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OCR for page 265
Ecological Problems Associated With
Agricultural Development:
Some Examples in the United States
WARREN E. JOHNSTON
University of California, Davis
The primordial symbiotic relationship between agriculture and envi-
ronment is one that has been respected by centuries of traditional farmers.
Modern agriculture, however, appears to be responsible for a number
of significant environmental problems that deer easy explanation and/or
mitigation.
Idday's agriculture, engaging only three percent of the U.S. population,
differs substantially from earlier structures which occupied the majority of
the population in "hunter and gatherer" or in "husbander" roles. The
agricultural sector now consists of a mosaic of specialized types of farms
ranging in size and intensity from part-time operators of small farm units
with only modest economic outputs to large-scale, industrialized farms
with significant economic presence in the agricultural sector, and which
are sometimes involved in nonagricultural production activities, as well.
The sector's evolution to one dominated by large, economically efficient
"industrialized" farms is revealed by the statistic that roughly one-eighth of
America's farms produce two-thirds of the total U.S. agricultural output.
Technological innovations and national agricultural policies of this
century have had significant impacts on agricultural productivity and on the
structure of agriculture (Carter and Johnston, 1978~. However, there are
increasing sectorial and societal concerns about the longer-term ecological
consequences of recent cultural, mechanical, and biological innovations and
attendant scales of development in the U.S. agricultural sector (Johnston
and Carter, 1983~.
Agriculture is essentially a land-based enterprise, though it is depen-
dent on the total endowment of natural and environmental resources to
define both the set of production possibilities and effective natural con-
straints to production (e.g., soil fertility, growing season, drainage, climate,
265
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266
ECOLOGICAL RISKS
etc.~. In the United States, all but 12% of nonfederal land was devoted
to either agricultural or forestry uses in 1977 (USDA, 1981~. Human
actions have expanded the possibilities, reduced the influence of natural
constraints, and increased productivity per unit of land and of other scarce
or costly economic inputs. Unfortunately, human actions with respect to
agricultural development have also resulted in certain unfavorable impacts,
some of which were unanticipated in their severity or in the speed with
which they have negatively impacted on the environment.
Ecological systems require diversity and balance in order to support the
interactions of living organisms. Agricultural practices can alter ecological
balances and diversity, as well as modify basic agroecosystem properties of
productivity, stability, sustainability, and equitability (Altieri, 1986~. Recent
interests in organic farming and sustainable agricultural systems are efforts
to examine alternative production systems (University of California, 1986;
Carter, 1988~.
Production systems which adversely affect sensitive ecological systems
in severe and nonreversible ways burden both present and future gen-
erations. Ecological impacts can occur-both on-site and off-site from
agricultural land. On-site impacts generally result from land use patterns,
including the decision to develop land for more intensive agricultural uses.
These impacts are localized and generally result in reduced productivity or
in the displacement of wildlife and native plant species due to altered site
habitat They may also cause long-term changes in agricultural productiv-
ity. Off-site impacts can occur both nearby and at great distances from the
farming operation. For example, agriculture can change the ecology of wa-
terways and groundwater basins via changes in rates of flows or in amounts
of sediment and chemicals which may, in turn, contribute to turbidity, eu-
trophication, biochemical oxygen demand, or toxicity, and ultimately may
affect many downstream users of water in the same drainage system.
AGRICULTURAL AND ENVIRONMENTAL POLICY ISSUES
There are a number of areas in which agricultural and environmental
problems and policies seem to be in conflict. A recent Organization for
Economic Cooperation and Development (OECD) draft report (1988)
discusses major agricultural and environmental policy issues in developed
economies under the following classifications:
· intensive crop production and the use of agricultural chemicals;
· intensive animal production and the management of animal ma-
nure;
· dryland farming, soil conservation and erosion; and
· changing landscapes, land-use patterns and the quality of rural
landscapes.
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AGRICULTURAL IMPACTS
2~7
Observers from the arid west of the United States might also add as an
equally important issue:
· increased competition for scarce water supplies and water quality.
