The Weekly Fill-Up | September 21-25

September 21, 2026

Harvest is moving closer to full swing, and the energy picture entering the final stretch of September is becoming more complicated.

There was some welcome improvement in U.S. diesel inventories last week, but the bigger global supply problem has not disappeared. Propane, after spending much of the summer building a substantial supply cushion, has now started moving in the opposite direction. And here in South Dakota, updated crop estimates give us a better idea of just how much agricultural activity will need to be supported by fuel, propane, and equipment maintenance this fall.

For Sioux Valley Coop members, this is the point in the season when market conditions begin meeting actual demand.

Diesel Gets Some Breathing Room, But the Bigger Problem Remains

There was finally some encouraging news in the latest diesel inventory report.

U.S. distillate inventories increased from approximately 106.3 million barrels on September 4 to 107.9 million barrels on September 11. Here in the Midwest, stocks also moved in the right direction, increasing from approximately 28.5 million to 28.8 million barrels.

An inventory build during a period of tight supply is certainly welcome.

Unfortunately, it doesn’t mean the diesel market has turned the corner.

New reporting this week indicates the global diesel shortage could persist well into 2027. Storage levels in several major markets remain low, and disruptions to refining and international fuel movements continue limiting the amount of diesel available globally.

That creates an unusual situation for U.S. agriculture. Domestic refineries are producing significant amounts of fuel, but American diesel is also valuable on the international market. When overseas buyers are competing for those gallons, domestic inventories have a harder time rebuilding.

The U.S. Energy Information Administration highlighted that pressure on September 18, noting that tight global distillate supplies, elevated crude prices, and strong refining margins have all contributed to higher diesel prices in recent months.

For producers, the latest inventory increase is encouraging, but it isn’t a reason to stop paying attention.

Harvest is exactly the time when agricultural diesel consumption becomes concentrated. Combines, tractors, grain trucks, semis, and support equipment can consume substantial amounts of fuel in a relatively short period.

Having bulk fuel storage ready and communicating anticipated needs remains one of the most practical ways to stay ahead of that demand.

Propane Has Reached a Turning Point

Propane spent most of the summer moving in one direction: up.

That changed in the latest EIA report.

U.S. propane and propylene inventories declined from approximately 110.5 million barrels on September 4 to 109.1 million barrels on September 11.

Midwest inventories also declined, moving from approximately 26.6 million barrels to 26.3 million barrels.

One week does not establish a long-term trend, and inventories remain substantial. But the timing is noteworthy.

Summer is primarily about putting propane into storage. Fall is when those inventories begin facing grain-drying and eventually heating demand. Seeing stocks begin to move lower is one sign that the seasonal transition is underway.

For South Dakota producers, grain drying will be the next major variable.

USDA’s latest state estimates now put South Dakota corn production at approximately 846.8 million bushels, with 5.84 million acres expected to be harvested for grain.

That’s a lot of corn moving through combines, trucks, bins, elevators, and potentially dryers over the coming weeks.

The amount of propane required won’t be determined by bushels alone. Moisture at harvest will make the biggest difference. Corn that has more opportunity to dry naturally in the field will require less propane. Wetter corn harvested sooner can quickly increase regional demand.

That is why watching both crop conditions and propane inventories becomes increasingly important from this point forward.

Propane Contracting Moves From Planning to Protection

Earlier this summer, we talked about propane contracting as a way to prepare before fall.

We’re now entering the period customers were preparing for.

Heating season is getting closer, harvest is underway nationally, and propane inventories have recorded their first meaningful September decline.

Customers who have already contracted have greater certainty around at least part of their expected propane expense. Customers who haven’t should consider whether establishing that certainty still makes sense for their household, farm, or business.

Sioux Valley Coop offers several contracting options, including 100% prepay, no-money-down contracting, and consumption billing.

The market could move either direction from here. Contracting isn’t about guaranteeing that you’ve selected the lowest possible price. It’s about determining whether knowing your cost ahead of time has value for your budget.

September Bulk Oil Savings Are Still Available

Harvest also means we’re approaching the point when preseason equipment maintenance turns into in-season maintenance.

Machines that have started running long days are accumulating hours quickly. Engine oil changes, hydraulic service, grease intervals, and other routine maintenance can arrive faster than expected once equipment is operating consistently.

That makes this a good time to look at what’s left in the shop rather than only what was there before harvest started.

Sioux Valley Coop’s September bulk oil promotion is still underway, offering savings of more than $1 per gallon on delivered bulk oil.

For operations that regularly purchase oil in volume, replenishing inventory now can serve two purposes: taking advantage of the current savings and making sure frequently used lubricants are available when the next service interval arrives.

There’s also a broader market reason to pay attention to lubricants. Finished lubricant prices don’t necessarily follow diesel prices day by day. Base oils, additives, manufacturing, packaging, and transportation all contribute to the final cost. That means a movement in diesel or crude doesn’t automatically translate into the same movement for engine oil or hydraulic fluid.

For producers, the better strategy is to focus on the products the equipment actually requires and the quantities the operation is likely to use.

Harvest Is Changing the Equation

The biggest difference between this week’s market and the one we were watching a month ago is that demand is no longer theoretical.

Nationally, corn harvest was already 8% complete as of September 13. Here in South Dakota, hundreds of millions of bushels are moving toward harvest.

Every acre harvested creates activity throughout the energy side of agriculture.

Fuel moves equipment through the field and grain down the road. Propane may be needed to bring harvested grain to safe storage moisture. Lubricants protect equipment as operating hours accumulate.

At the same time, the markets supplying those products are moving in different directions.

Diesel received a welcome inventory increase, but global supply remains unusually tight. Propane still has a strong inventory cushion, but stocks have started drawing down as fall begins. Lubricant needs are shifting from preseason preparation to keeping equipment serviced during harvest.

For Sioux Valley Coop members, the most useful strategy is to keep those markets separate.

Know what’s in the bulk fuel tank. Watch grain moisture and expected propane requirements. Review contracts and anticipated winter usage. Keep enough of the correct lubricants available to handle upcoming service intervals.

Harvest doesn’t wait for ideal market conditions. The goal is to make sure the operation doesn’t have to either.

Sources

U.S. Energy Information Administration (EIA) – Weekly Petroleum Status Report, September 16, 2026
U.S. Energy Information Administration (EIA) – U.S. and Midwest Distillate Fuel Oil Stocks, week ending September 11, 2026
U.S. Energy Information Administration (EIA) – U.S. and Midwest Propane/Propylene Stocks, week ending September 11, 2026
U.S. Energy Information Administration (EIA) – What Goes Into Diesel Prices?, September 18, 2026
USDA National Agricultural Statistics Service (NASS) – 2026 South Dakota Agriculture Overview, updated September 21, 2026
USDA National Agricultural Statistics Service (NASS) – Crop Progress Report, September 14, 2026
Reuters – Global Diesel Shortage Likely to Last Into 2027 as Storage Tanks Drain, September 21, 2026