372 - 1 

NRCS, CA 

Sept. 2010 

Conservation practice standards are reviewed periodically, and updated if needed. To obtain 

the current version of this standard, contact the Natural Resources Conservation Service 

State Office, or download it from the Field Office Technical Guide.

NATURAL RESOURCES CONSERVATION SERVICE 

CONSERVATION PRACTICE STANDARD 

COMBUSTION SYSTEM IMPROVEMENT 

(No.) 

CODE 372 

DEFINITION 

Installing, replacing, or retrofitting agricultural 

combustion systems and/or related 

components or devices for air quality and 

energy efficiency improvement. 

PURPOSE 

To improve air quality by addressing the 

air quality resource concerns for 

particulate matter and ozone precursors by 

mitigating actual or potential emissions of 

oxides of nitrogen and/or fine particulate 

matter

To improve the energy efficiency of 

agricultural combustion systems 

CONDITIONS WHERE PRACTICE APPLIES 

This practice applies to any agricultural 

operation that operates an agricultural 

combustion system, including stationary, 

portable, mobile, and self-propelled equipment. 

The combustion system must be used 

primarily for agricultural and/or forestry 

activities. 

For a combustion system associated with a 

pumping plant (i.e., pumping plant power unit), 

use Conservation Practice Standard, Pumping 

Plant, Code 533. This standard (Combustion 

System Improvement for Air and Energy, 

Code 372) may be applied in addition to the 

Pumping Plant standard for addressing air 

quality resource concerns associated with a 

pumping plant power unit, if applicable. 

CRITERIA 

General Criteria Applicable to All Purposes

Size the new or replacement combustion 

system and related components or devices 

appropriately to accomplish its intended task. 

Where required, certify that the new, 

replacement, or retrofit combustion system and 

related components or devices meets or 

exceeds currently-applicable Federal, State, 

and local standards and guidelines. 

All replaced combustion systems shall be 

rendered inoperable or used to replace 

higher-emitting or lower-efficiency combustion 

systems. Certification of use as a replacement 

system can be accomplished by providing 

certification of inoperability of one or more 

higher-emitting or lower-efficiency combustion 

system(s). 

Certification of inoperability can be 

accomplished by: 

Obtaining a receipt for the combustion 

system disposal from a scrap metal 

recycling operation and keeping this 

receipt available for inspection; or 

Creating a permanent hole in the engine 

block or combustion chamber of the 

combustion system (minimum size to be 

determined by Federal, State, or local 

guidelines). The disabled engine must be 

kept on-farm for inspection, or a written 

and signed certification that a permanent 

hole has been created and the engine is 

disabled must be prepared and kept 

available on-farm for inspection. 
372 - 2 

NRCS, CA 

Sept. 2010 

Additional Criteria Applicable to Improving 

Air Quality

A new or replacement combustion system and 

related components or devices shall utilize a 

non-combustion power source or a combustion 

power source that utilizes cleaner-burning 

technologies, techniques, and/or fuels. 

When installing a new combustion system that 

is not a replacement system, the new 

combustion system shall emit fewer oxides of 

nitrogen and/or less fine particulate matter 

than the most commonly-installed alternative 

system. When installing a new or replacement 

diesel-powered engine, use the 

newest-available EPA engine TIER 

technology. 

When installing a replacement combustion 

system and related components or devices, 

the replacement system shall emit less oxides 

of nitrogen and/or fine particulate matter than 

the replaced combustion system and related 

components or devices. 

Retrofit can include actions or combinations of 

actions that reduce emissions of oxides of 

nitrogen and/or fine particulate matter. 

Examples of individual retrofit actions include: 

Adding one or more emissions control 

device(s), 

Altering air/fuel mixtures to achieve more 

complete combustion and less emissions, 

Adding a device that allows for reduced 

combustion of fuel to accomplish the same 

intended task, 

Accommodating the use of a 

cleaner-burning fuel, and/or 

Other physical modifications or changes in 

combustion techniques that reduce 

emissions formation or release. 

Additional Criteria Applicable to Improving 

Energy Efficiency

Only the replacement or retrofit of an existing 

combustion system is allowed under this 

practice standard for the energy efficiency 

purpose. Installation of new combustion 

systems where none existed prior are not 

allowed if energy efficiency is the sole 

purpose. 

Replacement combustion systems shall be 

certified to be at least 20% more energy 

efficient than the systems they replace. 

Retrofit to improve energy efficiency may 

involve adding a device that allows for reduced 

operation of an existing combustion system, 

such as a variable frequency drive or 

automated sensors and controls. 

CONSIDERATIONS 

Installation of new or replacement combustion 

systems with non-combustion renewable 

energy sources, such as solar, wind, and 

water, are preferred means of reducing air 

emissions associated with agricultural 

combustion systems. Non-combustion 

renewable energy sources do not release air 

emissions directly and do not increase air 

emissions from off-site electricity generation. 

The impacts of non-combustion renewable 

energy sources on other resources should also 

be considered to analyze their overall 

conservation benefit. 

PLANS AND SPECIFICATIONS 

Specifications for application of this practice 

shall be prepared for each site or planning unit 

according to the criteria. Specifications shall 

be recorded using State-developed 

specification sheets, job sheets, practice 

requirement sheets, narrative statements in 

conservation plans, or other acceptable 

documents. 

As a minimum, the plans and specifications 

shall provide the following: 

Identification and description of the 

existing combustion system and related 

components or devices, if applicable, and 

the new or replacement combustion 

system and related components or 

devices. If the combustion system is being 

retrofitted, identification and description of 

the type of modifications being made to the 

existing system. 

Requirements on disposal of replaced 

combustion system and related 

components or devices, including assuring 

permanent disabling and rendering 

inoperable. 
372 - 3 

NRCS, CA 

Sept. 2010 

Documentation requirements to determine 

combustion system usage and resulting air 

emissions from the new, replacement, or 

retrofit combustion system and related 

components or devices. Average annual 

air emissions for the existing combustion 

system (for replacements and retrofits) or 

alternative combustion system (for new 

installations) shall be calculated prior to 

the installation of the new combustion 

system or replacement or retrofit of the 

existing combustion system to determine 

the expected air emissions reductions from 

the application of this practice and to serve 

as a baseline for later air emissions 

calculations. 

OPERATION AND MAINTENANCE 

An operation and maintenance plan shall be 

developed that is consistent with the purposes 

of this practice, its intended life, safety 

requirements, and the criteria used for its 

design. 

The new, replacement, or retrofit combustion 

system and related components or devices 

shall be operated and maintained in 

accordance with the manufacturer’s 

recommendations. 

NRCS recommends that records be retained 

and updated for a minimum of five years from 

the beginning of operation of a new, 

replacement, or retrofitted combustion system. 

The recommended records to be retained 

include: 

Total actual hours operated 

Types and amounts of fuel used in the 

combustion system(s), or electricity used 

for electric motors that have replaced an 

existing combustion system 

Documentation of maintenance conducted 

on the new, replacement, or retrofitted 

combustion system and related 

components or devices 

REFERENCES 

United States Environmental Protection 

Agency (U.S. EPA) National Clean Diesel 

Campaign for Agriculture (Clean Agriculture 

USA) website. 

California Environmental Protection Agency Air 

Resources Board (CARB) Diesel Programs 

and Activities website.
372B-OM-1 

NRCS, CA 

August, 2013 

UNITED STATES DEPARTMENT OF AGRICULTURE 

NATURAL RESOURCES CONSERVATION SERVICE 

372B - COMBUSTION SYSTEM IMPROVEMENT, 

MOBILE OFF-ROAD AGRICULTURAL ENGINES AND EQUIPMENT 

OPERATION AND MAINTENANCE

Producer: Date:

Address: 

 

County where the equipment is housed: 

Operating and maintaining the agricultural vehicle and equipment per the owner’s operation 

manual and guidance is essential for assuring the life of the equipment. With proper operation 

and maintenance, the expected vehicle and equipment lifespan is 10 years and longer. 

The operator must fully understand and follow the manufacturer’s operation and maintenance 

instructions and safety requirements before operating any agricultural off-road vehicle and 

equipment. 

Emission reductions from replacing mobile off-road agricultural engines will be credited toward 

the applicable State Implemenation Plan for compliance with the Clean Air Act. The following 

operation and maintenance items are required over the expected 10-year lifespan of the mobile 

engine and equipment. 

i The agricultural vehicle and equipment shall be operated in a safe manner. The operator 

must understand and follow all safety requirement specified by the manufacturer. 

i The engine shall be equipped with a functional, non-resettable hour meter. The producer 

shall record annually the total hours of operation and maintain these records a minimum of 

10 years. 

i For San Joaquin Valley producers, operational information over the previous calendar year 

shall be submitted annually to the NRCS. Use the attached “California Mobile Engine and 

Equipment Annual Reporting Worksheet”. 

i Do not allow any operation that exceeds design limitations. 

i Maintain the vehicle and equipment (i.e. engine, drive-train components, hydraulics, tires, 

and electrical and mechanical equipment) in good operational condition by following the 

manufacturer’s recommended service intervals. 

i Check all fluids routinely. Motor oil, gear oil, water, engine coolant, hydraulic fluid, 

transmission fluid, brake fluid, and diesel exhaust fluid (DEF) must be replenished whenever 

necessary. Lubricate often where grease fittings are provided. Change fluids and filters 

according to manufacturer’s recommended service intervals. 
372B-OM-2 

NRCS, CA 

August, 2013 

i Precautionary measures must be taken to prevent spills of fuels, lubricants, and fluids. 

Promptly clean-up spills and prevent movement to any water body. 

i All emissions control devices and technology shall be in operational condition and well 

maintained. 

i Avoid making modifications to the engine, components, or emissions control systems, 

including modifications that would result in the manufacturer voiding the engine and 

equipment warrenty. 

CONTACT YOUR LOCAL NATURAL RESOURCES CONSERVATION SERVICE 

OFFICE FOR ANY ADDITIONAL TECHNICAL ASSISTANCE YOU MIGHT NEED 

FOR IMPLEMENTATION OF THIS OPERATION AND MAINTENANCE PLAN. 
372B – OM-3 

NRCS, CA 

August, 2013 

CALIFORNIA MOBILE ENGINE AND EQUIPMENT 

ANNUAL REPORTING WORKSHEET 

Air Quality – 372 Combustion System Improvement

Reporting Year: Date: Contract No: 

Participant Name: 

Contact Name: 

Contact Phone No: Email Address: 

Engine/Equipment Address: 

Equipment/Vehicle Make: Equipment/Vehicle Model: 

Equipment/Vehicle Model Year: Vehicle ID Number: 

Engine Make: Engine Model: 

Engine Model Year: Engine Serial No: 

Is the equipment in service per the original contract? Yes No – Please explain: 

Record the total hours from the non-resettable hour meter: Hours

Percent use within the San Joaquin Valley over the reporting year: 

(San Joaquin Valley counties are: San Joaquin, Stanislaus, Merced, Madera, Fresno, 

Tulare, Kings, and the valley portion of Kern) 

Percent

Percent use in other counties: 

(Report each county name and percent use) 

Identify any maintenance performed on the engine/equipment: 

Identify any conditions that significantly affected the annual usage: 

Please complete 

and return this 

reporting 

worksheet to: 

USDA Natural Resources Conservation Service 

Fresno Area Office – Air Quality 

1907 N Gateway Blvd, Suite 101 

Fresno, CA 95727 

Phone: 

Fax: 

559-252-2191 

559-252-5483 
372-1 

NRCS, CA 

Sept. 2010 

UNITED STATES DEPARTMENT OF AGRICULTURE 

NATURAL RESOURCES CONSERVATION SERVICE 

372– COMBUSTION SYSTEM IMPROVEMENT 

IRRIGATION ENGINES 

OPERATION AND MAINTENANCE 

Sponsor/Land user: Date:

Address: 

 

Location GPS Coordinates Map Datum: E N

Quad Sheet Name SEC T R

A properly operated and maintained pumping plant is an asset to your farm. This pumping plant was 

designed and installed to convey water in a pipeline where it can be distributed for use. The estimated 

life span of this installation is at least 10 years. The life of this installation can be assured and usually 

increased by developing and carrying out a good operation and maintenance program. 

This practice will require you to perform periodic operation to maintain satisfactory performance. 

Here are some recommendations to help you develop a good operation and maintenance program: 

GENERAL RECOMMENDATIONS

i Maintain all pumps, agitators, piping, valves and other electrical and mechanical equipment in 

good operating condition following the manufacture's recommendations. 

i Precautionary measures should be taken to prevent spills of fuels and lubricants. Promptly clean 

up spills and prevent movement of fuels or lubricants to any water body. 

i Maintain grounding rods and wiring of all electrical equipment in good working condition. 

i Maintain all safety shields on pumps, motors, or other electrical or mechanical equipment. 

i Check all pump bases and mountings for durability and ability to hold the pump in place without 

vibration, repair when necessary. 

i Replace, repack or tighten the seals when leakage is in excess of manufacturer's 

recommendations. 

i Drain all pumps and piping including valves that are subject to freezing. If parts of the system 

cannot be drained, a non-corrosive anti-freeze solution shall be added. 

i Minimize erosion in collection ditches and pipeline inlets. Controlling erosion helps minimizes 

sediment deposits in storage facilities and sumps. 

i Periodically check all above ground pipeline connections and structures for proper operation, 

including leaks. A 10 gal/min leak totals over 1400 gal/day and 10,000 gal/week. Repair leaks 

immediately. 

i Determine cause of cracks and structure displacement, and repair as needed. 
372-2 

NRCS, CA 

Sept. 2010 

i Periodically clean trash racks, sediment traps, sumps, reservoirs, and ditches to maintain design 

capacity and efficiency. 

i Prevent, and if necessary, remove foreign debris from entering water facilities. Properly cleaned 

and maintained screens help minimize required system maintenance. 

i Replace weathered or displaced rock riprap to constructed grade. 

i Do not allow the operation of any equipment that exceeds the design limit on or within twenty 

feet of the structure. 

i Maintain surface drainage around the pumping plant to avoid ponding of water. 

i Immediately repair any vandalism, vehicular or livestock damage to the structure, earthen areas 

surrounding the structure, or any appurtenances. 

i Inspect for damage from rodents or burrowing animals. Repair any damage. Take appropriate 

corrective actions to alleviate further damage. 

SPECIFIC RECOMMENDATIONS FOR YOUR PUMPING PLANT

CONTACT YOUR LOCAL NATURAL RESOURCES CONSERVATION SERVICE OFFICE 

FOR ANY ADDITIONAL TECHNICAL ASSISTANCE YOU MIGHT NEED FOR 

IMPLEMENTATION OF THIS OPERATION AND MAINTENANCE PLAN FOR YOUR 

PUMPING PLANT. 
December 30, 2011

Updated May 2, 2012

Environmental Quality Incentive Program

California Air Quality 

Emission Reductions from Replacing Engines

Fiscal Year 2012

Guidelines, Policies, and Procedures

Combustion Systems Improvement

(Code 372)

Emission reductions are achieved by improving existing high polluting combustion 

systems. This category can provide real emission reduction benefits by retiring the high 

polluting reciprocating engines earlier than through normal attrition and replacing with 

new, cleaner technology.

In 1998, the California Air Resources Board identified diesel particulate matter as a toxic 

air contaminant. Exposure to diesel emissions may result in negative health effects.

Diesel emissions also include oxides of Nitrogen (NOx), a precursor to ozone in smog 

formation that has also been shown to cause adverse health effects. Cost-effective 

measures for reducing the toxic air contaminants and NOx emissions can be achieve 

with early replacement of old diesel engines powering agricultural equipment.

In December 2010, the NRCS-California signed a “Statement of Principles” with the 

Environmental Protection Agency-Region 9, the California Air Resources Board, and the 

San Joaquin Valley Air Pollution Control District establishing a general framework for 

ensuring the emission reductions from voluntary incentives replacing engines from

mobile off-road agricultural equipment receive credit in the State Implementation Plan 

(SIP). As such, the NRCS is working collaboratively with these agencies, the 

agricultural communities, and participants in an effort to provide SIP-credible emission 

reductions that are “surplus, quantifiable, enforceable, and permanent”.

Eligible Projects

The program replaces high-polluting, fully functional reciprocating engines with the 

latest reduced-emission engines meeting the most current model-year California

emissions standards. 