The traditional approach to many environmental problems associated
with agriculture has been "effect" oriented (Young, 1988~. As problems
emerged, environmental policies were implemented to control and prevent
the perceived negative impacts of agriculture on the environment. This
often resulted in partial and piecemeal approaches. For example, prescrip-
tions for testing and registration of agricultural chemicals and governmental
regulations for application and handling of chemicals have been designed
to protect the health of farm workers and consumers of food products.
Public zoning policies were developed to restrict concentrations of animal
production units and control the collection and disposal of animal wastes.
Conservation of soil has been attempted by providing economic incentives
and by mandated farming practices to reduce erosion. Land-use zoning by
local and state governments often seeks simultaneously to maintain a viable
agriculture sector and a pleasing rural landscape, but is often ineffective
when confronted by decisions that either intensify agricultural uses or de-
velop higher, economically valued nonagricultural uses. Resource policies
to maintain air and water quality sometimes prohibit certain agricultural
practices.
Throughout the recent experience in the United States, there has
been an the uneasy awareness that linkages between agricultural price
and income policies and resource and environmental policies have been
inadequate. In fact, numerous examples can be cited in which independent
agricultural and environmental policies have been in direct convict (Phipps
et al., 1986; National Research Council, 1974; National Research Council,
1982~. For example, agricultural price policies and world market conditions
in the 1970s increased incentives for farmers to both intensify production
on cropped acreage and expand agricultural production onto marginal
lands, leading to increases in chemical applications and soil erosion. At the
same time, environmental policies sought increased water quality and soil
conservation. A current assessment of environmental issues in agriculture in
a period of apparent global agricultural surplus capacity is that this "effect-
oriented" and uncoordinated approach to environmental issues has been
inadequate. Unacceptable levels of agricultural pollution, soil erosion, and
degradation in water quality continue, while landscape quality continues to
decline.
Young (19~) notes four reasons for the failure of environmental
regulations which were designed to protect the environment against impacts
from agricultural development and production activities:
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268
ECOLOGICAL RISKS
· failure to enforce existing regulations and to introduce regulations
necessary to keep agricultural practices within sustainable limits;
· the reluctance of governments to use economic instruments to
internalize the external costs of many agricultural practices;
· the existence of a wide range of price support, market interven-
tion, and tariff policies which tend to stimulate and intensify agricultural
production; and
the dominance of agricultural policy instruments over environ-
mental instruments and, in particular, the failure to develop integrated
agricultural and environmental policies.
The remainder of this chapter discusses some of the more prominent issues
in the recent U.S. experience, addresses the need for integration of envi-
ronmental and agricultural policies, and presents a selected bibliography
for the interested reader.
NEGATIVE IMPACTS OF AGRICULTURE ON THE ENVIRONMENT
The physical processes of erosion of agricultural lands and runoff of
sediment and nutrient or pesticidal chemicals create impacts that are felt
both on-site and ofI-site. Most individual farmers' decisions to invest in
soil conservation measures are made primarily to avoid on-site productivity
declines. Erosion generally affects soil productivity lay depleting and/or
degrading the inherent physical, biological, and chemical characteristics of
the surface layer of the soil (USDA, 1986~. Incentives to promote good
soil management via conservation investments have, for much of the 1980s,
been blunted by the depressed financial situation affecting much of U.S.
agriculture. The problem is compounded by the off-site (and therefore
externalized) water pollution and sedimentation problems which affect
downstream users and ecological systems.
Agricultural Runoff
When the United States enacted the Federal Water Pollution Control
Act in 1972, the nation's waterways were under tremendous assault from
the industrial development that had occurred since World War II. The leg-
islation set forth a mandate to improve water qualifier and reduce pollution.
Sources of water pollution can be attributed to point sources (where there is
an identifiable discharge) and to nonpoint sources that contribute to water-
quality degradation through diffuse mechanisms. Regulations and standards
set controls on the quantities and methods of disposing of waste products
and discharges. The initial target for implementing the law addressed point
source polluters, primarily industrial sources that were discharging wastes
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AGRICULTlJRAL IMPACTS
269
into water systems. Point source polluters, though still major sources of bi-
ological oxidation damage and dissolved heavy metals, are relatively minor
contributors of other pollutants, suspended and dissolved solids, phospho-
rus, and nitrogen which stem mainly from nonpoint sources (USDA, 1981~.
