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Development of C.M. Stripling Irrigation Research Park
Protection of the farm's natural resources
Conservation plans were prepared to assure protection of the farm's outstanding live oaks. Whenever feasible conservation tillage practices have been used to maximize entry of irrigation and rainfall into the soil and minimize wind and water erosion. Pine trees not removed during development of the facility are being managed according to accepted forest practices. back to top
Background site and soil characterization
The farm was thoroughly characterized to make most effective use of its topography, soil, resources and natural beauty. To facilitate location and positioning of research equipment and utilities, a detailed topographic and aerial survey was completed using Beeline tractor-mounted navigation equipment. A background soil fertility map was created using point samples on 1 acres grids, and separating 0 to 6 and 6 to 12 in. deep layers. Analysis of the 200 samples was provided by Waters Agricultural Laboratory in Camilla. High resolution sampling is also completed for experimental unit prior to individual cropping decisions. Physical soil properties were determined to a depth of 6 feet using hydraulic core sampling, undisturbed soil coring, and field and laboratory tests using the same one per acre characterization. Well logs were maintained from drilling operations to characterize stratum underlying the farm, and detailed water quality analysis was made on samples taken during pump tests. back to top
Selection and layout of the major experimental units
Because the farm will always be limited in areas available for irrigation experiments, the primary design criteria was to accommodate those experiments that the University of Georgia cannot do on its existing farms throughout the Coastal Plain. Most of the other farms provide irrigation so that crop breeding, variety evaluation, weed, insect, and disease control, fertility, etc. can be studied under typical irrigated production practices of Southeast agriculture. However most of those farms irrigation systems have limited flexibility. Comparisons of separate irrigation rates, time of application, and depth of irrigation control zone cannot be studied. Additionally, competition for water has made and will continue to make water resources more precious than in past years. Efficiency in all phases of irrigated agriculture - from irrigation of most productive land, elimination of off-target spray, and in-field variable rate adjustments for crop needs, to application efficiency and scheduling methodology - will be needed just to maintain current levels of production. Improvements in existing systems, especially the 10,000 center pivots in Georgia, places a need for retrofit designs. New crop options in the region also suggest new irrigation systems, especially drip with all its attendant plastic and other mulches chemical injection. Finally, educational needs for irrigators from home lawns to orchards to row and vegetable crops dictate that a wide variety of equipment be available on the farm.
To accommodate as many of the needs within one facility, we have carefully selected a variety of field sites. These include small center pivots where the emphasis has been on application efficiency and pivot and end gun controls. A 4-tower pivot system has been used to design and test precision control and variable rate irrigation technology. Two linear systems with variable rate controls supply water to replicated plot designs getting the most area out of overhead irrigation systems as feasible. Several drip and buried drip (SDI) irrigation areas have been used in replicated field designs for vegetable and other high value crop use, including chemigation studies, as well as layout and controls for uneven topography common in the Dougherty Plain area of SW Georgia. An existing pecan grove could be used for demonstration of irrigation equipment and management options in groves (the area is too small for replicated research on pecans). One field has been used for studies on traveler systems. Wooded areas are available for container plant nurseries under shade, and at least one field area could be set up for plant container management on plastic with catchment and recycling of excess water. back to top
Selection, design, and purchase of irrigation equipment
Given the field design criteria listed above, we sought appropriate equipment. Our initial efforts concentrated on basic superstructure and controls of mechanical irrigation - center pivots and linear move. To facilitate testing on a variety of manufacturers equipment and controls, especially in light of retrofit needs, we selected four matched 2-tower pivots, one each from Zimmatic (Dixie Irrigation, Camilla, GA), Valley (Shiver Tractor Co., Sylvester, GA), Reinke (TCA Irrigation, Tifton, GA), and TL hydraulic drive (Sowhatchee Equipment Sales, Blakely, GA). These represent the majority of center pivots currently available in the Southeast US. For each we included the manufacturer's state-of-the art control panels. Each was also equipped with an end gun, a troublesome, but popular feature on most center pivots in Georgia. Multiple manufacturers gives us maximum flexibility in testing new controls, nozzle packages, and end gun operation, as well as offering training opportunities with each modern system.
