Case Studies
Demonstrating Irrigation Water Management Practices to Mid-South Farmers By Chris Henry, PhD, PE, and L. Jason Krutz, PhD
Summary Statement
Southern regional water management programs have identified a number of technologies and management practices that have the potential to reduce the overdraft on the Mississippi Valley Alluvial and Sparta Aquifers. In Arkansas, groundwater withdraws from the alluvial aquifers are only about 42 percent sustainable and 54.6 percent sustainable from the Sparta/Memphis aquifer. In Mississippi, state regulators have responded with withdraw permits, voluntary metering requirements and changes in irrigation practices.
Success in 2015 with on-farm furrow irrigation demonstrations in Mississippi and Arkansas have shown a 26 percent reduction in water use while maintaining profitability. Implementation of such practices on a large scale will improve water sustainability in the region.
Without sustainable irrigation practices, yields could be 30 to 50 percent less in the future if water becomes limited in the region. Aquifer overdrafts in this region pose a real concern about the future of row crop production in the region. For example, in Arkansas 3.8 million acres are expected to have limited or no water resources by 2050, according to a recent study. For comparison, 3.8 million is also about the amount of acres on which soybeans are grown annually in Arkansas.
What Was Done
On-farm demonstrations were conducted using paired fields and a control field that was instrumented with a portable flow meter. The farmer cooperator managed and irrigated the field using normal irrigation practices.
On a nearby field, irrigation water management practices were deployed using computerized hole selection for lay flat (poly) pipe, a portable flow meter, a surge valve, soil moisture sensors and either data loggers or AgSense Aquatracs. In Arkansas, atmometers were also used. Agents and producers followed extension recommendations for termination. Cost of water was determined for the irrigation pumps at each demonstration. Yields were determined from yield monitors or scale tickets.
Results
For the 20 site areas, no significant difference in yields (69 bushels per acre) between control fields and IWM fields were found. For water use, fields with IWM demonstrations used 26 percent less water than the control fields. Eighty-five percent of irrigators applied more water on the control fields than the fields where IWM was used. Sensors were placed at three to four depths from 6 – 30 inches, and irrigation sets varied between 8 to 60 acres. The results demonstrate that one sensor location in a production scale furrow irrigation field is sufficient to maintain soybean yields.
We also evaluated the irrigation pumping plants for improvements in irrigation efficiency. On average we found that
$511.66 in savings per pump could be realized by making changes. The range of savings from changing the operation was $35 to $1,518. Most of the changes were simply how the pumps were operated, such as engine speed.
As an example, one tested pump shows an annual savings potential of $1,518 if engine speed is slowed to 150 rpm. Another demonstration with three electric pumps in a network showed that not using one of pumps could have saved $1,008 annually and still met crop water demand. In both cases, by making these changes the irrigation efficiency would have been improved due to longer soaking times.
In essence, this work provides key baseline data for farmers in the Southern region about how to implement IWM practices. Through these demonstrations, agents and farmers learn how to implement IWM practices.
Collaborators: Ron Levy and Stacia Davis, Louisiana State University, Joe Henggeler, University of Missouri, and Larry Falconer, Mississippi State University
Funding Sources: United Soybean Board, Mid-south Soybean Board, Arkansas Soybean Promotion Board, and Mississippi Soybean Promotion Board
Christopher Henry, PhD, PE, is the assistant professor and water management engi- neer of the Rice Research and Extension Center at the University of Arkansas.
L. Jason Krutz, PhD, is a research/ extension irrigation specialist with Mississippi State University.
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