Author
 |
Vories, Earl |
|
STEPHENSON, DANIEL - UNIVERSITY OF ARKANSAS |
|
Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 6/12/2006 Publication Date: 7/27/2006 Citation: Vories, E.D. 2006. What is the cost and potential of precision pivots? [Meeting Abstract]. Annual NoTill Field Day, Milan, TN., July 27, 2006 Interpretive Summary: Technical Abstract: Farmers across the US are adopting aspects of site-specific management, commonly called precision agriculture. For some, it may have started with their consultant offering to grid sample fields to save money on fertilizer or lime with variable-rate application. Many cotton growers in the Mid-South now use variable-rate application for seed, fertilizer, plant growth regulators, and defoliants. However, some of the potential benefit of variable-rate application can be masked by applying a uniform rate of water across the field. While producers have known that different parts of their fields need different amounts of water, there hasn't been an easy way to apply variable irrigation rates. Center pivot manufacturers have controllers that can be programmed to vary the pivot speed in different portions of the circle, thereby applying more or less water. However, the application amount is still constant along the length of the pivot, so many variability situations couldn't be addressed by the systems. Until recently no commercial systems were available for adapting an existing center pivot to true variable-rate application. The University of Georgia Precision Farming team at the National Environmentally Sound Production Agriculture Laboratory (NESPAL) in Tifton, Georgia, and their collaborators developed a system they call Variable-Rate Irrigation (VRI). The system varies the amount of water applied to different portions of a field by varying the system speed and pulsing individual sprinklers. Prototype systems were installed and tested, and recently a private company (Hobbs and Holder, LLC, Ashburn, Ga.) began selling and installing a system for existing pivots based on the NESPAL design. In some areas cost-share money for potential water savings through improved irrigation management is available to producers who install the VRI system. The cost for a producer to convert a center pivot to VRI will vary greatly, depending on how many individual "zones" he wants to control independently and whether he qualifies for cost-share funds. What situations in the Mid-South would benefit from VRI? Almost every field has variable soils. Unusually shaped fields may have a towable center pivot with a large overlap area. One pivot-irrigated field may be planted to both corn and cotton. If the crops are divided into quarters of the field it can be easy to manage; however, in many cases it may be desirable to irrigate both crops at once with different application amounts. For rolling fields like those in much of West Tennessee, it would be beneficial to apply different amounts to the sloping and flat portions of a field. In 2006, one of the VRI systems was installed on a quarter-mile long center pivot irrigating a cotton field on the Judd Hill Plantation near Trumann, Arkansas. The field has variable soils and overlapping areas from two adjacent pivots. The system will be programmed to apply variable irrigation rates based on the soils, overlap areas, and irrigation studies in the field. In this way the potential of VRI in the Mid-South will be evaluated. |
