# Agricultural Air Quality

Conservation Measures

Reference Guide for Cropping Systems

A nd General Land Management



# October 2012Introduction

1 | P a g e Purpose

The United States Environmental Protection Agency (EPA) and the United States Department of Agriculture

- Natural Resources Conservation Service (USDA

- NRCS) have collaborated to develop th is reference g uide to provide a compilation of conservation measures for air pollutant emission reductions and/or reduction of air quality impacts from agricultural land management and cropping operations. L ivestock operations will be covered in a separate reference guide in

the future . This reference g uide can be used to address agriculturally

- related air resource concerns in areas where agricultural emissions from cropping systems and general land

management are determined to be significant contributors to air quality impairment

. The methods presented in this g uid e are consistent with USDA objectives that promote the use of

cost

- effective practices and innovative technologies to address air resource concerns from agricultural operations and to meet federal, state and local regulatory requirements. Many of the

measu res provided in this g uide also have additional resource benefits such as soil, water or energy conservation. Some co

- benefits are identified, but this document is primarily focused on air quality.

Over the past several years, EPA has received multiple r equests to identify USDA

- approved measures that may be considered to manage air emissions from cropping systems and general land management sources and potentially satisfy State Implementation Plan (SIP) requirements. These requests have come from a variet y of stakeholders

, including USDA’s Agricultural Air Quality Task Force, agricultural producers , industry representatives and state and local agencies.

I n the 2006 Particulate Matter ( PM ) National Ambient Air Quality Standards ( NAAQS ) and 2008 Ozone NAAQS preambles, EPA recommended that in areas where agricultural activities have been identified as a contributor to a violation of the NAAQS, when properly implemented to control airborne emissions of the desired NAAQS pollutant, USDA

- app roved conservation systems and activities may be implemented to achieve reasonably available control measure (RACM) and best available control measure (BACM) levels of control

.

This r eference guide is chiefly designed as a technical tool to provide a com pilation of USDA

NRCS approved practices to address air emissions from agricultural sources in areas where agricultural activities have been demonstrated to contribute to air quality issues. To learn more about NRCS practice standards please c ontact your local NRCS state office. Contact information

for NRCS state offices can be found under the “browse by location” link at www.nrcs.usda.gov

. USDA

- NRCS may be able to offer technical and financial assistance to agricultural producers for implementing these and other conservation practices. Additionally, national funding assistance may be available from the EPA.

Furthermore , the USDA

- NRCS was involved in the development of additional conservation measures for air quality purposes in California and Arizona and, where appropriate, reference s to
these USDA

- NRCS approved measures are included in this g uide. Some of the se conservation activities were patterned after NRCS conservation practice standards, but despite similarities in some of the names, application of the se co nservation activities may differ slightly from application of the NRCS practice standards.Introduction

2 | P a g e

For more inform ation on the California measures , please see the Agricultural Air Quality Conservation Management Practices for San Joaquin Valley Farms handbook and table , which

are available at:

Handbook: http://www.valleyair.org/farmpermits/updates/cmp_handbook.pdf

Table: http://www.valleyair.org/farmpermits/applications/cmp/cmp_list.pdf

For more inf

ormation on the Arizona measures , please see the handbook for Agricultural PM 10 Best Management Practices, which is available at :

Handbook: http://www.azda.gov/ACT/Best%20Management%20Practices%20Guide%20 for%20web%20view%20reducec.pdf

Th is Reference Guide is Intended to:

Provide a broad, though not comprehensive, set of USDA

- NRCS approved practices that may be relied upon to address air resource concerns. Provide regional, state and local regulatory agencies with technical tools and information on how to manage agricultural air emissions with USDA

- NRCS approved measures and USDA

and EPA expertise

. Allow stakeholders the flexibility in choosing which measures are best suited for their specific situations/conditions and desired purposes.

Th is Reference Guide is NOT Intended to:

Identify agr icultural sources as a significant contributor to air quality issues in all areas.

o There are currently only a handful of areas in the United States where agricultural sources have been identified as a significant contributor to nonattainment of the PM and Ozone NAAQS. However, for those areas where it is demonstrated that agricultural sources are a significant contributor, this document can be useful to the state or local regulatory agency as it reviews options for managing air emissions from agricultural s ources. Provide a comprehensive listing of all potential emissions reduction measures for mitigating agriculturally

- related air quality impacts

. Provide conservation measures that will be suitable for every specific case.

o Geographic location, environment al conditions and intended purposes will differ for each particular agricultural situation. Thus, USDA and EPA strongly encourage state and local agencies to work with individual producer s and NRCS conservationists to develop plans

that include feasible and effective measures for each site. Provide any regulatory measures from the EPA.

o This document is solely for informational purposes. It may be useful for states and local air agencies need ing additional information on how to reduce emissions in areas w here agricultural sources are demonstrated to contribut e to a non

- attainment designation.

Provide details about the numerous co

- benefits of these measures with respect to water quality, soil health, energy savings, greenhouse gases and many others.

o Many of the practices listed in this g uide may already be implemented to achieve other resource benefits (e.g. soil conservation, water conservation, etc.). T his document wasIntroduction

3 | P a g e

designed to solely focus on the air quality benefits achieved from implementation of the

conservation measures. It should be noted that in some cases

, measures taken to achieve air quality benefits may cause other environmental impacts, and each situation needs to be carefully analyzed to achieve mutually beneficial outcomes.

When Imp lementing Conservation Measures:

Regional, s tate, and l ocal r egulatory a gencies should c oordinate (as appropriate) with the producers

, land owners, operators, state and local agencies, NRCS

, and EPA to determine which measures may be best suited for a particular situation to attain the desired goals. Consider the geographic location and environmental conditions (soil type, precipitation, humidity, temperature, water availability, wind conditions, terrain, etc.) in which the practices will be implemente d

, as they will also play a role in deciding which conservation measures are most suitable. Assess implementation costs and benefits to determine the most cost

- effective control measures that provide the greatest emissions reductions. Refer to the most up

- to

- date NRCS conservation practice standard s or guidance to ensure that implemented measures follow current guidelines.Introduction

4 | P a g e Using the Reference Guide

This technical tool identifies the current USDA

- NRCS approved conservation measures available to the agri cultural industry for the emission reductions of PM, PM precursor and o zone

precursor emissions from agriculture operations. The measures are listed in eight sections

, each categorized by type of activity or result to be achieved

. For example, measures int ended to maintain soil surface cover, and thus reduce PM emissions from erosive agents (wind, vehicle tires, implements, etc.) are included in Section 1.

It should be noted that all practices will not be well

- suited for every region or specific farm /ranch or land management operation . Thus, the conservation measures are designed so that producer s will have options and flexibility in selecting the most eff ective practices for their operation

.

This g uide is intended to provide information on USDA

- NRCS approved measures that reduce

air emissions

. However, many of the se measures also provide co

- benefits for other resource

concerns that are not identified in the document

. To learn more about co

- benefits from practices

outlined in this g uide, please contact your local NRCS State Office

. Note that USDA

- NRCS may

also be able to offer technical and financial assistance to agricultural producers for implementing these and other conservation practices.

