How to stretch your fuel dollar

These days, the inputs you bought are passing out of your planter as the diesel churns out of your tractor. Unlike other inputs, though, you can get more mileage out of the fuel you’re now using.

Mark Hanna, Iowa State University (ISU) Extension agricultural engineer, and other ISU researchers conducted tractor efficiency trials at seven ISU research and demonstration farms. Here are some of the findings they discovered that you can use in both the short term and the long term.

Gear up, throttle down

Consistently operating a tractor at 2,200 rpm means there’s room to cut back, says Hanna. “You could cut fuel bills by gearing up and throttling down when 100% drawbar power is not needed to 1,600 to 1,800 rpm,” he says.

The ISU tests showed that a low-gear/high-throttle combination increased fuel use an average 26% across seven field operations. “Gearing up and throttling down is a good strategy to lower your fuel bills,” says Hanna.

Consider tillage fuel costs

Tillage has its perks. For example, deep tillage that goes more than a foot deep can break up compacted areas. Just know that it costs money. Subsoiling operations, for example, can cost 2.3 to 2.7 gallons per acre in fuel at a 14- to 16-inch depth.

“I’m not saying to do no tillage, but be smart about why you are doing it,” says Hanna. “No-tillers may or may not be getting higher yields, but tillage costs money, and less of it gives you a competitive advantage.”

Tillage depth

The deeper you till, the more fuel you use. That was confirmed when the ISU researchers compared fuel consumption with tillage depth across several disking and field cultivator trips. Field cultivation at 3 inches vs. 4½ inches and disking at 4 inches vs. 6 inches sliced fuel use from 7% to 41%.

Travel speed

ISU tests showed there was little edge for slowing tractor speed.

“There was not always an increase in fuel consumption,” says Hanna. “In some cases, a faster speed coupled to shifting a gear or two upward and pulling the throttle back created better fuel mileage.”

Tire inflation

Past research has shown excess fuel consumption results with overinflated tires. This technique reduces contact of tire lugs in soft or adverse soil conditions. Little difference between optimum and overinflated tires occurred in ISU tests. Less fuel use occurred in three of five comparisons with correctly inflated tires, but fuel savings were just 1% to 2% in these cases where chisel plowing was studied.

Duals vs. singles

Duals typically support axle weight or improve flotation or stability. Another perk is that they also reduce fuel use. When the second tire was removed in the ISU tests, fuel consumption increased 4% during planting and 12% during field cultivation.

Front-wheel drive

Engaging front-wheel drive helps power front wheels to pull the load. It also saves fuel. The ISU researchers compared fuel consumption with and without mechanical front-wheel drive engaged during four field operations. Not powering the front axle boosted fuel use from 5% to 31% compared with front-wheel-drive engagement.  

“That is another reason for engaging the front-wheel drive,” says Hanna.