Payments are available to replace existing engines (engine repowers) with a newer 

emissions certified engine instead of rebuilding the existing engine to its original 
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 2

December 30, 2011

Updated May 2, 2012

specifications. The replaced equipment must perform a similar function as the old 

equipment. 

Replacing an engine, however, may not always result in the best value. Replacing only 

the engine on equipment may not be possible due to design constraints or the 

diminished value of the old equipment may not justify investing significant funds for 

engine replacement. These situations will be evaluated on a case-by-case basis. If 

approved, payments will be made for the reductions achieved from equipment replaced 

with new emissions technology.

If repowering with an engine meeting the current applicable emission standard is 

technically unfeasible, unsafe, or cost-prohibitive to develop at the time funds are 

obligated, then the engine must meet the most current practicable, previously applicable 

emission standard. The participant must submit a written statement of reason provided 

by the engine manufacturer verifying that a particular piece of equipment cannot 

accommodate an engine meeting current specifications without major modifications, 

safety risks, exorbitant costs, or for which engine or equipment models for repowers are 

not available or feasible.

The replacement engine and equipment must be certified for sale in California and meet 

the most recent model year emission standards and/or emissions standards established 

by the local air district, if applicable. Once in operation, the engine and equipment must 

be used exclusively in California.

Upgrading or installing fueling stations and infrastructure is not eligible, including but not 

limited to the expense of installing fuel storage tanks, construction of fueling depots, or 

construction of biodiesel manufacturing facilities.

Retrofits to an engine are eligible. A retrofit is the installation of an emission control 

system verified by the ARB, such as diesel particulate filters, diesel oxidation catalysts, 

or selective catalyst reduction systems. Retrofit technology may be installed on an 

existing engine that results in meeting current emission standards or on a new engine 

that results in additional emission reductions. 

The existing engine or equipment being replaced must be owned by the participant, 

have been used in the State of California for at least 12 months prior to the application 

submittal date, have some remaining life, must be rendered inoperable and disposed of 

at an approved metal-scrap facility in California, where it is destroyed. 

Destruction of the old engine and equipment permanently removes the existing, high 

emitting equipment from service and ensures that the emission reductions are real. It 

also prevents the existing equipment from being moved into another locale to continue 

emitting high levels of pollutants or used as parts that might prolong the life of similar 

engines. The participant must therefore certify that the old engine and equipment has 

been rendered useless and destroyed.
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 3

December 30, 2011

Updated May 2, 2012

The emission reductions achieved from contracts or parts of contracts funded under the 

air quality initiative are not required by any federal, state, or local regulation, settlement 

agreement, mitigation requirement, or other legal mandate. No emission reductions will

be used as marketable emission reduction credits, to offset any emission obligations, or 

for credit under any federal, state, or local emission averaging banking and trading 

program. 

NRCS payment schedules are available and vary depending on the type and size of the 

new engine and equipment. A minimum two-year contract period is required. The 

participant must initiate the project within the first year of the contract and payment is 

initiated once all contract obligations are met. It is the participant’s responsibility to use 

and maintain the engine and equipment for the life of the practice.
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 4

December 30, 2011

Updated May 2, 2012

Section 1: Definitions

Add-On Control Device: an air pollution control device, such as a catalytic converter, 

that reduces the pollution in exhaust gas. The control device usually does not affect 

the process being controlled and thus is "add-on" technology, as opposed to a 

scheme to control pollution through altering the basic process itself.

ARB: the State of California Air Resources Board.

Airborne Toxic Control Measure (ATCM) for Stationary Compression-Ignition 

Engines: under Title 17, Sections 93115.1 through 93115.15 of the California Code 

of Regulations, the ARB established emission limits that apply to stationary and 

portable diesel engines rated at greater than 50 break horsepower, including those 

used in agriculture. The compliance deadline specified in the ATCM and in any 

applicable air district rule essentially phases-out the continued use of older 

stationary and portable engines, including uncontrolled (Tier 0) diesel engines. 

Once deadlines have passed, replacing subject engines will not result in any 

emission reduction benefits since these engines are no longer allowed to operate. 

The ATCM is posted on-line at: 

http://www.arb.ca.gov/diesel/ag/documents/finalreg112807.pdf.

Ambient Air Quality Standards (AAQS): National and State health- and welfarebased standards for outdoor air, which identify the maximum acceptable average 

concentrations of air pollutants during a specified period of time. 

A chart of the national and state AAQS is posted on-line at: 

www.arb.ca.gov/research/aaqs/aaqs2.pdf.

Auxiliary Engine: does not self-propel a vehicle or equipment, but provides power for 

other functions. The fuel, cooling, and exhaust systems are an integral part of the 

vehicle or equipment.

Brake Horsepower (bhp): is the rated horsepower capacity of the engine as defined by 

the engine nameplate under standard conditions. It is the measure of an engine's 

horsepower without the loss in power caused by the gearbox, generator, differential, 

water pump, and other auxiliary components that may slow down the actual speed of 

the engine. For Practice Code 372, the engine horsepower and payment

determination is based on an engine’s brake horsepower rating.

Certified Compression-Ignited Engine: a Tier 1, Tier 2, Tier 3, Tier 4-Interim, and Tier 

4-Final compression-ignited engine certified by the EPA and/or the ARB. The 

California Tier schedule is on Table 1.
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 5

December 30, 2011

Updated May 2, 2012

Certified Spark-Ignited Engine: an ARB-certified spark-ignited engine as specified in 

Title 13, Division 3, Chapter 9, Article 4.5, Section 2433 of the California Code of 

Regulations.

Compression-Ignition Internal Combustion Engine: an engine that uses the heat of 

compression to initiate combustion. The majority of these engines are fueled by 

diesel fuel, but some may be designed to operate on bio-diesel or natural gas.

Criteria Air Pollutant: derived from EPA, an air pollutant for which acceptable levels of 

exposure can be determined and an ambient air quality standard has been 

established, based on the pollutant’s characteristics and potential health and welfare 

effects. These pollutants include ozone, carbon monoxide, nitrogen dioxide, sulfur 

dioxide, particulate matter (PM10 and PM2.5), and lead.

Diesel Engine: a compression-ignited two- or four-stroke internal combustion engine in 

which liquid fuel injected into the combustion chamber ignites when the air charge is 

compressed to a temperature sufficiency high for auto-ignition.

Diesel Exhaust Particulate Matter: the ARB designates diesel exhaust particulate 

matter as a toxic air contaminant (TAC) based on its potential to cause cancer, 

premature death, and other health problems. As a result, the ARB established 

several Airborne Toxic Control Measures (ATCM’s) that are codified in the California 

Code of Regulations. The ATCM’s establishes emission standards to reduce diesel 

exhaust particulate matter and health risks. 

Diesel-exhaust particulate matter ATCM’s are posted on-line at: 

www.arb.ca.gov/toxics/atcm/atcm.htm.

Drawbar Horsepower: is the power an agricultural tractor has to pull an implement. 

The power is determined by utilizing a special a dynamometer car coupled behind a 

tractor that keeps a continuous record of the drawbar pull exerted and the speed. 

For Practice Code 372, drawbar horsepower will not be used for comparison with 

rated break horsepower because this value varies under different operating 

conditions and does not necessarily correlate with the engine horsepower. 

Emergency Standby Engine: a stationary engine where the primary purpose is to 

provide electrical or mechanical power in an emergency and operate to provide 

electrical power or mechanical work during an emergency use. Such engines may 

operate during non-emergency situations for the purpose of testing, repair or routine 

maintenance to verify its readiness for emergency standby use. Examples include 

an engine powering an electric generator to provide electric power or powering a 

water pump for firefighting or flood control. 

Emission Control System: any device or system employed with engines or piece of 

equipment intended to reduce emissions. Examples of emission control systems 
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 6

December 30, 2011

Updated May 2, 2012

include, but are not limited to, closed-loop fuel control systems, three-way catalysts, 

fuel injection systems, and combinations of the above.

Engine Repower: the replacement of an existing engine with a new, emissions certified 

engine instead of rebuilding the existing engine to its original specifications.

EPA: The United States Environmental Protection Agency.

Family Emission Limit (FEL): an emission level declared by the manufacturer for use 

in any averaging, banking and trading program and in lieu of an emission standard 

for certification. It serves as the applicable emission standard for determining 

compliance of any engine within an engine family under 13 California Code of 

Regulations Sections 2423 and 2327. Any ARB Executive Order reporting a FEL 

value exceeding an applicable NOx, NMHC+NOx, CO or PM emission standard

(STD) is not eligible for NRCS payments, even if the engine certification values 

(CERT) are below the emission standards (STD). Only FEL values less than or 

equal to the emission standards are eligible.

Farm Bill: refers to the Food, Conservation and Energy Act of 2008.

Forklift: Applicability to this practice standard includes electric Class 1 or 2 rider trucks, 

large spark-ignition engine powered Class 4, 5 or 6 rider trucks, and compressionignition Class 7 rough-terrain forklifts as defined by the Industrial Truck Association 

and Occupational Safety and Health Administration (OSHA). Electric Class 3 trucks

are not forklifts for the purposes of this practice standard.

Gross Horsepower (ghp): for purposes of Practice Code 372, the maximum gross 

horsepower will be considered to be equivalent to the rated break horsepower only 

when bhp information is not available.

Gaseous Fuel: a fuel that is a gas under standard conditions, including but not limited 

to: natural gas, methane, propane, butane, bio-gas, and liquefied petroleum gas.

Independent Source Test Contractor: a program administered by the ARB that 

approves private independent source testing contractors to conduct required 

compliance emissions verification testing. Source operators may select from a list of 

contractors. The ARB does not require that testing contractors be approved prior to 

conducting testing in California; however, approval is required if the contractor 

wishes to conduct source testing for compliance verification. 

A list of contractors is available at: www.arb.ca.gov/ba/icp/current.pdf.

Internal Combustion Engine (IC Engine): any spark- or compression-ignited 

reciprocating engine.
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 7

December 30, 2011

Updated May 2, 2012

Mobile Source Certification: new motor vehicles and engines are certified by the ARB 

for emission compliance before they are legal for sale, use, or registration in 

California. Certification is granted annually to individual engine families and valid for 

one model year. Certifications are described through ARB Executive Orders, which 

are posted on-line at: www.arb.ca.gov/msprog/offroad/cert/cert.php

National Air Quality Initiative: refers to 2008 Farm Bill [16 USC 3839aa-8, Sec 1240H 

– “Conservation Innovation Grants and Payments”, Part (b) – “Air Quality Concerns 

from Agricultural Operations”], which provides payments to producers using 

innovative technologies and cost-effective methods to address air quality concerns.

National Air Quality Initiative Eligible Counties: counties or areas within counties 

designated by the EPA as “nonattainment” of the NAAQS for a given pollutant are 

eligible for funding under the National Air Quality Initiative. These counties are:

Alameda, Amador, Butte, Calaveras, Contra Costa, El Dorado, Fresno, Imperial, 

Inyo, Kern, Kings, Los Angeles, Madera, Marin, Mariposa, Merced, Mono, Napa, 

Nevada, Orange, Placer, Riverside, Sacramento, San Bernardino, San Francisco, 

San Diego, San Joaquin, San Mateo, Santa Clara, Solano, Sonoma, Stanislaus, 

Sutter, Tulare, Tuolumne, Ventura, Yolo, and Yuba.

Nonattainment Area: a geographic area identified by the EPA as not meeting the

National AAQS and/or identified by the ARB as not meeting the California AAQS 

standards for a given pollutant.

EPA maintains a list of federally designated nonattainment areas for criteria air 

pollutants on-line at: http://www.epa.gov/oar/oaqps/greenbk/ancl.html.

Non-Methane Hydrocarbon (NMHC): The sum of all hydrocarbon air pollutants, except

methane.

NOx: a general designation pertaining to compounds of nitric oxide (NO), nitrogen 

dioxide (NO2) and other oxides of nitrogen. NOx is typically created during the 

combustion processes and are major contributors to ozone formation and acid 

deposition. NO2 causes adverse health effects, is a criteria air pollutant and a major 

component in smog formation. This designation does not include nitrous oxide 

(N2O), which is designated as a greenhouse gas.

Off-Road Compression-Ignition Equipment: mobile equipment that cannot be 

registered and driven safely on a road or was not designed to be driven on a road. 

Newer equipment use engines certified by the ARB to the off-road compressionignition or diesel engine standards and used to self-propel the vehicle.

Off-Road Spark-Ignited Equipment: mobile equipment that cannot be registered and 

driven safely on-road or was not designed to be driven on-road. Newer equipment 
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 8

December 30, 2011

Updated May 2, 2012

use engines certified by the ARB to the off-road spark ignition engine standards and 

used to self-propel the vehicle.

Ozone: a form of molecular oxygen that consists of three oxygen atoms linked together 

(O3). Ozone in the upper atmosphere occurs naturally and protects life on earth by 

filtering out ultraviolet radiation from the sun. However, ozone at ground level is a 

noxious pollutant that causes numerous adverse health effects, is a criteria pollutant 

and the major component of smog. Ozone is not emitted directly, but is formed in 

the atmosphere through a complex chemical reaction involving hydrocarbons, oxides 

of nitrogen, and sunlight. Problematic ozone levels occur most frequently on hot 

summer afternoons. 

Ozone Precursors: chemicals involving reactive hydrocarbons and oxides of nitrogen, 

occurring either naturally or as a result of human activities, contribute to the 

formation of ozone.

PM: a general designation pertaining to particulate matter emissions. PM2.5 has an 

aerodynamic diameter equal to or less than 2.5 microns and PM10 has an 

aerodynamic diameter equal to or less than 10 microns as measured by the 

applicable State and Federal reference test methods. Their small size allows them 

to make their way to the air sacs deep within the lungs where they may be 

deposited, resulting in adverse health effects. PM also causes visibility reduction and 

contributes to regional haze.

Portable Agricultural Engine: an internal combustion engine designed and capable of 

being carried or moved from one location to another, does not propel a vehicle, and 

is used in the production of crops or the raising of fowl or animals. Portable engines 

operate similar to stationary engines by providing power to stationary components, 

such as irrigation wells or emergency electrical energy. Portable engines are 

generally not designed to operate while being moved from one location to the other.

Indicators of portability include: wheels, skids, carrying handles, dolly, trailer, or 

platform.

Power Take-Off Horsepower: is the “usable” horsepower measurement at the power 

take-off (PTO) shaft’s output and is the power available for tractor attachments and 

implements. For purposes of Practice Code 372, situations where the horsepower 

of an existing engine cannot be determined from an engine label, manual, or engine 

records, the engine horsepower can be estimated by multiplying the PTO 

horsepower value by 1.15.

Estimated HPExisting Engine = PTO HPExisting Engine x 1.15

Rated Brake Horsepower: the continuous brake horsepower rating specified for the 

engine by the manufacturer or listed on the nameplate of the unit without regard to 
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any de-rating or modification. For Practice Code 372, this value is the basis for

determining engine eligibility and payment rate.

Retrofit: the installation of an ARB-verified emission control system on an existing 

engine. Examples include, but are not limited to, diesel particulate filters and catalyst 

systems on spark-ignited engines. 

Verified technologies for diesel engines are posted on-line at: 

www.arb.ca.gov/diesel/verdev/vt/cvt.htm.

Rebuilt or remanufactured: engines offered by the original engine manufacturer 

(OEM) or by a non-OEM rebuilder who demonstrates to the ARB that the rebuilt 

engine and parts are functionally equivalent from an emissions and durability 

standpoint to the OEM engine and components being replaced.

Reactive Organic Gas (ROG): sometimes referred to as non-methane hydrocarbons 

(NMHC), a photo-chemically reactive chemical gas composed of non-methane 

hydrocarbons that may contribute to ozone formation. 

Rough Terrain Forklift: Class VII forklifts powered by compression-ignition engines

and equipped with pneumatic tires that handle uneven surfaces. Such forklifts

include straight-mast and extended-reach forklifts.

Spark-Ignition Internal Combustion Engine: a liquid or gaseous fueled engine 

designed to ignite its air/fuel mixture by a spark across a spark plug. These engines 

may operate on gasoline, natural gas, propane, or bio-fuel. Engines that consume 

dairy digester gas for electric generation are most likely spark-ignition engines.