USDA

- NRCS has developed conservation practice standard s using scientifically

- proven research

and demonstration of techn ologies. For measures that have related practice standards , the NRCS

Practice Codes are listed. The conservation practice standard s contain information on why and where the conservation practice is applied and set forth minimum quality criteria that must b e met during application to achieve the intended purpose(s).

State

- specific versions of the conservation practice standards are available through the NRCS Field Office Technical Guide ( FOTG ) for each state. If no state conservation practice standard is

av ailable in the FOTG , please contact the appropriate NRCS State Office or local USDA Service

Center. These offices are available to answer state and local questions and provide many forms

of assistance. The locations of these offices can be found at the following websites:

NRCS State (and Local) Offices : www.nrcs.usda.gov

USDA Service Center Locator : http://offices.sc.egov.usda.gov

Additional Resources

NRCS has developed educational tools that are designed to provide information about air quality and are accessible to the public. To view these online courses please visit : www.airqua lity.nrcs.usda.gov

.

EPA has developed a website that provides links to various agriculture and air quality related topics. For more information, please visit: http://www.epa.gov/airquality/agriculture

.



## Contributors

USDA

– Natural Resources Conservation Service (NRCS)

– Air Quality and Atmospheric Change Team

U.S. EPA

– Office of Air Quality Planning and Standards (OAQPS)Table of Contents

5 | P a g e 

### Table of Contents

Page

Section 1: Maintaining Soil Surface Cover

................................ ................................ .............. 6

Section 2: In

- Field Pass Reductions

................................ ................................ ........................ 10

Section 3: Soil Conditioning and Timing of Operations Modifications

................................ 1 3

Section 4: Unpaved Roadways and Other Areas

................................ ................................ ... 1 7

Section 5: Wind Barrier s

................................ ................................ ................................ ........ 2 1

Section 6: Equipment Modifications

................................ ................................ ...................... 2 5

Section 7: Fire and Smoke

................................ ................................ ................................ ...... 2 7

Section 8: Other

................................ ................................ ................................ ....................... 3 1Section 1: Maintaining Soil Surface Cover

6 | P a g e 

## Section 1: Maintaining Soil Surface Cover

Soil surfaces can be sources of PM

emissions when winds of sufficient speed s act upon the surface to cause erosion, suspension and entrainment of soil particles or when the action of machinery on soils leads to particulate generation. Both wind

erosion and machinery action can lead to significant soil quality issues with the loss of valuable topsoil and deposition of soil on areas where it is not desired, including water bodies and streams (becoming a water quality issue). The degree to

which soils erode an d particles become airborne by wind or mechanical action is dependent on several factors, including the amount, type and spatial distribution of surface cover (residue, vegetation or other cover), soil type, soil moisture, the amount of compaction versus l ooseness of the top soil layer and the roughness (micro

- topography) of the soil. Conservation practices that maintain soil cover and

reduce these wind

- and machinery

- driven erosion factors will greatly reduce the risk of wind erosion and mechanically

- gener ated PM by separating contact of the erosive agent ( i.e., wind, vehicle tires, or implements) from the soil surface. This section is focused on soil cover measures, and S ection 3 addresses soil condition measures.

Measures: Residue and Tillage Management and Mulching Cover Crops and Other Vegetative Surface Covers

Perennial Cr ops and O ther Vegetation

 Conservation Measure Description: Residue and Tillage Management and Mulching

Utilizing tillage systems that retain residue on the soil surface and reduce tillage intensity (less soil disturbance), as well as the reduction in vehicular traffic on fields will reduce the potential for PM generation. Where tillage and/or vehicular movement are needed, adopting conservation tillage and residue management, to the extent possible, will help retain topsoil structure and the ability of the soil surface to stay intact and not generate PM. Soil surface cover can also be achieved by mulching, which utilizes materials not present on the field. In cases where soils are

ba re (especially during times of severe drought when maintaining some type of surface cover becomes impossible) mulching can be very effective. I f mulching is not feasible it may become necessary to invoke other conservation actions to prevent significant PM emissions (such as surface roughening, wind barriers, etc.

— see S ections 3 and 5).Section 1: Maintaining Soil Surface Cover

7 | P a g e

Several NRCS conservation practices are specifically designed for managing tilla ge and residue

on soil surfaces and for application of mulches. Residue and Tillage Manageme nt No Till/Strip

Till/Direct Seed is used for managing the amount, orientation

, and distribution of crop and other plant residue on the soil surface year

- round

, while limiting soil

- disturbing activities to those necessary to place nutrients, condition residue

, and plant crops

. This is the most stringent NRCS residue and tillage management practice, and its application retains the most residue of any practice. It also can greatly reduce tillage

- induced PM generation

, since tillage is eliminated or greatl y reduced. One of the specified purposes of this practice is to reduce soil particulate

emissions.

Other conservation tillage practices

, such as Residue and Tillage Management Mulch Till

, Residue and Tillage Management Ridge Till

, and Resid u e and Tillage Management Seasonal manage both tillage and surface residue retention, and thus reduce the potential for PM generation compared to conventional tillage systems ( though not to the extent of the no

- till practice )

. Mulching is the a pplication of plant residu es ( or other suitable materials produced off

site ) to the land surface. Other suitable materials include natural products like wood chips and rice hulls, as well as artificial materials like plastic or fabric. Among other purposes, mulching

can be used to reduce airborne particulates, conser ve soil moisture, moderat e soil temperatures, and impro ve soil condition.

NRCS Conservation Practice Standards Residue and Tillage Management No Till/Strip Till/Direct Seed (329) Residue and Tillage Management Mulch Till (345) Residue and Tillage Management Ridge Till (346) Residue and Tillage Manageme nt Seasonal (344) Mulching (484)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Alternate Till

o Conservation Tillage

o Mulching

o Non Tillage / Chemical Tillage

o Soil Amendments

o Transplanting

From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Reduced Tillage System

o Residue Management

o MulchingSection 1: Maintaining Soil Surface Cover

8 | P a g e

 Conservation Measure Description: Cover Crops and Other Vegetative Surface Covers

Cover crops and other vegetative surface covers are typically annual plantings that are part of a cropping sequence. They often are used during the non

- cropping part of a rotation to maintain

soil surface cover, as well as to increase soil organic matter content, manage soil moisture, minimize and reduce soil compaction, and capture and recycle or redistribute nutrients in the soil profile. Cover Crop is typically used in conjunction with Conservation Crop Rotation

.

Stripcropping , the practice of growing planned rotations of row crops, forages, small grains, or fallow in a systematic arrangement of equal width strips across a field, can also be used effectively for seasonal soil cover maintenance.

