The fertility problems of these valleys have not been defined clearly.

The need for both nitrogen and sulfur is widespread. Nitrogen will aid in increasing the yields of tree fruits, grasses, grains, and vegetables in fact, all crops except legumes.

The soils are low in available sulfur. Sulfur therefore is recommended, especially for legumes, grains, and vegetables, unless a sulfur-carrying fertilizer was applied in the previous year.

Some soils respond to applications of phosphorus, potassium, and boron. Soil tests are used in making recommendations for applying them.

Spray applications of iron chelates are made to correct the chlorotic condition found on pear trees in the Rogue River Valley.

The soils of the Rogue and Umpqua Valleys are less acid than those in the rest of the North Pacific area. Most of the soil samples from the Rogue Valley, which were tested at Oregon State College, have been above pH 5.8. Many soil samples from the Umpqua Valley are less than pH 5.7 and typically have lime requirements of 1.5 to 2 tons an acre. Little lime has been used in the area, and additional research is needed to determine its effects. Limestone is recommended on the basis of soil tests.

Because most of the sloping land is in pasture or forest, erosion is not a widespread problem. The greatest erosion problem occurs on nonirrigated sloping land devoted to grain crops and on slopes where gravity irrigation is used for cultivated crops. Accelerated erosion following logging operations is an overall problem in the area.

ZONE 5, the coastal areas, extends from Puget Sound in the north along the entire coast of Washington, Oregon, and the two northernmost counties of California nearly 500 miles.

This zone has higher rainfall, cooler summers, and warmer winters than the rest of the area. Agriculture is confined largely to alluvial soils along the coast and coastal streams. The adjacent uplands mostly are covered with forest.

The organic matter in the surface of most of these soils is high or very high (4 to 12 percent or more). The soils are usually very acid commonly about pH 5. They are severely leached of bases.

The soils on the upland and terraces usually are well drained. The alluvial soils typically are poorly drained. Many are perpetually waterlogged. The wetter soils often are mottled in the surface, with gleying in the subsoil.

Forage crops occupy nearly all of the cultivated land in the coastal zone. They are used mainly for pasture, but some grass silage and hay also is produced. The pastures consist largely of grass species, but red clover, alsike clover, lotus major, Ladino clover, New Zealand whiteclover, and sub-clover also are used in improved pastures and meadows.

The principal income is derived from dairying, but poultry and sheep are important in some parts of the zone. A limited acreage is devoted to small grains, such grass seed crops as bent-grass, lily bulbs, and cranberries.

The soil-management problems in the coastal areas include inadequate drainage, insufficient summer rainfall, high acidity, and low fertility.

Drainage by diking, ditching, and tiling has been the means by which most of the tideland, river bottoms, and terraces on which forage crops are grown have been brought into profitable production. The easiest jobs have been done. Much remains to be done if farmers are to achieve maximum production. Clearing of timber and brush is needed in many instances, as well as drainage. Many localities will require community action to solve their drainage problems.

Even with drainage improvement, the soils may be wet or flooded from November to April. The average rainfall is 6 to 12 inches a month in winter in most of the coastal zone. Forage crops must be adapted to such conditions.

Rainfall in the summer is not enough for the best forage production. The average rainfall in July and August is 0.75 inch in the southern part and as high as 3 inches along part of the Washington coast.

Rainfall in June and September also is low in the southern part. Irrigation is essential for maximum forage production in summer. Irrigation has been increasing and will likely continue to expand as long as suitable soils and available water can be combined for profitable production. Marked improvements in irrigation practices are possible on many farms in this zone.

Inadequate available nitrogen limits the production of grass. The total nitrogen content of the soil is high, but the nitrification rate is quite low. The cool soil temperatures throughout the year, often poor aeration, high acidity, and low fertility all contribute to reduce the rate of release of nitrogen from soil organic matter in these soils.

Applications of nitrogen fertilizers can be made throughout the season to increase the growth of grass, especially if moisture is adequate.

The soils along the coast have a high requirement of lime. More than two-thirds of the samples tested in the Oregon State College soil-testing laboratory showed a lime requirement of more than 4 tons an acre. It will take 12 to 16 tons of high-quality limestone to raise many of the soils to pH 6.5.

Results of soil tests in this zone indicate that most of the soils are deficient in phosphorus and some lack potassium. Phosphorus and potassium have been recommended for legumes when soil tests indicate a low level in the soil.

It is expected that the needs for potassium will increase in this area. The grasses compete strongly with the legumes for the available soil potassium, and frequent applications of potassium may be needed on many soils if legume stands are to be maintained in connection with the grass.

Many of the soils in zone 5 contain quite low amounts of exchangeable magnesium.