State Implementation Plan (SIP): comprehensive plans describing how an area will 

attain the NAAQS. The 1990 federal Clean Air Act amendments establish 

attainment deadlines based on the severity of an area’s air pollution problem. In 

California, SIPs are multiple documents where the ARB is the lead agency for all 

purposes related to California’s SIP. Local air districts, the California Bureau of 

Automotive Repair, and the California Department of Pesticide Regulation each 

prepare SIP elements that are submitted to ARB for review and approval. The ARB 

forwards SIP revisions to the EPA for approval and publication in the Federal 

Register. All SIP elements are referenced in Code of Federal Regulation Title 40, 

Chapter 1, Part 52, Subpart F, Section 52.220.

Stationary Agricultural IC Engine: an internal combustion engine attached to a 

foundation, designed to remain and operate at a single location, and used in the 

production of crops or the raising of fowl or animals. May include engines residing at 

the same location for specified periods of time (longer than six months or one year)

or are used as backup to replace another engine at a location that is intended to

perform the same or similar function.
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Tier 1, Tier 2, Tier 3, and Tier 4 Engines (See Table 1 for the applicable Tier 

schedule):

(1) an EPA-certified compression-ignited engine that meets the Tier 1, Tier 2, or Tier 

3 emission standards of Table 1 on page 56970 of the Final Rule (October 23, 

1998) or the Tier 4 emission standards of Table II.A.2 (Tier 4 NOx and NMHC 

Standards and Schedule) on page 38971 of the Final Rule (June 29, 2004) or 

Table II.A.4 (Tier 4 Standards for Engines Over 750 HP (G/BHP-HR)) on page 

38980 of the Final Rule (June 29, 2004), respectively.

(2) An ARB-certified compression-ignited engine that meets the standards according 

to Title 13, Section 2423(b)(1)(A) and/or Title 40, CFR, Part 89.112(a) of the 

California Code of Regulations. Tier 4 engines that are subject to the interim or 

final after-treatment based Tier 4 emission standards in Title 13, Section 

2423(b)(1)(B) and/or Title 40, Part 1039.101 of the California Code of 

Regulations. This also includes engines certified under the averaging, banking, 

and trading program with respect to the Tier 1, 2, and 3 Family Emission Limits 

(FEL) listed in Title 13, Section 2423(b)(2)(A) and/or Title 40, Part 89.112(d) of 

the California Code of Regulations and to the Tier 4 FEL listed in Title 13 Section 

2423(b)(2)(B) and/or Title 40, Part 1039.101 of the California Code of 

Regulations

Toxic Air Contaminant (TAC): an air pollutant, identified in regulation that may cause 

or contribute to an increase in deaths or in serious illness, or which may pose a 

present or potential hazard to human health. TACs are considered under a different 

regulatory process than that of criteria pollutants. 

Uncontrolled Compression-Ignition Engine: also referred to as “Tier 0”, is any diesel 

engine not meeting any established Tier emission standard. Generally, these are 

engines manufactured:

1999 and earlier: >750 hp

1998 and earlier: 25-49 hp

1997 and earlier: 50-99 hp

1996 and earlier: 100-174 hp

1995 and earlier: 175-750 hp

Volatile Organic Compounds (VOCs): many definitions describe VOCs, but are 

primarily organic, carbon-containing compounds having high enough vapor pressure 

under normal conditions to vaporize into the atmosphere. VOCs defined in a legal or 

regulatory concept are carbon compounds that contribute to the formation of ozone, 

as many VOCs are exempt from regulation. For example, methane is a VOC that 

has little to do with the formation of ozone, but is designated a greenhouse gas. 

VOCs by themselves may also be classified as toxic air contaminants (TAC’s). 
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Other terminology describing the photo-reactivity of VOC includes Non-Methane 

hydrocarbons (NMHC); Reactive Organic Gases (ROG); and Total Organic Gases

(TOG).
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Section 2: Stationary Heavy-Duty Engines

This category primarily refers to stationary (engines bolted to a foundation or concrete 

slab) or portable (including engines mounted on a trailer or skid, and auxiliary engines 

on mobile equipment yet not drive a vehicle) engines. This section does not apply to 

engines that propel mobile vehicles, including vehicles used at a stationary site (such as 

a tractor powering an irrigation gear-head or pump via a power take-off). The majority 

of stationary heavy-duty engines used in agriculture are for crop irrigation.

The California Air Resource Board (ARB) established emission standards and 

requirements that regulate the sale, purchase, rental, lease, and operation of diesel 

engines, including stationary and portable equipment used exclusively in agriculture. In 

addition, an Air Pollution Control District (APCD) or Air Quality Management District 

(AQMD) may impose emission standards through a rule or require permits with 

emission limits that may be more restrictive than required by the ARB. It is 

recommended that the participant consult with the local APCD or AQMD to determine 

permitting and emissions requirements prior to seeking assistance from the NRCS.

The ARB and several California air districts have established compliance deadlines to 

phase-out the continued use of old compression-ignition stationary engines, primarily 

Tier 0 diesel engines. Unless exempted, these engines are no longer allowed to 

operate once a deadline has passed and replacing them will not provide any real 

emission reductions since continued operation would likely result in excess emissions. 

Therefore, repowering engines subject to compliance deadlines will not result in any 

credible emission reductions.

Only engine repowers are eligible for payment under this category. Also eligible are 

retrofits or add-on control devices. Payments for equipment replacements do not apply 

to stationary, portable, or auxiliary engines. New electric motor installations are also 

eligible for payments under this category.

Program Requirements

New electric motor for a new irrigation well site:

Participants are encouraged to install new electric motors or electric technology in lieu 

of installing internal combustion engines.

A) The project must be a new well installation and not a pre-existing well.

B) The new motor must be rated at least 25 horsepower (19 kilowatts). Electric 

motors rated at less than 25 hp are not eligible for new installations.

C) The participant must provide information whether an adequate electric power 

supply is at the site or provide documentation from the local utility company for 
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power installation. Infrastructure and installation costs associated with the new 

electric motor are ineligible for funding.

D) Electric motors installed at pumping plants must adhere to Practice Code 533, 

Pumping Plant guidelines, where applicable. An engineering analysis may be 

required.

Existing Engines:

A) Existing engines must be situated in its operating location, connected to the 

equipment it powers (wellhead, booster trailer, or auxiliary engine on harvesting 

equipment), and in operational condition.

B) The existing engine must be rated at 50 bhp (37 kilowatts) or more. Engines 

rated at less than 50 bhp are not eligible.

C) An operation outfitted with an uncontrolled (Tier 0), Tier 1- or Tier 2-certified 

diesel engine will be repowered with one of the following:

A new electric motor; or

A new off-road Tier-certified diesel engine meeting the most current model 

year ARB/EPA emission standards or local air district emission and permitting 

requirements (as applicable).

D) An operation outfitted with an emissions-controlled spark-ignition engine will be

repowered with one of the following:

A new electric motor, or

A new spark-ignited engine certified to the current ARB applicable emission 

standards or local air district emission and permitting requirements (as 

applicable).

E) Existing engines may operate on diesel fuel, gaseous fuels, gasoline, or 

renewable fuels (such as bio-diesel, bio-fuel, or bio-gas).

F) Existing spark-ignition engines cannot be replaced with new diesel engines.

G) Any mobile off-road agricultural, construction, or on-road vehicle powering an 

irrigation gear-head or pump are not eligible under this section.

H) The participant must own and operate the existing equipment in California for at

least the past 12 months.

I) The participant must complete the supplemental application form that includes 

the existing engine manufacturer, fuel-type, model year, serial number. 
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Complete all required fields in the supplemental application, as leaving fields 

blank may prolong the application process.

J) Unless specifically exempted, uncontrolled (Tier 0) diesel stationary engines are 

no longer permitted by the ARB and/or air district to operate in California. Any

proposed project replacing applicable engines will no longer result in emission 

reductions.

Replacement with New Engines or Electric Motors:

A) The new replacement engine is rated at least 50 bhp (37 kilowatts).

B) The new replacement electric motor is rated at least 25 horsepower (19 

kilowatts), provided that the bhp rating of the existing engine is rated not less 

than 50 bhp. The applicant shall provide documentation that the lower hp is 

necessary and conforms to Practice Code 533, Pumping Plant. An engineering 

analysis or appropriate justification for reducing hp is required. The participant 

must provide information whether an adequate electric power supply is at the site 

or provide documentation from the local utility company for power installation. 

C) The new replacement engine and equipment must be a new Original Equipment 

Manufacturer (OEM) engine certified by the ARB for sale in California, certified 

for the current model year standards, and meet the most recent model year 

emission standards and/or emissions standards established by the local Air 

district, as applicable. 

D) Repowering to a Tier-1 or Tier-2 certified diesel engine is not eligible.

E) Once in operation, the engine and equipment must be used exclusively in 

California.

A) The certification emission standards and Tier designation must be determined 

from the California Air Resources Board Executive Order or EPA Certificate of 

Conformity (for federally preempted engines) issued for the specific engine. ARB 

Executive Orders for certified off-road engines are posted on-line at: 

http://www.arb.ca.gov/msprog/offroad/cert/cert/php.

F) Engines where an ARB Executive Order specifies a Family Emission Limit (FEL) 

that exceeds the applicable emission standards are not eligible for NRCS 

payments. Only FEL values at or lower than the applicable emission standards 

are eligible.

G) Spark-ignited engines must meet or exceed the applicable emission standards 

established by the ARB or local Air district, whichever is more stringent.
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H) The horsepower rating of the replacement equipment engine must be within 

125% of the original manufacturer rated bhp (baseline) for the old equipment 

engine. If the horsepower rating of the new engine is greater than 125% of the 

existing engine, the participant must provide sufficient information for the 

increase in horsepower that will be evaluated on a case-by-case basis. If the 

information provided is not approved, the maximum eligible payment will be

capped at the hp rating of the existing engine and not the hp rating of the new 

engine.

I) IC engines or electric motors installed at pumping plants must adhere to Practice 

Code 533, Pumping Plant guidelines, where applicable. An engineering analysis 

may be required.

J) The replacement engine must report at least a 15% NOx reduction and no 

increase in particulate matter emissions, compared with the applicable standards 

or emission levels for that engine year and type of application through ARB 

Certification Testing, EPA Certification Testing, or emissions testing at a 

laboratory approved by the EPA or ARB.

K) The participant must possess an approved “Registration” or an “Authority to 

Construct” from the local air district prior to installation, if a registration or permit 

is required.

L) The ARB or local air district may require an emissions source test on the new 

engine depending on the conditions specified on an applicable Authority to 

Construct or Permit to Operate. Source testing using accepted testing protocols 

must be completed by an ARB-certified independent contractor to the satisfaction 

of the ARB or local air district before NRCS payments will be provided. The 

costs associated with source tests or monitoring requirements are not eligible for 

payments. A list of approved independent contractors is posted on the Internet 

at: www.arb.ca.gov/ba/icp/current.pdf

M) The participant must complete the supplemental application form for the new 

engine. If available, record the new engine manufacturer, fuel-type, model year, 

serial number. Complete all required fields in the supplemental application, as 

leaving fields blank may prolong the application process.

N) Future engine operational hours for determining emission reductions must be 

based only on readings from an installed and fully operational hour meter. The 

participant must maintain a record of annual hourly usage for life of the project by 

recording hours at the beginning and end of each calendar year. If the hourly 

meter is no longer functioning, it must be repaired or replaced as soon as 

possible at the participant’s cost. An alternative method for documenting 

equipment usage and emission reductions may be evaluated on a case-by-case 
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basis, including fuel usage logs. For electric motors, records from dedicated 

utility meters may be used.

O) For emissions calculations and cost effectiveness purposes, the project life is 10 

years.

Retrofits

Retrofit projects must install ARB-verified emission control systems meeting the 

following minimum standards:

A) For an uncontrolled diesel engine, the retrofit kit that must be verified to reduce 

NOx or NOx+NMHC (non-methane hydrocarbons) emissions to the applicable 

current Tier standard for a given engine type and size.

B) For an uncontrolled spark-ignited engine, the retrofit kit must be verified to 

reduce NOx+NMHC emissions to the currently applicable standards for sparkignited engines.

C) For an emission-certified (1996+ model year) diesel engine, the retrofit kit must 

be verified to reduce NOx or NOx+NMHC emissions by at least 15% from the 

applicable NOx or NOx+NMHC emission standard.

D) The retrofit kit to reduce PM must use the highest level ARB-verified technology 

available for the engine being retrofitted. 

A complete list of ARB-verified retrofits may be found via the Internet at: 

http://www.arb.ca.gov/diesel/verdev/verdev.htm.
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Section 3: Mobile Off-Road Agricultural Equipment

Equipment in this category includes: tractors, bailers, harvesters, combines, loaders, 

forklifts, and other agricultural off-road support equipment. These engines provide 

power to self-propel an off-road agricultural vehicle and do not include portable engines, 

auxiliary engines mounted on mobile equipment, or on-road mobile equipment.

Replacing engines on mobile off-road agricultural equipment is funded under the 

National Air Quality Initiative. 

Program Requirements

Existing Equipment:

A) The existing engine and equipment shall be fully functional and in operational 

condition to qualify. At a minimum:

(1) The tires are in usable condition (able to hold air, sufficient tread, etc.)

(2) Steering is operational

(3) The equipment is able to start-up and move backwards and forwards

(4) Buckets, blades, hydraulics, rollers, etc. are in working order

(5) Undercarriage is structurally sound

(6) Fuel tank is in usable condition

(7) No parts have been stripped

(8) Equipment has not been vandalized

B) The existing engine must power a mobile off-road agricultural vehicle, be rated at 

50 or more bhp, and used to self-propel the vehicle.

C) Engine Repowers: In-use mobile off-road agricultural equipment outfitted with:

(1) An uncontrolled (Tier 0), a Tier 1-, or a Tier 2-certified diesel engine and 

repowered with a new off-road Tier-certified diesel engine meeting the 

most current model year ARB/EPA emission standards; or

(2) A spark-ignited engine and repowered with a new spark-ignited engine 

certified to the current ARB emission standards. Existing spark-ignited 

engines cannot be replaced with new diesel-powered engines.

D) Equipment Replacement: Consultation with the equipment vendor and/or 

manufacturer may determine that certain equipment cannot accommodate an 

engine repower without performing major modifications, safety risks, or exorbitant 

costs. Where an engine repower is deemed infeasible, projects will apply to 

replacing mobile off-road agricultural equipment. Eligible projects are:
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(1) A tractor, loader, harvester, bailer, Class 7 rough-terrain forklift, or other 

self-propelled agricultural equipment outfitted with an uncontrolled (Tier 0),

Tier 1-, or Tier 2-certified diesel engine and replaced with equipment 

outfitted with the latest current model year Tier-certified diesel engine.

(2) An existing forklift equipped with a compression- or spark-ignition internal 

combustion engine is replaced with an electric-powered forklift. Eligible 

are new Class 1 electric forklifts with life codes 4, 5, or 6, rated with at 

least 3,000 pound lift capacity. Electric hand carts are not eligible, as 

these are not forklifts. 

Replacement:

A) The replaced engine shall be rated at least 50 bhp.

B) Existing equipment outfitted with spark-ignited engines cannot be replaced with 

new diesel-powered engines.

C) The new replaced engine and equipment must be a new Original Equipment 

Manufacturer (OEM) engine certified by the ARB for sale in California, certified 

for the current model year standards, and meet the most recent model year 

emission standards and/or emissions standards established by the local Air 

district, as applicable. Once in operation, the engine and equipment must be 

used exclusively in agriculture within California.

D) The certification emission standards and Tier designation must be determined 

from the California Air Resources Board Executive Order or EPA Certificate of 

Conformity (for federally preempted engines) issued for the specific engine. ARB 

Executive Orders for certified off-road engines are posted on-line at:

http://www.arb.ca.gov/msprog/offroad/cert/cert/php.

E) Engines where an ARB Executive Order specifies a Family Emission Limit (FEL) 

that exceeds the applicable emission standards (STD) are not eligible for NRCS 

payments. Only FEL values equal to or lower than the emission standards are 

eligible.

F) An engine repower may include a new Original Equipment Manufactured (OEM),

remanufactured, or an ARB-certified/recertified rebuilt off-road engine meeting 

the latest California emission standards. 

