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The Effects of Relaxing Subsurface Drip Irrigation (SDI) Design Uniformity Standards on Returns on Investment and Net Present Values of the Irrigation System. Curtis Wilde, Jeff Johnson, James Bordovsky Texas Tech University and Texas Agricultural Experiment Station - Lubbock.
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The Effects of Relaxing Subsurface Drip Irrigation (SDI) Design Uniformity Standards on Returns on Investment and Net Present Values of the Irrigation System Curtis Wilde, Jeff Johnson, James Bordovsky Texas Tech University and Texas Agricultural Experiment Station - Lubbock Beltwide Cotton Conference New Orleans, Louisiana January 9-12, 2007
Background • Efficient in-season water application • High water use efficiencies • High initial cost to install • Installation design uniformity standards • Not to exceed Flow Variation of 20% (USDA – NCRS)
Objective • Apply NPV and ROI analysis to installation of SDI systems with varying design uniformities • Can design uniformity standards be reduced to decrease the initial cost of the SDI system
Methods and Procedures • Study looks at: • Returns on investment (ROI) and Net Present Value (NPV) for: • Two irrigation levels • 1.0 BI Level (80% of the evapotranspiration demand of the crop) • 0.6 BI Level (60% of the 1.0 BI Level) • Three designs with different uniformities • 5.0% Flow Variation • 16.7% Flow Variation • 37.1% Flow Variation
Methods and Procedures P = annual profits IC = initial cost of the system IC = initial cost of the system ATCF = after tax cash flows for year i TV = terminal value of the system in year n n = number of years considered in the analysis
Methods and Procedures • 7 year simulation analysis • Cumulative Distribution Functions (CDFs) show the probability of a NPV occurring • Allows the system designs to be ordered based on risk
SDI Designs 1.0FV5.0 Design layout 0.6FV5.0 Design layout 1.0FV16.7 & 1.0FV37.1 Design layout 0.6FV16.7 & 0.6FV37.1 Design layout
CDF Results (cont.) • Cost share programs (EQIP) increase NPVs
Conclusions • SDI design uniformity standards could be relaxed under certain conditions to reduce the initial cost of installation • When a lower irrigation level is used system uniformity can be decreased without an detriment to NPV • At lower irrigation levels ROI and NPV could be greater for lower design uniformities
The Effects of Relaxing Subsurface Drip Irrigation (SDI) Design Uniformity Standards on Returns on Investment and Net Present Values of the Irrigation System