CASNR, TAWC researchers battle to slow decline of Ogallala Aquifer
The Texas South Plains produces about 30 percent of the nation's cotton, 15 percent of the livestock and most of those products depend on the groundwater below us. And while the South Plains isn't failing yet as a whole, human activities continue to deplete water resources faster than they can rejuvenate.
Municipalities use it to drink, wash clothes and water lawns. Farmers need it for crops and livestock. Now, energy companies use it for fracking purposes. It keeps animals, plants and people alive. It drives the region's economy.
Everyone needs water. The problem is, the Ogallala underneath the South Plains, a good 20 percent of the actual aquifer, doesn't recharge at the same rate as the northern parts. The whole water system stretches from Western Texas up to South Dakota. However, a geological barrier near the panhandle of Oklahoma prevents recharge from the north. Little, if any, makes it through from the top.
The arguments of how much and where are largely academic because the amount that might make it down into the aquifer is negligible compared to that removed. So while irrigation methods have improved, humans currently use about 5.5 million acre-feet of water a year on the South Plains. That's a foot of water covering eight Lubbock counties (Lubbock County is 901 square miles).
Quick fixes and one-size-fits-all answers won't work. Answers need to come from scientific research, and the answer for one area may not apply to another. Go back in time to the 1950s, and farming looked much different on the South Plains of Texas, said Chuck West, director of College of Agricultural Sciences and Natural Resources (CASNR) Water Center and project leader of Texas Alliance for Water Conservation (TAWC).
While we're used to seeing circular fields with a center-pivot irrigation system when we look out of an airplane window, it wasn't that long ago that farmers plowed straight fields and allowed water from their wells to pour down the furrows to irrigate them.
It wasn't a problem then, West said, and well output of 600 gallons per minute was more than enough water to irrigate easily. That meant, though, that farmers would flood their fields to get the coverage they needed. Crops closest to the well usually received more water than they needed. Crops farther down, maybe not so much. The tail water, or the excess produced from irrigation either drained away or was re-channeled into the field.
Overall, about 70 percent of the water made it to the plant roots.
That shifted in the '60s, he said, when farmers in Nebraska adopted a locally invented center-pivot system. Instead of opening the well and running water down the furrows, water was moved around a circular field, first with sprinklers throwing water through the air, then eventually using drop-lines and special nozzles that sprayed or dribbled out the water to reduce evaporation.
"That technology alone changed water usage," he said. "With the center pivot sprinklers, water efficiency jumped up to 85 or 90 percent. Advances in spray nozzle design further improve efficiency. Some nozzles make the water drip out in large droplets instead of a lot of fine droplets that evaporate."
That 90 percent efficiency sounds great until you realize how much some parts of the Ogallala aquifer have declined. That's changing the landscape as to what producers grow and how they irrigate.
A more recent option developed in Israel called subsurface irrigation puts the water in the root zone about a foot beneath the soil surface and bumps the efficiency up to almost 98 percent. However, at up to $2,000 an acre for installation, this method won't replace most of the center-pivot systems.
"That's tremendous progress from the way we used to do it," West said. "There isn't a lot of subsurface irrigation out there yet. Pivot irrigation was put in a while ago in most of these fields, so it's already paid for. It would be easier for producers to modify the pivot spray systems with drip lines that drag along the soil surface than to tear the pivots out and put in subsurface drip."
West said agricultural researchers strive to improve water use efficiency in many different aspects of production. The rub? Farmers depend on quality yield to make a profit, and the right amount of water translates into better yields and quality. Urban sprawl means fewer acres for crops. A growing worldwide population demands more from those fewer acres for food, meat and fiber.
The Ogallala is only one area facing water resource issues, he said. The Mississippi Delta and the Central Valley of California also face dwindling water resources.
"We do get worldwide attention at Texas Tech because of the seriousness of the problem and the vigor with which we are addressing it," West said.
In a community-outreach effort, West said that CASNR created the Texas Alliance for Water Conservation (TAWC) to assist farmers with the water challenges they face. The group, funded by the state of Texas by a bill promoted by then-Sen. Robert Duncan (now Texas Tech's chancellor), promotes water conservation through demonstration of water-saving irrigation technologies, increased producer awareness and improved management of major crops, such as corn, cotton and sorghum.
Through the programs, West and his team have taught local growers about important scientific phenomena that impact water usage. Evapotranspiration, for example, is the amount of water sucked out of the soil by the sun and the amount of water used by the planted crop and exhaled through the leaves. And on a hot summer day in West Texas, that amount can be immense, West said. About a third of an inch of water leaves through evapotranspiration every day.