G) Spark-ignition engines must meet the application emission standards established 

by the ARB.
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H) Replacement equipment must serve the same function and perform the same 

work equivalent as the existing equipment. Replacements intended to account 

for increases in production are not eligible. Acceptable examples are:

(1) Replacing a loader with another loader or a tractor for another tractor; or,

(2) Replacing different types of equipment that will perform similar functions,

improve operations efficiency, and reduce emissions (such as replacing a 

tracked dozer used for disking with a wheeled tractor that will perform the 

same work).

This requirement may be waived on a case-by-case basis where general 

purpose farming equipment changes commodities.

I) The horsepower rating for the new, replacement equipment engine shall not be 

greater than 125% of the original manufacturer rated brake horsepower 

(baseline) for the existing equipment engine. In limited situations, this 

requirement may be waived if the horsepower increase results in cost-effective 

and significant annual emission reductions. The participant must document that 

the replacement equipment will serve the same function and perform the same 

job as the old equipment. Requests for waivers will be evaluated on a case-bycase basis for the following:

(1) The original horsepower range is not available for the existing engine.

(2) The higher horsepower is required where the existing equipment is 

replaced by another type of equipment that will perform the same work, 

improve operations efficiency, and reduce emissions (i.e. tracked dozer to 

wheeled tractor for disking).

(3) The higher horsepower replacement equipment is the result of 

implementing a conservation system.

J) Equipment is in new condition, has not been sold or associated with any rental or 

lease agreement, and has less than 100 operating hours recorded on a 

permanently mounted non-resettable hour meter.

K) The replacement engine must report at least a 15% NOx reduction and no net 

increase in particulate matter emissions, compared with the applicable standards 

or emission levels for that engine year and type of application through ARB 

Certification Testing, EPA Certification Testing, or emissions testing at a 

laboratory approved by the EPA or ARB.

L) The participant is to maintain a record of new engine and equipment usage for at 

least the first five years of operation. Hours of operation may be accomplished 
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by recording the readings from a fully operational hour meter at the beginning 

and end of each year.

M) For electric equipment, the participant must include a description whether battery 

chargers have been installed. The participant shall describe the number of the 

battery chargers installed or to be installed.

N) At this time, replacement with zero-emissions equipment other than electric (i.e. 

fuel cell equipment) is not eligible for payments.

O) The 372 Practice Standard project life is 15 years; however a 10-year life will be 

used for calculating emissions and cost effectiveness. A cost effectiveness 

evaluation of the estimated emission reductions may be performed on a case-bycase basis using criteria similar to those specified in California’s Carl Moyer 

program. The evaluation will determine whether the cost of replacing an engine 

and/or equipment significantly exceeds the emission reduction benefits. 

Replacing More Than One Existing-Equipment for New Equipment:

Significant air quality benefits can result if the new equipment is replacing more than 

one existing-equipment. All existing and new equipment must meet the eligibility 

requirements and are reviewed on a case-by-case basis. Not more than three existing 

units may be considered for the replacement of one unit.

Replacing up to three equipment units with one new unit is not intended as a means to 

increase the horsepower rating determination for the new engine or equipment, as any 

increase in horsepower of the new engine is limited to 125% of the baseline horsepower 

rating of the existing engine. The intent is to allow for additional emission reduction 

benefits by permanently retiring additional equipment earlier than through normal 

attrition, which might improve the final ranking scores for application prioritization.

A) The emission benefits are determined by subtracting the estimated annual 

emissions from the new replacement engine from the sum of the annual 

emissions from the two or three subject existing engines.

B) To be eligible, the new equipment must serve the same function and perform 

similar work as one of the existing equipment it’s replacing. The other existing 

equipment may be different in type or perform functionality different to the new 

equipment.

C) The horsepower rating for the new, replacement equipment engine shall not be 

greater than 125% of the original manufacturer rated brake horsepower 

(baseline) for the similar function engine. The greatest hp rating of the existing 

engines may be used as the baseline hp. The hp from other existing equipment 
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that differ in type or function to the new equipment shall not be used for 

determining the baseline hp. 

D) The summed emission reductions are used for ranking purposes. HP shall not 

be summed for determining a baseline hp rating for determining the maximum 

new engine hp limit.

E) Examples include the following:

(1) An existing 92 hp 1979 tractor that operates 500 hours/year is retired for a 

new 105 hp Tier 3 tractor that also plans to operate about 500 hours/year.

In addition, a 150 hp 1985 loader that operates 800 hours/year will be 

retired. In this example, the 92 hp tractor is used as the baseline hp rating 

(i.e. like for like), limiting the maximum hp rating of the new equipment to 

115 hp (92 hp x 125%). The NOx emissions are:

Sum of existing engine emissions = 1.17 tons NOx/year

1979: 0.43 tons = {(92 hp x 12.09 g/bhp-hr x 500 hrs/yr x 0.70)/907,200}

1985: 0.74 tons = {(150 hp x 10.23 g/bhp-hr x 800 hrs/yr x 0.55)/907,200}

New engine emissions = 0.09 tons NOx/year

Tier 3: 0.09 tons = {(105 hp x 2.32 g/bhp-hr x 500 hrs/yr x 0.70)/907,200}

Total NOx emission reductions = 1.08 tons/yr (92% NOx reduction)

(2) An existing 152 hp 1981 loader that operates 500 hours/year and an 

existing 125 hp 1975 loader that operates 900 hours/year will be retired for 

a new 160 hp Interim Tier 4 Phase-in loader that plans to operate about 

700 hours/year. In this example, despite which equipment is directly 

replaced with the new, the maximum hp of the two like equipment may be 

applied as the baseline hp rating, thus limiting the maximum hp rating of 

the new equipment to 190 hp (152 hp x 125% = 190 hp). Applying the 125 

hp engine instead would have limited the hp rating of the new to 156 hp, 

but because 160 hp is within the 125% of the highest rated hp, this project 

is eligible. The NOx emissions are:

Sum of the existing engines emissions = 1.23 tons NOx/year

1981: 0.47 tons = {(150 hp x 10.23 g/bhp-hr x 500 hrs/yr x 0.55)/907,200}

1975: 0.76 tons = {(125 hp x 11.16 g/bhp-hr x 900 hrs/yr x 0.55)/907,200}

New engine emissions = 0.15 tons NOx/year

Tier 4-I: 0.15 tons = {(160 hp x 2.15 g/bhp-hr x 700 hrs/yr x 0.55)/907,200}

Total NOx emission reductions = 1.08 tons/yr (88% NOx reduction)
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(3) A single piece of equipment may utilize more than a single engine 

mounted on the unit. Such equipment outfitted with multiple engines 

operate together to perform a single function or task (such as a PTO on 

the propulsion engine plus a dedicated auxiliary engine). The horsepower 

from each engine may be summed to determine the overall existing 

horsepower baseline since this is the total hp needed to perform the 

function. However, hours of operations for each engine will differ since 

one engine is used to propel the equipment while the auxiliary engine is 

shut down. In this example, the total emissions calculated from each 

engine may be summed. The total maximum horsepower ratings for the 

new replacement equipment shall not exceed 125% of the summed 

horsepower of the existing equipment, even if the new equipment is 

outfitted with multiple engines. However, such proposals might result in 

the purchase of new equipment outfitted with a single engine.

F) All existing engines and equipment used to achieve these emission benefits must 

be destroyed.

Retrofits

Retrofit projects must install ARB-verified emission control systems meeting the 

following minimum standards:

A) For an uncontrolled diesel engine, the retrofit kit that must be verified to reduce 

NOx or NOx+NMHC (non-methane hydrocarbons) emissions to the applicable 

current Tier standard for a given engine type and size.

B) For an emission-certified (1996+ model year) diesel engine, the retrofit kit must 

be verified to reduce NOx or NOx+NMHC emissions by at least 15% from the 

applicable NOx or NOx+NMHC emission standard.

C) The retrofit kit to reduce PM must use the highest level ARB-verified technology 

available for the engine being retrofitted. 

A complete list of ARB-verified retrofits may be found via the Internet at: 

http://www.arb.ca.gov/diesel/verdev/verdev.htm.
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Section 4: Engine and Equipment Destruction

Engine and equipment destruction must be performed in a safe manner that avoids any 

risks to personal safety.

Personal Safety always comes first.

After being replaced, the existing engine and mobile off-road agricultural equipment

must be destroyed. Destruction removes the existing high-emitting engines and 

equipment from service and ensures that the emission reductions are real and 

permanent. It also prevents the old engine and equipment from being rebuilt or moved 

into another locale to continue emitting high levels of pollutants. Therefore, destruction 

includes the engine, drive-train and vehicle structural components, which shall not be 

recycled to be used as parts where they may prolong the life of other engines or 

vehicles, or used to rebuild equipment for continued use.

Under certain circumstances, an existing Tier 2-certified diesel engine may be relocated 

and used to replace an uncontrolled Tier 0 or Tier 1-certified diesel engine. The 

replaced existing engine and equipment must then be destroyed.

Procedures for disabling and rendering engines and equipment permanently inoperable:

(A) Prior to disabling the engine and equipment, the existing engine and equipment 

must be in operable working condition.

(B) After being replaced, the existing engine must be physically disabled in such a 

manner to eliminate the possibility of future use. At a minimum, the old engine 

block must be punctured with at least a six inch diameter hole to include a portion 

of the oil pan rail (sealing surface).

(C) The structural components on mobile equipment must be physically 

compromised. At a minimum, this shall be accomplished by cutting the vehicle 

frame railings in half or by destroying bell-housing and transmission components 

if not equipped with a frame. 

(D) The disabled engine and equipment shall be permanently destroyed and 

disposed of at a dismantling facility approved by the NRCS. The approved 

dismantler has the equipment to and will scrap the engine and equipment 

components either by shearing, crushing, or shredding. Disabled engines or 

equipment shall not be transported outside of California for final destruction, but 

may leave the state once it has been permanently destroyed and scrapped.

(E) The producer shall provide the NRCS with a written certification that the engine 

and associated equipment has been permanently destroyed. If destruction was 

performed by an approved dismantler, the dismantler will provide the producer 
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 24

December 30, 2011

Updated May 2, 2012

with the written certification for submittal to the NRCS. The certification shall 

describe:

The existing engine and equipment type, 

The existing engine serial number and equipment vehicle identification 

number, 

The date the existing engine and equipment were compromised, 

Provide a description on how the existing engine and equipment were 

destroyed, and

Provide date-stamped photographs that include visible images of the engine 

serial number and vehicle identification numbers.

The certification must also specify that no parts or components were or will be 

parted-out, used or sold as parts, or used to rebuild an engine or equipment that 

was intended for destruction.

(F) NRCS staff may follow-up with a site visit to verify engine and equipment 

destruction. Additional destruction procedures may also be directed to assure 

destruction.

(G) It should be recognized that this certification is intended for NRCS contracts only. 

Using NRCS documents for other incentive programs may not be transferable.
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 25

December 30, 2011

Updated May 2, 2012

Section 5: Applications, Instructions, and Certifications

Several documents have been developed to assist the participant and NRCS staff.

(A) Supplemental Applications:

The participant must complete and attach the two supplemental applications

along with the CPA-1200 and the other program forms. The information provided 

will be used for determining priority and ranking for funding and payment 

eligibility purposes. In addition, the participant may attach maintenance records, 

receipts, ARB Executive Orders, estimates, or any additional information 

requested by NRCS staff. A complete application will take less time to process.

The following supplemental applications are:

1. Existing Engine Information

2. New Engine Information

(B) Destruction Certification:

The participant must provide a written certification that the existing engine and (if 

applicable) existing equipment equipped with the existing engine have been 

destroyed. The certification must specify that no parts or components were or 

will be parted-out, used or sold as parts, or used to rebuild an engine or 

equipment that was intended for destruction.

(C) Emissions Reduction Calculations:

The attached worksheet is used for calculating the emission benefits associated 

with the proposed projects. A ranking calculator developed by Jon Chilcote of 

the NRCS Fresno Field Office can be used to generate a completed emissions 

calculation form. The emission factors provided through the State of California 

“Carl Moyer Memorial Air Quality Standards Attainment Program” guidelines are 

used for estimating emissions.
December 30, 2011

Updated May 2, 2012

Environmental Quality Incentives Program (EQIP)

CALIFORNIA SUPPLEMENTAL APPLICATION 2012

Air Quality - Combustion System Improvement

Agricultural Producer Name:

Existing Engine Information

Complete a separate form for each existing engine or equipment

Describe the type of equipment the existing engine powers:

Irrigation Engine Tractor Loader Harvester Forklift Other:

Report the total acres this engine serves: Years operated on these acres:

Primary Fuel Type

(check one):

Diesel

Biodiesel

Natural Gas

LPG

Biogas

Other: 

Engine Type

(check one):

Non-Tier Diesel 

Tier 1 

Tier 2 

Spark Ignited

Other:

Verified Retrofit Technology: 

No retrofits have been installed on the existing engine

The existing engine is equipped with the following equipment:

Manufacturer:

Model:

Verification Level: Level 1 Level 2 Level 3

Verified Emission Reductions:

ROG: % NOx: % PM: %

Engine Manufacturer and Model No:

EPA Engine Family:

(If applicable –

required for Tier 1 or Tier 2 diesel)

Max Rated Brake HP:

Engine Year: Annual fuel usage:

Engine Serial No: Annual hours of operation:

Equipment Manufacturer & Model:

Equipment VIN No:

Equipment Model Year: Year Purchased:

Name of Equipment Owner:

Months in Operation: January February March

April May June

Operates throughout the year July August September

October November December

Planned location on where engine/equipment will be scrapped and destroyed:

(not applicable if retrofitting an existing engine)

Additional Information:
December 30, 2011

Updated May 2, 2012

Instructions

Existing Engine Information

1. Complete a separate form for each existing engine or equipment.

2. Describe the type of equipment the existing engine powers: This may include an irrigation pump, 

loader, tractor, combine, harvester, forklift, etc. 

3. Report the annual total acres this engine serves: Estimate the annual total acres of cropland this 

engine irrigates or the annual total acres the mobile equipment operates on.

4. Years Operated at this location: Approximate length of time the existing engine or equipment has 

been operating at this location.

5. Primary Fuel Type: Only select the primary fuel the engine consumes. 

6. Engine Type: Select the type of existing engine (i.e. Non-Tier Diesel). Please consult your engine 

vendor.

7. Verified Retrofit Technology: If applicable, describe the manufacturer, model, ARB-Verification 

Level, and the emission reductions associated with the installed technology. Attach documentation, 

including the applicable ARB Executive Order. This information should be available through your 

engine vendor or on-line at: www.arb.ca.gov/diesel/verdev/vdb/vdb.php.

8. Engine Manufacturer and Model No: Make and model number of the existing engine. For example, 

Cummins (make) 6BTA5.9C (model). Please do not report the Equipment Model Number here.

9. EPA Engine Family: Required for Tier-certified engines. Include the certified engine family name 

assigned by the EPA and attach the applicable ARB Executive Order for this engine. This information 

should be available through your engine vendor or is on-line at: 

www.arb.ca.gov/msprog/offroad/cert/cert.php. 

10. Engine Year: The year the engine model was manufactured.

11. Engine Serial No.: The serial number listed on the engine block or ID label.

12. Max Rated Brake HP: Identify the engine break horsepower rating.

13. Annual Fuel Usage: Amount of annual fuel usage in gallons.

14. Annual Hours of Operation: Engine’s annual operation in hours. 

15. Equipment Manufacturer and Model: The make and model number of the equipment. For 

example, a Case (make) 721 (model). This number is not the engine model number.

16. Equipment VIN: The equipment Vehicle Identification Number.

17. Equipment Model Year: The model year in which the equipment was manufactured.

18. Year Purchased: The year the equipment was purchased.

19. Name of Equipment Owner: Identify equipment ownership.

20. Months in Operation: Select whether the engine operates throughout the year or by month.

21. Planned location where engine/equipment will be scrapped and destroyed: Identify where the 

engine/equipment is planned to be taken for final disposal and destruction. No engine, drive-train or 

equipment components shall be recycled as used parts that might prolong the life of other engines 

and equipment.

