Writer: Rod Santa Ana III, (956) 968-5581,r-santaana@tamu.edu
Contact: Dr. Bob Wiedenfeld, (956) 968-5585,r-wiedenfeld@tamu.edu
WESLACO – When future generations look back on the South Texas drought of the 1990’s, they may learn that the lack of normal rainfall for six years turned the type of irrigation used from flood irrigation to more innovative drip and overhead irrigation systems.
“Flood irrigation is simply not a very efficient means of irrigating our crops,” said Dr. Bob Wiedenfeld, soils scientist at the Texas A&M Agricultural Research and Extension Center at Weslaco.
To determine the feasibility of alternative systems, the Weslaco center has been testing drip irrigation systems for several years and will soon be installing and testing overhead mechanical type systems.
“These overhead systems are traditionally called central pivot irrigation systems,” said Wiedenfeld, “but the ones we’ll be looking at move laterally across a field. And instead of using sprinkler heads, these systems use drop tubes, which cut down dramatically on evaporation loss. These are new and improved systems that have a huge potential in high water use crops such as sugarcane and high value crops such as vegetables.”
Flood irrigation, used here for almost a century, is inefficient because so much water is lost to evaporation, seepage, and misdirected flows.
“The water distribution itself is terrible in flood irrigation,” said Wiedenfeld. “You may have too much water at one end of the field, and not enough at the other. Irrigation water also carries with it weed seeds from the river that then germinate in a flood-irrigated field. And flood irrigation leeches out expensive insecticides, fungicides, and herbicides that a grower wants to maintain on the field as long as possible.”
Wiedenfeld says two or three overhead irrigation systems will be installed at research field plots in Weslaco to assess their reliability and efficiency.
“Water here is still relatively cheap, compared to other areas of the world,” he said, “so there has to be more than water savings to justify the high costs of these systems. We’d have to see other economic benefits such as increased yields, reduced pest problems, and lower fertilizer expenses. But since these systems are designed to last 25 to 30 years, it’s possible they’ll pay for themselves over the long haul.”
Wiedenfeld says the circular, central pivot type irrigation systems seen in other parts of the state and nation, are not feasible here because of the area’s high winds and because those systems are designed to cover huge tracts of land not typically found in South Texas. These newer systems can be customized to cover small and irregularly shaped acreage.
“We’re very excited to be testing these new systems,” said Wiedenfeld, “because there’s no doubt that Valley agriculture will have to move to much more efficient methods of irrigation. Water is getting too scarce and too expensive to continue flood irrigation.”
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