Economics of conversion to mobile drip systems
In the High Plains region, where precipitation is limited (20 inches a year or less) and where irrigators depend on declining water supplies, many producers are considering how to make their irrigation systems more efficient. Research trials have suggested that Mobile Drip Irrigation (MDI) can provide water application efficiency comparable to that of subsurface drip irrigation (SDI), which is estimated to have a water application efficiency of ~97%. MDI may also offer comparative benefits related to improving seed germination, cost of installation, and the potential reduction of wheel rutting and/or runoff.
So, how long might it take to recoup an investment to convert a system over to MDI, and what might the cost savings look like for producers in the central Ogallala region areas of northern Texas and southwestern Kansas?
As part of her graduate studies, Sydney Reynolds (West Texas A&M University, Department of Agricultural Sciences) compared MDI to Low Elevation Spray Application systems (LESA) which was estimated for this study to have an application efficiency of 88%). She evaluated the changes in variable cost per hectare to calculate the payback period for an MDI system under three levels of investment cost for crops with different water use requirements: corn (high), medium (sorghum and wheat) and low (cotton). Yield and commodity prices were held constant for this study.
Results. The duration for payback related to converting LESA systems to MDI to varied from 2 years to more than 14 years, depending on the crop and investment level. "As the water use of the crop drops, the payback period rises as it takes longer to realize the gain in system efficiency," Reynolds observes. Meanwhile, total variable costs (including fuel, lubrication, maintenance, and repairs) were lower for MDI compared to LESA systems.
Cost-share assistance for conversion to MDI through NRCS EQIP or other programs, if that becomes available, could decrease the payback period. A rise in crop prices, or yield increases as a result of converting systems to MDI are scenarios that merit additional study, along with looking at if and how MDI might improve water use efficiency (measured as decreased costs or increased yield/volume of applied irrigation).
More on these ideas, along with a range of practical considerations and observations from others who have had the opportunity to work on research and field work to evaluate MDI are covered by Reynolds in an excellent presentation she gave recently for her graduate studies thesis defense (jump to 21:50 to hear her talk about this MDI study- the first part of her talk covers work on integrated modeling that will be shared in another newsletter) as well as in a paper she lead-authored titled "Economic feasibility of conversion to mobile drip irrigation in the Central Ogallala region" published recently in a special Ogallala-focused issue of Irrigation Science organized by some of our team members.
For more research results on mobile drip irrigation supported by our project, visit our website's page on irrigated production systems research and enter "mobile drip" or "MDI" into the search field at the top of the page.
Reynolds's work was supported in part by our project as well as by the USDA-Agriculture Research Service (ARS) supported Ogallala Aquifer Program.
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