Fact Sheet - Mobile Agricultural Off-Road Diesel Engines (Code 372)

Air Quality - Combustion System Improvement


The Natural Resources Conservation Service (NRCS) is offering California growers and ranchers opportunities to apply new and innovative agricultural emission reduction practices and technologies that provide significant environmental benefits to our natural resources.

The Combustion System Improvement practice improves air quality by reducing oxides of nitrogen (NOx), volatile organic compounds (VOC), and particulate matter (PM10 and PM2.5) emissions from reciprocating internal combustion engines and related components. This practice provides a payment to reduce emissions by permanently removing in-use mobile off-road diesel engines and replacing with new emissions-certified mobile diesel engines that meet or exceed Federal, state, or local emission standards and guidelines. Real emission reductions are achieved when high-polluting diesel engines are replaced with new, cleaner emissions diesel engines earlier than through normal attrition. Priority is on diesel engines operating within nationally designated air quality non-attainment areas in California.

Program Guidelines:  372 - Combustion System Improvement

Program Specifics

California growers and ranchers must meet eligibility requirements to qualify.

·        The in-use mobile diesel engine is:

  • Fully functional, in good operating condition, and has useful life remaining.
  • An uncontrolled (Tier 0) or Tier 1-emissions certified off-road diesel engine rated at least 50 brake-horsepower (bhp) that self-propels an off-road agricultural vehicle. Stationary engines, auxiliary engines, portable engines mounted on trailers or skids, or engines that self-propel on-road agricultural vehicles are not off-road mobile engines.
  • Used routinely and exclusively in California by the participant for at least the past 12 months.

·        The new replacement mobile diesel engine is:

  • Rated at least 50 bhp and within 125% of the in-use engine horsepower rating.
  • New and covered under the manufacturer’s warranty.
  • Powering new mobile equipment components that serve the same function and performs the same work equivalent as the in-use unit (like-for-like).
  • Equipped with a fully functional, non-resettable hour meter.
  • Verified as meeting the most current model-year California emission standards available. Certification is by California Air Resources Board Executive Order based on the applicable EPA engine family and off-road engine model description.

·        The participant must not purchase, make payments toward, or take possession of any new engine or equipment prior to receiving a fully executed contract.

·        The participant under contract must provide the NRCS field office with the applicable EPA Engine Family Name, engine model number or code descriptions, VIN and engine serial number prior to purchasing the new engine and off-road vehicle for emissions verification. Any new engine reporting a Family Emission Limit shall not exceed the applicable emission standards for any air pollutant.

·        ARB Off-Road Certifications may be found on-line at:

·        To assure the emission reductions are real and permanent, the existing engine must be destroyed and scrapped at a California metal recycling facility.

  • Recycling engine parts is not allowed.
  • The participant must provide the NRCS field office with the appropriate documents and photographs of engine destruction.
  • Please consult with your NRCS field office representative on where engines may be properly disposed and scrapped. A list of Destruction Facilitiesis available and includes known destruction and scrapping facilities.

·        Projects must conform to the Combustion System Improvement Specifications.

·        A minimum two-year contract period is required. The participant initiates the project within one year. The practice life is 10 years. 

·        Participants must adhere to the Combustion System Improvement Operation and Maintenancerequirements over the 10-year practice life, which includes reporting annually the total hours of operation of the new engine and vehicle as recorded from the fully functional, non-resettable hour meter.

·        The payment rate is based on the new engine horsepower.

For More Information

For more information about the Environmental Quality Incentives Program, please contact your local USDA Service Center, listed in the government section of the phone book under U.S. Department of Agriculture. Information is also available on the internet at