Erosion and runoff from agricultural lands are leading sources of
nonpoint pollutants. They make up about 50% of the total sediment load
carried by waterways, and contribute significant amounts of pesticides,
fertilizers, salts, and metals that affect the ecology of both water and land
environments (Clark, 1985~. Pollution problems from nonpoint sources,
nutrients, suspended solids, total dissolved solids (salts), pesticides, and
bacteria affect nearly every region of the country.
Soil Erosion
Erosion generally occurs via one of four modes: sheet, fill, gully (i.e.,
water-induced modes), and wind erosion. In an attempt to estimate the
amounts of soil erosion from various lands, the National Runoff and Soil
Loss Data Center developed the Universal Soil Loss Equation (USLE).
This formula estimates soil erosion loss as a multiplicative function of six
variables: rainfall intensity and duration, soil erodibility, slope length, slope
grade, vegetative cover, and tillage practices (USDA, 1981~.
Additionally, in order to identify problem areas, the U.S. Department
of Agriculture (USDA) has estimated the maximum annual soil losses that
can be sustained on a land area without adversely affecting soil productivity.
These are referred to as tolerance values (t-values) and usually range from
one to five tons per acre per year depending on climate and soil charac-
teristics. In 1977, the national average soil erosion loss from croplands
was estimated to be about 4.8 tons per acre (TPA), equivalent to about
1.75 metric tons per hectare, which is approximately 1/30 of an inch (0.84
mm) of topsoil per year. Local erosion rates can range from insignificant
amounts to well over 100 I PA (36.7 metric tons per hectare) in some areas,
depending upon local conditions (Katie, 1983~.
Soil Sedimentation
The USDA Soil Conservation Service's appraisal of soil and water
resources in the United States, which was carried out in response to the Soil
and Water Resource Conservation Act of 1977, identified agriculture as the
primary cause of nonpoint water pollution for more than 68% of the nation's
watershed areas (USDA, 1981~. The most significant constituents with
respect to volume were suspended solids, which contributed approximately
50% (i.e., about 760 million tons) of the total sediment load. Increased
amounts of sediment decrease the viability of aquatic ecosystems and can
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270
ECOLOGICAL RISKS
produce both direct and indirect impacts on living systems. In very heavy
concentrations, sediment can clog the gills, and thus, decrease the uptake
of oxygen by fish. More likely, however, are indirect effects that arise from
increased water turbidity. Increased turbidity reduces the penetration of
sunlight and consequently the primary production of photosynthetic plants
and algae, which in turn reduces the productivity of higher trophic levels.
In addition to a general decrease in the biomass sustained in the system,
shifts in the biological mix of species is also likely to occur in which
sediment-tolerant and adaptive species replace less tolerant organisms.
METHODS FOR REDUCING SOIL EROSION AND RUNOFFS
Clearly, erosion from agricultural lands severely impacts the ecology of
U.S. waterways. Negative off-site impacts affect recreation, flood control,
municipal and industrial water use, navigation, and other water-based or
water-dependent economic activities. However, these negative off-site ef-
fects are generally not considered by individual farmers or nonfarm owners
of agricultural lands. Thus, they are not likely to utilize soil conservation
techniques to as large an extent as is socially optimal. Such erosion is seen
as an "externality" which adversely effects other members of society, but
has no direct impact on the farmer who has a vested (ownership) interest
in agricultural land. The "external" nature of this problem suggests that
governments may need to develop incentives that will encourage erosion
control and reduce agricultural runoffs. National agricultural policies in the
1970s encouraged production on marginal lands that were previously un-
cultivated. New land development activities, sometimes called "sodbusting"
and "swampbusting," increased soil erosion and agricultural runoffs, and
adversely impacted wildlife habitats (National Research Council, 1982~.