22. Additional Information: Include any additional information pertinent to this engine/equipment, 

including applicable permits or documentation issued by a local air district.
December 30, 2011

Updated May 2, 2012

Environmental Quality Incentives Program (EQIP)

CALIFORNIA SUPPLEMENTAL APPLICATION 2012

Air Quality – Combustion System Improvement

Agricultural Producer:

New Engine Information

Verified Technology Retrofit Installation

Complete a separate form for each engine or equipment

Describe the type of equipment the new engine will power:

Irrigation Engine Tractor Loader Harvester Forklift Other:

Report the total acres this engine will serve:

Primary Fuel Type

(check one):

Diesel

Biodiesel

Natural Gas

LPG

Biogas

Electric

Other:

Engine Type

(check one):

Tier 3 

Tier 4 Interim

Tier 4 Final

Spark Ignited

Electric

Other:

Verified Retrofit Technology: 

No retrofits are proposed for the new engine

Propose to install the following retrofit on the existing engine:

Propose to install the following retrofit on the new engine:

Manufacturer:

Model:

Verification Level: Level 1 Level 2 Level 3

Verified Emission Reductions: 

NOx: % PM: % ROG: %

Engine Manufacturer and Model:

EPA Engine Family:

(attach ARB Executive Order)

Max Rated Brake HP:

Engine Year Annual Fuel Usage:

(Estimate)

Engine Serial Number

(if available)

Annual Hours of Operation:

(Estimate)

Equipment Manufacturer and Model:

Equipment VIN No:

(if available)

Equipment Model Year:

Months in Operation: January February March

April May June

Operates throughout the year July August September

October November December

Cost of New Engine and/or Equipment :

(Attach an estimate)

Cost to Retrofit:

(Attach an estimate)

Describe the fuel source (i.e. location of fuel storage and dispensing system, battery recharging station, etc.):

Additional Information (May include documentation from the vendor regarding repower solutions or equipment limitations): 
December 30, 2011

Updated May 2, 2012

Instructions

New Engine Information

Verified Technology Retrofit Installation

1. Complete a separate form for each new engine or equipment.

2. Describe the type of equipment the new engine will power: This may include a tractor, irrigation 

pump, forklift, loader, etc. 

3. Report the annual total acres this engine will serve: Estimate the annual total acres of cropland 

this engine will irrigate or the annual total acres the mobile equipment will operate on.

4. Primary Fuel Type: Only select the primary fuel the engine consumes. 

5. Engine Type: Select the type of engine (i.e. Tier 3). Please consult your engine vendor.

6. Verified Retrofit Technology: Will retrofit technology be installed on the new or existing engine? If 

yes, include the manufacturer, model, ARB-Verification Level, and the associated emission 

reductions with the installed technology. Attach documentation, including the applicable ARB 

Executive Order. This information should be available through your engine vendor or on-line at: 

www.arb.ca.gov/diesel/verdev/vdb/vdb.php.

7. Engine Manufacturer and Model No: Make and model number of the new engine. For example, 

IVECO (make) F4GE9484D*J (model). Please do not report the Equipment Model Number here.

8. EPA Engine Family: Required by including the certified engine family name assigned by the EPA

and attaching the applicable ARB Executive Order for this engine. This information should be 

available through your engine vendor or is on-line at: www.arb.ca.gov/msprog/offroad/cert/cert.php. 

Any ARB Executive Order reporting a Family Emission Level (FEL) value exceeding an applicable 

NOx, NMHC+NOx, CO, or PM emission standard is not eligible for NRCS payments. 

9. Engine Year: The year the engine model was manufactured.

10. Engine Serial No.: If available, include the serial number listed on the engine block or ID label.

11. Max Rated Brake HP: Identify the new engine break horsepower rating.

12. Annual Fuel Usage: Estimate the annual fuel usage in gallons.

13. Annual Hours of Operation: Estimate the engine’s annual operations in hours. 

14. Equipment Manufacturer and Model: The make and model number of the equipment. For 

example, a Case (make) 721 (model).

15. Equipment VIN: The equipment Vehicle Identification Number, if available.

16. Equipment Model Year: The model year in which the equipment was manufactured, if available.

17. Months in Operation: Select whether the engine will operate throughout the year or by month.

18. Cost of New Engine and/or Equipment: Attach an estimate that clearly itemizes the costs.

19. Cost to Retrofit: Attach an estimate from the vendor and/or mechanic that clearly itemizes the costs 

to retrofit the engine.

20. Describe the fuel source: How will fuel be supplied to the new equipment. 

21. Additional Information: Include any information pertinent to this engine or equipment, including: 

engine-repower solutions or equipment limitations to repower from the vendor or manufacturer, and 

applicable permits or documentation issued by a local air district
December 30, 2011

Updated May 2, 2012

Environmental Quality Incentives Program (EQIP)

CALIFORNIA ENGINE/EQUIPMENT DESTRUCTION CERTIFICATION 2012

Air Quality – Combustion System Improvement

This certification serves to document that the engine/equipment identified below has been disabled 

and permanently destroyed by shearing, crushing, or shredding into scrap metal. No engine or drivetrain components were or will be parted-out, used or sold as parts, or used to rebuild equipment,

including equipment intended for destruction. The completed certification shall be signed and 

submitted to the NRCS Field Office after destruction.

Agricultural Producer:

Contract Number:

Engine Manufacturer and Model: Equipment Manufacturer and Model:

Diesel Engine Spark-Ignition Engine Equipment Type:

Engine Serial No: Equipment VIN:

Engine Model Year: Equipment Model Year:

Date engine/equipment was disabled (a 6” minimum hole punched in the block, etc.):

Engine/Equipment Owner’s Name (Print):

Owner’s Signature: Date:

The engine/equipment identified above were delivered for disposal and destruction at: 

Destruction Company Name:

Address:

City: State: Zip Code:

Date engine/equipment was scrapped:

The engine/equipment has been destroyed and scrapped. 

Destruction Facility Contact Name (Print): Phone No:

Contact Signature: Date:

Please attach date stamped photographs of the disabled engine/equipment identifying engine serial 

number and/or vehicle identification number, the hole punched in the engine block, and locations 

where the drive train and structural components were compromised.
December 30, 2011

Updated May 2, 2012

CALIFORNIA EMISSIONS CALCULATION WORKSHEET 2012

Air Quality - Combustion System Air Emissions Management

Off-Road Mobile/Stationary Engine Emissions Determination

Producer Name: Date:

Existing Engine Emissions Calculations

Existing Engine: Manufacturer:

Model Year Engine: Fuel Type:

Equipment Type:

Serial Number:

Baseline Emissions NOx ROG PM10

Maximum Rated Brake Horsepower: bhpmaximum

Annual Hours of Operation: x Hours/Year

Emission Factors: x g/bhp-hr

Load Factor: x

Conversion to Tons: ÷ 907,200 907,200 907,200 Grams/Ton

Annual Emissions (EE) = Tons/Year

New Engine Emissions Calculations (Report as zero emissions if electric)

New Engine: Manufacturer:

Model Year Engine: Fuel Type:

Equipment Type:

Serial Number (if available):

New Engine Emissions NOx ROG PM10

Maximum Rated Brake Horsepower: bhpmaximum

Annual Hours of Operation: x Hours/Year

Emission Factors: x g/bhp-hr

Load Factor: x

Conversion to Tons: ÷ 907,200 907,200 907,200 Grams/Ton

Annual Emissions (NE) = Tons/Year

Calculation Results

NOx ROG PM10

Annual Emission Reductions: 

(EE) – (NE) = Tons/Year

Percent Emission Reductions: 

[(EE – NE) / (EE)] x 100 = %
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 32

December 30, 2011

Updated May 2, 2012

Section 6: Emission Factors and 

Standards for Agricultural Engines

The emission estimation methods summarize the data needed to calculate the emission 

reductions and cost effectiveness of potential projects. Included data are engine 

emission factors, load factors, and other conversion factors used for calculating 

emissions.

At a minimum, emission calculations require the following data:

Engine Model Year

Engine Rated Brake Horsepower

Type of equipment the engine powers (to determine the load factor)

Annual hours the engine operations

Applicable emission factors

Emissions calculations will examine the emissions from the existing engines to establish 

a baseline and from the new engines. An emissions inventory will be developed based 

on this data to estimate the annual emissions of NOx, ROG (NMHC or VOC), and PM10 

and to calculate the emission reductions that results from implementing this 

conservation practice.

Emissions Calculations

Pounds/hour = (EF g/bhp-hr) x (engine max rated bhp) x (load factor) x (1 lb/456 grams)

Tons/year = [(EF g/bhp-hr) x (engine max rated bhp) x (annual hours) x (load factor)]

(907,200 g/ton)
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 33

December 30, 2011

Updated May 2, 2012

Table 1

Diesel Equipment Default Load Factors

Tillers 0.78 Crawler Tractors 0.43

Combines 0.70 Mowers 0.43

Tractors 0.70 Shakers 0.43

Irrigation Pumps 0.65 Forage Harvesters* 0.43

Bailers 0.58 Graders 0.41

Loaders/Backhoes 0.55 Rough Terrain Forklifts 0.40

Swathers 0.55 Forklifts 0.20

Sprayers 0.50 Other Agricultural 0.51

Hydro Power Units 0.48

Source: 2011 Carl Moyer Program Guidelines, Table D-10

* Mowers EF

Table 2

Uncontrolled Off-Road Compression-Ignition (Diesel) Engines 

Emission Factors (g/bhp-hr)

Horsepower Model Year NOx ROG PM10

50 – 119 Pre 1988 12.09 1.73 0.605

1988 – 1995 8.14 1.19 0.497

120 +

Pre 1970 13.02 1.59 0.554

1970 – 1979 11.16 1.20 0.396

1980 – 1987 10.23 1.06 0.396

1988 – 1995 7.60 0.82 0.274

Source: 2011 Carl Moyer Program Guidelines, Table D-11
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 34

December 30, 2011

Updated May 2, 2012

Table 3

Controlled Off-Road Compression-Ignition (Diesel) Engines 

Emission Factors (g/bhp-hr)

Horsepower Tier NOx ROG PM10

50-74

1 6.54 1.19 0.552

2 4.75 0.23 0.192

3 2.74 0.12 0.192

4 Interim 2.74 0.12 0.112

4 Final 2.74 0.12 0.008

75-99

1 6.54 1.19 0.552

2 4.75 0.23 0.192

3 2.74 0.12 0.192

4 Phase-Out 2.74 0.12 0.008

4 Phase-In/

Alternative NOx 2.14 0.11 0.008

4 Final 0.26 0.06 0.008

100-174

1 6.54 0.82 0.008

2 4.17 0.19 0.128

3 2.32 0.12 0.112

4 Phase-Out 2.32 0.12 0.008

4 Phase-In/

Alternative NOx 2.15 0.06 0.008

4 Final 0.26 0.06 0.008

175-299

1 5.93 0.38 0.108

2 4.15 0.12 0.088

3 2.32 0.12 0.088

4 Phase-Out 2.32 0.12 0.008

4 Phase-In/

Alternative NOx 1.29 0.08 0.008

4 Final 0.26 0.06 0.008

300-750

1 5.93 0.38 0.108

2 3.79 0.12 0.088

3 2.32 0.12 0.088

4 Phase-Out 2.32 0.12 0.008

4 Phase-In/

Alternative NOx 1.29 0.08 0.008

4 Final 0.26 0.06 0.008

751+

1 5.93 0.38 0.108

2 3.79 0.12 0.088

4 Interim 2.24 0.12 0.048

4 Final 2.24 0.06 0.016

Source: 2011 Carl Moyer Program Guidelines, Table D-12
Combustion Systems Improvement

FY2012 Guidelines, Policies, and Procedures

Page 35

December 30, 2011

Updated May 2, 2012

Table 4

Off-Road Large Spark-Ignited Equipment Default Load Factors

Combines 0.74 Sprayers 0.50

Rough Terrain Forklifts 0.63 Loaders/Backhoes 0.48

Tractors 0.62 Forklifts 0.30

Balers 0.55 Other Agricultural 0.55

Swathers 0.52

Source: 2011 Carl Moyer Program Guidelines, Table D-13

Table 5

Off-Road Large Spark-Ignited Engines 

Emission Factors (g/bhp-hr)

Horsepower Fuel Model Year NOx ROG PM10

50-120

Gasoline

Uncontrolled – Pre 2004 11.84 2.66 0.060

Controlled 2001-2006 1.78 0.26 0.060

Controlled 2007-2009 1.19 0.18 0.060

Controlled 2010+ 0.36 0.05 0.060

Alt Fuel

Uncontrolled – Pre 2004 10.51 1.02 0.060

Controlled 2001-2006 1.58 0.11 0.060

Controlled 2007-2009 1.05 0.07 0.060

Controlled 2010+ 0.32 0.02 0.060

>120

Gasoline

Uncontrolled – Pre 2004 12.94 1.63 0.060

Controlled 2001-2006 1.94 0.16 0.060

Controlled 2007-2009 1.29 0.11 0.060

Controlled 2010+ 0.39 0.03 0.060

Alt Fuel

Uncontrolled – Pre 2004 10.51 0.90 0.060

Controlled 2001-2006 1.58 0.09 0.060

Controlled 2007-2009 1.05 0.06 0.060

Controlled 2010+ 0.32 0.02 0.060

Source: 2011 Carl Moyer Program Guidelines, Table D-14
Environmental Quality Incentives Program (EQIP)

CALIFORNIA EXISTING ENGINE

Air Quality – 372 Combustion System Improvement

2013

Agricultural Producer Name:

Existing Engine Information

Complete a separate form for each existing engine or equipment

Describe the type of equipment the existing engine powers: Irrigation Engine Wheeled Tractor 

Crawler Tractor Loader Rough-Terrain Forklift Other: 

Report the total acres this engine serves: Years operated on these acres:

Primary Fuel Type

(check one):

Diesel

Biodiesel

Natural Gas

LPG

Biogas

Other: 

Engine Type

(check one):

Non-Tier Diesel 

Tier 1 

Tier 2 

Spark-Ignited

Other:

Verified Retrofit Technology: 

No retrofits have been installed on the existing engine

The existing engine is equipped with the following equipment:

Manufacturer:

Model:

Verification Level: Level 1 Level 2 Level 3

Verified Emission Reductions:

ROG: % NOx: % PM: %

Engine Manufacturer and Model No:

EPA Engine Family:

(If applicable –

required for Tier 1 or Tier 2 diesel)

Max Rated Brake HP:

Engine Year: Annual fuel usage:

Engine Serial No: Annual hours of operation:

Equipment Manufacturer & Model:

Equipment VIN No:

Equipment Model Year: Year Purchased:

Name of Equipment Owner:

Months in Operation: January February March

April May June

Operates throughout the year July August September

October November December

Planned location on where engine/equipment will be scrapped and destroyed:

(not applicable if retrofitting an existing engine)

Additional Information:
Instructions

Existing Engine Information

1. Complete a separate worksheet for each existing engine or equipment.

2. Describe the type of equipment the existing engine powers: This may include an irrigation pump, 

tractor, loader or other agricultural equipment. If “other”, please describe: (rough-terrain forklifts, 

crawler tractors, forage harvesters, shakers, etc.). 

3. Report the annual total acres this engine serves: Estimate the annual total acres of cropland this 

engine irrigates or the annual total acres the mobile agricultural equipment operates on.

4. Years Operated at this location: Approximate length of time the existing engine or equipment has 

been operating at this location.

5. Primary Fuel Type: Only select the primary fuel the engine consumes. 

6. Engine Type: Select the type of existing engine (Tier-level for compression-ignition). Please consult 

your engine vendor.

7. Verified Retrofit Technology: If applicable, describe the manufacturer, model, ARB-Verification 

Level, and the emission reductions associated with the installed technology. Attach documentation, 

including the applicable ARB Executive Order. This information should be available through your 

engine vendor or on-line at: www.arb.ca.gov/diesel/verdev/vdb/vdb.php.

8. Engine Manufacturer and Model No: Make and model number of the existing engine. For example, 

Cummins (make) 6BTA5.9C (model). Please do not report the Equipment Model Number here.

9. EPA Engine Family: Required for Tier-certified engines. Include the certified engine family name 

assigned by the EPA and attach the applicable ARB Executive Order for this engine. This information 

should be available through your engine vendor or on-line at: 

www.arb.ca.gov/msprog/offroad/cert/cert.php. 

