Farmers looking to shave input costs may need to look no further than their farm equipment’s gas tanks. That’s because a recent case study conducted at Iowa State University’s Armstrong Research and Demonstration Farm showed possible fuel savings of 10% to 20% just by using the “shift up, throttle back” technique. The savings could add up quickly, as ISU says diesel fuel is the largest direct energy purchase for many farmers.
Researchers used an auxiliary 12-gallon tractor fuel tank to measure fuel consumption for different gear and throttle combinations as they disked, plowed and planted with a John Deere 7420 tractor.
“Improving tractor fuel efficiency is one of many ways to reduce energy expenses on the farm,” says ISU ag engineer Mark Hanna.
The “shift up, throttle back” concept is comparable to how a semi-truck operates during highway travel. At slower starting speeds, when greater force and higher torque is needed for acceleration, the transmission transmits greater torque from the engine by reducing axle speed in a lower transmission gear. But once that force is no longer needed to continue acceleration, engine power shifts to higher gears, and the throttle is reduced.
The study also looked at the effects of tillage depth on fuel consumption during tandem disking.
“As expected, deeper tillage generally requires more fuel,” Hanna says. “In this case, increasing the disking depth from 3” to 5” increased fuel use by 9%.”
Future research might focus on tire inflation, ballasting, fuel and air filter maintenance, and managing tractor gear and throttle settings with partial drawbar loads.