Idling of Highly Erodible Marginal Lands
Some highly erodible lands should not be used for crop production and
therefore should be returned to native grass or forest cover (Webb et al.,
1986~. Identification and retirement of marginal lands is a key component of
current agricultural policy in the United States which also seeks to reduce
excess productive capacity in U.S. agriculture. Supporting studies have
indicated that soil conservation policies are effective in reducing off-site
erosion problems and, simultaneously, in decreasing agricultural production
and government expenditures for purchasing, storing, and disposing of crop
surpluses.
Soil conservation policies include the Conservation Reserve Program,
the Sodbuster Provision, and the Conservation Compliance Provision of
the Food Security Act of 1985, which established current U.S. agricultural
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AGRICULTURAL IMPACTS
271
policy. While the law is in effect through 1990, it may be extended without
major revision for another four- to five-year period.
The Conservation Reserve Program pays farmers annual rental payments
and one-half the cost of establishing permanent cover to retire highly
credible cropland for 10 years. About 100 million acres are eligible for
enrollment. The goal is to enroll 45 million acres, and approximately 28
million acres have been enrolled since the program began in 1986.
The Sodbuster Provision denies price support and deficiency payments,
farm storage facility loans, crop insurance, disaster payments, and FmHA-
insured loans to any person producing an agricultural commodity on highly
erodible land converted since December 23, 1985, unless an approved con-
servation plan is adopted and implemented (USDA, 1988~. This provision
affects about 227 million acres with some potential for conversion.
The Conservation Compliance Provision of the Food Security Act re-
quires that farmers with highly credible cropland begin implementation of
a conservation plan by 1990 and complete it by 1995 in order to retain eli-
gibility for programs identified under the Sodbuster Provision. This policy
could affect production possibilities and costs on up to 65 million acres,
and as many as 10 million acres could drop out of production or out of
government programs (USDA, 1988~.
Erosion Control Practices
A number of physical techniques have been developed and utilized
to control erosion and stabilize the movement of soil. These techniques
include tillage, cropping, and structural measures that limit undesirable
soil transport. Tilling of the soil is a primary factor that mobilizes soil
particles and reduces or eliminates ground cover and cover crops that oth-
envise would stabilize the soil and decrease erosion, especially during rainy
seasons. Conservation tillage practices ("no-till" and "minimum tillage"
practices) have increased in terms of farmer acceptance and use over the
past several years, for both economic and soil-conserving reasons. The
effectiveness of conservation tillage techniques varies by region and by
crop, and is also related to the amount of crop residues retained in fields.
Studies have shown that sediment losses can be reduced by 15% to 90%.
However, these consecration tillage practices often include increased use
of herbicides to control weeds (Clark, 1985~. Thus, reduced soil erosion
practices may transfer the relative balance of agricultural runoff problems
from sedimentation to higher concentrations of pesticides in runoffs.
Contour farming can also be used to substantially reduce erosion
rates on lands that are sloping and are consequently more susceptible to
erosion processes. The principle of contouring involves cultivating lands
in a pattern to reduce the effects of the slope by farming along natural
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272
ECOLOGICAL RISKS
gradients and topography. Contouring can result in erosion reductions of
25% to 50%, with concomitant decreases in the transport of nutrients and
pesticides (Clark et al., 1985). The practice of mechanical levelling of
fields is also effective in reducing agricultural runoffs in irrigated areas and
making possible the more efficient application of irrigation water. There
are also benefits with respect to mechanization of cultural and harvesting
operations.
Other structural possibilities include the construction of diversion chan-
nels and sediment basins that catch runoff and decrease sediment loads.
Planting grass along waterways and irrigation canals also will reduce erosion
losses from stream banks. Altered cropping rotations may also decrease
soil erosion losses. Clark et al. (1985) found a decrease in soil loss from
19.7 tons per acre with continuous corn cultivation to 2.7 tons per acre with
a corn, wheat, and clover rotation.
