland produce forage crops.

In 1945 there were 213,000 dairy cows, 170,000 beef cattle, 27,500 sheep, more than 7,000,000 chickens, and approximately 600,000 turkeys in western Washington. The dairy cows produce about 160,000,000 gallons of milk annually. In 16 of the 19 western Washington counties, dairying is the most important agricultural industry.

The remaining 255,000 acres of cropland produces vegetables, berries, soft fruits, nuts, flower bulbs, and vegetable seed. Several counties grow a fairly large acreage of oats.

Western Washington, like other Pacific coast areas, has a maritime climate. The average January temperature varies from 32 to 40 F.; the July temperature varies from 54 to 66 . Except during July and August, the relative humidity is high. Approximately 70 percent of the precipitation comes during the fall, winter, and early spring. The average precipitation received during the growing season, April to September, ranges from 6 inches to approximately 18 inches. Rainfall in July and August is insufficient to support grassland vegetation, except in low subirrigated valleys. During the remainder of the growing season enough rainfall is usually received to keep grass and other forage crops growing vigorously. The lowest average annual rainfall is 17 inches at Sequin, on the leeward side of the Olympic Mountains; the highest precipitation, 140 inches, is recorded at Wynoochee Ox Bow on the windward side of the Mountains. The average over the farming area is 35 to 45 inches.

The growing season is about 180 days in the area adjacent to the Cascade Range and more than 260 days in the area close to the Pacific Ocean.

Two groups of soils have developed: The Pedalfers, in which iron compounds accumulate and which are commonly found in the forested regions of the State, and the Interzonal soils.

The representatives of the Pedalfers group west of the Cascades usually do not have a definite sesquioxide accumulation layer, but are characterized by the presence of considerable quantities of iron pellets throughout the entire profile. These "shot" occur both in soils developed from glacial material and in those developed from bedrock. The reaction of the soils west of the Cascades ranges from pH 4.5 to 6.5. The average value for more than 300 samples was found to be pH 5.9. These soils are of intermediate fertility. There is seldom any calcium carbonate present in the parent material and no accumulation of this material occurs in the profile.

Prairie soils occur in western Washington under a variety of rainfall conditions. Two extensive prairies are found on the Olympic Peninsula under an annual rainfall of 120 inches. Others occur in regions with only 17 inches of annual rainfall. Some of these soils, but not all, occur on extremely gravelly substrata. These areas aptly illustrate the power of the vegetative factor in a region of similar rainfall and temperature conditions since the soils produced on the prairies are markedly different from those in the adjacent forested areas.

In the vicinity of Mount St. Helens, extensive areas are covered with pumice. The shallow soils support a heavy forest growth; the soils are only a few inches thick and are light gray in color, with a peculiar fluffy structure. Brown staining along root channels extends to depths of nearly 5 feet, but the material a few inches lower is practically unweathered.

Nearly every major stream flowing from the Cascades contains considerable quantities of gray glacial flour derived from active glaciers on the higher mountain peaks. This material, together with local alluvium, is deposited in the lower river valleys and results in soils of exceptionally high fertility. These gray alluvial soils support some of the most successful farming enterprises in the State. In the southwestern part of the State, several river systems have produced alluvial soils without glacial flour, causing the dominant color in such areas to become dark brown and resulting in soils of somewhat lower fertility. It is a notable fact that the Columbia River, the second largest river system in the United States, has deposited only minor areas of recent alluvium, and soils from this source are of minor importance.

Within these two groups of soils a wide variety of types occurs, varying as to structure, texture, substrata, and conditions of drainage. The inherent fertility of the soils varies markedly and has exerted considerable influence on the crops that can be grown in western Washington.

The use of subterranean clover, alta fescue, orchardgrass, perennial rye-grass, meadow foxtail, Ladino clover, and big trefoil have done much to increase the production of pastures and hay meadows in western Washington. There are still large acreages which can be seeded to these species. Forage crops are much less specific with regard to their response to various soil types than they are to moisture relationships. Experimental evidence and experience of farmers demonstrate that species are distributed through the area on the basis of the water level in the soil when it is at a maximum. Thus it is more important to know the minimum depth to the water table during the year than it is to know the soil type in determining the species to be seeded. The fertility level of the soil will influence the production but has little influence on choice of species.

