Farm Industry News used data from reports published by the Nebraska Tractor Test Lab, or NTTL, in the last five years, from 2009 to 2013, to arrive at a measure that best reflects a tractor’s fluid efficiency. Fluid efficiency is the new term used by the lab that takes into account the diesel exhaust fluid and additional fuel consumed by tractors equipped with emissions-compliant engines. The Tier 4 interim standard went into effect in January 2011, and final standards came due this year. Only Tier 3 and Tier 4 interim engines are included in this report. Testing of Tier 4 final engines will begin this spring, according to the NTTL.

In 2011, the NTTL revised its reporting procedures to reflect the fluid efficiency accounting for the extra diesel fuel and diesel exhaust fluid used to meet EPA emissions standards. Fluid efficiency includes diesel fuel and, in the case of Tier 4a engines, diesel exhaust fluid, or DEF. Like fuel efficiency, fluid efficiency is measured in horsepower-hours per gallon (hp-hr./gal.). Measured directly, it means that burning 1 gal. of fuel or fluid in the tractor at full load and at rated engine speed produces a certain amount of horsepower for an hour. The higher the number, the greater the fuel or “fluid” efficiency; that is, more work is being done with a given amount of fuel or fluid.

The lab measures horsepower and fuel use at the PTO and drawbar, and at varying rates of power and pull to replicate the full range of field conditions. Fluid consumption at each operating point is obtained by dividing the power output (horsepower) by the fuel and fluid consumption (gallons per hour).

The NTTL provided us with the parameters on which operating points would best reflect a typical-use cycle for tractors in the size category of 150-plus hp. As such, fluid efficiency ratings for this report are based on “drawbar performance” at 75% of pull at maximum power to reflect performance during typical heavy fieldwork.

PTO numbers also are included for power comparisons and, in some cases where the tractor is being used primarily for PTO work, may be a better reflection of the amount of fluid burned during work.

DEF use was measured at the PTO at 85% and 63.75% resistance, and interpolated to come up with DEF use at the drawbar at 75% of pull at maximum power, fifth gear, which the NTTL would represent as typical field conditions. Where EGR is used, tractors are docked 1% for the fuel they use during regeneration.

HP was measured at the PTO at rated engine speed, which the lab says is a good indicator because it is one that is calculated for all tractors and is always run at the maximum level. Ratings will vary according to the intended use of the tractor. So the NTTL advises farmers to consider all operating points in the test report when making comparisons.

The ratings, published here or online, include all high-horsepower, row-crop tractors (over 150 hp) tested by the NTTL in the last five years. If a tractor model is not included in the chart, it means it hasn’t been tested yet.

The NTTL will not endorse or recommend any tractor.