Soil conservation policies of the sort required for highly credible
lands under the Sodbuster and Conservation Compliance Provisions of the
Food Security Act can include prescriptions that will mandate conservation
tillage, structural modifications, and changes in cropping systems singly or
in combination to reduce soil erosion and agricultural runoff. Batie (1985)
estimates that soil erosion rates can be reduced by 60-95% by a combination
of conservation tillage, contour planting, strip cropping, terracing, and
other known conservation techniques. One USDA study concludes that
modification of USDA commodity and conservation programs to achieve
greater consistency in program objectives could affect one-third to one-
half of the nation's cropland acres that are eroding at unacceptable rates
(Reichelderfer, 1985).
1
CHEMICAL CONSEQUENCES OF AGRICULTURAL
DEVELOPMENT AND PRODUCTION ACTIVITIES
Fertilizers and pesticides are important nonpoint pollutants in surface
waters. More recently, however, concern about chemical pollution from
agriculture has spread to include the nation's groundwaters. The seri-
ousness of many of these problems is still not certain, though they have
emerged rapidly as important environmental issues.
Accelerated erosion processes, in addition to carrying sediment into
waterways, also bring other constituents of the soil including agricultural
chemicals. The U.S. agricultural system is highly reliant on the use of
chemical inputs to provide nutrients for growth and production as well as
pesticides to control destructive plant and animal infestations. ('~Pesticide"
is the term used to describe general classes of chemical-controlled agents,
such as herbicides, insecticides, fungicides, nematocides, and rodenticides).
These chemicals can be carried into aquatic ecosystems either directly
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AGRICULTU~4L IMPACTS
273
through runoff or by absorption to soil particles that are subsequently
eroded.
The 1977 amendments to the Federal Water Pollution Control Act
of 1972 expanded the regulation of pollutants in groundwater, surface
water, and coastal waters by providing stronger incentives to protect water
quality from agricultural sources of pollution than had been provided by
any previous national legislation (Crowder et al., 1988~. The Act extends
emphasis beyond point sources of pollution to nonpoint agricultural sources.
In areas where nonpoint source pollutants endanger water quality, farmers
could be subject to state or local restrictions on land use and agricultural
chemical use (USDA, 1988~
Fertilizers
Farming accounts for roughly 97% of all fertilizer use. Fertilizers
containing nitrogen, phosphorus, and potassium are often applied to soils
to increase crop yields. total application of nitrogen and phosphate in 1983
was in excess of nine and four million tons, respectively (USDA, 1986~. In
the United States, fertilizer use in kilograms of plant nutrient per hectare
of arable and permanent cropland increased by 50% in a 20-year period,
from 63 kilograms in 1964-66 to 94 kilograms in 1981-83 (World Resources
Institute, 1986~. Corresponding values for Poland were 84 kilograms per
hectare in 1961-63, rising by nearly threefold to 237 kilograms in 1974-76,
and declining somewhat to 220 kilograms in 1981-83.
The application of large amounts of fertilizers in intensive agricultural
production activities creates a situation where water transport of soluble
chemicals can easily occur. Once carried into an aquatic ecosystem, these
nutrients are available for aquatic plant and algae growth. Phosphorus is
the most common limiting nutrient in aquatic systems. Increased amounts
of phosphorus and nitrogen increase biological production and the aging
process (eutrophication) in lakes and reservoirs. Eutrophication is a natural
process in many lakes and streams, but the influx of nutrients from agri-
cultural sources greatly accelerates the process. Eutrophication of streams,
lakes, and reservoirs usually results in excessive growth of aquatic weeds
and algae, which in turn can create toxins and remove available oxygen,
thereby killing fish and greatly reducing the recreational value of lakes
and reservoirs (Clark et al., 1985~. The USDA estimates that between
15% and 54% of all nutrients applied to agricultural lands reach surface
water systems. This tremendous inflow of agricultural nutrients creates a
significant impact on the nation's waterways, its surface-water supplies, and
the ecological composition and maturation of water bodies.
