The Nebraska pioneer of center pivot irrigation has died

Robert B. Daugherty was a Nebraska businessman who helped transform the rural landscape into a patchwork of circular fields by popularizing an irrigation system that used a pipe on wheels pivoting around a central point. He died on Wednesday at his home in Omaha, he was 88.

Mr. Daugherty’s company, originally called Valley Manufacturing, started out making agricultural implements. Now known as Valmont Industries, it became an international manufacturing giant. The breakthrough for Mr. Daugherty came in 1953, when he bought the rights to manufacture a new irrigation system, the brainchild of a Nebraska farmer, Frank Zybach. The new system came to be called center-pivot irrigation. It involved a long pipe on wheels that rotated around a point at the center of a field, spraying water as it went.

Engineers working for Mr. Daugherty improved the system, but he had difficulty at first persuading farmers to try it. By the 1960s, however, it began to take hold. Today, about 42% of irrigated farmland in the United States uses center pivot machinery or similar mechanized systems. Its prevalence can perhaps be best recognized from the air, where travelers on cross-country flights can see the landscape converted into a polka dot pattern of irrigated circles inside square fields.

Before the center pivot, farmers would typically irrigate their fields by allowing water to run downhill in furrows. But the center-pivot system allowed for a much more efficient use of water. It also requires less labor and can be used on uneven or hilly terrain where traditional methods of irrigation may not be an option. It is now used around the world and is credited with expanding the acreage of irrigated land and increasing farm productivity.

Mr. Daugherty, who retired from the company in 1996, left a large part of his fortune to a foundation he created. In April the foundation pledged $50 million to the University of Nebraska to found the Global Water for Food Institute, a center for research and policy analysis related to the use of water for agriculture.

Center pivot irrigation

Center-pivot Irrigation, is a method of crop irrigation in which equipment rotates around a pivot. A circular area centered on the pivot is irrigated, often creating a circular pattern in crops when viewed from above. The system is fed with water from the pivot point at the center of the circle.
Central pivot irrigation is a form of sprinkler irrigation consisting of several segments of pipe galvanized steel or aluminium, joined together and supported by trusses, mounted on wheeled towers with sprinklers positioned along its length. The inner sets of wheels are mounted at hubs between two segments and use angle sensors to detect when the bend at the joint exceeds a certain threshold, and thus, the wheels should be rotated to keep the segments aligned.
Centre pivots are typically less than 500m in length (circle radius) with the most common size being the standard 1/4 mile machine (400 m). Most center pivot systems now have drops hanging from a u-shaped pipe called a gooseneck attached at the top of the pipe with sprinkler heads that are positioned a few feet (at most) above the crop, thus limiting evaporative losses and wind drift. Drops can also be used with drag hoses or bubblers that deposit the water directly on the ground between crops. This type of system is known as Low Energy Precision Application. Crops may be planted in straight rows or are sometimes planted in circles to conform to the travel of the center pivot.
Most systems today are driven by an electric motor mounted at each tower. The equipment can also be configured to move in a straight line, where the water is pulled from a central ditch. In this scenario, the system is called a linear move irrigation system. Terrain needs to be reasonably flat, but one major advantage of centre pivots over alternative systems is the ability to function in undulating country.