While the midnight sky is no longer bathed in eerie Aurora Borealis light, the farm financial impact of this spring’s solar storm still is being calculated. According to a Kansas State University economist, it came during 2024’s most crucial planting timeframe, costing American farmers an estimated $500 million in potential profit.

“The timing of the GPS outage — in the middle of May — was a bottleneck in agriculture. That’s the time of year when planting and seeding was happening across the United States,” says Terry Griffin, professor of economics at K-State. “If this had happened in January, no one would have cared from an agriculture perspective. The timing was really important.”

Exactly how much farm income was lost hinges on several factors, such as when farmers were able to resume planting, what type of equipment they used, how inefficient (or imprecise) their machines became if they chose to plant through the disruption, and how well they were able to make up ground after the delay. Farmers who used mechanical row markers weren’t affected at all.

Planting delays

The “space weather” followed weeks of rain, exacerbating its impact. American farmers already were running late when the solar storm happened. As of May 12, 2023, 60% of U.S. corn crops had been planted, compared with just 49% by the same date this year, according to the USDA. Likewise, 45% of the soybean crop was in the ground by that date in 2023, compared with about 35% immediately after the solar storm.

Griffin says the GPS outage lasted at least four hours and had lingering effects. Given that 70% of U.S. farmers rely on GPS guidance, Griffin described the financial loss as “nontrivial” in a blog post published by the University of Illinois Urbana-Champaign’s farmdoc daily. Per acre, some farms “might be talking about a 1% or 2% loss,” he says. But for farmers delayed more significantly, “those yield penalties might be severe.”

Griffin has been exploring the impact of GPS outages on precision agriculture equipment for decades. He first quantified GPS’s effectiveness 20 years ago by comparing machinery efficiency with and without it. Using visual markers, Griffin says, tractor operators can expect to overlap rows by about 10% with each pass. With a 40-foot cultivator, for example, a farmer accomplishes 36 feet of work. Precision guidance dramatically reduces that overlap, putting the entire span to work.

“With RTK [a type of positioning system], we can assume that it’s something close to 1 centimeter. I measured the value of doing that. Basically, you can farm a lot more acres,” Griffin says.

Following the GPS outage, he leveraged that same model to ask, “What if I take GPS away for half a day?”

“That is roughly what we had on May 10,” Griffin says. “How many acres in the heartland were pushed back?”

Optimal planting time for best yield

Citing research by Emerson Dale Nafziger, professor emeritus at the University of Illinois Urbana-Champaign, Griffin says corn planted in mid-April produces the maximum yield possible. The yield for corn planted in the middle of May is about 95% of that maximum. By June, it drops to about 85%.

Because the storm shifted the planting timeline, “there’s a marginal acre out there that gets pushed back to the end of the season” — outside the most ideal planting window, he says. “Those are some pretty severe yield penalties. You’re talking about a 20% yield penalty, or 80% of [maximum] harvest. That’s real money.”

He estimates that affected farms lost about $1 per acre. Nationally, this equates to an estimated half-billion dollars in lost earning potential, Griffin says. That’s not accounting for the ripple effects and downstream impacts.

Some effects won’t be felt for some time. Modern farmers leverage data to dictate best practices. Machines didn’t collect accurate data during the GPS outage. Further, guess rows were skewed. This could affect the efficiency and data-collection capability of machines during spraying and harvesting activities.

The data deficiency also could be felt downstream.

“The farmer isn’t the only one interested in that data. A lot of seed representatives are also trying to get data to support their own programs,” Griffin says, noting that retailers, co-ops and universities are among others that rely on field data. “Without logging what actually went into the field, those on-farm experiments are useless. That’s going to affect the farmer’s ability to compare hybrids and varieties. It’s going to have a big ripple effect after 2024, because a lot of the time it’s a multiyear study.”