PNW Conservation Tillage Handbook Series
Chapter 2 - Conservation Tillage Systems and Equipment, No. 28, December 2003

Dryland Cropping in the Western United States

Authors: William F. Schillinger, Robert I. Papendick, Stephen O. Guy, Paul E. Rasmussen, and Chris van Kessel

W.F. Schillinger, associate scientist, Department of Crop and Soil Sciences, Washington State University, Lind, WA; R.I. Papendick, supervisory soil scientist, USDA-ARS (retired), Pullman, WA; S.O. Guy, professor, Department of Plant, Soil, and Entomological Sciences, University of Idaho, Moscow, ID; P.E. Rasmussen, soil scientist, USDA-ARS (retired), Pendleton, OR; and C. van Kessel, professor, Department of Agronomy & Range Science, University of California, Davis, CA., Corresponding author (schillw@wsu.edu). This article is printed with the permission of the American Society of Agronomy, Crop Science Society of America, and the Soil Science Society of America.

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  Abstract

  The major regions for dryland cropping in the western United States are in the inland Pacific Northwest (PNW), situated contiguously in eastern and central Washington, eastern and north-central Oregon, the Idaho panhandle and the intermountain region of southeastern Idaho, northern Utah, and western Montana (Figure 1). Elsewhere, limited dryland crop production occurs in the foothills along the Central Valley in California and, except for small, scattered areas, is almost nonexistent in Nevada and Arizona.
  We define dryland cropping as that practiced where average annual precipitation is 24 inches or less and no irrigation is used. Approximate land area devoted to dryland cropping in the western United States is 10,817,000 acres (Table 1). Of this, 8,271,000 acres are in the inland PNW, 2,124,000 acres in the intermountain region, and 422,000 acres in California. This chapter focuses on these dryland cropping regions (Figure 1, Table 1). Because of climatic variability, the inland PNW is subdivided into three average annual precipitation zones: low–less than 12 inches of precipitation; intermediate–12 to 18 inches of precipitation; and, high–18 to 24 inches of precipitation.

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