NRCS Conservation Practice Standards Conservation Crop Rotation (328) Cover Crop (340) Stripcropping (585)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices

, ( Table

, Handbook ):

o Cover Crops From the Arizona Guide to Agricultural PM 10 Best Management Practices

, ( Handbook ):

o Cover Crop

o Sequential Cropping

 Conservation Measure Description: Perennial Crops and other Vegetation

Greater s oil cover (both spatially and temporally) can be achieved by utilizing perennial crops or perennial vegetation, when appropriate. With these practices, soil cover is almost always maintained, and PM generation from wind erosion or mechanical/vehicular action is greatly reduced or eliminated. These practices can be very effective for long

- term soil stabil ization and improvement in soil quality. They can be grouped into: Perennial cropping and cropping

- related practices which allow for the permanent and

semi

- permanent establishment of forage and/or biomass crops, and buffer areas that

maintain soil cover. These include Field Border and Forage and Biomass Planting. Perennial vegetation practices that establish vegetation for a long period of time. These

include Conservation Cover, Range Planting and Tree/Shrub Establishment

. Critical Area Planting is inten ded to establish permanent vegetation on sites that have, or are expected to have, high erosion rates, and on sites that have physical, chemical or biological conditions that prevent the establishment of vegetation with normal practices. Agroforestry pract ices such as Alley Cropping

, Multi

- Story Cropping, Silvopasture

Establishment and Windbreaks also can be used to maintain soil cover, and thus reduce potential PM generation, as well as provid e additional natural resource benefits. These

are also very effective wind barriers and are described more fully in S ection 5.Section 1: Maintaining Soil Surface Cover

9 | P a g e

NRCS Conservation Prac tice Standards Alley Cropping (311)
Conservation Cover (327) Critical Area Planting (342) Field Border (386) Forage and Biomass Planting (512)

Multi

- Story Cropping (379) Range Planting (550) Silvopasture Establishment (381) Tree/Shrub Establishment (612)

W indbreak/Shelterbelt Establishment (380) Windbreak/Shelterbelt Renovation (650)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices

, ( Table

, Handbook ):

o Permanent Crop From the Arizona Guide to Agricultural PM 10 Best Management Practice s
, ( Handbook ):

o Multi

- Year Crop

o Permanent Cover

Geographic and Physiographic Factors:

In general, areas of the United States with lower precipitat ion and higher winds will be most likely to benefit from implementing measures f ound in this section . The High Plains from eastern

Montana and the Dakotas southward to west ern Texas and eastern New Mexico can frequently

be vulnerable to wind erosion and PM generation and transport, especially during drought periods. Other areas like the winter wheat / summer fallow region of eastern Washington and Oregon also occasionally experience these issues, with the juxtaposition of bare soils, dryland farming and inf

requent high wind events. In general, erosive wind events are quite rare in the

United States , and years may pass in some areas before atmospheric and soil conditions align for PM generation and transport. Since soil moisture and topsoil conditions are cri tical for PM generation

, it is necessary that these factors, in addition to wind statistics, be strongly considered in determining a location’s vulnerability for erosive events and consequent ly air quality degradation. Thus, during severe drought episodes

, there may be very little that can be done to avoid significant wind erosion and PM generation. In fact, this is the very source of the world’s

loess soils.

Tool: The NRCS/ Agricultural Research Service ( ARS ) Wind Erosion Prediction

System (WEPS) is the primary model used by USDA to estimate wind erosion potential. Users can specify soil surface characteristics and management options,

such as those described in this section. WEPS also has the capability to mod el crop growth and include cover crops or perennial vegetation (and barriers). The model delivers estimates of total

soil loss as well as PM 10 emissions from a specified land area. WEPS is not an online tool, but those interested in applying the model shou ld work through their appropriate state and/or local NRCS agronomist.Section 2: In

- Field Pass Reductions

10 | P a g e 

## Section 2:


# In

- Field Pass Reductions

Agricultural field operations

, such as tilling, planting, weeding, fertilizing, harvesting, mowing, cutting, baling, and spreading of

manure or compost can produce air pollution emissions. These emissions can be directly emitted from the action of wheels and machinery on soil or from e ngine

combustion. Vehicular and machinery

action can break up soil aggregates

, making the finer particles more likely to be suspended by additional field actions and/or

wind

. The amount of dust produced and transported off the field is largely a function of the number of individual operations on a given field and associated atmospheric conditions

. R educing the number of operations reduc es the amount of dust produced i n the field, as well as engine emissions. Therefore, a reduction in the number of passes o ver a field can : 1) reduce soil abrasion and the breakup of soil aggregates, 2) reduce direct suspension of PM from vehicle wheels/etc., and 3) reduce engine emissions (ozone precursors [ e specially oxides of nitrogen ( NO

x ) ]

, and PM )

.

Measure s : Modify Operations

Precision D elivery

 Conservation Measure Description: Modify Operations

Reducing in

- field passes can be accomplished by modify ing operations and improving operational efficiency. This can be achieved by applying conservation tillage, increasing equipment efficiencies, optimizing field space, or combining operations

. O verall , these

conservation measures can be quite effective at reducing PM emissions. Reduced engine

emissions are approximately proportional to the number of reduced passes, taking into account implements used and additional power needs with the combined operation. Conservation tillage

limits soil

- disturbing activities to only those necessary to place nutrients, condition residue and plant crops. Optimizing field space through adjust ments in bed / row spacing ( which can increase plant density/canopy through reduction of row width ) reduces the number of passes and the

resultant soil disturbance. Certain c rop cultur al practices (including organic practices for reducing pesticide application passes , hand harvesting, and those practices associated with fruit crops, including the use of a continuous tray/dried

- on

- the

- vine system such as that applied in

California ) can also result in reduced passes. However, in some cases organic production can actually increase field passes, such as increasing cultivation for weed control. In these cases, this measure should not be used as a control measure for reducing PM emissions. Many i n

- field pass reductions can be applied relatively independently of geographic location. Residue and TillageSection 2: In

- Field Pass Reductions

11 | P a g e

Management Mulch Till and Residue and Tillage Management No Till/Strip Till/ Direct Seed are conservation practice standards that may be used for managing the residue on soil surface s , thus reducing required in

- field passes.

NRCS Conservation Practice Standards

Residue and Til lage Management Mulch Till (345) Residue and Tillage Management No Till/Strip Till/Direct Seed (329)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Alternate Till

o Bed/Row Size or Spacing

o Combined Operations

o Continuous Tray/Dried on the Vine, New Drying Techniques for Dried Fruit

o Conservation Tillage

o Floor Management

o Equipment Changes/Technology Improvements

o Green Chop

o Hand Harvesting

o Fallowing Land

o Mulching

o Non

- Tillage/Chemical Tillage

o Organic Practices (for biological control of pests)

o Shed Packing

o Shuttle System/Large Carrier

o Transplanting From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Combining Tractor Operations

o Green Chop

o Reduced Harvest Activity

o Reduced Tillage System

 Conservation Measure Description: Precision Delivery

Application of advanced technologies and methodologies

, such as Integrated Pest M anagement,
Nutrient M

anagement, Irrigation System Microirrigation, Irrigation System Surface and Subsurface

, application efficiencies, precision farming and chemigation/fertigation

, can precisely deliver herbicides/pesticides and water to crops . These technologies and methodologies can also

reduce : operation overlap, number of field passes, soil compaction (which requires additional tillage) and excess water that can enhance weed growth (where weed treatment could require additional tillage and field passes ). Integrated pest management and nutrient management are comprehensive practices designed to precisely deliver pesticides and nutrients to the agricultural

system. Nutrient and pest management conservation practices strive to apply fertilizer and pesticides from the right source, at the right rate , at the right time, and in the right place ( known as the 4R’s of nutrient stewardship )

. Getting the nutrient or pesticide applied in the right placeSection 2: In

- Field Pass Reductions

12 | P a g e

( precision d elivery) can take the form of smart sprayer technology , which places the pesticide precisely on the desired plant location or precision delivery systems , which lead to the elimination of operation overlap . These practices not only reduce direct PM emissions from vehicles and mechanical disturbance of the soil, but also can prevent or mitigate pest icide and

nutrient volatilization losses and drift (including volatile organic compounds ( VOC ) and NO

x ).

