The soils over the entire areas of eastern Washington on the arid
lands is a volcanic ash mixed with disintegrated basaltic rocks and
some humus, varying in depth and in the amount of sand it contains.
The low lands are usually more sandy and warmer and earlier in season.
The depth of this soil is in some places 80 feet and generally so
deep as to insure great permanency to its fertility. It readily
absorbs and holds moisture, and is admirably adapted to artificial
watering. In some spots there is an injurious surplus of alkali.
It is generally covered with sagebrush and has the appearance of
sterility, but upon cultivation under irrigation, produces wonderful
results in quantity and quality of grains and grasses and fruits
and vegetables.