10. Engine Year: The year the engine model was manufactured.

11. Engine Serial No.: The serial number listed on the engine block or ID label.

12. Max Rated Brake HP: Identify the manufacture’s engine break horsepower (bhp) rating.

13. Annual Fuel Usage: Amount of annual fuel usage in gallons.

14. Annual Hours of Operation: Report the engine’s actual annual hours of operation. If asked, please 

provide justification. (Exaggerating hours of operations may deem this application ineligible).

15. Equipment Manufacturer and Model: The make and model number of the equipment. For example, 

a Case (make) 721 (model). This number is not the engine model number.

16. Equipment VIN: The equipment Vehicle Identification Number.

17. Equipment Model Year: The model year in which the equipment was manufactured.

18. Year Purchased: The year the equipment was purchased by the applicant.

19. Name of Equipment Owner: Identify equipment ownership.

20. Months in Operation: Select whether the engine operates throughout the year or by month.

21. Planned location where engine/equipment will be scrapped and destroyed: Identify where the 

engine/equipment is planned to be taken for final disposal and destruction. No engine, drive-train or 

equipment components shall be recycled as used parts that might prolong the life of other engines and 

equipment. 

22. Additional Information: Include any additional information pertinent to this engine/equipment, 

including applicable permits or documentation issued by a local air district.
Environmental Quality Incentives Program (EQIP)

CALIFORNIA NEW ENGINE WORKSHEET

Air Quality – 372 Combustion System Improvement

2013

Agricultural Producer:

New Engine Information

Verified Technology Retrofit Installation

Complete a separate form for each engine or equipment

Describe the type of equipment the existing engine powers: Irrigation Engine Loader 

Wheeled Tractor Crawler Tractor Rough-Terrain Forklift Other: 

Report the total acres this engine will serve:

Primary Fuel Type

(check one):

Diesel

Biodiesel

Natural Gas

LPG

Biogas

Electric

Other:

Engine Type

(check one):

Tier 3

Tier 3 Flexibility

Tier 4 Interim

Tier 4 Final

Spark-Ignited

Electric

Other:

Verified Retrofit Technology: 

No retrofits are proposed for the new engine

Propose to install the following retrofit on the existing engine:

Propose to install the following retrofit on the new engine:

Manufacturer:

Model:

Verification Level: Level 1 Level 2 Level 3

Verified Emission Reductions: 

NOx: % PM: % ROG: %

Engine Manufacturer and Model:

EPA Engine Family:

(attach ARB Executive Order)

Max Rated Brake HP:

Engine Year Annual Fuel Usage:

(Estimate)

Engine Serial Number

(if available)

Annual Hours of Operation:

(Estimate)

Equipment Manufacturer and Model:

Equipment VIN No:

(if available)

Equipment Model Year:

Months in Operation: January February March

April May June

Operates throughout the year July August September

October November December

Cost of New Engine and/or Equipment :

(Attach an estimate)

Cost to Retrofit:

(Attach an estimate)

Describe the fuel source (i.e. location of fuel storage and dispensing system, battery recharging station, etc.):

Additional Information (May include documentation from the vendor regarding repower solutions or equipment limitations): 
Instructions

New Engine Information

Verified Technology Retrofit Installation

1. Complete a separate application for each new engine or equipment.

2. Describe the type of equipment the new engine will power: This may include an irrigation pump, 

tractor, loader or other agricultural equipment. If “other”, please describe: (rough-terrain forklifts, 

crawler tractors, forage harvesters, shakers, etc.). New engines or equipment shall serve the same 

function and perform the same work, unless pre-approved by NRCS.

3. Report the annual total acres this engine will serve: Estimate the annual total acres of cropland 

this engine will irrigate or the annual total acres the mobile agricultural equipment will operate on.

4. Primary Fuel Type: Only select the primary fuel the engine consumes. 

5. Engine Type: Select the type of engine (i.e. Tier 4i). Please consult your engine vendor.

6. Verified Retrofit Technology: Will retrofit technology be installed on the new or existing engine? If

yes, include the manufacturer, model, ARB-Verification Level, and the associated emission 

reductions with the installed technology. Attach documentation, including the applicable ARB 

Executive Order. This information should be available through your engine vendor or on-line at: 

www.arb.ca.gov/diesel/verdev/vdb/vdb.php.

7. Engine Manufacturer and Model No: Make and model number of the new engine. For example, 

IVECO (make) F4GE9484D*J (model). Please do not report the Equipment Model Number here.

8. EPA Engine Family: Required by including the certified engine family name assigned by the EPA 

and attaching the applicable ARB Executive Order for this engine. This information should be 

available through your engine vendor or is on-line at: www.arb.ca.gov/msprog/offroad/cert/cert.php. 

Any ARB Executive Order reporting a Family Emission Level (FEL) value exceeding an 

applicable NOx, NMHC, NMHC+NOx, CO, PM or other emission standard is not eligible to 

receive NRCS payments. Please consult your vendor over FEL values.

9. Engine Year: The year the engine model was manufactured.

10. Engine Serial No.: If available, include the serial number listed on the engine block or ID label.

11. Max Rated Brake HP: Identify the new engine break horsepower rating.

12. Annual Fuel Usage: Estimate the annual fuel usage in gallons.

13. Annual Hours of Operation: Estimate the engine’s annual operations in hours. (Exaggerating hours 

of operations may deem this application as ineligible).

14. Equipment Manufacturer and Model: The make and model number of the equipment. For 

example, a Case (make) 721 (model).

15. Equipment VIN: The equipment Vehicle Identification Number, if available.

16. Equipment Model Year: The model year in which the equipment was manufactured, if available.

17. Months in Operation: Select whether the engine will operate throughout the year or by month.

18. Cost of New Engine and/or Equipment: Attach an estimate that clearly itemizes the costs.

19. Cost to Retrofit: Attach an estimate that clearly itemizes the costs.

20. Describe the fuel source: How will fuel be supplied to the new equipment. 

21. Additional Information: Include any information pertinent to this engine or equipment, including: 

engine-repower solutions available or equipment limitations to repower from the vendor or 

manufacturer, and applicable permits or documentation issued by a local air district.
CALIFORNIA EMISSIONS CALCULATION WORKSHEET

Air Quality – 372 Combustion System Improvement 2013

Producer Name: Date:

Existing Engine Emissions Calculations

Existing Engine: Manufacturer:

Model Year Engine: Fuel Type:

Equipment Type:

Serial Number:

Baseline Emissions NOx ROG PM10

Maximum Rated Brake Horsepower: bhpmaximum

Annual Hours of Operation: x Hours/Year

Emission Factors: x g/bhp-hr

Load Factor: x

Conversion to Tons: ÷ 907,200 907,200 907,200 Grams/Ton

Annual Emissions (EE) = Tons/Year

New Engine Emissions Calculations (Report as zero emissions if electric)

New Engine: Manufacturer:

Model Year Engine: Fuel Type:

Equipment Type:

Serial Number (if available):

New Engine Emissions NOx ROG PM10

Maximum Rated Brake Horsepower: bhpmaximum

Annual Hours of Operation: x Hours/Year

Emission Factors: x g/bhp-hr

Load Factor: x

Conversion to Tons: ÷ 907,200 907,200 907,200 Grams/Ton

Annual Emissions (NE) = Tons/Year

Calculation Results

NOx ROG PM10

Annual Emission Reductions: 

(EE) – (NE) = Tons/Year

Percent Emission Reductions: 

[(EE – NE) / (EE)] x 100 = %

Compression-Ignition Emission Factors
Tons/year = [(EF g/bhp-hr) x (engine max rated bhp) x (annual hours) x (load factor)] 

(907,200 g/ton)

Table 1: Diesel Equipment Default Load Factors

Equipment Type Load Factor

Tillers 0.78

Combines 0.70

Ag Wheeled Tractors 0.70

Irrigation Pumps 0.65

Bailers 0.58

Loaders 0.55

Swathers 0.55

Forage Harvesters10.55

Shakers20.51

Sprayers 0.50

Hydro Power Units 0.48

Ag Crawler Tractors 0.43

Agricultural Mowers 0.43

Ag Graders 0.41

Rough Terrain Forklifts 0.40

Other Agricultural 0.51

Source: 2011 Carl Moyer Program Guidelines, Table D-10

1 Similar LF to Swather

2 “Other Agriculture” LF

Table 2: Uncontrolled Off-Road Compression-Ignition (Diesel) Engines Emission Factors 

Horsepower Model Year

NOx Emission 

Factor (g/bhp-hr)

ROG Emission 

Factor (g/bhp-hr)

PM10 Emission 

Factor (g/bhp-hr)

50 – 119 Pre 1988 12.09 1.73 0.605

1988 – 1995 8.14 1.19 0.497

120 +

Pre 1970 13.02 1.59 0.554

1970 – 1979 11.16 1.20 0.396

1980 – 1987 10.23 1.06 0.396

1988 – 1995 7.60 0.82 0.274

Source: 2011 Carl Moyer Program Guidelines, Table D-11
Table 3: Controlled Off-Road Compression-Ignition (Diesel) Engines Emission Factors

Horsepower Tier

NOx Emission 

Factor (g/bhp-hr)

ROG Emission 

Factor (g/bhp-hr)

PM10 Emission 

Factor (g/bhp-hr)

50-74

1 6.54 1.19 0.552

2 4.75 0.23 0.192

3 2.74 0.12 0.192

4 Interim 2.74 0.12 0.112

4 Final 2.74 0.12 0.008

75-99

1 6.54 1.19 0.552

2 4.75 0.23 0.192

3 2.74 0.12 0.192

4 Phase-Out 2.74 0.12 0.008

4 Phase-In/

Alternative NOx 2.14 0.11 0.008

4 Final 0.26 0.06 0.008

100-174

1 6.54 0.82 0.008

2 4.17 0.19 0.128

3 2.32 0.12 0.112

4 Phase-Out 2.32 0.12 0.008

4 Phase-In/

Alternative NOx 2.15 0.06 0.008

4 Final 0.26 0.06 0.008

175-299

1 5.93 0.38 0.108

2 4.15 0.12 0.088

3 2.32 0.12 0.088

4 Phase-Out 2.32 0.12 0.008

4 Phase-In/

Alternative NOx 1.29 0.08 0.008

4 Final 0.26 0.06 0.008

300-750

1 5.93 0.38 0.108

2 3.79 0.12 0.088

3 2.32 0.12 0.088

4 Phase-Out 2.32 0.12 0.008

4 Phase-In/

Alternative NOx 1.29 0.08 0.008

4 Final 0.26 0.06 0.008

751+

1 5.93 0.38 0.108

2 3.79 0.12 0.088

4 Interim 2.24 0.12 0.048

4 Final 2.24 0.06 0.016

Source: 2011 Carl Moyer Program Guidelines, Table D-12
Environmental Quality Incentives Program (EQIP)

CALIFORNIA ENGINE/EQUIPMENT DESTRUCTION 

CERTIFICATION

Air Quality – 372 Combustion System Improvement

2013

This certification serves to document that the engine/equipment identified below has been disabled 

and permanently destroyed by shearing, crushing, or shredding into scrap metal. No engine or drivetrain components were or will be parted-out, used or sold as parts, or used to rebuild equipment, 

including equipment intended for destruction. The completed certification shall be signed and 

submitted to the NRCS Field Office after destruction.

Agricultural Producer:

Contract Number:

Engine Manufacturer and Model: Equipment Manufacturer and Model:

Diesel Engine Spark-Ignition Engine Equipment Type:

Engine Serial No: Equipment VIN:

Engine Model Year: Equipment Model Year:

Date engine/equipment was disabled (a 6” minimum hole punched in the block, etc.):

Engine/Equipment Owner’s Name (Print):

Owner’s Signature: Date:

The engine/equipment identified above were delivered for disposal and destruction at: 

Destruction Company Name:

Address:

City: State: Zip Code:

Date engine/equipment was scrapped:

The engine/equipment has been destroyed and scrapped. 

Destruction Facility Contact Name (Print): Phone No:

Contact Signature: Date:

Please attach date stamped photographs of the disabled engine/equipment identifying engine serial 

number and/or vehicle identification number, the hole punched in the engine block, and locations 

where the drive train and structural components were compromised.
 372-1 

NRCS, CA 

Sept. 2010 

NATURAL RESOURCES CONSERVATION SERVICE 

CONSERVATION PRACTICE SPECIFICATION 

372 – COMBUSTION SYSTEM IMPROVEMENT 

I. SCOPE 

Real emission reductions are achieved when removing 

and permanently destroying old, high-polluting internal 

combustion engines and replacing with new, cleaner 

technologies. Retiring high-polluting engines earlier 

than through normal attrition assists agricultural 

producers with reducing oxides of nitrogen (NOx) and 

volatile organic compounds (VOC) [ozone precursors] 

and particulate matter [PM = respirable (PM10) and 

fine (PM2.5) particulate] emissions from the engines 

they operate. 

Existing engines are fully-functional and operational 

agricultural engines that have some remaining life and 

will be permanently destroyed soon after being 

replaced. Included are stationary, portable, auxiliary, 

and mobile off-road agricultural engines. 

II. GENERAL 

Depending on their use, agricultural engines operate at 

different times through the year. Irrigation engines are 

typically seasonal sources of emissions because the 

majority operate during the primary crop growing 

season in the spring and summer months of the year 

when irrigation is needed. A variety of mobile off-road 

agricultural engines may only operate during specific 

times of the year, such as during the harvest season. 

However, some engines that drive tractors or loaders 

may operate routinely all year round. 

Periods of high utilization often coincides with the 

summer ozone season, underscoring the need to reduce 

NOx and VOC emissions. PM emissions may also be a 

seasonal issue, especially during the fall and winter 

months under stable metrological conditions. In 

general, PM is a year round challenge as the California 

Air Resources Board (ARB) has identified diesel 

particulate exhaust as a toxic air contaminant and a 

carcinogenic. Replacing old diesel engines with new 

California-certified diesel engines or with engines 

utilizing other fuel types (i.e. natural gas, liquid 

petroleum gas, or biogas) can substantially reduce 

emissions. Replacing engines with electric motors will 

eliminate emissions at the source. 

The widespread use of new, lower-polluting engines 

and electric motors will assist with attaining or 

maintaining federal and state ambient air quality 

standards thereby providing significant air quality 

improvements in California. 

III. CRITERA 

An existing engine is fully functional, in operational 

condition and has the ability to start-up. 

Existing mobile off-road agricultural equipment shall 

meet the following criteria: 

i The tires are in usable condition (ability to hold 

air, sufficient tread, etc.). 

i The engine is able to start-up and propels the 

vehicle forwards and backwards. 

i Buckets, blades, hydraulics, rollers, etc. are in 

working order. 

i Undercarriage is structurally sound. 

i Fuel tank is in usable condition with no leaks. 

i No parts have been stripped. 

i Equipment has not been vandalized. 

Existing spark-ignition engines may not be replaced 

with new diesel engines. 

Any installation of exhaust after-treatment devices 

must conform to the most current ARB-verified 

standards and be operated and maintained according to 

manufacturer’s recommendations. 

The new replacement engine must be equipped with a 

non-resettable, operational time meter. 

Engines or electric motors installed at pumping plants 

must adhere to Practice Code 533, Pumping Plant 

guidelines. An engineering analysis may be required. 

Fuels consumed by the new engine, whether 

petroleum-based, renewable, or blends of petroleumbased and renewable fuels must conform to new engine 

warranties and shall meet any applicable air quality 

standard and specification. 

IV. EMISSION STANDARDS 

Any new replacement engine must report at least a 

15% NOx reduction and no increase in particulate 

matter emissions compared with the applicable 

standards or emission levels for that engine year and 
 372-2 

NRCS, CA 

Sept. 2010 

type of application through EPA or ARB certification 

testing. 

The ARB establishes emission standards and 

requirements that regulate the sale, purchase, rental, 

lease, and operation of diesel engines, including 

stationary and portable equipment used exclusively in 

agriculture. In addition, a local air quality authority 

may impose emission standards through a rule or 

require permits with emission limits that may be more 

restrictive than required by the ARB. 

V. EMISSIONS CALCULATIONS 

Emissions reductions are determined by calculating the 

emissions from the existing engines to establish a 

baseline. The emissions of the new engines are 

calculated and subtracted from the baseline, thus 

reporting the estimated emission reductions. An 

emissions inventory will report the estimated annual 

emissions and track the emission reductions as a result 

of implementing this conservation practice. 

