Agricultural Economics Department


First Advisor

Cory Walters

Second Advisor

Lia Noguira-Rodriguez

Third Advisor

Roger Hoy

Date of this Version


Document Type



A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Agricultural Economics

Under the supervision of Professors Cory Walters and Lia Nogueira-Rodriguez

Lincoln, Nebraska, May 2023


Copyright © 2023, Jerin TeKolste


Since its inception the U.S. Environmental Protection Agency (EPA) has been tasked with the assessment, research, and education, of the nation’s environment while also maintaining and enforcing national standards. A characteristic display of this agency’s work is the Exhaust Emission Standards for Nonroad Compression-Ignition Engines that began in 1995. Since the introduction of exhaust emissions standards in 1995, no study has fully examined the subsequent impact on fuel efficiencies.

In this paper we analyze the resulting fuel efficiency caused by the EPA’s exhaust emission standards. We identify the impact of the emissions standards on tractor fuel efficiency through a statistical analysis during various field operations across multiple tractor drivetrains, sizes, policy tiers, and horsepower while controlling for fuel efficiency advancements developed during the introduction of emission standards. To accomplish our objective, we use the University of Nebraska-Lincoln’s Nebraska Tractor Test Lab database. Preliminary results suggest that overall emissions standards have negatively impacted fuel efficiency. However, the most recent emission standards, Tier 4 and Tier 4 Final have not impacted fuel efficiency as harshly as earlier emission standard tiers.

Advisor: Cory Walters