No matter what color tractors you use, your face is likely red when you see how much green is being spent on fuel.

With $1.50-2/gal. farm diesel prices, not to mention $2.20 gal. or more for gasoline used in that pickup or SUV, record high fuel costs have run typical production budgets off the road. And state and federal emission control standards could be fueling the fire under poor engine fuel economy.

But you can minimize your fuel usage by using a little common sense and practicing some proven methods, like the traditional “shift up and throttle back” (SUTB).

SUTB works for older tractors that are still far from reaching their maximum use of about 12,000 hours, says Howard Doster, an agricultural economist at Purdue University, West Lafayette, IN.

And newer tractors with the “power bulge” capabilities can also see dramatic reductions in fuel use through SUTB, adds Dave Morgan, assistant director of the Nebraska Tractor Test Laboratory in Lincoln.

SUTB works like this: Instead of operating a tractor at full-throttle in a lower gear, shift up to a higher gear and throttle back to the same ground speed. For many jobs, this can provide the same drawbar horsepower while the engine runs at near its peak torque at the lower throttle setting.

Loren Fairbanks of Fairbanks Case IH and New Holland in Kearney, NE, says SUTB can be a great benefit to virtually any tractor. “Tractors are running fewer hours now due to more minimum- and no-till programs,” says Fairbanks, “but growers can still benefit from SUTB.”

Morgan points out that 15-20% or more fuel savings can be easily accomplished using SUTB. Potential savings levels for virtually any tractor can be obtained by visiting the Nebraska test Web site at http://tractortestlab.unl.edu. From there, click on the “Test Reports” menu bar. From that site, you can select test results on any brand and model of tractor from 1999 on.

“Look at the drawbar performance portion of the test report,” says Morgan, noting that this section will be listed beneath the power take-off (PTO) performance section.

Look at the tractor's power rating levels for horsepower used and the hp-hours/gal. Then, divide the hp by the hp-hours/gal. to obtain the amount of fuel used per hour at that power level.

At rated engine speed in eighth gear the tractor produces 225 hp and has a hp-hours/gal. rating of 15. Dividing the 225 by 15 shows a fuel usage of 15 gal./hour.

If the drawbar requirement for a field operation only requires 75% of the load the tractor produces at rated engine speed, the operator has three options.

  • “Option one is to leave the throttle wide open in the same gear with the reduced load,” says Morgan. “This is shown in the test labeled ‘75% of Pull at Maximum Power — 8th Gear.’ The tractor produces 176 hp, with a fuel efficiency of 14.1 hp-hours/gal. This calculates out to 12.5 gal./hour.”

  • Option two (SUTB) is to shift up to 10th gear and set the throttle to the same travel speed as in the full throttle test. Drawbar pull, power and travel speed remain the same, but the engine runs at 1,700 rpm rather than 2,200 rpm, and the fuel efficiency is 16.7 hp-hours/gal.

    “The fuel consumption here is only 10.5 gal./hour, a 2 gal./hour fuel reduction or 16%,” says Morgan.

  • “Option three is to stay in the same gear (eighth) and throttle back, but reduced travel speed will increase field time, which also increases total fuel consumption,” Morgan says. “There can be some tremendous fuel savings under SUTB if a tractor is equipped to do specific jobs under those conditions.”

Purdue's Doster says that in regions where older tractors are plenty capable of doing the job, likewise older methods of fuel savings can make the well-used tractors more efficient.

“SUTB can help, even in situations where the main tractor on a farm may run only 300-350 hours a year,” says Doster, adding that other practices such as keeping air and fuel filters clean and using proper tire inflation can help growers save fuel.

Fairbanks says that he sees fuel ratings getting better, even though some newer tractors may be less fuel efficient than those a few years ago due to stricter clean air regulations.

“As the government has mandated lower emissions, some engines have a lower fuel economy,” he says. “It may not be as good as it was 10 years ago. But I believe the next generation of engines (available in the next year or two) will see the return to better fuel economy.”

Morgan says applying the horsepower divided by hp-hours/gal. theory shows that some new tractors are less fuel efficient than older models. “So again, better use of SUTB can help on the newer tractors,” he says.

Fairbanks says one real plus in 21st century tractor is the availability of GPS auto guidance systems. “Each farmer who has installed a GPS system in one of our tractors has seen a substantial reduction in fuel usage because the tractors operate more efficiently with the auto guidance systems,” he says.

“They are about 20% more efficient. That is something we had not expected from our GPS supplier.”