Science News by AGU
Lowell King plunged his hands into the frosty soil and scooped up a radish framed in a knot of earth, roots, and the odd worm. This, King stated proudly, is healthy soil.
“When we have healthy soils, we have healthy plants, healthy animals, and healthy people,” said King, who started practicing the regenerative agricultural techniques of his Mennonite ancestors on his farm in Fruita, Colo., several years ago. Healthy soil also retains water: Since King started focusing on soil health practices, he has reduced the water he needs for irrigation while almost doubling his net profit per acre.
King now feels calmer in the face of impending water scarcity and is helping other farmers in the region make the transition to soil-sustaining and water-conserving practices. He’s also working with the nearby Colorado State University (CSU) Agricultural Experimental Station, where researchers are investigating irrigation systems that optimize water use, the impacts of soil health on water conservation, and crop and farming practices that use less water.
Colorado River flow has shrunk by nearly 20% in the past 2 decades. And in 2022, the nation’s largest reservoirs—Lake Mead (in Arizona and Nevada) and Lake Powell (in Arizona and Utah)—were at unprecedented low levels. If the water levels at Lake Powell were to drop much further, in the future, the dam would no longer be able to deliver hydropower or water to people, farmers, and businesses in Arizona, California, and Nevada. To prevent this doomsday scenario, in 2022, the Interior Department said that the seven states relying on the Colorado River need to reduce water usage by as much as 4 million acre-feet (493 cubic kilometers)—30% of what the states have historically used.
Agriculture uses about 80% of the water in the Colorado River Basin, and in March 2023, Agriculture Secretary Tom Vilsack met with the basin’s state agricultural leaders to highlight the resources and programs available that use science and technology to grow crops using less water. In May, the Department of the Interior announced a consensus-based approach to conserving the water supply in the basin.
Such programs will prove essential as some of the water cuts will inevitably come from farming. That’s true even for agricultural communities that hold senior water rights to the Colorado, such as Yuma, Ariz. “We’re at the very tail end of the river, and the water has to get here, or we can’t use it,” said Paul Brierley, director of the Yuma Center of Excellence for Desert Agriculture (YCEDA), a public-private partnership that connects scientists to the desert agricultural industry.
Large-scale, industrial agriculture dominates in Yuma County. The region is known as the world’s winter salad bowl, and close to 90% of the leafy greens for North America are grown there between Thanksgiving and Easter. Yuma’s agricultural industry represents a gross economic return of $3.2 billion.
“People have this idea that farming is all cows and plows and it’s all backwards, but it’s really a high-tech endeavor.”
With less than 4 inches (10 centimeters) of rainfall a year, Yuma farmers rely entirely on Colorado River water to irrigate their crops. For years, farmers have been using science-informed techniques to reduce water use—from increasing the efficiency of irrigation systems to expanding crop portfolios. Working with scientists, their quest to grow “more crop per drop” is reaching new heights.
“People have this idea that farming is all cows and plows and it’s all backwards, but it’s really a high-tech endeavor,” Brierley said.
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Back in Fruita, King is finding that science and technology are helping his efforts to boost land productivity and drought resiliency by improving soil health.
To keep his soil healthy, King doesn’t till his fields, and he plants cover crops—plants grown between the main cash crops. After harvesting his winter wheat in July, for example, King planted a diverse mix, including warm-season grasses, collards, turnips, sunflowers, peas, and beans. “They’re all working together,” King said. “The diversity of the roots helps loosen and build fertility in the soil.” (The cover also provides grazing for livestock—the cattle “flat out love” turnips and will bite entire sunflower heads off, King said.)
Every additional 1% of organic matter increases the water-holding capacity in soil by 27,000 gallons per acre.
The roots break down in the soil, increasing the organic matter that can hold water. Every additional 1% of organic matter present increases the water-holding capacity in soil by 27,000 gallons per acre (252,557 liters per hectare). King knows he’s been diverting less water from the Colorado River and has an experimental plot at the nearby CSU research station, where scientists are trying to determine exactly how much water can be saved through no-tilling practices.
The experiments have demonstrated the water-saving benefits of boosting soil health, said Perry Cabot, a water resources specialist at the CSU station. “I was already a convert, but Lowell is making me a firm believer,” Cabot said. And though King might have learned the concepts of sustaining soil from his grandparents, he credits science and technology with giving him the tools to make it easier to put those principles into action. “Because of the science, we actually understand more what’s going on in the soil and why it actually works,” King said.
The fact that he is growing more crops with less water while sustaining the land means King’s excited about his future—and his children’s future—in farming. “We’re trying to figure out what we can help live and grow and flourish, rather than what we need to go out and kill and destroy and get rid of,” King said. “It’s the difference between attending a birth and a funeral.”
On a chilly November day, Cabot drives around the fields of the CSU research station in an electric cart, pointing out the various experiments. The researchers are investigating the water consumption and yields for a range of crops using handheld devices, drones, and satellites.
One field contained King’s sweet corn, planted with a drill that doesn’t disturb the soil; another plot housed his cocktail of cover crops.
