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adaptability or maintenance needs (water,
fertilizer, and pest control). As a result, millions of
homeowners spend millions of dollars and
countless hours to maintain attractive, healthy
landscapes, often at significant costs to the
environment. By following simple design and
maintenance practices, homeowners, landscape
contractors, lawn care providers, developers, and
cities can have attractive, easy to maintain
landscapes that are also easy on the environment.
Suitable plants, proper landscape design, soil
preparation, and maintenance practices all
contribute to trouble-free and environmentally
friendly landscapes.
The Benefits of Resource Efficient Plants
w
conditions o
require few i
water and fe
pesticides, tc
They can als
or nonpoint
The amount
ell-designed
landscapes
should use native
and resource
efficient plants
(REPs). These
plants are
well-adapted to
the natural
f an area and
resources, such as
rtilizers or
) remain attractive.
o prevent runoff
source pollution.
of chemicals
Table 1. — Landscape management systems.
LANDSCAPE
xeriscape
low-maintenance
medium-
maintenance
high-maintenance
PLANT
prairie
buffalograss,
autumn sage,
wax myrtle
same plants as
xeriscape
tiffgreen bermuda
grass, dwarf
yaupon hollies,
wax myrtle
same plants as
medium
FERTILIZATION
no fertilizer
65.2 Ibs N/acre (73 kg/ha)
split between two
applications
130.5 Ibs N/acre (146 kg
N/ha) in three applications
261 .6 Ibs N/acre (293 kg
N/ha) applied in 6
applications; 1 8 8 Ibs
P/acre (21 kg P/ha) and
32.1 Ibs K/ha) application
IRRIGATION
no irrigation
at 15 percent pan
evaporation level
(about 1.5 in/month
during growing
season)
to equal 40 percent
pan evaporation
(about 4 in/month
during growing
season)
to equal 60 percent
pan evaporation
(about 1 .5 in each
week)
plant irrigation requirements, and infiltration rate
of water into the soil affect chemical runoff from
landscapes. These factors offer the most
opportunity to apply best management practices
such as the selection of appropriate plant species.
Researchers at the Texas Agricultural Experi-
ment Station in Dallas have begun to quantify the
nutrient and pesticide reductions that can be
achieved by landscapers who select resource
efficient plants. Using 20 microwatersheds (each
microwatershed was replicated five times),
Professor Billy Hipp and colleagues are evaluating
four different landscape management systems in
clay soils: high-maintenance, medium mainten-
ance, low-maintenance, and xeriscape (no
maintenance). The researchers compared
representative resource efficient plants to typical
high-maintenance plants that require significant
amounts of water and chemicals to remain
attractive. Two-thirds of each microwatershed was
planted to turfgrass, and the other third was
planted to shrubs with a bark nugget cover. Table 1
shows the management systems and types of
plants used in the microwatersheds.
Preliminary data from Texas show that during
most rainfall and irrigation events, less runoff and
more infiltration occur in landscapes with dry
soils. Thus, landscapes containing resource
efficient plants adapted to conditions of low soil
moisture contribute less pollution to nearby
waterbodies. The data also indicate that landscapes
with limited inputs of fertilizers and pesticides
contribute fewer nonpoint sources of pollution,
and the concentration and amount of pollutants
that do occur in the runoff are low. Figure 1
illustrates the differences in nitrate runoff between
the high- and medium-maintenance systems.
Figure 1.—Differences in nitrate runoff between high-
and medium-maintenance systems.
a
JC
o
c
E
2.00
1.50
1.00
n
-2 0.50
I
n
o
z
0.00
runoff from 6.35 cm irrigation
O—O med maint (1 mo since N)
•—• high maint (2 da since N)
0.0 0.5 1.0
accumulated runoff (cm)
1.5
Source: B Hipp, Texas Agricultural Experiment Station, Dallas, TX
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municipal mowing ordinances exist. U.S.
Department of Agriculture soil scientists and
range conservationists can advise
homeowners, landscape designers, and
contractors on how to indentify and plant
various grass plants and forbs native to the
area. Native grass plants have low nutrient
requirements and can be effective in uptake
or interception of nutrients.