On the TAWC website, farmers can input the type of crops they have and learn how much water should be applied and when. The program, based on years of Texas Tech research, automatically calculates for local weather so that farmers water not only when it's needed to replenish the soil, but also when it's critical during the plant's growth cycle to achieve the highest yields.
"Traditionally, a lot of producers didn't know those numbers," West said. "They didn't know how much was in soil. So, a lot of them would turn irrigation rigs on all summer long. When in doubt irrigate. Most producers have gotten away from that because they don't have enough water anymore to support that luxury. We've tried to teach them how they can target that water where it's needed most in space and time. That is one very useful way to meet critical needs of the crop and avoid wasting water."
Researchers also suggest monitoring soil water content with sensors three to four feet in the ground. While somewhat expensive to rent, the devices give growers real-time data on soil moisture conditions.
Genetics might hold the answer to more water-efficient crops, and West said many Texas Tech researchers are improving water usage through genetic manipulation, such as low-water peanuts and cotton. Crop genetics research is supported by a combination of state and federal grants and private companies and foundations to locate desirable genes that make the plants more drought tolerant.
Other Texas Tech faculty are testing drought-tolerant turf grasses and landscaping plants that homeowners can use, and fine-tuning water-efficient grapes for wine production. The trick for all crops, he said, is finding the sweet spot in low water usage to make every drop count while producing a profitable yield.
"Over the past 20 years, there's been good progress on cotton and corn breeding," West said. "The goal is not necessarily to have higher yields at high irrigation input, but to minimize yield losses as irrigation becomes more limited. Much of the cotton and sorghum are grown out here as dryland (rain-fed) crops. Plains Cotton Growers Inc. estimated only 43 percent of the crops planted in 2015 on the High Plains of Texas were irrigated. Both dryland and irrigated crop yields benefit from breeding for drought tolerance because even irrigated crops need timely rains to produce profitable yields."
The testing fields for future seed lines are high-tech these days, he said. Not only are students counting bolls of cotton, but specially designed cameras also scan the rows of crops looking for water-stressed plants. The way light reflects off the leaves can tell researchers which experimental seeds do well and which do not.
The TAWC project demonstrates water-saving irrigation technologies and improved crop management on 36 sites covering 5,300 acres in nine surrounding counties. Rick Kellison, director for the TAWC, said each site represents a particular cropping system such as single-crop monoculture, multiple cropping, or forage for livestock. These sites are managed by 20 different producers, who were chosen by a producer board to reflect a realistic range of management styles.
All farming management decisions are made independently of the project leaders. The project collects production data and provides information to aid in producer decisions. The crops are monitored for use of irrigation water, water demand, yields, and input costs. Calculations are made of amounts of irrigation water conserved, crop water-use efficiency, and net economic returns. A survey revealed barriers to change, such as the high cost of water-monitoring technology.
"Specifically after the 2011 drought, we began to see vendors offering different types of irrigation technology. We went from zero technology to growers being overwhelmed with what to do and which technologies to pick. We don't say we think Technology A is better than Technology B. We're about getting that technology into growers' hands and trying to assist them on how it impacts a specific farming operation. We also thought the best way to share information with producers is through other producers. That's been our main method to help farmers use less irrigation, or even rainfall, and get the most out of it; while being as conservative as we can."
The organization hosts field days in the fall and during the growing season where attendees can walk through a producer's field and evaluate how that grower implements water-savings techniques. The group also hosts a Water College once a year as a crash-course in conservation with speakers who cover primary crops in region and talk about technologies that conserve water.
Kellison said he's been pleased with the positive reception the outreach project has gotten and believes it serves as a source of non-biased information for growers.
"I think, as a whole when we look at growers and environmental issues, farmers and ranchers are first conservationists," he said. "They make a living off their land. It's to their advantage not to misuse their land. Our focus always asks, does what we're doing have the possibility to have a positive impact on growers. If it does, we'll try to do it."
Reporting by John Davis
CONTACT: Eric Hequet, Department Chair, Department of Plant and Soil Science, Texas Tech University at (806) 742-2838 or firstname.lastname@example.org
1102NM16 / For a full text of the story produced by TTU Communications and Marketing's John Davis, click http://www.depts.ttu.edu/vpr/discoveries/fall-2016/water-withdrawal.html
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