Farm News
03/17/06
Rising fuel prices cause farmers to seek solutions
KRISTIN GREINER- Farm News staff
AMES — Cutting costs this spring is important to producers’ bottom line. One
area where producers can save money is with fuel expenses.
Total diesel use for all field operations, including tillage, planting and harvest, is
typically four to six gallons per acre. Specifically, using a disk-chisel plow
requires 1.3 gallons of diesel fuel per acre, while a planter with fertilizer and
seedbed attachments for a 30-inch row tilled seedbed uses slightly more than
half a gallon of diesel fuel per acre.
For example, a rotary hoe uses almost one-fourth of a gallon of diesel fuel per
acre, and a combine picking corn consumes almost 1.5 gallons of diesel fuel per
acre.
But because fuel consumption values for any particular operation vary among
tractors and soil type, actual fuel requirements may be as much as 35 percent
higher, according to Iowa State University (ISU) Extension. Furthermore, engine
efficiencies decrease over time. Older tractors manufactured before 1990 or in
poor repair may use 10 percent or more additional fuel. Older gasoline powered
equipment can use up to 50 percent more gallons of gasoline.
Mark Hanna, Iowa State University Extension agricultural and biosystems
engineer, suggests producers pay attention to several key points to minimize
fuel consumption. First, tractor engines and transmissions should be well
maintained. Make sure inflation pressure in rear and front tires is correct for
tractor axle loads. For mechanical front-wheel assist tractors, closely match front
tire size with rear tire size as detailed in the operation manual.
Although well-maintained diesel engines are efficient, if possible, producers
should match tractor horsepower to the required load or task. 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.
Also, a tractor must be properly ballasted to be most energy efficient when
pulling heavy drawbar loads. A properly ballasted tractor under drawbar load will
generally have 5 to 10 percent wheel slip on firm surfaces or soil and about 10 to
15 percent slip on looser tilled soil. Slip is often not visually noticed until in
excess of 20 percent.
Proper ballasting should be according to manufacturer’s recommendations in the
operator’s manual or from the dealer. Two-wheel drive tractors may have a total
tractor weight of 115 to 135 pounds per (power take off) PTO horsepower and
four-wheel drive tractors about 90 to 105 pounds per PTO horsepower. Static
weight splits between rear and front axles, respectively, will be approximately 75
percent/25 percent for a two-wheel drive tractor, 60 percent/40 percent for a
mechanical front wheel assist tractor and 45 percent/55 percent for a true fourwheel drive tractor.
In addition to field operations with a tractor, trucks should be well maintained
(engine, tires and transmission). Some trips may be able to be combined or
eliminated with advance planning, Hanna said.
Watching how much fuel is used to conduct certain tasks also is important.
Eliminating a deep, primary tillage operation can save one gallon per acre, and
eliminating a secondary tillage operation can save one-half gallon per acre or
“Because nitrogen fertilizer uses so much natural gas as a feed stock, it’s a
significant energy user in field crop production. Using an ammonia manifold with
improved distribution uniformity can allow fertilizer application rate to be reduced
while still maintaining the same minimum amount of nitrogen available to corn
plants,î” Hanna added.