Fine-textured soils, especially without plant or residue cover, tend to reduce water infiltration. Idaho has many different kinds of soil which reflect a wide array of parent material and varying climates. Idaho has soils that are both formed in place and on weathered materials such as sand and silt that has been transported by wind or water from its original location. Idaho has a great diversity of climates. Annual precipitation ranges from as little as 6 inches along the Snake River south of Boise to over 60 inches at the higher elevations in northern Idaho.
Temperatures also vary over a wide range.
Water and temperature both have a major impact on the soil formation processes. Living organisms including plants, grazing animals, insects, microorganisms and man all affect the development of soil. In addition to their energy-providing role, plants are the main barrier between soil and the erosive forces of wind and water. The roots help hold the soil in place, and the foliage, both live and dead reduce the impact of falling rain drops and slow the movement of surface water and increase its infiltration into the soil. Microorganisms play an important role in recycling nutrients, improving soil tilth and enhancing infiltration.