• In many new subdivision developments,
builders offer "landscape packages" as part
of the purchase price of new homes. Polluted
runoff from these landscapes can be
prevented by requesting a resource efficient
landscape design as the standard package.
• Group plants according to similar growing and
resource requirements and match them with the
existing site conditions. Placing plants that
require moist or saturated soil conditions in a wet
area, instead of draining the area for less tolerant
species, avoids the constant battle of keeping the
site in an altered conditions so the plants can live.
• Landscape zoning or creating outdoor rooms
based on the homeowner's desired use is an
accepted concept in landscape design. This
principle can be modified to include selecting
uses according to the site's ecological zones.
• A high-maintenance turfgrass could be used
as a specimen or accent area, with the
remaining areas planted with resource
efficient plants. One small but exquisite area
of lawn has more visual appeal than a large
area of difficult-to-maintain turf.
Additionally, even though resource
requirements are high, the smaller area of
lawn will receive much lower total inputs
than a larger area, thus reducing potential
for pollution off site.
Water Quality Goals for Landscape Maintenance and
Management
esource efficient landscapes can be
designed to require minimum
maintenance to prevent pollution.
Existing landscapes that do not have
resource efficient plants can be
managed more efficiently to provide
some protection to water resources.
Key management principles to observe
include the following:
• Manage water efficiently. Simple methods to
conserve water and prevent runoff consider both
irrigation quantity and timing. Use trickle
irrigation systems, manually operate sprinklers
(based on soil moisture conditions), and routinely
test soil moisture to determine irrigation amount.
Irrigate in the morning to allow plants to dry
instead of the evening when low evaporation rates
can lead to disease.
• Use mulch. The infiltration rate in mulched
areas is often more than double that of unmulched
areas because the mulch intercepts the impact of
raindrops and prevents the soil from developing a
less permeable crust. Mulch also controls weeds,
reducing the need for herbicides or labor to pull
weeds. Mulched soil is cooler than bare ground
and provides a favorable environment for
earthworms and insects that increase infiltration
and build soil. A healthy soil is the first step to a
healthy plant and may prevent diseases or pests
from attacking the plant. Consider composting as
another way to build a better soil while
eliminating nonmeat household food scraps and
landscape clippings. The new composters are
self-contained, unobtrusive, inexpensive, easy to
use, and virtually odor free.
• Manage nutrients wisely. All plants need
nitrogen, phosphorus, potassium, and various
micronutrients to grow. Even resource efficient
landscapes sometimes need supplemental
fertilizer. The key to water quality protection
through proper nutrient management is to test the
soil and plants to determine the missing nutrients,
select the least mobile form of the nutrient
available, and apply the nutrient to coincide with
growth cycles. Avoid applying fertilizer just before
rainfall, place fertilizer only when and where it is
needed, and avoid overwatering. Research shows
that a significant pollution load can wash off
sidewalks to which fertilizer has been
inadvertently applied. Figure 3 illustrates the high
nitrogen pollution load that may result in runoff
from a sidewalk.
• Begin pest management with plant selection.
Site-adapted and native plants may be more pest
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intercepting and filtering pollution in runoff. Most
small suburban lots (less than a quarter-acre)
cannot accommodate a buffer designed to control
pollution from the entire watershed but may be
sufficient to control on-site runoff.
Critical areas to protect with buffer zones
include creeks, drainage swales, storm sewer
outlets, and wet areas. A mixture of trees, shrubs,
and ground cover is a more effective design than
a single species. If soil conditions are suitable,
these buffer zones may operate like a seepage
trench (a soil-covered, gravel-filled trench) or
Dutch drain (a surface drain that consists of a
shallow, gravel-lined trench with curbing and a
grate) by improving infiltration and slowing
runoff velocity. Water infiltration into forest soils
is one-third to one-half higher than turf covered
soils. Thus, using woody plants to retain water in
the buffer can minimize runoff and increase
infiltration.