Establishment of Pastures

The establishment of adapted, high-yielding species and mixtures for hay and pasture production is of primary concern in western Washington. It follows, also, that the maintenance of these stands at high levels of productivity is an essential part of the forage program.

A good seedbed is of primary concern in establishing forage crops. Performance of pastures or hay meadows will depend largely on careful and thorough seedbed preparation. Small-seeded crops, such as alfalfa or the perennial grasses, are best established on a firm, fine-textured, moist seedbed. Packing the seedbed will bring the soil particles into close contact with the small seeds. This will result in good germination because of rapid moisture absorption. A desirable seedbed can best be fitted on land that has been cropped to annual or intertilled crops the year before planting. When permanent pastures or meadows must be reseeded, it is advisable to grow an annual or intertilled crop on the area before attempting reestablishment of the perennial crop.

Early spring seeding is recommended for the perennial grasses and legumes. The most satisfactory method of preparing a seedbed is to plow the area in late summer or early fall, leaving it rough over winter. Cultivation should begin as early as possible the following spring and the soil should be worked sufficiently to destroy any weeds on the area. Two or three cultivations usually will be needed to kill existing weeds; this will leave the seedbed in the proper condition for seeding. Additional cultivations may delay seeding to such an extent that summer drought may reduce stands.

It is recommended that the fertilizers be applied before the seeding. If phosphate and potash fertilizers are needed for maximum production, 200 to 300 pounds of treble superphosphate applied before seeding time and worked into the surface of the soil will get the plant food into the root zone where it is absorbed by the plants. The application of 20 pounds of actual nitrogen before seeding is important, particularly on lands of low fertility. Only a few areas have been shown to be deficient in potash; phosphates have been found to give a good response throughout western Washington for maximum production of legume species. Nitrogen fertilizer is necessary for maximum production of the grass species.

It is recommended that most of the species be seeded in the spring while there is sufficient moisture in the soil to insure germination and establishment. The exception to this is on light, sandy soils where drought conditions may develop rapidly. On these soils, early fall seedings may be desirable.

Subterranean clover, likewise, is an exception to the rule of spring seeding. It is a winter annual that does well on the drier sites in western Washington. The most successful stands have been obtained by planting in September or early October, although some farmers have been successful in establishing stands very early in the spring, seeding not later than March 1.

Whenever possible, a drill should be used for seeding the new stands. Drilling insures a uniform depth of planting, prompt emergence, and the development of a smooth, even sward. Less seed is necessary to get a good stand when a drill is used. Broadcasting is still practiced, especially in the smaller fields where the use of a drill or other large farm machinery is not possible. When seed is broadcast, every precaution should be taken to cover the seed very lightly.

New stands should be managed to reduce competition from weeds to a minimum. One or two mowings the first year are usually necessary to control the annual weeds that usually occur in new forage seedings. It is recommended that the new forage seedings be mowed early in the fall to utilize the forage produced. Grazing is not recommended as the young forage plants are not well enough established by the end of the summer growing season to withstand even moderate grazing.

The use of fertilizer is one of the most important factors in good management of older meadows and hayfields. Phosphates are necessary for maximum legume production, while nitrogen stimulates the grasses. Yearly applications of 100 to 200 pounds of treble superphosphate and 40 to 60 pounds of actual nitrogen per acre are recommended. The nitrogen is usually applied in three equal applications, in March, May, and September. Split applications of nitrogen are particularly advisable when irrigation is practiced.

Some soils are slightly acid, and 2 to 4 tons of lime to the acre have given economic returns. Boron is necessary in most of the alfalfa-producing areas of western Washington. Applications of 50 to 60 pounds of borax an acre on heavy soils and 30 to 40 pounds on light soils will supply the needs of the alfalfa plants for boron.