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274
ECOLOGICAL RISKS
Pesticides
Agriculture accounts for about 75% of all pesticide use in the United
States, equivalent to about 725 million pounds of active ingredients (USDA,
1986~. Prior to World War II, pest control was largely accomplished through
a variety of cultural, mechanical, and tillage practices. However, the advent
of the chemical pest-control era brought abrupt changes in agricultural
systems which resulted in increased production, increased quality, and
greater efficiency in the production of food.
Almost all crops are subject to attack by diseases, insects, and weeds.
This susceptibility often increases when mixed croping is replaced by con-
tinuous monocultures (Altieri, 1986~. Efforts to control pests have included
the application of various toxic chemicals. More than 1,800 biologically ac-
tive compounds have been developed to protect agricultural crops. In 1977,
herbicides were applied to more than 200 million acres, insecticides to over
75 million acres, and fungicides to 8 million acres in the United States.
Eichers (1981) estimated that 5% of applied herbicides and insecticides
eventually reach surface waters, but the USDA has estimated that, under
normal rainfall conditions, pesticide losses in runoff tend to average no
more more than 0.5% of the quantities applied (USDA, 1986~. However,
the latter source notes differences in losses depending on type of substance,
with wettable powders having runoff rates of up to 5.053.
Pesticides may enter other environments from spray drift, soil erosion,
precipitation and irrigation runoff, soil moisture seepage, groundwater flow,
direct contact with animals and humans, or by other means (USDA, 1986~.
Monitored concentrations of pesticides in waterways has generally been
low except when heavy rains follow applications (USDA, 1981~. However,
this observation can be deceptive due to the relatively high toxicity of
these chemicals and the unknown or unmonitored potential of a number
of these compounds to accumulate at very high concentrations as they
rise through the food chain. While pesticide use has become prevalent in
modern agricultural systems, it is not uniformly applied to all crops. For
example, Eichers (1981) estimates that cotton represented the largest share
of insecticide use in 1976, accounting for nearly 40% of the total, while
corn accounted for another 20%. He also estimated that corn accounted
for 52% of total herbicide use while soybeans accounted for 20%.
Environmental effects of pesticides can vale substantially. Regulations
often favor less persistent and more selective compounds in order to be
less environmentally disruptive. In general, insecticide use has trended
away from the persistent, biomagnifiable organochlorine compounds that
are suspected of causing chronic diseases to nonpersistent substances such
as carbonate and organophosphate products (USDA, 1986~. The Federal
Insecticide, Fungicide, and Rodenticide Act (FIFING) empowers the U.S.
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AGRICULTURAL IMPACTS
275
Environmental Protection Agency (EPA) to curb the use of a pesticide
if, among other affects, it poses undue risk to human health or is an
imminent hazard in the environment because of its persistence or toxic
effects (Crowder et al., 1988; Chapter 6, this volume).
Salinity and Heavy Metals
In addition to sediment and chemical intrusion into surface water
systems, suspended solids such as salts and heavy metals are also carried
into waterways by erosion. Salinity problems are common in the arid
western United States and can significantly affect the aquatic environment.
For example, it is estimated that between 24% and 41% of the total salt
load in the Colorado River results from percolation of agricultural drainage
water through salt-laden soils (USDA, 1981~. Alterations in diversity and
patterns of species dominance can also occur with the replacement of less
salt-tolerant species by more salt-tolerant species. These changes can also
negatively affect the food chain and the higher trophic levels that depend
on the aquatic systems for food.
While the erosion of heavy metals from agricultural lands does not
appear to be a widespread problem, regional soil differences and irriga-
tion patterns can create potential heavy-metal problems in water systems.
For example, elevated soil selenium levels in the Westlands area of the
San Joaquin Valley in California~ombined with high soil salinity, saline
irrigation water, distinct irrigation patterns, and a high water table have
created a situation where high concentrations of selenium have accumulated
in drainage water and have consequently severely affected the ecosystem at
Kesterson reservoir. Impacts have included deformities in birds and signif-
icant declines in fish reproduction (University of California, 1987~. Interim
policies have led to the cessation of off-farm drainage flows, to increased
on-farm investments in drainage ponds, and to more precise management
of applied irrigation water and drainage flows.