• Limit impervious areas. Research in urban and
suburban watersheds shows that once a watershed
exceeds 12 percent imperviousness, stormwater
flow and pollutant loadings increase
proportionally. On a typical 100 by 75-foot lot with
a 2,000-square-foot home, a driveway, and a
garage, the site is approximately 33 percent
developed. Since roof area generally cannot be
reduced, other methods to reduce site
imperviousness will help control pollution.
Replacing lawn areas with decks, paving, and
mulched areas underlain with plastic is often
recommended for a xeriscape system. Although
these nonporous soil coverings are effective in
reducing high-maintenance lawn areas and
subsequent water needs, they can increase runoff
velocity and amount and contribute to water
pollution.
More efficient methods can limit impervious
surfaces during landscape design and installation.
For example, residential and commercial sites
might use porous pavements, nonsolid decking
without a plastic or nonpermeable liner, organic
mulch, bricks and sand for walkways instead of
concrete, and crushed gravel within curbing for
driveways and utility areas.
• Manage runoff and pollution from impervious
surfaces. Driveways, sidewalks, and gutters need
not drain to the pavement—they can drain to a
well-vegetated area by appropriately sloping,
crowning, or redirecting water flow.
• Direct the flow to infiltration trenches or
Dutch surface drains as long as the runoff
only comes in contact with normal home
construction and landscape material and is
not installed on a clay soil, an impervious
claypan soil, or an area with a high water
table.
• During home construction, use techniques
that minimize soil compaction. Since heavy,
compacted clay soils around existing homes
usually cannot be replaced, planting
materials with deep fibrous roots will help to
improve infiltration.
• Improve existing soil infiltration capacity by
incorporating organic material into planting
beds, and where possible, into lawns.
• Select resource efficient plants. A resource
efficient landscape should have attractive plants
that are suited to the site but require minimal
levels of fertilizer, pesticides, and irrigation to
thrive. Each area of the country has a wealth of
attractive native plants—trees, shrubs, ground
cover, grasses, and flowers—as well as many
well-adapted introduced species that the
homeowner, landscape designer, or contractor can
choose from. Most local county extension
specialists have lists of resource efficient plants
adapted to each region and will provide the names
of recommended plants suited to local soils,
climate, and landscape needs.
• Replace large areas of high-maintenance
landscapes with adapted or native plants. The
largest consumer of water, time, fertilizers, and
other resources is a high-maintenance landscape
area. Research at Texas A&M University in Dallas
shows that selecting reduced-input and
low-maintenance plants results in significantly
reduced nutrient concentrations in runoff when
compared to typical landscape materials.
• Portions of the high-maintenance landscape
can be replaced with resource efficient
ground cover, shrubs, and trees that
generally have lower resource requirements.
For example, in the north Texas area, native
tree seedlings require a weekly one-inch
watering for their first three years but only
supplemental irrigation during especially
dry summers or early falls thereafter.
• Establishing native grass and herbaceous
flowering plants in a meadow-like setting is
an excellent alternative for high-maintenance
landscapes unsuited for shrubs or ground
cover. This includes suburban areas where
homes are sited on a few acres and no
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Resource Efficient Landscapes
properly designed landscape not
only adds beauty to a residential or
commercial site, but it can also
increase property values, decrease
heating and cooling expenses,
provide security, buffer noise, screen
unsightly views, preserve water
supplies, mask or remove
objectionable odors, and control nonpoint source
water pollution.
Some of the factors that influence the selection
of resource efficient plants also guide the
development of a resource efficient landscape
design. In particular, the site's soils and drainage
and the area's climate must be carefully considered
to design a landscape that prevents pollution. Any
existing vegetation, prevailing wind direction,
slope, available water, existing or desired
impervious surfaces, and proximity to street must
also be considered.
Design Principles for Pollution Prevention
he key to a landscape design that
prevents nonpoint source pollution
is understanding the site to be
designed and the resources to be
protected. Basic landscape design
principles that reduce potential
nonpoint source pollution include
the following:
• Work with the hydrology instead of altering it.