At a minimum, emission calculations require the 

following data: 

i Engine Model Year 

i Engine Rated Brake Horsepower 

i Type of equipment the engine powers (to 

determine the load factor) 

i Annual hours the engine operates 

i Applicable emission factors. If emissions data 

from an approved source test is not available for 

the specific engine, the emission factors in the 

tables below shall be used as default values. 

VI. DESTRUCTION AND DISPOSAL OF 

REPLACED ENGINES AND MOBILE 

OFF-ROAD AGRICULTRAUL 

EQUIPMENT 

After being replaced, the existing engine and mobile 

off-road agricultural equipment must be destroyed. 

Destruction removes the existing high-emitting engines 

and equipment from service and ensures that the 

emission reductions are real and permanent. It also 

prevents the old engine and equipment from being 

rebuilt or moved into another locale to continue 

emitting high levels of pollutants. 

Under certain circumstances, an existing Tier-certified 

diesel engine may be relocated and used to replace an 

uncontrolled Tier 0 diesel engine. The uncontrolled 

Tier 0 engine it’s replacing must then be destroyed. 

Engine and equipment destruction must be performed 

in a safe manner that avoids any personal injury risks. 

At a minimum, the old engine block must be punctured 

with at least a six inch diameter hole to include a 

portion of the oil pan rail (sealing surface). 

The structural components on mobile equipment must 

be physically compromised. At a minimum, this shall 

be accomplished by cutting the vehicle frame railings 

in half or by destroying bell-housing and transmission 

components if not equipped with a frame. Additional 

means may include compromising the drive-train 

components by knocking at holes in the transmission 

casing and cutting axles and axle housings. 

The disabled engine and equipment shall be properly 

disposed of at a dismantler approved by the NRCS. 

The approved dismantler will scrap the engine and 

equipment either by shearing, crushing, or shredding. 

The producer shall provide the NRCS with a written 

certification that the engine and associated equipment 

has been permanently destroyed. If destruction was 

performed by an approved dismantler, the dismantler 

will provide the producer with the written certification 

for submittal to the NRCS. The certification shall 

describe the following:

i The existing engine and equipment type, 

i The existing engine serial number and equipment 

vehicle identification number, 

i The date the existing engine and equipment were 

compromised , 

i How the existing engine and equipment were 

destroyed

i Specify that no parts or components were or will 

be parted-out, used or sold as parts, or used to 

rebuild and engine or equipment intended for 

destruction.

i Provide date-stamped photographs.

VII. PERFORMANCE AND MAINTENANCE 

REPORTS 

Producers are to maintain records of new engine usage 

for at least five years of operation. At a minimum, 

producers shall record the annual hours of operation 

and gallons of fuel used or kilowatts consumed (if 

electric) over a calendar year. Records should also 

record routine maintenance performed on the engine 

and equipment. The objective is to determine engine 

usage and the resulting emissions. 
 372-3 

NRCS, CA 

Sept. 2010 

REFERENCES 

Air Resources Board, Carl Moyer Program Guidelines, 

April 22, 2008. 

Air Resources Board, Off-Road Engine Certification 

Database, 

www.arb.ca.gov/msprog/offroad/cert/cert.php

Air Resources Board, Verified Diesel Emission Control 

Strategies, www.arb.ca.gov/diesel/verdev/vt/cvt.htm

Air Resources Board, Independent Contractors 

Approved under Section 91207, Title 17, CCR, 

www.arb.ca.gov/ba/icp/current.pdf

San Joaquin Valley Air Pollution Control District, 

Heavy-Duty Engine Program, Off-Road Equipment 

Component, www.valleyair.org/

United States Environmental Protection Agency, Nonroad Diesel Equipment, www.epa.gov/nonroaddiesel/index.htm


 372-6 

NRCS, CA 

Sept. 2010 
 372-spec-1 

NRCS, CA 

November, 2013 

NATURAL RESOURCES CONSERVATION SERVICE 

CONSERVATION PRACTICE SPECIFICATION 

372 – COMBUSTION SYSTEM IMPROVEMENT 

I. SCOPE 

Real emission reductions are achieved when removing 

and permanently destroying old, high-polluting 

internal combustion engines and replacing with new, 

cleaner technologies. Retiring high-polluting engines 

earlier than through normal attrition assists agricultural 

producers with reducing oxides of nitrogen (NOx) and 

volatile organic compounds (VOC) [ozone precursors] 

and particulate matter [PM = respirable (PM10) and 

fine (PM2.5) particulate] emissions from the engines 

they operate. 

Existing engines must be fully-functional, operational, 

in-use agricultural engines that will be permanently 

destroyed soon after being replaced. Included are 

stationary, portable, auxiliary, and mobile off-road 

agricultural engines. 

II. GENERAL 

Depending on their use, agricultural engines operate at 

different times through the year. Irrigation engines are 

typically seasonal sources of emissions because the 

majority operate during the primary crop growing 

season in the spring and summer months of the year 

when irrigation is needed. A variety of mobile offroad agricultural engines may only operate during 

specific times of the year, such as during the harvest 

season. However, some engines that drive tractors or 

loaders may operate routinely all year round. 

Periods of high utilization often coincides with the 

summer ozone season, underscoring the need to reduce 

NOx and VOC emissions. PM emissions may also be 

a seasonal issue, especially during the fall and winter 

months under stable metrological conditions. In 

general, PM is a year round challenge as the California 

Air Resources Board (ARB) has identified diesel 

particulate exhaust as a toxic air contaminant and a 

carcinogenic. Replacing old diesel engines with new 

California-certified diesel engines or with engines 

utilizing other fuel types (i.e. natural gas, liquid 

petroleum gas, or biogas) can substantially reduce 

emissions. Replacing engines with electric motors 

will eliminate emissions at the source. 

The widespread use of new, lower-polluting engines 

and electric motors will assist with attaining or 

maintaining federal and state ambient air quality 

standards thereby providing significant air quality 

improvements in California. 

III. CRITERA 

An existing engine must have been owned by the 

producer and operated in California for at least the 

past 12 consecutive months prior to commencing 

conservation plan development or the date of a 

contract application. 

The engine and associated components are fully 

functional, in operational condition, are able to startup, and powers the component or equipment it is 

intended to operate. 

Existing mobile off-road agricultural equipment shall 

meet the following criteria: 

i The tires are in usable condition (ability to hold 

air, sufficient tread, etc.). 

i The engine self-propels the vehicle forwards and 

backwards. 

i Buckets, blades, hydraulics, rollers, etc. are in 

working order. 

i Undercarriage is structurally sound. 

i Fuel tank is in usable condition with no leaks. 

i No parts have been stripped. 

i Equipment has not been vandalized. 

Existing spark-ignition engines may not be replaced 

with new diesel engines. 

Any installation of exhaust after-treatment devices 

must conform to the most current ARB-verified 

standards and be operated and maintained according to 

manufacturer’s recommendations. 

A replacement engine is in new condition, has not 

been sold or associated with any rental or lease 

agreement, and has less than 100 operating hours 

recorded on a permanently mounted non-resettable 

hour meter. 

The new replacement engine must be equipped with a 

non-resettable, operational time meter. The meter 

must be functional over the practice lifespan. 

The new replacement engine horsepower rating is 

within 125% of the existing engine original 

manufacturer’s rated horsepower. Case-by-case 

exceptions include: 

i The manufacturer’s horsepower rating is not 

available for the existing engine; or, 
372-spec-2 

NRCS, CA 

November, 2013 

i Additional horsepower is required to implement 

NRCS conservation practices associated with 

Conservation Residue and Tillage Management, 

or Field Operations Emissions Reductions 

practice standards. 

The rated horsepower is the manufacturer’s advertised 

break-horsepower rating. If not available, the rated 

horsepower may be determined by multiplying the 

advertised power take-off (PTO) horsepower by a 

factor of 1.20. 

The new engine powers equipment that serves the 

same function and performs equivalent work to the 

equipment being replaced (i.e. replace an old tractor 

with a new tractor; replace an old irrigation engine 

with a new irrigation engine; etc.). Replacements are 

intended to reduce emissions and not for any other 

production related purpose. 

Engines or electric motors installed at pumping plants 

must adhere to Practice Code 533, Pumping Plant 

guidelines. An engineering analysis may be required. 

Fuels consumed by the new engine, whether 

petroleum-based, renewable, or blends of petroleumbased and renewable fuels must conform to new 

engine warranties and shall meet any applicable air 

quality standard and specification. 

CPS 372 practice lifespan is 10 years. ARB Executive 

Orders specify the manufacturers expected lifespan for 

emissions-certified engines under an EPA Engine 

Family designation; for most engines the lifespan is 

8,000 hours. 

IV. EMISSION STANDARDS 

Any new replacement engine must be certified for at 

least a 30 percent NOx reduction and no increase in 

particulate matter emissions compared with the 

applicable standards or emission levels for the existing 

engine. 

The new replacement engine must meet the most 

recent California emission standards (e.g. current 

Tier). Certified emission standards and Tier-level 

determinations are by ARB Executive Order (or EPA 

Certificate of Conformity for federally preempted 

engines) based on the EPA Engine Family 

designation. ARB Executive Orders are accessible online at: 

http://www.arb.ca.gov/msprog/offroad/cert/cert.php

Engines certified to a Family Emissions Limit (FEL) 

may be installed provided that the engine’s FEL 

emission value does not exceed the applicable EPA, 

ARB or local emission standards (STD). 

The ARB establishes emission standards and 

requirements that regulate the sale, purchase, rental, 

lease, and operation of diesel engines, including 

stationary and portable equipment used exclusively in 

agriculture. In addition, a local air quality authority 

may impose emission standards through a rule or 

require permits with emission limits that may be more 

restrictive than required by the ARB and may require 

emissions source testing. ARB-certified independent 

contractors conduct the source tests using accepted 

testing protocols approved by the applicable air quality 

authority. A list of ARB-certified independent 

contractors is maintained and posted on-line at: 

http://www.arb.ca.gov/ba/icp/currenteo.pdf. 

V. EMISSIONS CALCULATIONS 

Emissions reductions are determined by subtracting 

the calculated emissions of the new engine from the 

baseline emissions calculated for the existing engines. 

An emissions inventory will report the annual 

emissions and track the emission reductions as a result 

of implementing this conservation practice. 

At a minimum, emission calculations require the 

following data for both the existing and the new 

replacement engine: 

i Engine Model Year 

i Engine Rated Brake Horsepower 

i Type of equipment the engine powers (to 

determine the load factor) 

i Annual hours the existing engine operates and the 

annual hours the new engine operates 

i Annual fuel usage data is also useful to calculate 

emissions. 

i Applicable emission factors. If emissions data 

from an approved source test is not available for 

the specific engine, the emission factors in the 

tables below shall be used as default values. 

The calculation primarily used for estimating annual 

emissions is based on hours of operation (tons/year). 

Other methods may be used to calculate emissions as 

described in the ARB 2011 Carl Moyer Program 

Guidelines, Appendix C and D. 

Estimate annual emissions based on hours of operation 

for each pollutant (tons/year): 

AE = (EF x LF x HP x HR) / 907,200 

AE: Annual Emissions (hours/year) 

EF: Emission Factor of the specific pollutant 

(grams/brake-horsepower) 

LF: Equipment Load Factor 

HP: Rated Horsepower 

HR: Hours of Operation/year 

907,200: Units conversion (grams/ton) 
 372-spec-3 

NRCS, CA 

November, 2013 

Estimate annual emission reductions for each 

pollutant (tons/year): 

AER= AEExisting – AENew 

AER: Annual Emission Reductions 

Emission reductions from replacing two existing offroad mobile engines for one new off-road mobile 

engine are determined by subtracting the calculated 

emissions of the new engine from the baseline sum 

calculated of the two existing engines. 

The new engine powers equipment that serves the 

same function and performs equivalent work as each 

of the two engines and equipment being replaced (i.e. 

replace two old tractors for one new tractor). The 

new replacement engine horsepower rating is within 

125% of either one of the two existing engine 

original manufacturer’s rated horsepower. 

Estimate emission reductions for replacing two 

engines powering similar equipment with one new 

engine powering similar equipment for each pollutant 

(tons/year): 

AER = (AEExisting1 + AEExisting2) – AENew 

VI. DESTRUCTION AND DISPOSAL OF 

REPLACED ENGINES AND MOBILE OFFROAD AGRICULTRAUL EQUIPMENT 

After being replaced, the existing engine and 

equipment must be destroyed. Destruction removes 

the existing high-emitting engines and equipment from 

service and ensures that the emission reductions are 

real and permanent. It also prevents the old engine 

and equipment from being rebuilt or moved into 

another locale to continue emitting high levels of 

pollutants. 

Under certain circumstances, an existing Tier-certified 

diesel engine may be relocated and used to replace an 

uncontrolled (Tier 0) diesel engine. The Tier 0 engine 

must then be destroyed. 

Engine and equipment destruction must be performed 

in a safe manner that avoids any personal injury risks. 

The old engine block must be disabled by puncturing 

at least a six inch diameter hole to include a portion of 

the oil pan rail (sealing surface). 

The structural components on mobile equipment must 

be physically compromised. At a minimum, this shall 

be accomplished by cutting the vehicle frame railings 

in half or by destroying bell-housing and transmission 

components if not equipped with a frame. Additional 

means may include compromising the drive-train 

components by knocking holes in the transmission 

casing and cutting axles and axle housings. 

The disabled engine and equipment shall be properly 

disposed of at a dismantler facility approved by the 

NRCS. An approved dismantler facility is capable of 

scrapping the engine and equipment by shearing, 

crushing, or shredding. 

The producer shall provide the NRCS with a written 

certification that the engine and associated equipment 

has been permanently destroyed and properly 

disposed. If destruction was performed at an approved 

dismantler facility, the dismantler will provide the 

producer with the written certification for submittal to 

the NRCS. The certification shall describe the 

following:

i The existing engine and equipment type, 

i The existing engine serial number and equipment 

vehicle identification number, 

i The date the existing engine and equipment were 

compromised , 

i How the existing engine and equipment were 

destroyed

i Specify that no parts or components were or will 

be parted-out, used or sold as parts, or used to 

rebuild an engine or equipment intended for 

destruction.

i Provide date-stamped photographs.

VII. CREDITABLE EMISSION REDUCTIONS 

FOR STATE IMPLEMENTATION 

PLANS 

To help meet Clean Air Act objectives, emission 

reductions achieved through voluntary measures have 

the potential of becoming creditable toward meeting 

attainment goals under a State Implementation Plan 

(SIP). NRCS is committed to applying emission 

reductions achieved from replacing in-use off-road 

mobile engines and equipment toward a SIP. To be 

SIP creditable, emission reductions must be “surplus, 

quantifiable, enforceable, and permanent”. 

SIP creditable emission reductions must not be 

required by any air quality rule, regulation, or other 

local mandate; and not used as marketable credits or to 

offset any emission banking or trading program. The 

SIP creditability determination is made by the air 

quality authority responsible for implementing the 

SIP. 

VIII. PERFORMANCE AND MAINTENANCE 

REPORTS 

The producer will provide NRCS with the appropriate 

documents verifying ownership of the existing engine 

and equipment over the previous 12-consecutive 

month period. Two documents specific to the existing 
372-spec-4 

NRCS, CA 

November, 2013 

engine and equipment includes, but is not limited to 

the following: 

i Bill of Sale 

i Insurance records 

i Bank appraisal 

i Maintenance or service records 

i General ledgers 

i Fuel records 

i Other documentation approved by NRCS on a 

case-by-case basis. 

The producer must also provide at least one of the 

following documents reporting the operational status 

of the specific existing engine and equipment over the 

previous 12-month period. This includes, but is not 

limited to: 

i Maintenance or service records 

i Usage records that report operation, stand-by, and 

down hours 

i Routine inspections documenting the engine and 

equipment operational condition 

i Hour meter reading log collected at least once per 

year from an installed and fully functional hour 

meter 

i Historical fuel usage logs, purchase receipts or 

ledger entries 

i Other documentation approved by NRCS on a 

case-by-case basis. 

Producers are to maintain records of new engine and 

equipment usage for at least ten years of operation. At 

a minimum, producers shall record the annual hours of 

operation based on the reading from the non-resettable 

time meter and the percent of time the new engine was 

used within a pertinent air district. 

