This section is from the book "The Potato: A Compilation of Information from Every Available Source", by Eugene H. Grubb, W. S. Guilford. Also available from Amazon: The Potato: A Compilation Of Information From Every Available Source.
One of the most important factors in the establishment of a market for all high class agricultural products is the uniform permanency of supply. The conditions are under such perfect control, and the Twin Falls country is of such extent, that this is absolutely provided for.
The Twin Falls country of southern Idaho is in about the centre of what is commonly called the Snake River lava plains. Until the recent application of water to large tracts of land here it has been known as the Snake River desert. It was never a barren desert, however, but covered with a growth of desert plants and grasses, making an excellent winter stock range.
Geologists report that southern Idaho was originally a rough, rocky country, the rocks being granite, rhyolite quartzite, and limestone. The valley of the ancient Snake River was broad and several valleys opened out from it into the mountains to the north and the south. After the river had worn to a deep channel, a flow of lava or a volcanic upheaval obstructed it in the western part of the state, and a lake covering a large part of the Snake River plains was formed. This lake was gradually filled up with wash and sediment, and with dust blown from volcanoes. In places this sediment is known to be 1,000 feet deep. Flows of lava from numerous vents, and deposits blown in by the wind, added to the superstructure of the country. The lava flows to the eastward of the lake region have been covered with wash from the mountains, dust blown from the old lake bed and lava dust from old volcanoes. The disintegration of lava rock has also probably added to the present soil. While in one way a plain, the Snake River country is more or less broken, making soil drainage perfect. The valley is surrounded by mountains rising from a few hundred to 6,000 feet above the plains, and 7,000 to 10,000 feet above the sea level.
The lava ash soil of the Twin Falls country is fine in texture. It is classed as an arid or desert soil in comparison with those of the rain belt. Soils found in a country of light rainfall, where irrigation is absolutely essential for the production of maximum yields of most crops, are high in the mineral elements of fertility because the soluble salts have never been leached out by the rains. Muck, peat or sour acid soils are not found in the Twin Falls country. A large number of tests of samples of arid and humid soils shows that the average arid soils contain three times as much potash, thirteen times as much lime, and six times as much magnesia as the humid soils. There is less humus in an arid soil. Humus is one of the chief sources of nitrogen, and nitrogen is one of the principal elements of plant food. The humus of an arid soil, however, contains three times as much nitrogen as the humus of a humid soil. Limestone soils are usually rich in phosphorus, and it is proverbial that "a limestone country is a rich country." The average per centage of lime in clay soils is .617. In the lava ash soil of the Twin Falls North Side tract there is 4.5 per cent. An acid soil is almost invariably a hard soil to grow crops on. As a general statement, all good soils show an alkali reaction - that is, they contain more alkali salts than acids.
I. B. Perrine H. L. Hollister.
Two men who have been prominently identified with the upbuilding of the Twin Falls country in the fact that the soil of the Snake River plains is partly an seolian or wind deposit classes it with the richest soils in the world. It is the deposits of the dust of ages swept from a desert country in addition to the lava dust from volcanic eruptions. The fine particles of soil are those from which the rootlets of the plant obtain their chief food supply. The Twin Falls North Side soil classes as 100 per cent. fine. In the regions embracing these fine, rich deposits there are dust storms while the country is a desert, but after irrigation and cultivation, with the consequent filling of the soil with moisture and vegetation, dust storms do not occur. The great plains of North America, including a large part of the Mississippi Valley, is a wind deposited loess or loam. The fertile loess soil region in northwestern China, which supports a dense population, is of seolian origin. The soil of the Twin Falls country consists of a mixture of the finest particles of the deposits from the disintegration of the rock of the mountains and plains, the wash of the same, and dust blown off the lake deposits to the west and south.
The altitude of the Twin Falls country is from 2,800 to 4,800 feet. It lies just south of the 43d degree of north latitude, almost centrally north and south in that section around the globe in which has been made the major part of the world's progress. It is about 400 miles east of the Pacific Ocean, 1,320 miles west of Lake Michigan, 432 miles south of the Canadian line, and 700 miles due north of the mouth of the Colorado River at the Gulf of California. Three mountain ranges separate the Snake River Valley from the Pacific Ocean. The main range of the Rockies protects it on the north and east from the moisture-laden winds of the Japan current and from the fury of winds and blizzards that are common in the plains country of the eastern slope. This makes the air dry, and while not free from winds or from some rain and snow, destructive wind is not known. The freedom from blizzards and excessive changes, and the perfect altitude, make possible the greatest perfection in all crops.
The growing season is comparatively long and the combination of cloudless, hot days, rich soil, and irrigation water in the growing season matures crops of quality and great quantity. The annual precipitation is about fourteen inches; the number of clear sunny days average annually 300; the highest temperature 101 degrees; and the lowest 12 to 20 degrees below zero. The dry climate makes prostrations from heat unknown. There are some snowstorms in winter, as everywhere in this zone, and in the transformation of the desert wind and dust storms occasionally occur. Almost all of the rainfall is in winter and spring, making the growing and harvesting season practically free from profit losing storms. The last killing frost in the spring is about May 15th, and the first in the fall about September 25th.