Oct. 6 (UPI) — Peak grain has already passed for several High Plains states, according to a new survey of groundwater depletion across the region.

To more accurately predict future grain yields, researchers looked at the relationship between levels of water extraction from the Ogallala aquifer and the amounts of grain harvested in each state over the last 50 years.

Researchers adapted analysis techniques previously used to study the relationship between peak oil production and peak grain production. The research team detailed the results of their analysis in a new paper, published Tuesday in the journal PNAS.

“We were inspired by insightful analyses of U.S. crude oil production,” lead study author Assaad Mrad, doctoral candidate at Duke University, said in a news release. “They predicted a peak in crude oil production a decade in advance.”

The new analysis showed Texas and Kansas reached peak grain in 2016. Grain yields in the two High Plains states have been declining over the last four years. Without new yield-boosting technologies, grain production in Texas could decline as much as 40 percent by 2050.

Water demand has outstripped supply in recent years, researchers said, as a result of excessive aquifer extraction and delays in irrigation regulations designed to sustainably manage water usage.

“This shows quite clearly that the aquifers are not being used in a sustainable way and it’s essential to find new technologies that can irrigate crops in a sustainable way,” said study co-author David Hannah, professor at the University of Birmingham.

Unlike Texas and Kansas, Nebraska enjoys a wetter climate. Rainfall in Nebraska has allowed farmers to expand grain production without increasing groundwater pumping.

Overall, the latest findings suggest depleted groundwater levels will continue to pose a serious threat to grain production across the High Plains. Many farmers in the region rely on the Ogallala aquifer to supply as much as 90 percent of their irrigation.

“Overall, the picture we see emerging from these calculations is bleak,” Hannah said. “The ultimate consequence of the aquifers continuing to be overused will be the decline and collapse of grain production. We have already seen this happen in Texas, where over the course of fifty years, peak water use has twice led to peak grain production followed by production crashes.”

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