Records for other operating parameters may include 

gallons of fuel or kilowatts consumed (if electric) over 

a calendar year. Records should also record routine 

maintenance performed on the engine and equipment. 

The objective is to determine engine usage and the 

resulting emissions in comparison with the baseline 

emissions. 

For San Joaquin Valley producers or others intended 

to generate SIP credit, the recorded information 

gathered from the non-resettable hour meter shall be 

submitted annually to the NRCS. The report shall 

include the total hour meter reading, hours of 

operations over the calendar year, and the percent 

usage within the San Joaquin Valley or other Clean 

Air Act non-attainment area over the calendar year. 

REFERENCES 

Air Resources Board, 2011 Carl Moyer Program 

Guidelines, 

http://www.arb.ca.gov/msprog/moyer/guidelines/curre

nt.htm

Air Resources Board, Off-Road Engine Certification 

Database, 

www.arb.ca.gov/msprog/offroad/cert/cert.php

Air Resources Board, Verified Diesel Emission 

Control Strategies, 

www.arb.ca.gov/diesel/verdev/vt/cvt.htm

Air Resources Board, Independent Contractors 

Approved under Section 91207, Title 17, CCR, 

www.arb.ca.gov/ba/icp/current.pdf

San Joaquin Valley Air Pollution Control District, 

Heavy-Duty Engine Program, Off-Road Equipment 

Component, www.valleyair.org/

US EPA-Region 9, Air Resources Board, San Joaquin 

Valley APCD and USDA NRCS; “Statement of 

principles Regarding the Approach to State 

Implementation Plan Creditability of Agricultural 

Equipment Replacement Incentive Programs 

Implemented by the USDA Natural Resources 

Conservation Service and the San Joaquin Valley Air 

Pollution Control District”; December 2010 

US EPA and USDA NRCS, “Implementation 

Principles for Addressing Agriculture Equipment 

under the Clean Air Act”, July 2012 

United States Environmental Protection Agency, Nonroad Diesel Equipment, www.epa.gov/nonroaddiesel/index.htm

United States Environmental Protection Agency, 

“Incorporating Emerging and Voluntary Measures in a 

State Implementation Plan (SIP), September 2004. 

http://www.epa.gov/ttn/oarpg/t1/memoranda/evm_iev

m_g.pdf
 372-spec-5 

NRCS, CA 

November, 2013 

Emissions Calculations 

Tons/year = [(EF g/bhp-hr) x (engine max rated bhp) x (annual hours) x (load factor)]

 (907,200 g/ton) 

 

Table 1 

Diesel Agricultural Equipment Default Load Factors 

Tillers 0.78 Swather 0.55 

Combines 0.70 Sprayers 0.50 

Tractors 0.70 Hydro Power Units 0.48 

Irrigation Pumps 0.65 Mowers 0.43 

Balers 0.58 Other Agricultural 0.51 

Source: 2011 Carl Moyer Program Guidelines, Table D-10 

Table 2 

Diesel Powered Construction & Industrial Equipment used in Agriculture Default Load Factors

Crawler Tractors 0.43 Backhoes/Loaders 0.37 

Graders 0.41 Rubber-Tired Loaders 0.36 

Rough Terrain Forklifts 0.40 Forklifts 0.20 

Source: 2011 Carl Moyer Program Guidelines, Table D-10 

Table 3 

Diesel Powered Logging Equipment Default Load Factors 

Skidders 0.74 Fellers/Bunchers 0.71 

Source: 2011 Carl Moyer Program Guidelines, Table D-10 

Table 4 

Uncontrolled (Tier 0) Off-Road Compression-Ignition (Diesel) Engines 

Emission Factors (g/bhp-hr) 

Horsepower Model Year NOx ROG PM10 

25 – 49 Pre 1988 6.51 2.21 0.547 

1988 + 6.42 2.17 0.547 

50 – 119 Pre 1988 12.09 1.73 0.605 

1988 + 8.14 1.19 0.497 

120 + 

Pre 1970 13.02 1.59 0.554 

1970 – 1979 11.16 1.20 0.396 

1980 – 1987 10.23 1.06 0.396 

1988 + 7.60 0.82 0.274 

Source: 2011 Carl Moyer Program Guidelines, Table D-11 
372-spec-6 

NRCS, CA 

November, 2013 

Table 5 

Controlled Off-Road Compression-Ignition (Diesel) Engines 

Emission Factors (g/bhp-hr) 

Horsepower Tier NOx ROG PM10 

25 – 49 

1 5.26 1.74 0.480 

2 4.63 0.29 0.280 

4 Interim 2.75 0.12 0.128 

4 Final 2.75 0.12 0.008 

 50 – 74 

1 6.54 1.19 0.552 

2 4.75 0.23 0.192 

3 2.74 0.12 0.192 

4 Interim 2.74 0.12 0.112 

4 Final 2.74 0.12 0.008 

75 – 99 

1 6.54 1.19 0.522 

2 4.75 0.23 0.192 

3 2.74 0.12 0.192 

4 Phase-Out 2.74 0.12 0.008 

4 Phase-In/Alt NOx 2.14 0.11 0.008 

4 Final 0.26 0.06 0.008 

100 – 174 

1 6.54 0.82 0.274 

2 4.17 0.19 0.128 

3 2.32 0.12 0.112 

4 Phase-Out 2.32 0.12 0.008 

4 Phase-In/Alt NOx 2.15 0.06 0.008 

4 Final 0.26 0.06 0.008 

175 – 299 

1 5.93 0.38 0.108 

2 4.15 0.12 0.088 

3 2.32 0.12 0.088 

4 Phase-Out 2.32 0.12 0.008 

4 Phase-In/Alt NOx 1.29 0.08 0.008 

4 Final 0.26 0.06 0.008 

300 – 750 

1 5.93 0.38 0.108 

2 3.79 0.12 0.088 

3 2.32 0.12 0.088 

4 Phase-Out 2.32 0.12 0.008 

4 Phase-In/Alt NOx 1.29 0.08 0.008 

4 Final 0.26 0.06 0.008 

751 + 

1 5.93 0.38 0.108 

2 3.79 0.12 0.088 

3 2.24 0.12 0.048 

4 Interim 2.24 0.12 0.048 

4 Final 2.24 0.06 0.016 

Source: 2011 Carl Moyer Program Guidelines, Table D-12 
 372-spec-7 

NRCS, CA 

November, 2013 

Table 6 

Off-Road Large Spark-Ignited Agricultural Equipment Default Load Factors 

Combines 0.74 Swathers 0.52 

Tractors 0.62 Other Agricultural 0.55 

Balers 0.55 

Source: 2011 Carl Moyer Program Guidelines, Table D-13 

Table 7 

Off-Road Large Spark-Ignited Construction Equipment used in Agriculture Default Load Factors 

Rough-Terrain Forklifts 0.63 Backhoes/Loaders 0.48 

Rubber Tired Loaders 0.54 Forklifts 0.30 

Source: 2011 Carl Moyer Program Guidelines, Table D-13 

Table 8 

Off-Road Large Spark-Ignited Engines 

Emission Factors (g/bhp-hr) 

Horsepower Fuel Model Year NOx ROG PM10 

25 – 49 

Gasoline 

Uncontrolled – Pre 2004 8.01 3.81 0.060 

Controlled 2001-2006 1.33 0.72 0.060 

Controlled 2007-2009 0.89 0.48 0.060 

Controlled 2010+ 0.27 0.17 0.060 

Alt Fuel 

Uncontrolled – Pre 2004 13.00 0.90 0.060 

Controlled 2001-2006 1.95 0.09 0.060 

Controlled 2007-2009 1.30 0.06 0.060 

Controlled 2010+ 0.39 0.02 0.060 

50 – 120 

Gasoline 

Uncontrolled – Pre 2004 11.84 2.66 0.060 

Controlled 2001-2006 1.78 0.26 0.060 

Controlled 2007-2009 1.19 0.18 0.060 

Controlled 2010+ 0.36 0.05 0.060 

Alt Fuel 

Uncontrolled – Pre 2004 10.51 1.02 0.060 

Controlled 2001-2006 1.58 0.11 0.060 

Controlled 2007-2009 1.05 0.07 0.060 

Controlled 2010+ 0.32 0.02 0.060 

>120 

Gasoline 

Uncontrolled – Pre 2004 12.94 1.63 0.060 

Controlled 2001-2006 1.94 0.16 0.060 

Controlled 2007-2009 1.29 0.11 0.060 

Controlled 2010+ 0.39 0.03 0.060 

Alt Fuel 

Uncontrolled – Pre 2004 10.51 0.90 0.060 

Controlled 2001-2006 1.58 0.09 0.060 

Controlled 2007-2009 1.05 0.06 0.060 

Controlled 2010+ 0.32 0.02 0.060 

Source: 2011 Carl Moyer Program Guidelines, Table D-14 
372-spec-8 

NRCS, CA 

November, 2013 

CALIFORNIA EMISSIONS CALCULATION WORKSHEET 

Air Quality – 372 Combustion System Improvement

Producer Name: Date: 

Existing Engine Emissions Calculations

Existing Engine: Manufacturer:

Model Year Engine: Fuel Type:

Equipment Type:

Serial Number:

Baseline Emissions NOx ROG PM10 

Maximum Rated Brake Horsepower: bhpmaximum

Annual Hours of Operation: x Hours/Year 

Emission Factors: x g/bhp-hr 

Load Factor: x 

Conversion to Tons: ÷ 907,200 907,200 907,200 Grams/Ton 

Annual Emissions (EE) = Tons/Year 

New Engine Emissions Calculations (Report as zero emissions if electric) 

New Engine: Manufacturer:

Model Year Engine: Fuel Type:

Equipment Type:

Serial Number (if available):

New Engine Emissions NOx ROG PM10 

Maximum Rated Brake Horsepower: bhpmaximum

Annual Hours of Operation: x Hours/Year 

Emission Factors: x g/bhp-hr 

Load Factor: x 

Conversion to Tons: ÷ 907,200 907,200 907,200 Grams/Ton 

Annual Emissions (NE) = Tons/Year 

Calculation Results

NOx ROG PM10 

Annual Emission Reductions: 

(EE) – (NE) = Tons/Year 

Percent Emission Reductions: 

[(EE – NE) / (EE)] x 100 = % 

723 - 1 

NRCS, CA 

May 2009 

Conservation practice standards are reviewed periodically, and updated if needed. To obtain the current 

version of this standard contact your Natural Resources Conservation Service State Office, or download 

it from the electronic Field Office Technical Guide for your state. 

NATURAL RESOURCES CONSERVATION SERVICE 

INTERIM CONSERVATION PRACTICE STANDARD 

COMBUSTION SYSTEM AIR EMISSIONS MANAGEMENT 

(No.) 

Code 723

DEFINITION 

Installing, replacing, or retrofitting an agricultural 

combustion system and/or related components or 

devices. 

PURPOSE

The purpose of this standard is to manage air 

emissions from agricultural combustion systems. 

Specifically, this standard is intended to address the 

particulate matter and ozone precursors air 

resource concerns by reducing emissions of oxides 

of nitrogen and/or fine particulate matter that arise 

from the use of any type of combustion system. 

CONDITIONS WHERE PRACTICE APPLIES 

This practice applies to any agricultural operation 

that operates an agricultural combustion system, 

including stationary, portable, mobile, and 

self-propelled equipment. The combustion system 

must be used primarily for agricultural and/or 

forestry activities. 

CRITERIA

The new or replacement combustion system and 

related components or devices shall be sized 

appropriately to accomplish its intended task. 

The new, replacement, or retrofit combustion 

system and related components or devices shall 

utilize a non-combustion power source or 

cleaner-burning technologies, techniques, and/or 

fuels, or allow for the reduced operation of an 

existing combustion system. 

Retrofit can include actions or combinations of 

actions that are intended to reduce emissions of 

oxides of nitrogen and/or fine particulate matter. 

Examples of individual retrofit actions include: 

Adding an emissions control device, 

Altering air/fuel mixtures, 

Adding a device that allows for reduced 

operation of an existing combustion 

system, and/or 

Other physical modifications or changes in 

combustion techniques that reduce 

emissions formation and release. 

Where required, the new, replacement, or retrofit 

combustion system and related components or 

devices shall be certified to meet 

currently-applicable federal, state, and local 

standards and guidelines. 

When installing a new diesel-powered engine, the 

newest-available EPA engine TIER technology shall 

be chosen. 

The new, replacement, or retrofit combustion 

system and related components or devices shall be 

operated and maintained in accordance with the 

manufacturer’s recommendations. 

All replaced combustion systems shall be rendered 

inoperable or used to replace higher-emitting 

combustion systems. 

Certification of inoperability can be 

accomplished by: 

Obtaining a receipt for the combustion 

system disposal from a scrap metal 

recycling operation and keeping this 

receipt available for inspection; or 

Punching a permanent hole through the 

engine block or combustion chamber of 

the combustion system (minimum size 

to be determined by federal, state, or 

local guidelines at

http://www.valleyair.org) and 

maintaining a certification for inspection 

that this process has been completed; 

or
Certification of use as a replacement 

system can be accomplished by providing 

certification of inoperability of one or more 

higher-emitting combustion system(s). 

CONSIDERATIONS

Installation of new, or replacement of existing, 

combustion systems with non-combustion 

renewable energy sources, such as solar, wind, and 

water, will provide the greatest air quality benefit. 

To maximize the air quality benefits of this practice, 

replacement combustion systems should be similar 

in size and hours of operation to the existing 

combustion systems. 

Cultural Resources Considerations 

NRCS policy is to avoid any effect to cultural 

resources and protect them in their original location. 

Determine if installation of this practice or 

associated practices in the plan could have an 

effect on cultural resources. The National Historic 

Preservation Act may require consultation with the 

California State Historic Preservation Officer. 

http://www.nrcs.usda.gov/technical/cultural.html is 

the primary website for cultural resources 

information. The California Environmental 

Handbook and the California Environmental 

Assessment Worksheet also provide guidance on 

how the NRCS must account for cultural resources. 

The e-Field Office Technical Guide, Section II 

contains general information, with Web sites for 

additional information. 

Document any specific considerations for cultural 

resources in the design docket and the Practice 

Requirements worksheet. 

Endangered Species Considerations 

If during the Environmental Assessment NRCS 

determines that installation of this practice, along 

with any others proposed, will have an effect on any 

federal or state listed Rare, Threatened or 

Endangered species or their habitat, NRCS will 

advise the client of the requirements of the 

Endangered Species Act and recommend 

alternative conservation treatments that avoid the 

adverse effects. Further assistance will be provided 

only if the client selects one of the alternative 

conservation treatments for installation; or with 

concurrence of the client, NRCS initiates 

consultations concerning the listed species with the 

U.S. Fish and Wildlife Service, National Marine 

Fisheries Service and/or California Department of 

Fish and Game. 

PLANS AND SPECIFICATIONS 

Specifications for application of this practice shall 

be prepared for each site or planning unit according 

to the criteria. Specifications shall be recorded 

using State-developed specification sheets, job 

sheets, practice requirement sheets, narrative 

statements in conservation plans, or other 

acceptable documents. 

As a minimum, the plans and specifications shall 

provide the following: 

1. Identification and description of the existing 

combustion system and related components or 

devices, if applicable, and the new or 

replacement combustion system and related 

components or devices. If the combustion 

system is being retrofitted, identification and 

description of the type of modifications being 

made to the existing system. 

2. Requirements on disposal of replaced 

combustion system and related components or 

devices, including assuring permanent disabling 

and rendering inoperable. 

3. Documentation requirements to determine 

combustion system usage and resulting air 

pollutant emissions. 

OPERATION AND MAINTENANCE

An operation and maintenance plan shall be 

developed that is consistent with the purposes of 

this practice, its intended life, safety requirements, 

and the criteria used for its design. 

NRCS recommends that records be retained and 

updated for a minimum of five years from the 

beginning of operation of a replacement or 

retrofitted combustion system. The recommended 

records to be retained include: 

Total actual hours operated 

Types and amounts of fuel used in the 

combustion system(s), or electricity 

used for electric motors 

Documentation of maintenance 

conducted on the replacement or 

NRCS, CA 

May 2009 
NRCS, CA 

May 2009 

retrofitted combustion system and 

related components or devices 

REFERENCES 

NRCS National Air Quality and Atmospheric 

Change Technology Development Team, West 

National Technology Support Center, Portland, 

Oregon