A 4-tower, 600 ft center pivot (Valley from Rogers Irrigation, Camilla, GA) was purchased for work with precision application and variable rate controls (VRI). Design for variable rate controls is from Greg Harting, AgriNorthwest Inc., Kennewick, WA) and Ole Hansen (Computronics Corporation Ltd., Bentley, Western Australia). This system is also under evaluation by NESPAL in new and retrofit designs on several other pivots on Georgia farms. VRI offers considerable flexibility in automation and variable rate control.
In addition to the large pivot, two 4-tower linear move systems (Valley from Shiver Tractor Co., Sylvester, GA) were being installed with precision valve controls. These controls will be used to create a rectangular field with replicated, randomly assigned irrigation plots and blocks for use in studies of rates of application, timing of irrigation, and scheduling methods for row and selected vegetable crops. For these systems, as well as all mechanical systems above, we expect to make several sprinkler package changes as we evaluate packages, spray patterns, nozzles, and application losses.
Drip and subsurface drip (SDI) systems have been implemented in various designs to fit specific research needs. In two large fields, buried submains and risers as well as control wires were installed on 80 ft centers to allow flexible layout of drip and drip under mulch. At each riser, four pressure-regulated flow and valve systems can be attached and controlled at a central panel. In a separate area, a SDI system, complete with flushing system was installed to demonstrate feasibility of SDI in row crop systems for small fields in the Dougherty Plain. back to top
Engineering plans for water and power supply and distribution
Three 8-inch wells (AAA Well Drilling, Albany, GA) and 6-inch PVC pipe and electric power supply (United Irrigation Supply, Inc., Quitman, GA) were arranged in a loop form the backbone of the water and power distribution network. Initially a 10,000 gallon pressurized tank was installed to provide flexibility in the widely varying flow needed to meet individual experiments, including drip. This proved unfeasible for the larger center pivot systems, and pressure regulated flow valves were installed on each well pump as an alternative to maintain varying flow at system design pressures. Later a variable frequence drive was added to one of the wells to allow direct power and performance comparisons between VFD and pressure-regulated valves for variable flow control systems.
All basic risers from the water distribution system have water flow and pressure measurement that can be relayed by radio to a computer in the headquarters. The information has been part of the basic efficiency data recorded in field studies. In drip, SDI and other fields where system controls of the irrigation are compatible with an independent monitoring and control system, actual scheduling will be done from the headquarters. We are currently working with vendors for a central monitoring and control system. Additionally, individual software control and monitoring provided by pivot manufacturers will be used for monitoring, control (where feasible) and for training of farmers and students. back to top
Design, construction, and layout of multipurpose headquarters building
The Stripling Irrigation Research Park will required two structures at the onset. One building is a strand steel building 60 by 125 feet. Initially, about one third of the building was air conditioned and used for office, work, and meeting rooms. The remainder has served as shop and assembly areas, clean storage areas, drying and preparation areas for plant and soil samples, and covered equipment shelter. The facility has a brick facade and matching brickwork for the Irrigation Research Park sign. Other design elements included a north-facing open entryway built into the structure, moderate windows for lighting and visibility of parts of the farm, a reception area, office and communications and equipment monitoring area. A separate steel structure was built to provide a protected chemical mixing and tank rinse area with an associated sprinkler system to safely distribute rinsate. To avoid chemical hazards at the facility, all fertilizers and farm chemicals are purchased on a just-in-time basis, custom applied when feasible, and excess returned to the supplier. back to top
Plans for management, maintainance and operations, and upgrades
With aid from the Assistant Dean for the UGA-CAES Campus at Tifton, who has fiscal responsibilities, operating budgets have been established. With input from the Advisory Committee and equipment dealers and manufacturers, a plan for maintenance as well as upgrades will be established. back to top
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Planning for C.M. Stripling Irrigation Research Park
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