Groundwater Contamination
Although groundwater has many sources of contamination, evidence
suggests that agricultural pesticides and fertilizers are significant sources
(Nielsen and Lee, 1987~. The United States relies heavily on its ground-
water. Over 97% of rural drinking water comes from groundwater sources
and 40% of the population served by public water supplies (i.e., nearly 74
million people) use groundwater sources.
The distribution of potentially affected groundwater areas is influenced
by the magnitude, extent, and duration of contamination, and conditioned
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ECOLOGICAL RISKS
by land use, agricultural practices, climate, hydrogeology, soil characteris-
tics, net aquifer recharge rate, depth to the water table, and characteristics
of the unsaturated zone and the aquifer (Nielsen and Lee, 1987~. Char-
acteristics of the potential pollutant (i.e., water solubility, adsorption, and
persistence) strongly affect its ultimate fate. About 800 of the 3,000 coun-
ties in the United States have potential for contamination by pesticides;
another 300 have potential for nitrate contamination; and 300 more have
potential for both types of contamination. More than 50 million people
rely on groundwater for drinking in these 1,400 potentially affected counties
(USDA, 1988~.
As mentioned previously, the 1977 amendments to the Federal Water
Pollution Control Act applies to groundwater and specifies that agricultural
practices may be subject to state or local restrictions on land and agricultural
chemical uses. Under FIESTA, more attention has generally been given to
pesticides that are known to leach into groundwater than to chemicals which
primarily run off cropland. The Safe Drinking Water Act also deals with the
possibility that nonpoint sources could contaminate groundwater sources of
public wells (Crowder et al., 1988~. The rising concern about contamination
of groundwater especially because contamination can persist for many
years and cleanup costs can be prohibitively expensive has heightened
awareness of rural and urban inhabitants.
REDUCING CHEMICAL DEPENDENCE
Since intrusion by agricultural chemicals is a one of the serious off-site
impacts affecting surface water and groundwater quality, a reduction in
the use of environmentally damaging chemicals should help enhance water
quality. A number of techniques have been developed that can, in some
cases, reduce use and need for chemicals, as well as encourage the use
and safe application of less environmentally damaging chemicals. These
techniques include biological control, host resistance, cultural control, and
physical and mechanical control, in addition to use of chemical pesticides.
Additionally, application modes can also have a significant effect on the
efficiency of chemical use and reducing off-site migration.
Integrated pest management (IPM) techniques have increased in use as
farmers realize the economic and environmental advantages of combining
biological pest controls and management practices with reduced chemical
use. IPM seeks to control pests in an economically efficient and environ-
mentally sound manner by maximizing the use of natural control agents
(i.e., predators, parasites, weather, crop varieties, tillage, etc.) before re-
sorting to the use of chemical controls (Smith and Pimentel, 1978; Pimentel,
1981~.
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AGRICULTURAL IMPACTS
277
In many instances, IPM is a viable alternative to chemical pest man-
agement. This is true especially because of rising chemical costs, increased
genetic resistance of pests to pesticides, and the presence of significant
external impacts. IPM can often achieve equal yields at reduced costs,
thereby increasing the profitability of the operation (Archibald, 1984; Bot-
trell, 1979~. IPM uses both biological and economic criteria to gauge the
ability of a crop to tolerate pests. The economic threshold sought in the
control of pests is the density of the pest population below which the cost
of applying control measures exceeds the losses caused by the pest. These
economic threshold values are derived by assessing the potential value of
the pest damage and the ecological, social, and economic costs of controls.
Successes in the use and implementation of IPM have occurred with
many crops including cotton, citrus, walnuts, almonds, fruits, soybeans, and
alfalfa. In Texas, it has been demonstrated that cotton (the major target
of insecticides in the United States) can be produced with 50-75% less
insecticides, thus increasing farmers' profits from $62 to $170 per acre
(Bottrell, 1979~. Archibald (1984) has also demonstrated the efficacy of
IPM as an optimal strategy for pest management in California cotton,
especially in light of the dynamic nature of insect resistance to chemical
controls. The results of IPM research indicate that it is both possible
and economically feasible to pursue environmentally sound agricultural
practices with lesser applications of agricultural chemicals.
