Increases in diesel fuel prices and the need to conserve soil moisture have some farmers thinking about limiting spring tillage operations. Although total diesel use for all field operations (tillage, planting, harvest) is typically 4 to 6 gallons per acre, eliminating a deep primary tillage operation can save 1 gallon per acre, whereas eliminating a secondary tillage operation can save 0.5 gallon per acre or more. Fuel savings are in addition to wear and tear on machinery and the time devoted to labor. Tractor engines and transmissions should be well maintained. Inflation pressure in rear and front tires should be correct for the axle loading. Although well-maintained diesel engines are efficient, tractor horsepower should be matched to the required load or task, if possible. If a large tractor must be used for a smaller drawbar load, shift the transmission up to a higher gear and reduce engine speed by throttling back.
To make the most energy-efficient use of the tractor for heavy drawbar loads, the tractor should be properly ballasted. A properly ballasted tractor under drawbar load generally has 6 to 12 percent wheel slip on firm surfaces or soil and 10 to 16 percent slip on looser tilled soil. Slip may not be visually noticeable until it is more than 20 percent. Proper ballasting should be according to manufacturer's recommendations in the operator's manual or from the dealer. Two-wheel drive tractors generally should have a total tractor weight of 115 to 135 pounds per PTO horsepower and four-wheel drive tractors 90 to 105 pounds per PTO horsepower. Static weight splits between rear and front axles, respectively, are approximately 75/25 percent for a two-wheel drive tractor, 60/40 percent for a mechanical front-wheel assist tractor, and 45/55 percent for a true four-wheel drive tractor.
In addition to field operations with the tractor, trucks should be well maintained (engine, tires, transmission). Some trips may be able to be combined or eliminated with advance planning.
This article originally appeared on page 29 of the IC-484 (4) -- April 10, 2000 issue.