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Water availability may change cropping systems: Part three

Too common a sight on the TExas  High Plains dust rolling across bare fields
<p>Too common a sight on the TExas High Plains, dust rolling across bare fields.</p>
Farmers have come a long way toward improving irrigation efficiency

Farmers have come a long way toward improving irrigation efficiency, says Dana Porter, Texas AgriLife Extension engineer and irrigation specialist at the Lubbock Research and Extension Center.

Farmers may have drilled more wells across the region in recent years, but, along with the higher number of wells has come improved irrigation and management systems.

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“It is true they are drilling a lot more wells in the South Plains,” Porter said. “That’s because—in general—capacity (water-delivery rate) per well is dropping as the aquifer declines. It takes more wells these days to deliver the same amount of water. Some folks are drilling replacement wells hoping for higher delivery rates, as the delivery of older wells drops off for a variety of reasons.”

Others are reworking older systems to make them more efficient. “Many irrigators have had to renozzle center pivots as well capacities have dropped to maintain irrigation uniformity,” she said. “A nozzle package has to match the well's delivery.”

Dividing pivot circles is also common. “Many are irrigating only a portion of their pivots, as they don't have enough water to irrigate the full circles.”


Irrigation history

Porter looks back on irrigation history for the area. “In the 1950s, irrigation in the area was developing and increasing.” Most irrigation was through furrow irrigation (row water), and many farmers assumed that system and that much water would be adequate for a long time.

“Apparently they were mistaken. Unless it is well managed with a good layout, furrow irrigation can be very inefficient. Many irrigators (or so I've heard, as it happened before my time) stopped irrigating because water capacities and economics just didn't work anymore.” 

Three decades later technology changed the outlook. “In the 1980s (and continuing) the low pressure center pivots came in, offering greater efficiency and uniformity with relatively low energy costs (compared to high pressure center pivots) and relatively low labor requirements (compared to furrow irrigation),” Porter said.

“Since the 1990s, subsurface drip irrigation has gained ground, as well. Now, some farmers who had stopped using furrow irrigation have put land back into irrigation with center pivots or subsurface drip irrigation. In that time frame, irrigation water use surely increased in some areas.” 

Help available

Help to improve irrigation efficiency is available through USDA-NRCS programs such as the Environmental Quality Incentive Program (EQIP). “But EQIP cost-share funding can be used only to help replace less efficient irrigation systems with more efficient irrigation systems—converting fields from furrow irrigation to low pressure center pivot or subsurface drip irrigation, for instance,” she said.

“These funds can't be used to put irrigation systems on land not previously irrigated—that would not be conservation.”

Those more efficient irrigation systems do not necessarily save water, she said.  “Efficiency alone does not necessarily mean conservation. Sometimes efficient systems and practices help conserve water, and we see this happening in areas where water capacities are less limiting. Generally they help to make ‘more crop per drop,’ generating higher crop yields for the same water (higher water use efficiency) or mitigating yield losses from declining water. 

That’s fairly common, she said, in the Texas Southern High Plains “where well capacity is the primary limiting factor to crop yields. Growers pump what they have, and they try to maximize the productivity with their limited water.”

That’s not always a water conservation practice and they may be using more water or less.  “Hopefully they are seeing higher productivity or profitability as a result of the higher efficiency.”


Other factors play into improving irrigation efficiency, including, management and other local factors. “Some growers are managing crops more intensely, and since center pivots and subsurface drip irrigation allow relatively precise control of application rates and timing (as compared to furrow irrigation), they may be irrigating longer during the season (and running their wells longer). They may be using more water—or not—compared to furrow irrigation. Or they may be using the same water on a smaller area of land, concentrating inputs on that smaller area. 

“I have spoken with growers who used a ‘gosh awful’ amount of water in 2011 trying to germinate their crops. I have also spoken with growers who report surprisingly good yields with little water. Local conditions (soil, climate, timing of precipitation, etc.) and management can make a tremendous difference in water use efficiency.”


She said crop rotation and market economics also play a key role in water use. “Relatively high values for corn and other crops have motivated planting—and irrigating—these crops. Efficient irrigation technologies and good management are critical to producing drought-sensitive crops on limited water.

“A few years ago, energy prices spiked but commodity crop prices didn't, and we saw decreased pumping. Economics drove water conservation for a season.”  

Hopper said farmers must set realistic production goals, based on water availability and economics. “Yield heroes,” producers who want to make the highest yields possible may not be as efficient, particularly with water, as those who try to “make the most efficient yield with the water available. We need to take the high ground, especially in the court of public opinion, and possibly have them treat our views more favorably than those of our opponents.”

Water, most agree, will become a bigger and bigger target for regulation and control. Maintaining local jurisdiction over how an area’s water resources are managed will be crucial, and winning that battle for public opinion will play a significant role in assuring that all water stakeholders retain a fair share.


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