Originally published Vol.
3, Issue 4 (September 2005)
Improving Air and Water Quality Can be Two
Sides
of the Same Coin
Environmental regulations
and incentives that simultaneously address multiple
media, like air and water, are more likely to be
cost-effective in meeting resource quality goals.
Marc
Ribaudo, Marca
Weinberg
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This
article is drawn from . . . |
Managing
Manure To Improve Air and Water: Coordination
Works Better, by Marcel Aillery,
Noel Gollehon, Robert Johansson, Jonathan
Kaplan, Nigel Key, and Marc Ribaudo, ERR-9,
USDA, Economic Research Service, September
2005 |
Rural areas have long been idealized
as the place to go for good, clean air. However,
the “fresh” air of the countryside may
not be so fresh after all. Since farmers began tilling
the soil to grow crops and raise animals, agricultural
production practices have generated a variety of
substances that enter the atmosphere and have the
potential of creating health and environmental problems.
The relation-ship between agriculture and air quality
first entered the public psyche in the 1930s with
the severe dust storms of the Dust Bowl. Although
huge dust storms are long gone, and air emissions
in most rural areas are not high enough to cause
concern, the air in some farming communities can
now be as impaired by pollutants such as ozone and
particulates as air in urban areas.
Air quality policies have traditionally
focused on urban areas and industrial emissions.
Extending these laws to cover agriculture would
require an understanding of how farmers respond
to different policy incentives. Farmers have many
choices in deciding on what to produce and the production
practices to use. Their production decisions are
based on market prices, the characteristics of the
farm’s resources, the technologies that are
available, and the farmer’s particular level
of management skill. But incentives to consider
wider impacts of their production choices on environmental
quality are often lacking. Environmental policy
can influence a farmer’s decisions by changing
the costs of inputs to encourage or discourage input
use, or by mandating that particular management
practices be used or abandoned. Currently, a lack
of knowledge about air emissions from agriculture
could hinder the development of cost-effective policies.
Policy formation is also compounded
by the fact that possible efforts to reduce agricultural
air emissions could diminish the effectiveness of
ongoing efforts to address water quality concerns.
At a minimum, regulations and incentives designed
to address a problem in one medium (air or water)
may not be as cost effective at meeting resource
quality goals as those that are coordinated across
multiple media.
Putting the Brakes on Agricultural
Emissions
Agricultural production releases
a wide variety of material into the air—for
example, windblown soil, nitrogen gases from fields
and livestock, fine particulates from diesel engines
and controlled burning of fields, and pesticides.
Pesticides can move in air currents in two ways:
aerial drift (when applied with crop dusters), and
volatilization (a process by which solids or liquids
are converted into gases). Other potential pollutants
associated with agricultural production include
hydrogen sulfide, ammonia, odors, and other volatile
organic compounds from animal manure; methane from
dairy cows and cattle; and nitrogen oxides from
fertilized fields and internal combustion engines.
These pollutants can affect people’s health,
reduce visibility, contribute to global warming,
or simply be a nuisance.
Air quality is protected primarily
through the Clean Air Act and the Comprehensive
Environmental Response, Compensation, and Liability
Act (CERCLA). The Clean Air Act sets limits on how
much of a pollutant can be in the air anywhere in
the United States. When the air quality standard
for any of six air pollutants is exceeded, States
must inform the U.S. Environmental Protection Agency
(EPA) how they plan to respond. Any farm in a nonattainment
region (regions where air quality standards are
exceeded) found to be a “major source”
of regulated emissions could be required to apply
for and comply with an operating permit. CERCLA
requires facilities to report to EPA when more than
a “reportable quantity” (100 pounds
in a 24-hour period, for example) of a hazardous
substance is released.
Regulation of air emissions under
the Clean Air Act and CERCLA has focused on such
sources as factories and cars but not on emissions
from agriculture. Part of the reason is a lack of
information about the sources and effects of agricultural
air emissions that would be necessary to develop
regulations. Pollution from agriculture generally
has characteristics that make it difficult to control
through conventional policy tools that are applied
to industrial sources. Agricultural emissions tend
to be generated diffusely over a broad land area,
rather than from a single pipe or smokestack, so
it has not been cost effective to accurately monitor
emissions from individual agricultural sources using
current technology. For example, ammonia emissions
from an animal operation can come from a barn, manure
storage structure, and field. The difficulty and
cost of monitoring agricultural pollution sources
is one reason that agriculture is largely exempt
from environmental regulations that were primarily
designed to address urban and industrial air pollution
problems.
