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Alabama Cooperative Extension System Alabama Irrigation and Water Resources |
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BIOSYSTEMS ENGINEERING SERIES TIMELY INFORMATION Agriculture, Natural Resources & Forestry ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Department of Biosystems Engineering, Auburn University, AL 36849-5626 BSEN-IRR-07-01 MAY, 2007 140 Acre Pivot for Farm or Wastewater Irrigation Ted W. Tyson, Biosystems Engineer & Professor Larry M. Curtis, Biosystems Engineer & Professor (Retired)
General Description This publication attempts to evaluate a typical irrigation system in terms of initial and annual cost and its adaptability to Alabama conditions for farm and/or wastewater irrigation. The cost per acre to purchase, install and operate an irrigation system will depend on the design requirements for each individual unit. Where two irrigation sites have similar characteristics, (i.e, water source, land clearing requirements, field size, shape, elevation, etc.) the component requirements and cost analysis of one site may be used to get an idea of the requirements for the second site. While the design illustrated on the first page of this publication is not neccssarily a recommended layout, it is one example. Each farm or wastewater irrigation site must be evaluated on an individual basis to determine the exact design and component requirements and to develop a cost analysis for that particular location. The example system utilizes surface water. For farm irrigation, this is a stream, creek or pond. For wastewater irrigation this would be either a single or two stage animal waste treatment lagoon. In areas where wells are practical, well cost should be determined. Whether to go with a well or surface water development on a combination of these will vary with local conditions and must be evaluated on a case-by-case basis. For the example system discussed here, typical initial costs for each component are indicated and annual per acre ownership and operating costs are estimated. Annual costs are calculated over the useful life of the equipment. Available tax credits and/or other tax advantages or federal or state cost share for animal waste management systems are not figured in this example, but would reduce ownership costs when available. Also, remember that the loan repayment period for purchasing irrigation equipment is usually much shorter than the useful life used for calculating ownership cost. Where this is true, annual ownership cost may underestimate actual cash flow needed to meet loan obligations during the repayment period. Another alternative to direct purchase of irrigation equipment is equipment leasing. This may be desirable in some cash flow situations. The system described here uses a diesel power source. Electric power is also an option, threephase power, where available, or single phase-powered phase convertors, is also an option. This is particularly the case in the wastewater situation where the irrigation system will be needed on the site for lagoon level control over the entire life of the animal waste lagoon. DESCRIPTION: 140 Acre Center Pivot The 140-acre stationary center pivot system described here is considered a standard unit. When the pivot point is located at the center point of a 160 acre block of land, this system will irrigate approximately 140 acres. (In order to irrigate 140 acres, an end gun must be used to irrigate a portion of the comers.) This size is easily adapted to large fields where 160 acre square blocks are available. The only additional equipment necessary for wastewater irrigation is a float, to position the pump suction above the lagoon floor and about 18 inches below the lagoon surface to prevent solids pickup. A breakdown of component costs is shown on pages 4 and 5 for the irrigation system illustrated on page 1. Annual per acre ownership and operating costs are also calculated. COST ANALYSIS OF IRRIGATION SYSTEMS CENTER PIVOT SYSTEM 140 Acre Coverage, 1 Pivot Point140 Acre Coverage, 1 Pivot Point
Thus, additional yield worth at least $154 per acre would be required to cover the ownership and operating cost for this system. Additional production costs resulting from higher fertilizer rates, additional seed, increased harvesting and drying costs, etc., incurred due to intensified irrigation would also have to be covered in order to offset all additional expenses. Nutrient value of wastewater may reduce higher fertilizer costs. AIABAMA A&M AND AUBURN UNIVERSITIES, AND TUSKEGEE UNIVERSITY, COUNTY GOVERNING BODIES AND USDA COOPERATING The Alabama Cooperative Extension System offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability.
Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability. This document is author-produced (unedited).
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