The first consideration in landscape design is
generally how to alter a site's hydrology to meet
the landowner's objectives. A resource-intensive
approach is usually taken—wet areas are drained,
water flow patterns are altered, and dry areas are
irrigated. However, incorporating the existing
hydrology into the landscape design can meet the
objectives while still effectively controlling
pollution and saving money as well.
As shown in Figure 2, the landscape design
for a residential property should allow off-site
runoff to move across the property without
damaging the site or adding pollution to the
runoff. Using the areas that carry the runoff as
part of the landscape design integrates the
hydrology of the area into the landscape plan.
• If the site must be significantly modified,
ensure that all areas drain to
well-vegetated zones—never directly to a
stream or storm sewer—to minimize
pollution. Small on-site detention or
retention basins and gravel-filled seepage
pits can hold water to increase infiltration
or slow rapid runoff to a nonerosive rate.
Small berms or terraces can also increase
infiltration. Take care to protect
groundwater resources with these
installations.
• Siting recreation and other high-use areas in
stable and dry zones in the yard help
prevent unnecessary site alteration. New
developments offer expanded possibilities
for pollution prevention and control.
Developers should set aside wet or
streamside areas for community green space.
Porous pavement and detention and
retention basins can also improve the
management of water or site.
• Use buffer zones. Design buffer zones and
riparian protection areas for individuals or the
entire development. Properly designed and
vegetated buffer zones are highly effective in
Figure 2.—A resource efficient landscape design.
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Figure 3.—Calculated nitrogen concentration in
runoff from sidewalk.
cn
j*
\
cn
1600
O O 0.25 in. rain
• • 0.50 in.
A A 1 0 in.
A A 2.0 in.
O
N application rate (lbs/1000)
Source: B. Hipp, Texas Agricultural Experiment Station, Dallas, TX.
resistant than many introduced species because
plants established in suitable soils are less prone to
disease and attack by insects. If a problem does
occur, identify the cause to determine if it warrants
treatment. If a disease or insect problem reaches an
intolerable level, choose the least toxic but most
effective pesticide for the specific pest. Select the
least mobile pesticide with the shortest residual
time in the environment, and apply it according to
label directions. Some label directions can be
confusing or misread—take care to dilute and
apply correctly. Always dispose of containers
properly.
• Influence others. Many suburban homeowners
engage lawn care companies. As with any
business, these companies respond to consumer
demand. Encourage companies to expand their
services to promote the use of low-maintenance,
low-impact landscapes, and include more
customized assistance instead of routinely
scheduled care.
• Incorporate new lawn care knowledge into
routine practices. Many extension service agents
promote resource efficient use of grass clippings
through simple but effective programs such as
composting or "Don't Bag It." Reduced mowing
and increasing the mowing height of the blade are
simple conservation practices that can improve
water quality. Some grasses do poorly if mowing
height is increased. In some instances, evenness of
cutting is more important in reducing lawn water
loss.
Help is Available
any groups and agencies can provide
written materials, services, and on-site
assistance with resource efficient
landscaping. For specific help, contact
the following:
American Society of Landscape
Contractors, state chapters
American Society of Landscape
Architects
Cooperative Extension Service
Local nurseries
Local Environmental Protection Agency
offices
State Water Quality agencies
U.S. Department of Agriculture Soil
Conservation Service
Native plant societies
TBWEHE
INSTITUTE
This project was produced by the Terrene Institute under a cooperative agreement with the U.S. Environmental
Protection Agency, Region 6, Water Management Division, Water Quality Management Branch, and prepared by
Susan V. Alexander and the Terrene Institute staff. Special thanks to Sharon Collman, C.E.S. liaison to EPA Region
10, and Dan Rolf, president, Texas Association of Landscape Contractors. For copies of this publication and others
in the series, contact the Terrene Institute, 1717 K Street, NW, Suite 801, Washington, DC 20006, (202) 833-8317,
or the U.S. Environmental Protection Agency, Region 6,1445 Ross Avenue, Dallas, TX 75202, (214) 655-7140.
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