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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #90182

Title: GEOSPATIAL MANAGEMENT OF WATER AND NUTRIENTS WITH A MODIFIED CENTER PIVOT IRRIGATION SYSTEM

Author
item Camp Jr, Carl
item Sadler, Edward

Submitted to: Geospatial Information in Agriculture and Forestry International Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: The site-specific application of irrigation water and fertilizer should offer opportunities to conserve water, to reduce drought or flooding stress, and to reduce loss of fertilizer or pesticides from the field. Two center pivot irrigation systems were modified to permit a range of water and chemical application rates to areas about the size of a 2-car garage. The water application system consists of multiple segments 30 ft long, each with three manifolds. Each segment is controlled separately, allowing up to eight separate water application depths. Each system is controlled using a computer with specialized software and cultural information stored in a database. While the first system was being developed and improved, it was used to apply water and nitrogen to a corn-soybean field experiment with regular plot boundaries during 1995-97. A second system was modified to provide variable applications to areas with irregular boundaries that are typical of Coastal Plain soils. Small areas of similar properties or conditions are grouped together to form areas large enough to treat independently. These areas can then be treated according to the management strategy selected; e.g., maximum profit, optimum resource use, or minimum cost.

Technical Abstract: Traditionally, site-specific farming suggests the management of fertilizers and pesticides for optimum crop yield on spatially-variable soils. In the southeastern Coastal Plain, research suggests that spatial yield variability may be caused primarily by water relations. Together, these requirements cause difficulties in managing water and chemical applications with conventional center pivot irrigation systems. Site-specific center pivot irrigation systems were developed to independently apply variable rates of water, nutrients, and pesticides to 100-m2 areas. Two commercial center pivot systems were modified by adding manifolds and nozzles in 13 segments along the truss to provide eight application depths within each segment. Also, a programmable, computer-controlled management system was added to provide the appropriate application rate for each area and to collect and store data. Control is based on stored GIS data but current conditions can be updated via dynamic measurements. Unique geospatial data are required to optimally manage water and chemical applications to these areas of variation. Response functions for water, nutrients, and pesticides must be developed before specific management strategies can be applied.