Low Water on the Mississippi Costs Southern Corn Growers Up to 71 Cents

A $1-per-bushel increase in Mississippi barge freight rates pulled corn basis down by 60 to 71 cents in the most exposed Southern counties, according to new research from agricultural economists at the Arkansas Agricultural Experiment Station and collaborating institutions. Soybean basis in those same areas fell 49 to 53 cents.

The study, published in the journal Agribusiness, examined how barge transportation cost increases move through the grain marketing system and land on local basis — the gap between local cash grain prices and futures prices. Its lead authors are Yuan Zhang, a post-doctoral fellow, and Eunchun Park, an assistant professor, both with the University of Arkansas department of agricultural economics and agribusiness and its Fryar Price Risk Management Center of Excellence. Collaborators came from Utah State University and North Dakota State University.

For a corn farmer moving 100,000 bushels, a 70-cent basis decline represents roughly $70,000 in lost cash value before a single input bill is paid.

Why timing compounds the damage

The findings carry weight right now. The U.S. Army Corps of Engineers' August "State of the River" outlook warned that low-water trends seen in recent years could continue this year unless key river basins receive normal to above-normal rainfall. The current river conditions suggest low-water challenges may persist and disrupt navigation and commerce.

"The timing of the current low water levels is particularly concerning," Zhang said. "With large volumes of newly harvested grain entering the market, transportation demand is already high."

Harvest is when basis matters most. Farmers are selling into a crowded pipeline at the same moment barge capacity tightens.

"Low river levels can further constrain barge capacity and increase shipping costs, putting additional downward pressure on local grain basis," Zhang said. "This means farmers may receive lower cash prices for their crops at a time when many are making important marketing decisions."

The Mississippi River system is a critical export corridor for U.S. agriculture. A substantial share of Midwest corn and soybean exports moves by barge through the river system to Gulf Coast export terminals, the study notes. When water levels fall, navigation restrictions slow barge traffic and push freight rates up.

How the researchers reached the numbers

The team combined three data layers: elevator-level cash bids, barge freight data, and river-level information. That allowed them to estimate how transportation-cost shocks pass through to farmers rather than stopping at the elevator or the export terminal.

Their central result is unambiguous. Higher barge rates weaken both corn and soybean basis, effectively reducing local cash bids.

The analysis is a modeling estimate of pass-through, not a tally of harvested results. It measures how freight shocks translate into weaker bids at the elevator, based on historical bid, freight and river data.

Where the losses concentrate

The effects are not uniform across the country. A follow-up analysis published in Southern Ag Today, based on the study, found the strongest impacts in Southern states along the lower Mississippi and Ohio river corridors.

In the most exposed corn counties — including parts of Arkansas, Louisiana, Kentucky and Tennessee — more than half of a barge rate increase reaches the farmgate as weaker basis.

Local market structure shapes the outcome. Corn producers located near processing facilities, or in areas with more competition among grain buyers, tended to absorb less of the transportation cost increase. For soybean producers, distance from river export facilities played the larger role in moderating impacts.

What does this change for growers and policymakers?

Researchers said the findings can help farmers better understand basis risk, and help policymakers weigh the economic value of maintaining and improving transportation infrastructure.

"If low river levels become a persistent problem, transportation disruptions may need to be treated as a recurring source of price risk rather than occasional events," Zhang said. "Our research shows that these impacts are not evenly distributed across regions or commodities."

For growers, the practical answer is twofold: treat freight-driven basis weakness as a planning variable in marketing and storage decisions, and price in alternative shipping options where geography allows. For policymakers, the study provides a dollar-denominated case for river infrastructure investment, since the cost of dredging and channel maintenance now has a measurable farmgate counterpart.

"Understanding these differences can help farmers make more informed marketing and storage decisions, while highlighting the importance of transportation infrastructure and alternative shipping options," Zhang said. "The research underscores the importance of the Mississippi River not only as a transportation artery, but also as a factor shaping farm-level profitability across Arkansas and the broader Mid-South."

If drought persists in the river basins the Corps flagged in August, Southern corn and soybean growers will enter next season knowing exactly how much a low river costs them — down to the cent.