However, new State regulations
may seek to reduce air emissions from agriculture,
particularly from animal feeding operations. Under
the Federal Clean Air Act (and its amendments),
States are responsible for achieving the air quality
standards established by EPA. Recent lawsuits, court
decisions, and consent agreements have induced States
to start regulating emissions. California is the
first State where air quality regulations are significantly
affecting agriculture. Ozone and particulate levels
in the San Joaquin Valley of California, which has
some of the most polluted air in the country, with
nonattainment areas for both Federal ozone and particulate
matter standards, have led to new requirements for
agricultural producers. Farmers must develop management
plans showing how they will reduce dust, the burning
of crop residue (e.g., rice straw, orchard trimmings)
is restricted, and large dairies must manage their
manure to reduce ammonia emissions.
However, farmers do not bear the
cost alone. USDA helps farmers in California’s
nonattainment areas with a cost- share program funded
through the Environmental Quality Incentives Program
to help finance farming practices that reduce airborne
dust and ozone precursors. USDA also funds research
to understand the processes of air pollution emissions
from agricultural operations, to develop and test
control measures, and to provide decision aids that
can be used to reduce agricultural air pollution
emissions.
Protect Air Quality, Compromise
Water Quality?
An important issue in addressing
pollution from agriculture is that emissions to
the atmosphere do not necessarily occur in isolation,
but can be linked by biological and chemical processes
to emissions to water. Nitrogen emissions from animal
feeding operations are the best example. Nitrogen
excreted from an animal can follow any of a number
of pathways between collection and disposal, and
enter water or the atmosphere in the form of any
of a number of compounds. These interactions have
important consequences for policies to protect environmental
quality. Reducing nitrogen movement along one pathway
by changing its form will increase nitrogen movement
along a different path. For example, reducing ammonia
losses from a field by injecting animal waste directly
into the soil increases the amount of nitrogen that
can be made available for crop production, but,
because more nitrogen is now available in the soil
profile, the risk that nitrates will enter water
resources is increased. The fact that these processes
are linked requires that efficient management of
manure consider how different environmental media
(that is, land, water, and air) are affected. (See
“Nitrogen Follows Many Pathways
in a Livestock Operation.”)
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The
nitrogen cycle is a complex one, without a
beginning, middle, or end. The principle of
mass-balance ensures that the amount of nitrogen
in a closed system is constant. Thus, any
action to divert it from one pathway must
necessarily transfer it into another. In this
stylized figure: |
1
animals in the "house" release nitrogen
in three ways: they produce manure (which
then enters a storage system); they store
nitrogen internally, which is bound in animal
products distributed to markets; and they
produce gases (directly and indirectly in
manure production), which are released as
air emissions;
|
3
manure nitrogen applied to fields
may be stored in the soil, leached into groundwater,
run off into surface water, volatilized into
air emissions, and be bound in crops; or |
2
manure is stored in lagoons, tanks, pits,
or other structures
before being transported to fields for use
as fertilizer; |
4
nitrogen bound in crops
may be used for feed for the animals, and
the cycle begins again.
Nitrogen also enters and
exits the system through intermediate pathways,
for example, some of the nitrogen released
into the air will settle back on the fields
(deposition) and some new nitrogen will be
added in the form of commercial fertilizer. |
Potential cross-media links in
the emission process suggest possible advantages
to a multimedia perspective in developing regulations.
A multimedia perspective is neither new nor unique
to agriculture. Many industries generate multiple
pollutants that affect several environmental media.
Yet, environmental regulations, by and large, take
a single-medium perspective. The Clean Water Act
addresses surface water quality (not ground water).
The Clean Air Act addresses air quality. The Resource
Conservation and Recovery Act (RCRA) addresses hazardous
waste disposed on land.
Over the past decade, EPA has experimented
with coordinated implementation of the Clean Air
Act, Clean Water Act, and RCRA to reduce implementation
costs and to help regulated industries organize
pollution control activities more efficiently. The
pulp and paper industry was the first to benefit
from this multimedia approach. EPA developed integrated
air and water rules that set emission levels based
on the performance of a combination of source reduction
technologies and management practices, air pollution
control devices, and upgrades on existing wastewater
treatment systems.
Why might a multimedia approach
be important for agriculture? The increasing size
and geographic concentration of animal feeding operations,
driven by the economics of domestic and export markets
for animal products, have resulted in large quantities
of manure accumulating in relatively small areas.
In 2003, EPA introduced revised Clean Water Act
regulations to protect surface waters from nutrients
from concentrated animal feeding operations (CAFOs).
The regulations require CAFOs to follow a nutrient
management plan to minimize nitrogen and phosphorus
runoff to surface water. Those plans will specify
the application rate for nutrients that must be
followed when applying manure to land (the primary
disposal method). The cost to farmers of complying
with the plans can be relatively high because compliance
often will entail moving manure to a larger land
base. To meet the requirements as cheaply as possible,
and without any incentives to protect air quality,
farmers could continue to use (or adopt) uncovered
lagoons and apply animal waste to the surface of
fields without incorporating it into the soil. Those
practices reduce the nitrogen content of manure
spread on fields by volatilizing nitrogen to the
atmosphere. In so doing, however, nitrogen that
otherwise would be available for runoff to water
bodies is transformed into atmospheric ammonia emissions
to the possible detriment of air quality.