NRCS Conservation Practice Standards Integrated Pest Management (595) Nutrient Management (590) Irrigation System Microirrigation (441) Irrigation System Surface and Subsurface (443)

Additional Conservation Activities

From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Application Efficiencies

o Conservation Irrigation

o Chemigation/Fertigation

o Integrated Pest Management

o Precision Farming (Global Positioning System) From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Chemical Irrigation

o Integrated Pest Management

o Precision FarmingSection 3: Soil Conditioning and Timing of Operations Modifications

13 | P a g e 

## Section 3: 

# Soil Conditioning and Timing of Operations Modifications

Soil conditioning and timing are critical when it comes to cropping systems. Modifying agricultural activities that help condition the soil (such as cultivating, ridging, etc.), as well as modifying the timing of operations

, is not always practical but may sometimes be necessitated by local or regional air quality conditions. In regions of the country where agriculture has been

identified as a source that contributes to compromised air quality, atmospheric

concentrations can be minimized by adopting soil conditioning practices and modifying the timing of operations. Conservation measures and activities that can be adopted to reduce agricultural air emissions include: no

- till farming, precision agriculture, monitoring soil moisture, soil am endments, residue and tillage management, closely monitoring weather and atmospheric conditions, and adjusting the timing of operations to minimize air quality impacts.

Farming and ranching operations almost always involve critical timing components that are, at very best, marginally flexible. Producer operations almost always hinge on a suite of dynamic factors, and when the majority of these factors are favorable, the intended farming operations (i.e.

, tillage, harvest, soil amendments) occur. Implementi ng one or more proactive conservation measures and timing operations to coincide with favorable atmospheric conditions (wind speed and direction, relative humidity, atmospheric stability, background ambient air quality concentrations, etc.) can prevent adv erse agricultural air quality impacts. Producers often need to modify operations due to weather conditions. Air quality can sometimes benefit from modifying the timing of operations, where practicable. In some areas of the country, the calcul ations be hind agricultural decision making ha ve become more complex due to air quality . In these regions

, weather conditions and economics are the primary variables ; however, ambient air quality must also be considered as a variable in the agricultural decision

- making p rocess.

This section focuses on utilizing conservation techniques related to soil conditioning and timing of operations to minimize air emissions while accomplishing the necessary farm/ranch business requirements. Minimizing agricultural emissions can be accomplished through a variety of innovative solutions and good decision

- making.

In some regions of the country

, the adoption of conservation measures is required of produ cers

. Producers, particularly in these regions, should be cognizant of air emissio ns from agricultural activities. Careful evaluation of soil conditions and timing of operations to minimize the possibility of agriculturally

- produced emissions (which can contribute to compromised ambient Photo: Dusty Eddy, NRCSSection 3: Soil Conditioning and Timing of Operations Modifications

14 | P a g e

air quality ) should be pursued, when feasible. Cle arly

, producer s have many decision

- making

factors , and there are times when it is critical to proceed with operations (such as completing planting or harvest before a significant weather event). When economic and other considerations allow, modifying timin g of operations to ensure adequate air quality should be strongly

considered. For example, when meteorological and soil conditions align to indicate a high

- wind dust event could occur, limiting in

- field activity can be an effective measure for reducing PM

emissions.

Emission prevention techniques are generally applicable throughout the country in a variety of agricultural contexts. Conservation measures are most effective when they are prescribed and customized for a particular locality, even a specific agricultural operation under a specified set of
parameters. Conservation measures can be most effective in areas where topsoil can easily

become airborne due to moistu re and physical soil properties and may be most necessary in regions where agriculture oc curs in close proximity to population centers. Local regulations and

ordinances should be followed and harmonized with conservation measures to meet air quality objectives.

Many of the practices and activities that can be implemented to reduce agricultura l emissions also have ancillary benefits and can preserve valuable topsoil, conserve water, and increase productivity.

Measures : Soil Conditioning Modifying the Timing of Operations



##  Conservation Measure Description: Soil Conditioning

Increasing the soil moisture content through residue and cover crops can be an effective approach to increasing soil health and minimizing airborne PM

. Cover C rops can be used through fallow periods in some cropping systems and in areas with sufficient pre cipitation to reduce soil erosion, increase soil nutrients, and address wind erosion. Several NRCS conservation practices , such as Nutrient Management, have been identified as beneficial soil conditioning practices. PM emission reductions from R esidue and Tillage M anagement

, and Stripcropping are practices that can help address ambient air quality concerns while simultaneously improving soil tilth. Conservation C over and M ulching also add organic matter and stabilize the soils to effectively reduce air emis sions, even when soils are bare. Pre

- harvest soil preparation, such as I rrigation W ater M anagement and S

prinkler I rrigation S

ystems can be used to improve air quality. Water or stabilizing material can be applied to the soil prior to agricultural operation s to control dust. However, this should only be an option when ample water supplies exist. S urface R oughening is also a proven method of reducing wind

- blown PM in cases of extreme dryness, lack of vegetation, and impending strong winds. However, this is an emergency practice only utilized when no other options for controlling dust exist.

NRCS Conservation Practice Standards

Conservation Cover (327) Cover Crop (340)Section 3: Soil Conditioning and Timing of Operations Modifications

15 | P a g e

Irrigation Water Management (449) Irrigation System Sprinkler ( 442) Mulching (484) Nutrient Management (590) Residue and Tillage Management Mulch Till (345) Residue and Tillage Manag ement No

- Till / Strip Till / Direct Seed (329) Residue and Tillage Management Ridge Till (346) Stripcropping (585) Surface Roughening (609)

Additional Conservation Activities

From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices

, ( Table

, Handbook ) :

o Alternate Till

o Conservation Tilla ge

o Cover Crops

o Floor Management

o Mulching

o Non Tillage / Chemical Tillage

o Organic Practices

o Pre

- Harvest Soil Preparation

o Permanent Crops

o Soil Amendments

From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Reduced Tillage Systems

o Aggregate Cover

o Synthetic Particulate Suppressant

o Cover Crop

o Cross

- Wind Ridges

o Mulching

o Residue Management

o Surface Roughening



##  Conservation Measure Description: Modifying the Timing of Operations

Timing is critical in farming. Adjustments in the timing of operations and/or proper soil conditioning can minimize many agricultural air quality issues. Agricultural operators located in, or in close proximity to, air quality n onattainment areas should integrate air quality

considerations into their decision

- making criteria.

