Encyclopedia of the Great Plains

CENTER PIVOTS

Irrigation equipment in the Great Plains most often refers to center-pivot equipment. A center-pivot irrigation installation consists of a fixed, four-legged pivot structure with a long pipeline to which sprinklers are attached for dispersing water. The pipeline rotates around the central pivot in a straight radial-arm fashion, riding on wheeled tower structures and creating a large irrigated circle pattern on planted crops.

The industry originated in the Great Plains. Frank Zybach, a dryland wheat farmer in Colorado, developed the first system in 1948. The first prototype, made of steel and aluminum, was propelled by piston-driven actuators powered by water pressure from the pivot system water supply. In 1954 Robert Daugherty of Valley Manufacturing acquired the marketing rights to the patent and continued development of the concept over the next ten years, perfecting it into a strong, durable design and establishing an entire industry.

In the thirty years after World War II, more than sixty companies in the United States manufactured center-pivot irrigation systems. Today there are four major suppliers, all located in Nebraska: Valmont (in Valley and Mc- Cook, with plants in South Africa, Spain, and the United Arab Emirates), Lindsay (headquarters in Omaha and plants in Lindsay, Nebraska, and France), Reinke (in Deshler), and T-L (in Hastings). These four companies supply 85 percent of the global demand for center pivots and virtually all of the North American market requirement. All four companies go to market through networks of exclusive dealers and distributors. Center pivots are now used in more than 100 countries around the globe.

Major developments in center pivots have included the transition from water power to electric and oil-hydraulic power, the adoption of durable coatings for the pipes and structure, and the invention of special spans mounted at the end of the pivot arm to cover the corners in square and irregularly shaped fields. Linear move machines are built from the same components but are not fixed to a central pivot. Linear move machines, introduced in the 1970s, proceed in a straight line to cover rectangular fields. Special water application devices for the low-energy precision application of water were introduced in the 1980s. In the 1990s computerized controls were added, along with integration of controls with soil moisture monitoring and weather monitoring capability.

Mechanized pivot irrigation equipment has advantages over other methods of irrigation because of the uniform application of water to large fields, low energy consumption, relatively low cost, and the savings in labor required for irrigation. The average life of a center pivot is more than twenty-five years of annual usage, resulting in a very low total life-time cost of ownership. Its ability to operate over undulating ground gives the additional advantage of not requiring costly land leveling, as is the case with other forms of irrigation. Chemicals can also be applied to the crop through aqueous solution with the irrigation water or by separate spray manifolds mounted on the pipeline structure. Water runoff can be virtually eliminated by the precise application of only the amount of water that can be absorbed by the soil. There is a growing market for mechanized irrigation equipment to dispense wastewater through pivots to irrigate field crops such as alfalfa hay. Large industrial consumers of water such as food processors, paper producers, and municipalities can benefit from the reuse of the water through pivots in such productive ways.

Crops produced under center pivots include fruit tree orchards, commercial turf, high-value vegetables, cotton, and all major commodity grain crops.

See also WATER: Irrigation.

Dennis Schwieger Valmont Irrigation