Social concern about adverse consequences of agricultural technolo-
gies, including but not restricted to heightened levels of agricultural chemi-
cal applications, has lead to recent emphasis on "agricultural sustainability."
Carter (1988) discusses the various perceptions of "sustainable" agriculture
and notes that other terms for agricultural sustainability include alterna-
tive, regenerative, low-input, ecological, environmentally sound, and even
organic agriculture. He notes:
These terms are used by people interested primarily in alternative systems of
farming that will feed expanding populations while minimizing potential negative
effects whatever they might be. Defining negative ejects essentially separates or
categorizes the venous proponents of sustainable agricultural systems.
Other definitions of sustainability place emphasis on resource stewardship,
rural community sustainability, food self-sufficiency, and energy conserva-
tion. Use of these terms illustrate the social, ecological, economic, and
emotional connotations of concern about current agricultural practices.
Harwood (1987) identifies the following dimensions of the agricultural
sustainability concept:
· time;
· social sustainability;
· economic sustainability;
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ECOLOGICAL RISKS
· maintenance of soil and genetic resource bases;
· minimization of environmental pollution; and
· lowered use of industrialized inputs.
The USDA has recently developed the Low-Input Sustainable Agricul-
ture (LISA) program which supports research and education programs in
alternative farming systems that reduce the farmer's dependence on certain
kinds of purchased inputs in ways that increase profits, reduce environmen-
tal hazards, and ensure a more sustainable agriculture for generations to
come. The goals of this program include the following:
· develop economically viable crop and livestock systems to reduce
reliance on off-farm purchased inputs (especially synthetic chemical pesti-
cides and fertilizers that may pose environmental or human health hazards);
· maintain and enhance soil productivity;
· reduce soil erosion and loss of water and nutrients;
· conserve energy and natural resources; and
· minimize environmental contamination.
PROSPECTS
We currently find ourselves in the situation of having globally over-
responded in our efforts to meet the need for additional food and fiber
production which arose in the 1970s. All developed nations and many
less developed nations, as well, now find agricultural production capacities
and commodity markets to have shifted from "shortfalls" to "surpluses."
This achievement was possible in part due to food and agricultural policies
which both intensified production on existing lands with the aid of pur-
chased inputs, and expanded or developed additional cropland acreages,
often with less than due regard for environmental and ecological conse-
quences. However, the current costs of governmental policies to support
agriculture via supply control, export assistance, and other price and income
support programs are very large and are of concern not only in the United
States, but also in the nations of the European Common Market, and to
diverse members of the Cairns Group of developed and developing nations
which seeks fundamental change in agricultural and trade policies within
the current General Agreement on Tariffs and Trade (GATE negotiations.
The cumulative effects of past agricultural development and production
activities have brought into sharper focus some of the adverse environmen-
tal impacts which now seem to arise more quickly and more severely than
had been anticipated. It would appear that under such conditions of sur-
plus capacity and environmental threat, there is opportunity for greater
integration of agricultural and environmental policies. In fact, a recent
report by the Organization for Economic Cooperation and Development
OCR for page 279
AGRICULTURAL IMPACTS
279
(OECD) (1987) gives considerable attention to prospects for better inte-
gration of agricultural and environmental policies among OECD nations.
Young (19883 summarizes the OECD recommendations by noting that in
the development of new agricultural, environmental and related regional
development policies ". . . consideration needs to be given to a trilogy of
three factors:
· the need to enhance the positive contribution which agriculture can
make to the environment;
· the need to reduce agricultural pollution; and
· the importance of adapting all agricultural policies so that they
take full account of the environment."
The latter factor would involve targeting agricultural policies to be more
effective by simultaneously reducing surpluses and agricultural pollution
while enhancing environmental quality. Future examinations of ecological
problems associated with agricultural development will be less critical if
such holistic policy strategies are met with popular global support as well
as farmer and taxpayer acceptance.
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Representative terms from entire chapter:
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