Minimizing soil

- disturbing activities and timing these activities to coincide with favorable atmospheric conditions can reduce agricultural air emissions. Timing tillage, planting, and harvesting to occur when the soil has the appropriate moisture content has multiple benefits. In addition to the air quality benefits that also prevent wind erosion, performing field operations during times of favorable soil m oisture can improve yield and soil health. InnovativeSection 3: Soil Conditioning and Timing of Operations Modifications

16 | P a g e

conservation measures like Integrated Pest Management, Nutrient Management, and Residue

M anagement attempt to maximize the efficiency of field operations while minimizing adverse impacts.

Timing , one of the 4R’s of nutrient stewardship

, is also critical for integrated pest management. Producers can monitor crops for pests to ensure effective spray timing and incorporate biological practices into the farming operation to reduce the need for spraying.

O ther practices, such as limiting agricultural activities during high

- wind events, and farming at night when relative humidity and surface soil moisture is higher and temperatures and wind speeds are typically lower, can effectively reduce PM emissions

. Mai ntaining cover crops and managing residue can minimize wind erosion while adding valuable organic matter to the soil (see Se ction 1 for more details ). In regions where residue burning is common, smoke management should be considered as part of planning and executing the burn. See Section 7 of

this g uide for additional information on Prescribed B urning and smoke management.

NRCS Conservation Practice Standards Integrated Pest Management (595) Nutrient Management (590) Residue Management Seasonal (344) Prescribed Burning (338)

Additional Conservation Activities

From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices

, ( Table

, Handbook ) :

o Combined Operations

o Equipment Changes / Technology Improvements

o Fallowing Land

o Night Farming

o Night Harvesting

o Precision Farming (GPS)

o Time of Planting

o Transplanting

o Green Chop

o No Burning

o Reduced Pruning

o Integrated Pest Management

From th e Arizona Guide to Agricultural PM 10 Best Management Practices

, ( Handbook ):

o Green Chop

o Limited Activity during a High

- Wind Event

o Planting Based on Soil Moisture

o Tillage Based on Soil Moisture

o Timing of a Tillage Operation

o Integrated Pest Management

o Sequential CroppingSection 4: Unpaved Roadways and Other Areas

17 | P a g e 

## Section 4: 

# Unpaved Roadways and Other Areas

Roadways and farmstead areas that are unpaved or not covered with some type of vegetation or other surface bonding (grass, wood chips, etc.) can generate airborne soil particles. This includes roads, traffic areas, parking lots, staging or assembly

areas, eq uipment storage lots, runways and loading/unloading

areas of farms and ranches. Vehicular action on parental material (soil, rock, etc.) causes mechanical fracture (i.e.

, crushing) into smaller particles

that can become airborne. These unpaved areas can also produce dust by natural disaggregation of the pa rent material when wind acts upon them

— though typically wind

- eroded particles are larger than those produced by

vehicular action.

The principal means of preventing dust generation is via the use of dust suppressants. These are substances applied to unpave d roads and other areas that bind together soil, gravel, dust particles

and other materials. Suppressants, sometimes called palliatives, can be very effective in reducing or eliminating the generation and su spension of PM

. Another effective method of reduc ing PM is by controlling the frequency, duration and intensity of mechanical action on unpaved roads and

other areas via controls on vehicular actions. Finally, if PM is generated from unpaved roads and

surfaces on farms and ranches

, vegetation can be used to intercept it and retard its transport into adjoining lands.

Measures: Dust Suppressants

Vehicular Controls Vegetation Controls on Wind and Dust Interception

 Conservation Measure Description: Dust Suppressants

Dust suppressants, or palliatives, come in many forms, and can vary greatly in PM control effectiveness and longevity. Suppressants such as water are typically effective for only a short period of time (hours to a day or two), while biologically

- based products like lignosulfonate have longer lif etimes, and petroleum

- based products (like heavy road oil) can have lifetimes of a year

or more.Section 4: Unpaved Roadways and Other Areas

18 | P a g e

A primary NRCS conservation practice that can be used for this purpose is Dust Control on Unpaved Roads and Surfaces . This practice describes various means of controlling unpaved road and surface dust, most typically using some type of suppressant. Results from the utilization of this practice vary according to the suppressant used

, but may result in a 50% or greater re duction

in PM emissions over the untreated case. Cost and environmental impacts are considerations in suppressant choice. Long

- term cost

- benefit analyses typically inform landowner decision

making

. For instance, water may be the cheapest single

- application alternative, but due to the need for repeated applications

, it may be cost

- prohibitive for long durations and frequent applications. In addition, water may simply be unavailable in arid regions and/or during droughts. There may be environmental impacts of all other suppressants, including salts and petroleum products , and these impacts should be considered when making dust control decisions.

Additional NRCS practices that may also be used for PM emissions control on unpaved areas

include Irrigation System , Sprinkler; Heavy Use Area Protection and Mulching . These practices can be used to provide surface protection and cover to unpaved areas

, thus making them less susceptible to erosion.

NRCS Conservation Practice Standards Dust Control on Unpaved Roads and Surfaces (373) Irrigation System, Sprinkler (442) Heavy Use Area Protection (561) Mulching (484)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Chips / Mulches

, Organic Materials

, Polymer s, Road O il and Sand

o Grave l

o Paving

o Water From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Aggregate Cover

o Synthetic Particulate Suppressant

 Conservation Measure Description: Vehicular Controls

Control of both the speed and frequency of vehicular movement on roadways and other areas is

also a n effective strategy for PM control. Access Control and Dust Control on Unpaved Roads and Surfaces promotes PM control via posted speed limits, speed controls directly applied on engine components of vehicles/farm machinery, reduction of vehicular movement via combining operations, and other methods such as those suggested in S ection 2 for farm/ranch fields that

could be applicable to unpaved roads and surfaces. In addition, PM can be generated from soil transported from unpaved areas onto hard

- paved surfaces that is then disaggregated

, and can become airborne by vehicular action on the paved road. Reducing this “track

- out ” of soil (via mud on tires and other vehicle surfaces) onto hard

- surfaces can thus be an effective PM control
strategy.Section 4: Unpaved Roadways and Other Areas

19 | P a g e

NRCS Conservation Practice Standards Access Control (472) Dust Control on Unpaved Roads and Surfaces (373)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Combined Operations

o Mechanic al Prunin g

o Restricted Access

o Speed Limits

o Track

- out Control From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Access Restri ction

o Reduce Vehicle Speed

o Track

- out Control System

 Conservation Measure Description: Vegetation Controls on Wind and Dust Interception

Dust Control on Unpaved S urfaces may also be achieved by intercepting airborne particulates via vegetative barriers such as Windbreaks or Critical Area P lantings . However, dust control is best accomplished by preventing its initial generation. Vegetation placed along an unpaved roadway or other area can help contain and capture dust and prevent its transport away from the roadway area. This may be accomplished by following the practice standards: Field Border, Hedgerow Planting, Herbaceous Wind Barriers, or Tree/Shrub Establishment

. Care must be taken to apply the proper vegetation to withhold the expected dust load (es pecially on younger plantings) and will do an effective job of intercepting the dust. A complete description of wind

barriers can be found in S ection 5.

