WITH TIER 3 off-road diesel emission standards now in effect for large row-crop tractors, manufacturers are already working on engine designs to meet Tier 4. This next tier, to be phased in from 2008 to 2015, calls for an even greater reduction in the amount of soot and nitrous oxide allowable in diesel exhaust.

“The way I describe it is if you drove through a large city on a smoggy day with a Tier 4 engine, the air coming out of the tractor would be cleaner than the air coming in,” says Jim Wienkes, engineering manager for John Deere's high-horsepower tractors.

Specifically the final Tier 4 standards require a 90% reduction in oxides of nitrogen and particulate matter compared to the Tier 3 standards. The Tier 3 regulations are already providing a 60% reduction in emissions compared with the unregulated engines that were produced just 10 years ago.

Wienkes says meeting this new tier poses a significant engineering challenge for both the engine and the tractor configuration. “If the engineering challenge to meet Tier 3 was a factor of 1, Tier 4 is going to be a factor of 3,” he says.

Engineers have several methods they can use to create cleaner-burning engines. Each has its own set of trade-offs. For example, the trade-off for better fuel economy, serviceability and maintenance could be an increase in tractor cost. Which method a company chooses could become key in what differentiates the product or the reason why a consumer would pick one brand over another, Wienkes says. “We think our design concept is right for our customers,” he says.

John Deere's 8030 series, first in line to meet Tier 3 requirements, was recently awarded a gold medal at the European ag show AgriTechnica for its reduction in fuel consumption and atmospheric pollution. The 8030 series tractor also set a new industry standard for fuel efficiency in independent tests conducted at the Nebraska Tractor Test Lab.

Just how important is fuel economy when shopping for a tractor? Is it enough to cause a buyer to choose one brand over another? Yes, according to John Deere tractor marketing manager Ron Schwertner. And now, with the recent rise in fuel prices, fuel efficiency has become an even bigger factor in a farmer's tractor-buying decision.

“When you start having your input costs increase by 100% by one line item, you start to take significant action to try to get the cost back to what it was before,” Schwertner says. “And hence the reason why fuel efficiency has become very important.”