According to a 2003 National Academy
of Sciences study, animal feeding operations are
the primary source of ammonia emissions in the U.S.,
and ammonia emissions are already a cause for concern
in some rural communities. Ammonia emissions are
regulated in parts of California. Current Federal
air quality rules (e.g., Clean Air Act’s PM
2.5 standards and CERCLA) might force more States
to consider regulating ammonia emissions from animal
operations.
An ERS study estimates that farmers
would respond to hypothetical ammonia emission standards
by adopting manure management practices that reduce
nitrogen emissions to the air but increase the nutrient
content of animal waste spread on fields. Depending
on how the air quality regulations were applied,
this could have two impacts on CAFOs and water quality.
First, CAFOs might need to further increase the
amount of land on which they spread manure in order
to continue to meet nutrient application standards.
This increase could be particularly costly in a
region where animal concentrations are high and
cropland available for spreading manure is relatively
scarce. For example, in the Chesapeake Bay watershed,
ERS found that requiring CAFOs to adopt practices
that reduce ammonia emissions would increase the
nitrogen content of manure and thus the CAFOs’
cost of applying manure to land to meet water quality
requirements.
An uncoordinated approach between
air and water policies could also reduce water quality.
The Clean Water Act‘s manure regulations apply
only to CAFOs. If ammonia reductions are required
on farms other than CAFOs, the water quality benefits
of the CAFO regulations are potentially reduced
by increased nutrient applications on these other
farms. In the Chesapeake Bay watershed, for example,
ERS research estimates that the nutrient content
of manure produced on farms not covered by current
regulations would more than double if ammonia restrictions
were applied to all animal feeding operations. This
would increase the risk of nitrogen runoff that
eventually reaches the Chesapeake Bay.
USDA has long recognized the impacts
of conservation practices on multiple environmental
resources (soil, water, and air). Yet, when a set
of conservation practices is recommended to improve
water quality, full consideration is not always
given for accompanying air quality benefits. In
the Conservation Reserve Program, for example, the
Environmental Benefits Index used to rank applications
for enrollment includes wind erosion benefits but
not benefits for reduced ammonia, odor, fine particulates,
oxides of nitrogen, or pesticide volatilization.
A fuller accounting of the multimedia benefits in
the implementation of conservation programs could
result in a redirection of resources to producers
who could provide a higher level of overall environmental
quality for a given cost.
Better Data for Better Coordination
Information on environmental emissions
from production practices would improve coordination
of environmental policies. The National Academy
of Sciences review of air emissions from animal
feeding operations found that, while pressure to
regulate air emissions from animal operations has
mounted, the basic scientific information needed
for effective regulation and management of emissions
is lacking. The study was requested jointly by EPA
and USDA to assess the state of knowledge and to
recommend steps for bridging the information gap
that is hindering the development of effective regulations
and management measures. Existing data are insufficient
to establish thresholds for emissions from livestock
operations that would trigger compliance with air
quality requirements.
This need for better data about
air emissions from animal feeding operations has
led to an innovative agreement between EPA and some
sectors of the animal industry to monitor air quality
on farms. The Air Emissions Consent agreement and
National Monitoring Study between pork and egg producers
and EPA calls for a 2-year national air monitoring
study on animal feeding operations that agree to
participate in the study. The study will use state-of-the-art
technologies and standardized procedures to monitor
emissions from barns and lagoons. These data will
help State and Federal regulators and farmers identify
farm sizes and manure handling systems that exceed
thresholds for regulated pollutants. For farms that
participate, EPA has agreed to provide certain legal
protections for past and current emissions violations.
EPA has invited other sectors of the animal industry
(broilers, dairy, and fed beef) to participate.
The information gathered during
the study will be valuable for both farmers and
regulators. Many producers are not aware of their
operation’s contribution to emissions or whether
they are subject to existing air quality regulations.
Knowing the legal and financial risks for different
types of operations would help farmers make decisions
about reducing emissions to protect them from possible
lawsuits or enforcement actions and still remain
profitable.
Information on atmospheric emissions
from agriculture can help regulators identify the
emission thresholds that meet air quality goals
at minimum cost to the sector and develop coordinated
incentives to help farmers simultaneously protect
air and water quality. This would reduce unintentional
harm to the environment because of unconsidered
cross-media effects and minimize the cost to producers
who change their production practices to comply
with emerging environmental regulations.
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