NRCS Conservation Practice Standards Critical Area Planting (342) Dust Control on Unpaved Roads and Surfaces (373) Field Border (386) Hedgerow Planting (422) Herbaceous Wind Barriers (603) Tree/Shrub Establishment (612) Windbreak/Shelterbelt Establishment (380)Section 4: Unpaved Roadways and Other Areas

20 | P a g e

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Wind Barrier From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Artificial Wind Barrier

o Critical Area Planting

o Tree, Shrub or Windbreak Planting

Geographic and Physiographic Factors:

Regions of the U.S. where extended dry conditions occur and where there is an abundance of unpaved farm roads and surfaces are the most likely places where this issue will be most prevalent. This includes most of the western U.S., the high plains, and the eastern third o f the
country ( where more erosive soil types are found )

.Section 5: Wind Barrier s

21 | P a g e 

## Section 5: 

# Wind Barrier s

Vegetative and artificial barriers can: 1) disrupt

the erosive flow of wind over unprotected surfaces by changing (slowing) the airflo w pattern over the land surface and 2) provide filtration and/or interception of airborne particles and gases. Wind barriers can also reduce the area of exposed soils

, and in the case of vegeta tive barriers, the root structure will further hold the soil in place. Artific ial

windbreaks can include structures such as fences and stacked hay bales and can be designed with various physical dimensions and porosities to alter wind flow. For all cases, whether reducing the suspension of particles or intercepting airborne particles and gases, wind barriers are most effective when oriented perpendicular to the erosive wind direction. A dry and disturbed soil in flat terrain without vegetation is the situat ion most likely to lead to the suspension of surface material, and many of the conservation practices in this section are designed to keep soil at the surface and reduce its migration offsite.

Measures: Disrupt Erosive Wind Flow Intercept Airborne PM and Gases

 Conservation Measure Description: Disrupt Erosive Wind Flow

When wind blows over a surface, a vertical wind speed profile exists where wind speed is nearly zero at the surface and then increases with height away from the surface. On a bare sur face, wind speed quickly increases with height because the surface elements have little drag effect and thus wind speeds can be high quite close to the surface. Roughness elements such as soil aggregates and vegetation create additional drag on the wind, m odifying the vertical wind speed profile such that wind speed does not increase with height as rapidly. Thus, the wind in contact with the surface is decreased, reducing wind erosion. Air trapped by clods and other cover elements also

reduces the wind ener gy intensity at the surface. Barriers such as vegetative or artificial windbreaks, vegetative strips, or shallow barriers like surface residue and other type s of soil cover (see Section 1) or surface roughening (typically mechanical plowing or cultivation on bare soil) all to some degree alter the vertical wind speed profile, reducing wind speeds near the

surface.

NRCS has a selection of conservation practice standards that can be applied to disrupt and reduce the erosive flow of wind over the landscape. Windbreak/Shelterbelt Establishment is one of the most effective measures where single or multiple rows of trees or shrubs are planted in a

linear fashion , typically perpendicular to the predominant wind direction

. Barrier length andSection 5: Wind Barrier s

22 | P a g e

height have the greate st effect on the downwind shelter area. Shelter areas are described in terms of the windbreak height (H) and can range from 14.5H to 25H in length. Taller windbreaks reduce wind speed over a greater distance, with longer and wider windbreaks typically more effective than short and narrow ones. Local NRCS offices have information about recommended tree species for their specific areas

.

Other herbaceous and woody vegetation practices

, such as Field Border, Hedgerow Planting, Cross Wind Trap Strips, Herbaceo us Wind Barriers , and Tree/Shrub Establishment

, have the corollary benefit of reducing wind speeds, but are often implemented for other reasons (i.e., protecting crops from abrasion by windblown particles )

. Cropping practices such as Stripcropping and Alle y Cropping can also have corollary benefits of reducing wind speeds near the surface and providing shelter to crops downwind.

As a non

- primary means of controlling wind erosion, Surface Roughening can be implemented to

create random roughness at the soil surface. This is only applicable for bare soils with a surface layer suitable for clod formation and is generally an emergency procedure used in dryland drought situations. Cross Wind Ridges can also be formed, which are ridges formed by tillage, planting or other operations. In both cases, wind energy at the surface is somewhat reduced.

NRCS Conservation Practice Standards Alley Cropping (311) Cross Wind Ridges (588) Cross Wind Trap Strips (589C) Field Border (386) Hedgerow Planting (422) Herbaceous Wind Barriers (603) Stripcropping (585) Surface Roughening (609)
Tree/Shrub Establishment (612) Windbreak/Shelterbelt Establishment (380)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Cover Crop

o Permanent Crops

o Surface Roughening

o Wind Barrier From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Artificial Wind Barrier

o Cross

- Wind Ridges

o Cross

- Wind Strip

- Cropping

o Cross

- Wind Vegetative Strips

o Surface Roughening

o Tree, Shrub or Wind Break PlantingSection 5: Wind Barrier s

23 | P a g e

 Conservati on Measure Description: Intercept Airborne PM and Gases

Wind barriers such as vegetative or artificial windbreaks and other vegetative strips can also intercept airborne PM and gases. Their design effectiveness is dependent upon the barrier height and por osity, the particle size being intercepted, vegetative or structural elements

, and location of the particle or gas source in relation to the wind barrier. Higher barriers can intercept particles and gases that were released at greater upwind distances

. Porosity of the barrier plays a role in particle/gas interception. Porosity in vegetative barriers can increase with vegetation height (depending on the vegetation), and increasing wind speeds can increase porosity by streamlining the vegetation. Vegetativ e elements also help determine particle/gas capture where tighter vegetation elements (e.g. conifers) can capture more PM than broadleaf species. The type of pollutant being intercepted can also impact the health of the vegetative barrier. For example, if intercepting a nitrogen containing compound such as ammonia or oxides of nitrogen, a wide range of impacts have been observed from necrosis to enhanced growth (depending on the plant species). Other factors such as length of exposure, degree of exposure, a nd other environmental considerations (ex. atmospheric temperature, moisture, etc.) are important as well.

NRCS has a selection of conservation practice standards that can be applied to intercept airborne

PM and gases. Windbreak/Shelterbelt Establishment is one of the most effective measures where single or multiple rows of trees or shrubs are planted in a linear fashion. Barrier length, height, porosity, and vegetation type have the greatest effect on the interception of airborne PM and

gases. Local NRCS offices have information about recommended tree species for the ir specific

area s

.

