In response to decreased yields due to compaction, Iowa farmer Lowell Garrett runs his tractor tires at 7 psi (left) in the field.
To alleviate compaction, an inflation system allows quick adjustment of tire pressure for the field and the road
In 2011, compaction from tractor and planter tires cost Perry, Iowa, farmer Lowell Garrett more than $100,000 in yield—in just one field. His compaction woes were obvious from the pickup window.
Using the PTG system, he can inflate his tractor and planter tires for road transport speed and loads.
"Driving down the road at the same interval where the machinery ran, the corn was noticeably stunted," he says. "It was as if I had steamrolled the soil—the compaction was that great."
Garrett admits he is not a huge fan of aftermarket products on his machinery, but he realized something had to be done to alleviate the damage he was causing with his 120' John Deere central-fill planter and 9630 tractor with triple wheels on each axle.
After searching for the right solution and even contemplating fabricating something himself, he tested the PTG central tire inflation system in 2012. Made in Germany by PTG, a familyowned company operated by three brothers, the system has been used in agricultural applications in Europe for almost two decades. In the U.S., Sally Brodbeck markets the system under the name Precision Inflation LLC in Des Moines, Iowa.
"Generally, farmers are seeing the effects of the weight they are carrying through the fields as they move to larger equipment and use GPS. They are running over the same ground again and again, creating highways in their fields where the tire tracks repeatedly run," Brodbeck explains.
A deliberate focus on tire technology and proper tire operation has been building since tractor and tire manufacturers began to tackle the issue of "power hop."
"The technical issue of power hop brought proper tire pressure to the front of a lot of farmers’ minds," says Jack Wiley, a retired John Deere engineer who now does technical consulting work. "A key part of the recipe to correct power hop is to lower tire pressures in radial tires. But this change in habit takes a lot of psychology and technology."
The high-capacity air compressor for the PTG system, mounted on the rear of the tractor, provides quick inflation or deflation time—about 10 minutes.
Root of the issue. Wiley explains that the pressure where the rubber meets the soil is 1 to 2 lb. per square inch (psi) greater, on average, than the pressure in the tire. Thus, tire pressures need to be lower in the field to decrease the compaction caused by machinery, yet higher for over-the-road transport to keep the tires from overheating.
"The concept has become that farmers need to be able to easily run two pressures: one on the road and one in the field," Wiley says.
- January 2013
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