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Water is at the heart of agriculture. Every stage of the food-growing process depends on having reliable access to water. However, water levels are declining in many rivers and aquifers that function as key resources for agricultural producers, particularly in the Western U.S. Those declines threaten food supplies as well as critical ecosystems. A new review paper led by researchers at Colorado State University examines six strategies for addressing the challenge of water scarcity.

"There is no simple solution," said Thomas Borch, professor in CSU's Department of Soil and Crop Sciences with a joint appointment in the Department of Chemistry and the paper's principal investigator and a senior author. "But the systems-based approach we discuss in our paper offers a strong foundation for building a more sustainable and effective water management strategy."

Such strategies are critical in part because agriculture typically uses about 80% of available water supplies in the U.S.

Published this week in the journal Nature Water, the , titled "Advancing sustainable water use across the agricultural life cycle in the USA," explores the potential effectiveness, drawbacks and adoption challenges for six approaches to conserving water nationwide.

The approaches described are:

• optimizing where crops are grown
• deploying more forward-thinking soil management strategies
• better utilizing modern irrigation technologies
• embracing water treatment and reuse methods
• reducing water demand in animal agriculture and
• minimizing food loss and waste

Although water scarcity is a global challenge, the paper focuses on the United States. In 2023, according to the paper, the U.S. produced more than 30% of the world's corn and soybean crops; was the largest exporter of rice, cotton and almonds; and was the second-largest exporter of corn, soy and chicken meat.

One of the big takeaways, according to the authors, is that there is no "silver bullet" fix for this problem; a multi-faceted approach is needed. What's more, the authors write, each water-saving strategy has its own inherent complications and challenges.

For example, the scientists note that there is significant potential to save water by growing crops that are best suited to the climate in any given region, yet there are many barriers that may deter farmers from changing what they grow. Switching crops can require substantial financial investment and involves inherent market-related risks.

It's a similar story with using treated wastewater to irrigate crops—an approach the authors identify as having potential. But they also acknowledge there are barriers to adoption. Florida, California and Texas, as well as several European countries, already successfully use treated wastewater to irrigate agricultural fields and landscapes such as golf courses. And yet, the authors write, challenges remain with public's perception of using treated wastewater to grow food and inconsistent regulations governing how treated wastewater can be used.

"We felt it was important to do this review because conversations around agricultural water use often focus on isolated fixes like improving irrigation efficiency without considering the broader systems or the potential environmental and economic trade-offs," said Huma Tariq Malik, a doctoral student in Borch's lab at CSU and the lead author on the paper. "We wanted to pull together a range of approaches, look at how they interact and see where the real opportunities lie."

Two more routes the authors examine as possibilities for saving water are reducing water demand associated with animal agriculture and reducing the amount of water used to grow food that is eventually lost or wasted. Uneaten food in the U.S. accounts for about 22% of all water use in the country, the researchers note. They also note that prioritizing less-water-intensive feed crops could be an effective route to reducing water demand in animal agriculture.

"Our paper shows that each of us can play a role in protecting our limited water resources for agriculture," Borch said, "by supporting precision farming, choosing crops that suit our local climate, cutting down on food waste and even being more mindful about what we eat."

In addition to examining each strategy, the authors also noted the role of policy in addressing water scarcity. Implementing local, regional and national policies that promote water-saving measures in agriculture is critical, they write: "The key to achieving sustainable water management through these strategies lies in policies that effectively incentivize progress toward their implementation."