As another means of intercepting particles and gases, practices planting herbaceous and woody vegetation such as Field Border, Hedgerow Planting, Cross Wind Trap Strips, Herbaceous Wind
Barriers, Tree/Shrub Establishment, Alley Cropping, and Stripcropping can be implemented. Some of these practices are specifically intended to protect crops from abrasion by particles (e.g. Cross Wind Trap Strips ) or can be designed to inte rcept particles and gases from pesticide applications (e.g. Hedgerow Planting ).

NRCS Conservati on Practice Standards Alley Cropping (311) Cross Wind Trap Strips (589C) Field Border (386) Hedgerow Planting (422) Herbaceous Wind Barriers (603) Stripcropping (585) Tree/Shrub Establishment (612) Windbreak/Shelterbelt Establishment (380)Section 5: Wind Barrier s

24 | P a g e

Additional Co nservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Cover Crop

o Permanent Crops

o Wind Barrier From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handb ook ):

o Artificial Wind Barrier

o Cross

- Wind Strip

- Cropping

o Cross

- Wind Vegetative Strips

o Tree, Shrub or Wind Break Planting

Tool: The NRCS/ARS Wind Erosion Prediction System (WEPS) is the primary model used by USDA to estimate wind erosion potential. The model allows users to specify soil surface characteristics and management options. WEPS also has the capability to model crop growth and include cover crops or perennial vegetation. The model has a wind barrier submodel that takes into account important ve getative windbreak characteristics. The user defines the wind barrier’s length, width, height, porosity, number of rows, and tree

type. Users can choose from the following vegetation types for a wind barrier: shrub, conifer, deciduous, pruned trees, nut tr ees, dwarf/semi

- dwarf orchard, standard orchard, and vineyard.

WEPS delivers estimates of total soil loss as well as PM 10 emissions from a specified land area. WEPS is not an online tool, but those interested in applying the model should work through their appropriate state and/or local NRCS agronomist.Section 6: Equipment Modifications

25 | P a g e 

## Section 6: 

# Equipment Modifications

Various types of modifications to agricultural equipment can help to prevent or mitigate

emissions of PM, VOC, and/or NO

x . Since the emissions addressed by equipmen t modifications are typically episodic (related to equipment operation more so than geography or meteorological conditions), the use of equipment modifications may be appropriate in any area where agricultural emissions are contributing to an air quality i ssue. Equipment modifications can be a broad array of simple or sophisticated changes and can include new equipment, manufacturer options, and independently

- customized alterations.

Measures: Combustion Equipment Replacement/Retrofit and Operation

Non

- com bustion Equipment Changes/Technology Improvements

 Conservation Measure Description: Combustion Equipment Replacement/Retrofit and Operation

Uncontrolled, older and/or less efficient combustion equipment typically have higher air emissions (especially for PM and NO

x ) than controlled, newer and/or more efficient combustion equipment. Combustion equipment includes stationary and mobile sources, s uch as irrigation engines, tractor engines, heaters, boilers, etc.

Replacing higher

- emitting combustion units with lower emitting or non

- combustion alternatives can result in significant air quality improvement, as well as possible energy savings. Also

,

r etrofitting existing combustion units with air emission controls or new technologies to improve combustion efficiency can reduce the amount of air emissions from the units.

Proper maintenance and operation is extremely beneficial to minimizing emissions f rom existing combustion equipment, as well as ensuring the equipment performs as it was originally intended. The load on the engine is reduced w hen equipment is operating at maximum efficiency

, which can result in decreased engine operation time and thus l ess PM emissions. In some cases, making energy efficiency improvements can also result in decreased fuel use in combustion equipment

and/or decreased combustion emissions.

Combustion System Improvement and Pumping Plant may be used if agricultural combust ion systems and/or related components or devices are replaced or retrofitted for air quality and energy efficiency improvement.Section 6: Equipment Modifications

26 | P a g e

NRCS Conservation Practice Standards Combustion System Improvement (372) Pumping Plant (533)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Irrigation Power Units

o Conservation Irrigation

 Conservation Measure Description: Non

- combustion Equipment Changes/Technology Improvements

Agricultural equipment changes and technology improvements for reducing air emissions can take many shapes and forms. These can include relatively simpl e fixes

, like using a shield or deflector to knock particulates out of an airstream before they are released

, or using lower

pressure pesticide application nozzles to limit volatilization and chemical drift. These can also include more advanced techniques

, like making internal design changes to harvesting equipment to separate and deposit residue and dust prior to entrainment. Other examples include utilizing water spray bars and variable rate or targeted pesticide applicators.

NRCS Conservation Practice Standards Integrated Pest Management (595 )

Additional Conservation Activities

From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Equipment Changes/Technological Improvements

o Application Efficiencies From the Arizona Guide to Agricultural PM 10 Best Management Practices, ( Handbook ):

o Equipment ModificationSection 7: Fire and Smoke

27 | P a g e 

## Section 7: 

# Fire and Smoke

Federal, state, and p rivate landowners utilize fire for a range of

reasons
, such as to : Control undesirable vegetation Prepare sites for harvesting, planting or seeding Control plant disease

Reduce fuel hazards that lead to wildfire Improve wildlife habitat Improve plant productivity, health and vigor

Remove slash and debris Enhance seed and seedling production Facilitate distribution of grazing and browsing anima ls Restore and maintain ecological processes and ecological site integrity Protect air quality from wildfire smoke impacts

Fires impact air quality by releasing PM and ozone precursor trace gases into the atmosphere. The quantity of these trace gases

and particulates released to the atmosphere is a function of combustion efficiency, where complete combustion produces carbon dioxide (CO 2 ) and water, and incomplete combustion produces a complex mixture of trace gases and particulates. Combustion efficiency i s a function of the physical and chemical properties of the fuel ( i.e

. , fuel type, arrangement, moisture, and size) and environmental parameters ( i.e

. , wind speed, temperature, and relative humidity). Meteorological information, fuels information, and how such knowledge impacts fuel combustion are key facts used to manage a fire, help reduce emissions from a fire, and manage

the smoke from a fire. A suite of conservation practices are available to: mitigate the occurrence of wildfires, inhibit wildfire spre ad, reduce the quantity of emissions from a fire, provide alternatives to burning, and manage smoke before, during and after prescribed burning operations. I n all cases, practices should: be applied as part of a conservation management
system

, take into ac count landowner objectives

, and balance other ecological needs of soil, water, plants and animals.

Measures : Smoke M anagement

Alternatives to B urning

Reduce Trace Gas and PM Emissions from Prescribed B urns
Reduce Wildfire R iskSection 7: Fire and Smoke

28 | P a g e

 Conservation Measure Description: Smoke Management

Where Prescribed Burning is implemented, the fire manager should observe the rules and regulations governing burning activities in their area

, and follow the appropriate smoke management program (SMP), if one is in place. If a SMP is not in place

, there are basic smoke management practices (BSMPs) that can be implemented to manage the downwind smoke impacts. Sensitive receptors

, such as roads and highways, schools, housing developments

, etc.