In other fields, researchers had planted Kernza, a trademarked strain of intermediate wheatgrass that is particularly tolerant to drought. Alfalfa is the main forage crop grown in Colorado’s Grand Valley, and Kernza is typically grown farther east, but the scientists are trying to see what it takes to grow the crop at high altitude. Kernza won’t replace the high yields of alfalfa, but growing it could be one strategy farmers use during droughts, Cabot said.
“I’m always looking at things in the context of the reality that we will probably have less water to irrigate with,” Cabot said, “whether by choice or administrative action or Mother Nature throwing these droughts at us.”
Agribusiness, farmers point out, is not about conservation but about consuming water to make money.
Consequently, Cabot explores crops that can be grown outside the dry summer months such as winter peas and winter triticale (a wheat-rye hybrid primarily used as livestock fodder). These crops are planted in the fall, survive the winter, grow in early spring, and are ready to harvest before the summer, when water loss to evaporation is at its highest.
Paul Kehmeier, a fourth-generation farmer whose farm is in Delta County on Colorado’s Western Slope, used to harvest his crop in the summer and leave the land fallow until he prepared for planting the following spring. But he started to realize he could capitalize on the moisture that follows the winter snow and rain and decided to experiment with planting triticale. “Then I can capture that moisture that I typically wasted by tilling or letting the land dry out,” Kehmeier said.
Drawing from the nearby CSU station’s findings, Kehmeier has experimented with cover crops, intercropping, and switching crops. But to sell his new haul, Kehmeier’s also had to add new customers. Horse owners, for example, want only high-quality alfalfa, without triticale in the mix.
Kehmeier pointed out that his business is not about conservation but about consuming water to make money. Alfalfa, he said, makes the most profit and also uses the most water. Still, he continues to experiment with ways to reduce his water use and build soil health. “It feels better not to be beating the soil to death with tillage and poisoning it with chemicals,” Kehmeier said. “And it’s an adaptation I’m making towards more climate resilience.”
Yuma provides the ideal location to grow winter crops because of its mild winters, little danger of hard frost, ample labor, and some of the most fertile soil in the country. “If I was going to farm anywhere, I’d farm right here in Yuma,” Brierley said. “You are pretty much guaranteed that you are going to have a high yield of high-quality food.”
If farming were measured by crop produced for each gallon of water used, then Yuma would be a model of agricultural efficiency, Brierley said. The large industrial farmers in Yuma draw all their water from the Colorado River, and a network of canals crisscrosses the city like streets. In the past few decades, many of these canals have been lined with concrete to stop the water from seeping downward. And each year, using lasers and GPS technology, farmers level fields to within a couple of centimeters over the length of a football field.
“All the fields are pool table flat, so no water runs off,” Brierley said. “We don’t have any tailwater [water running off the end of the field], and that doesn’t exist anywhere else in the world.”
By the 1990s, Yuma farmers had switched from growing crops year-round to growing vegetables only in the winter. The season’s cooler temperatures mean less water is lost to evaporation—in Yuma’s hot, dry climate the evaporation rate is more than 3 meters a year. “That is part of how we’re able to produce the highest yield per acre-foot of water used in the Colorado River Basin,” Brierley said.
“What will happen if the fruits and vegetables grown here become a luxury, not a staple?”
Yuma’s quest to grow crops with less water continues. In 2022, the Arizona State Legislature and the Arizona Governor’s Office created the Water Irrigation Efficiency Program. The program, championed by Representative Tim Dunn, a Yuma farmer, is designed to help farmers improve irrigation efficiency.
The funding assists the University of Arizona Cooperative Extension agents, who are tasked with helping farmers meet the challenges they face, in researching and evaluating irrigation systems. It also reimburses growers up to $1,500 per acre to change to more efficient watering systems, contingent on them creating at least 20% water savings.
For Yuma County agricultural extension agent Robert Masson, the new program means his job involves vetting water-saving technologies from industry and academia, seeing if they work in Yuma’s fields, and then helping farmers put them into practice. The farmers he works with are keen to learn new techniques to become more water efficient. “They recognize that it is an essential cornerstone of their business,” he said.
Masson, a research agronomist, has a passion for solving challenges in agriculture using science, and his goal is to put healthy food on the plates of as many people as possible. “What will happen if the fruits and vegetables grown here become a luxury, not a staple?” Masson asked. “What are people going to eat instead? Cheap, processed, junk food? That’s a serious threat to our health as a nation.”
One of the research projects Masson has facilitated involves building soil health. In Yuma’s valley, the soils are rich and fertile, but up on the mesas, where citrus and dates are farmed, the soils are sandy and don’t retain water as well. “We can make some really good efficiency gains there,” Masson said.
Masson reached out to scientists and engineers at Desert Control, a Norwegian company that developed a form of liquid natural clay to recover soil, and asked if the company wanted to run a trial on Yuma’s sandy soils. The first experiments began within months. The March 2023 plot grew celery, a water-sensitive plant, with different formulations of the Desert Control product tested under different watering protocols. By April, the yield had improved up to 50%. Masson is now looking at the soil moisture data to answer the question “Does this allow less water to be used?”
