Non-road diesel engines are significant contributors to air pollution in the United States. These engines emit particulate matter (PM), nitrogen oxides (NOx), sulfur dioxide (SO2), and other pollutants. According to the EPA, the Clean Air Non-road Diesel Rule was put in place to reduce emission levels from agricultural, construction, and industrial diesel powered equipment. Biodiesel is a clean burning alternative fuel produced from plant oils or animal fats, according to the National Biodiesel Board. While biodiesel contains no petroleum, it can be blended with petroleum diesel to create a biodiesel blend. Pure biodiesel is essentially free of sulfur compared to petroleum diesel. Biodiesel blends, consequently, contain less sulfur than petroleum diesel. The research findings evaluated in this paper include measured concentrations of NOx, SOz, total hydrocarbons (THC), and carbon monoxide (CO), along with engine performance curves obtained during engine dynamometer testing using several blends of cottonseed oil biodiesel.