, should be identified and meteorological conditions can then be used to try to schedule the burn to avoid impacting those locations. Wind direction and speed, atmospheric stability, and mixing height are some of the key atmospheric parameters influencing w here and how the smoke disperses. Wind direction is a major determinant of where the smoke will go while wind speed controls how quickly the smoke will move and disperse

. Both surface and upper level transport

winds should be noted , as they can sometimes h ave very different wind directions. The mixing height is the height through the atmosphere wh ere pollutants can mix and the more unstable the atmosphere the greater is the mixing height, and the more vertical mixing is achieved. Unstable atmospheres can al so lead to erratic fire behavior. The National Weather Service (NWS) provides fire weather information that can often be used for managing smoke ( http://radar.srh.noaa.gov/fire/ ).

Other basic smoke management practices that can be employed include monitoring the effects smoke has on air quality, record keeping (smoke journal), communication / public notification, consideration of emission reduction techniques, and coordination of area burning. These various

smok e management practices have applicability depending on the type of burn, fuels to be burned and level of effort needed to address air quality concerns. Not all are applicable to all situations, therefore fire managers are urged to investigate the informati on available and applicable to their area and needs. Furthermore, the BSMPs mentioned here constitute only a subset of possible BSMPs and others can be adopted as needed.

NRCS Conservation Practice Standards Prescribed Burning (338)

 Conservation Measure Description: Alternati ves to B urning

Alternatives to burning include option s that may be viable to reduce PM and trace gas emissions to the atmosphere . They do, however, need to be evaluated in terms of the other ecological benefits that may only be achieved with fire. In many forest and rangeland systems

, fire is a natural and necessary component to the ecological health of the system : but in many areas

, the exclusion of fire has resulted in conditions that could be dangerous if re

- introduced directly. Furthermore, it is often not desirable to employ fire close to homes or other structures. In such cases mechanical treatments such as mowing, thinning, selective timber harvest and removal of

non

- commercial trees and brush can be employed. Thinning stands of trees (covered under the

NRCS Forest Stand Improvement c onservation p ractice s tandard) to reduce competition for light, moisture, and nutrients can enhance forest health and provide desired forest structure. Other

mechanical treatments that do not remove material from the fore st are shredding, lopping, or scattering, which are all covered under the Woody Residue Treatment c onservation p ractice

s tandard

. Other means of manipulating the landscape can potentially serve as an alternative toSection 7: Fire and Smoke

29 | P a g e

burning such as managing woody plants via Brush Management or herbaceous weeds via

Herbaceous Weed Control

. These practices involve managing the plant community with mechanical, chemical or biological methods. Biological controls can be grazing animals and in

that case the Prescribed Grazing prac tice applies.

Alternatives to burning are also available for cropping systems. A cost

- effective means of disposing of orchard tear

- outs, vineyard removals, and encroaching juniper trees is pile burning. However, as an alternative, chipping/grinding/shredding (covered under the NRCS Woody

Residue Treatment c onservation p ractice s tandard) may be an option, and depending upon the region, the residue can be used for animal bedding, ground cover, or biomass energy production. Soil incorporation of crop residue, chemical breakdown of the residue, or removal by baling are also options for cases suc h as grass seed and winter wheat systems. The best system is very locally

- dependent on climat e and other factors

.

NRCS Conservation Practice Standards Brush Management (314) Forest Stand Improvement (666)

Herbaceous Weed Control (315) Prescribed Grazing (528) Woody Residue Treatment (384)

Additional Conservation Activities From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices

, ( Table

, Handbook ) :

o Baling

o Soil Incorporation

o Grinding/Chipping/Shredding

o No Burning

 Conservation Measure Description: Reduce T race G as and PM E missions from

P rescribed B urns

Emissions from prescribed burning can be reduced by controlling how the burn is implemented and applying other conservation measures t o reduce fuel load to be consumed. Prescribed

B urn ing can be conducted to improve combustion efficiency and thus reduce the quantity of trace gases and PM emitted to the atmosphere. Backing fire s (fire spreading, or ignited to spread, into (against) the wind or downslope) ensure s that more fuel is consumed in the flaming phase where combustion is cleaner (i.e. fewer trace gases and PM are released) than during the smoldering phase. Burning in clean and dry piles or windrows also results in a fire that generates greater heat and burns more efficiently.

As part of the conservation planning process, many practices can have a corollary benefit of reducing fuel loads and thus the emissions from pr escribed burning operations. These practices

can include: Prescribed Grazing, Forest Stand Improvement, Brush Management, Herbaceous Weed Control, and Woody Residue Treatment.Section 7: Fire and Smoke

30 | P a g e

NRCS Conservation Practice Standards Brush Management (314) Forest Stand Improvement (666)

Herbaceous Weed Control (315) Prescribed Burning (338) Prescribed Grazing (528) Woody Residue Treatment (384)

 Conservation Measure Description: Reduce W ildfire R isk

The risk of wildfires can be increased by a build

- up of understory fuels, dense tree canopies, the

pres ence of ladder fuels (which allow the fire to climb from the ground into the canopy ) , and dry/dead vegetation. Certain invasive species can also be highly flammable. Many conservation practices can address these issues on the landscape to help reduce the r isk of a wildfire and the associated release of high concentrations of PM and ozone precursors to the atmosphere. Conservation practices such as Prescribed Grazing, Prescribed Burning, Forest Stand Improvement, Brush Management, Herbaceous Weed Control, and Woody Residue Treatment reduce the risk of wildfire by reducing the build

- up of understory fuels and ladder fuels, disrupting fuel continuity over the landscape ( giving a “patchiness” to the fuels ) , and by controlling weeds and invasive species , which can alter the natural fire regime. Conservation practices such as Firebreak and Fuel Break can inhibit wildfire spread thereby protecting air quality from the elevated PM and ozone concentrations associated with wildfires.

NRCS Conservation Practice Standards Brush Management (314)

Firebreak (394) Forest Stand Improvement (666)

Fuel Break (383)

Herbaceous Weed Control (315) Prescribed Burning (338) Prescribed Grazing (528) Woody Residue Treatment (384)Section 8: Other

31 | P a g e 

## Section 8: 

# Other

Additional measures that do not necessarily fit

into the other sections in this document may also be implemented to reduce air emissions. The need

for these measures and their usefulness can be dependent on geographic and/or climatic factors, or they may be independent of these influences. In particular, the handling of bulk solid mat erials, such as compost, soil, gravel, etc., in a manner

that reduces disturbance of the material

, will also reduce emissions from material storage piles.

Measures: Bulk Materials Handling

 Conservation Measure Description: Bulk Materials Handling

Handling and disturbance of bulk material piles can result in the entrainment of particles or the release of gases due to the exposure of a greater surface area of the material to the air and

airflow/wind. Minimizing the disturbance of a pile, such as cove ring the pile, limiting the surface area from which material is removed, and limiting the number of times the material is handled and the duration of disturbance, will reduce the potential for air emissions from the pile.

Additional Conservation Activitie s From the San Joaquin Valley Unified Air Pollution Control District Agricultural Air Quality Conservation Management Practices, ( Table

, Handbook ):

o Bulk Materials Control