Crop Yields at Risk in Kansas, Nebraska and Texas, Scientists Warn

Crop yields are at risk in Kansas, Nebraska and Texas as groundwater continues to be depleted, a study has found.

Irrigation for crops relies on the groundwater extracted from aquifers, which are underground layers of materials that contain water. Aquifers are naturally replenished by seasonal rainfall and snowmelt, but as climate change causes more severe and frequent droughts, their supply could be in jeopardy.

The new study from Nebraska researchers, published in Nature Water, analyzed 30 years of data and found that groundwater relied on by farmers for their crops could be in serious trouble. Depleting aquifers can cause crop yields to plummet, even during times when they appear saturated enough to meet irrigation demands, a summary of the research said.

Experts are attributing increased drought conditions to climate change. Global warming is making seasonal rainfall less predictable, and certain states are seeing prolonged dry periods for much longer than is normal.

“As you draw down an aquifer to the point that it’s quite thin, very small changes in the aquifer thickness will then have progressively larger and larger impacts on your crop production and resilience,” Nick Brozović said in a summary detailing the findings.

“And that’s a thing that we don’t predict well, because we tend to predict based on the past. So if we base what’s going to happen on our past experience, we’re always going to underpredict. We’re always going to be surprised by how bad things get,” said Brozović, director of policy at the Daugherty Water for Food Global Institute and a professor of agricultural economics at the University of Nebraska–Lincoln.

Researchers came to their findings after analyzing crop yields, weather and groundwater amounts from the High Plains Aquifer, which is the biggest in the U.S. The aquifer lies under portions of eight states, including almost the entirety of Nebraska.

They note that some areas of this highly important aquifer have been depleted significantly over the past few decades. These areas are beneath Texas and Kansas, which have been plagued by severe drought for several years. If the groundwater is not used for these crops, they would have little chance of surviving because of the dry conditions. In other words, the aquifer is essential for maintaining crop health.

Nebraska is also home to a massive reservoir that provides water for agricultural purposes.

However, Brozović said that regulations in the state focus on the amount of groundwater pumped, and when, as opposed to rules for safeguarding the aquifers’ saturation levels.

“In terms of things that let you address food security under extreme conditions—in particular, drought and climate change—we really can’t do without irrigation,” said Brozović. “If we want to feed the world with high-quality, nutritious food and a stable food supply, we need to irrigate.”

While there is already plenty of data to show how the aquifer responds to drought, this research shows that farmers are most concerned about how much groundwater they can continually pump out when attempting to save their crops amid dry conditions.

Overall, the researchers found that crop yields decreased when there was less groundwater. For example, they report that there was a much greater effect on corn and soybean crops when the aquifer went from 100 feet thick to 50, compared with going from 200 feet to 150.

“As a consequence, your resilience to climate decreases rapidly,” Taro Mieno, an associate professor of agricultural economics and lead author of the study, said in a summary of the findings. “So when you’re operating on an aquifer that is very thick right now, you’re relatively safe. But you want to manage it in a way that you don’t go past that threshold, because from there, it’s all downhill.

“And the importance of aquifers is going to increase as climate change progresses in the future, for sure,” Mieno continued. “As it gets hotter, you typically need more water. That means you need more irrigation, and you’re going to deplete the aquifer even faster, and things can get worse and worse.”

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