The project is just one example of the way farmers and scientists can work together to find water conservation solutions, Brierley said. YCEDA’s goal is to bring scientists and industry together to address the on-the-ground needs of desert agriculture. “It’s a critical time for us to be helping communities determine what futures they want,” Brierley said. “And it requires both cooperation and collaboration to identify those futures.”
In January 2023, a $6 million award from the state of Arizona to support the construction of a network of wireless broadband towers in Yuma County gave the endeavor a boost. The investment will mean that “AgTech,” in the form of remote sensors, drones, satellites, artificial intelligence, and automated equipment, can be harnessed to advance the county’s water conservation goals, Brierley said.
Investment in AgTech is not a new approach. In 2015, YCEDA’s 7-year Irrigation and Soil Salinity Research Project started using field-based instruments such as eddy covariance systems, scintillometers, and remote sensing data from satellites and drones to measure the evaporation from the soil and transpiration from plants.
Farmers could use these measurements to determine whether they were irrigating enough or overwatering, and the research team developed a mobile app called Desert AgWISE. The app, which is currently in its testing phase, will use results from the irrigation and soil salinity research, real-time weather data, and satellite imagery to suggest watering schedules and amounts for any crop grown in a specific location in Yuma.
“It actually turns into a classical arms race. Whoever can increase their water efficiency, first and best, will survive the longest.”
In Colorado, Cabot is also using technology to investigate more efficient ways to irrigate crops. Instead of using the traditional approach of assuming how much moisture a plant needs, he is monitoring soil moisture in real time to determine the optimal level of water needed.
Cabot cautions against the idea that more efficient irrigation systems will conserve water in the Grand Valley, where agricultural runoff merely makes its way back to the Colorado River. On the other hand, more efficient irrigation systems will help farmers build resilience to water use curtailments in the future, he said. “It actually turns into a classical arms race,” Cabot said. “Whoever can increase their water efficiency, first and best, will survive the longest.”
By 2015, most Yuma growers’ irrigation efficiencies were about 80%, and that average has only improved with the recent technological advances. Consequently, Brierley cautions that any water cuts would have dire consequences. “We’re so efficient that you can’t take 20% of the water out without reducing production,” he said.
In December 2022, the University of Arizona formed the Presidential Advisory Commission on the Future of Agriculture and Food Production in a Drying Climate to address challenges to agricultural production and food and economic security in the state and around the world. Brierley, the chair of the commission, stated that it is important for decisionmakers and policymakers to understand that it isn’t a waste of water to farm in the desert.
Most of the world’s growth is happening in arid or semiarid regions that aside from water concerns, are often ideal for growing crops, said Jim Holway, director of the Babbitt Center for Land and Water Policy, a center that seeks to advance the integration of land and water management to sustainably meet the needs of Colorado River Basin communities, economies, and the environment.
“You’d be hard pressed to find a historic civilization that gave up its ability to produce its own food and survived.”
Yuma agriculture boasts some of the highest crop yields per drop of water used in the basin, and it could be argued that future cuts to agriculture water use should focus purely on sustaining such highly efficient industrial farming enterprises. But Holway cautioned that we need to consider the importance of both large-scale and smaller farms because they are a driving force of the economy and culture in the rural West. “If you lose western agriculture, you’re going to have a much bigger issue in terms of economic disruption and mass migration to the cities,” Holway said.
Regardless, because agriculture uses so much water in the basin, it will have to bear some of the cuts. “There isn’t enough water in the system to meet current and projected demands, so everybody’s going to have to share in cutting back,” Holway said. “The basin-wide challenge is to accomplish this while maintaining a viable agricultural economy.”
Too many cutbacks reducing the water available for agriculture in general, however, will also affect the country’s food security and independence, Brierley cautioned. Cabot concurred. “You’d be hard pressed to find a historic civilization that gave up its ability to produce its own food and survived,” he said.
Cabot suggested a change in perspective to emphasize exactly what is at stake. “It is not farmers that are using all the Colorado River water,” he said. “It’s food consumption that uses all the water.”
The science and technologies exist to help agriculture produce food while using less water, but action has to be taken as soon as possible to put these solutions into practice, said farmer Mark Harris, who recently retired as the general manager for the Grand Valley Water Users Association. “We need to be planting the seeds of cooperation now and collaborating on how to make less water stretch between so many different demands,” Harris said. “The problem of letting things get to the point of crisis is a lot of the better ideas aren’t possible anymore because they can’t make a big enough difference quick enough.”
Farmers and ranchers have always had to be innovative to grow food in the American Southwest, and Harris is optimistic that the agricultural community will find solutions to the current crisis. “But it’s not going to be operations as usual, and we can’t hold on too tightly to the past,” he said.
—Jane Palmer (@TJPalmerWrites), Science Writer
Travel for this article was supported by The Water Desk, an independent journalism initiative based at the University of Colorado Boulder’s Center for Environmental Journalism.
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