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SoilFacts |
Managing Lawns and Gardens to Protect Water Quality |
Table of ContentsWater Quality: A Cause for Concern References and Suggested Readings
Prepared by Published by Publication AG-439-21
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Water quality is a major environmental issue. Society has been quick to point fingers at industry, agriculture, forestry, and other large land-disturbing activities as the culprits of groundwater and surface water contamination. Soil eroded from lawns and gardens may carry many contaminants to surface water. Water quality, therefore, is everyone's responsibility.
Normally, the contribution of water pollutants
from a homeowner's lawn, the grounds of a business establishment, or recreational
turf, such as golf courses or athletic fields, is small. However, when
millions of small inputs are added together, the impact on water quality
may be significant. The key to minimizing this collective impact is reducing
the levels of pollutants that enter The purposes of this fact sheet are to identify
several major pollutants that often originate in our lawns and gardens,
to describe the problems they may cause, and to outline some things we
can do to minimize their adverse effects on water quality. This information
should benefit home gardeners, landscape developers, contract lawn care
specialists, athletic field managers, and others who manage soil to grow
plants for food, pleasure,
Water Quality: A Cause for ConcernOne might ask why a single family with only a home lawn or garden should be concerned about the effects of their activities on water quality. The reason for concern is that the effects are not always confined to their land. Soil is a common pathway to groundwater, and soil characteristics determine the rate at which chemicals move through it. Once contaminants reach groundwater, they can travel long distances with the water. Thus, you should be sensitive to the off-site effects caused by the whole neighborhood's activities. Soil eroded from a homestead may carry many
contaminants to surface water. Contaminants may include certain kinds
of fertilizers and pesticides, petroleum-based products, the residue of
automobile emissions, and atmospheric deposition. Clearly, soil erosion
generates a variety of serious water quality problems. Furthermore, sediment
(deposits of eroded soil and organic matter) detracts from the appearance
of a neighborhood. By being part of a neighborhood, you assume responsibility
as a contributor to the cumulative impact of land use on water quality.
Perhaps the threat of greatest concern is damage to human health through
groundwater contamination. Residents in many rural and suburban areas
rely on groundwater for their drinking water supply. In North Carolina,
for example, over Even in urban settings, where surface runoff is collected from streets and road surfaces and channeled to a water treatment plant, contaminants from lawns and gardens affect water quality. Contaminants increase the degree of treatment required to purify the water before reusing it or discharging it into a public stream. Additional water treatment means an increased cost to a municipality, which passes the cost on to its residents. Thus, water quality affects the pocket books of all taxpayers.
Sources of PollutionClusters of housing, mobile home parks, convenience stores, recreation facilities, and other types of development increase the amount and diversity of pollutants cast into the community's watershed. Three main threats to water quality can be identified. Whenever water, as intensive rainfall or
irrigation, falls on bare soil surfaces in gardens or lawns, sand, silt,
clay, and organic matter may be moved away from the site. The potential
for erosion increases with slope, but unless there is runoff, raindrops
cannot do much damage. It is the transportation of soil particles and
organic matter in runoff that causes concern. This transported sediment
can choke lakes and carry chemicals into waterways, making them unsuitable
for recreational fishing, boating, or swimming. Everyone, including the
urban resident, farmer, gardener, recreational enthusiast, and taxpayer
must pay for An attractive lawn, vigorously growing shrubs
and flowers that show off the house, and a productive garden are the pride
and joy of many homeowners. Fertilizer nutrients, especially nitrogen,
phosphorus, and potassium, contribute to the health and beauty of these
plants. Nitrogen and phosphorus, however, must be managed carefully to
ensure that excessive amounts do not degrade water quality. Too much nitrogen
and phosphorus along with carbon in surface water cause eutrophication
(death from excessive algae growth) in rivers, lakes, and ponds. High
nitrogen levels in groundwater and surface water can lead to the ingestion
of nitrogen in its nitrate (NO3) form, which can cause health
problems in humans and livestock. Phosphorus accumulates in lakes and
ponds primarily from inflow of sediment that has phosphorus attached to
it. Preventing erosion greatly reduces the likelihood of phosphorus being
a threat to water quality. Nitrogen, whether from compost or fertilizer,
may leach past plant roots and accumulate in groundwater or eventually
move out to surface impoundments if not used completely by grass, shrubs,
or In addition to fertilizers, many homeowners
use numerous conveniently packaged pesticides (herbicides, insecticides,
and fungicides) to ward off pests around their house, lawn, and garden.
Excessive use of these products could lead to their deposition in lakes
and streams if they are carried off with sediments. Water-soluble pesticides
may leach in sandy soils with subsequent movement to groundwater or
Reducing Water PollutionStrategies for reducing or preventing water
contamination by sediment, fertilizers, and pesticides are based on common
sense. Homeowners, gardeners, and professional plant managers should determine
whether their activities cause sediment, fertilizers, or pesticides to
move and concentrate in an environmentally Land-disturbing activities, uncovered soil
surfaces, and the absence of water-retention structures may contribute
to excessive amounts of sediment in creeks and streams and on streets,
playgrounds, and neighbors' property. Try to hold soil in place so that
the amount of sediment generated from water erosion is small and does
not become Nitrogen is classified as a "mobile
nutrient," meaning it is water soluble and moves with surface water.
To reduce the risk of water contamination when applying nitrogen to lawns,
shrubs, flowers, trees, or vegetables, use Application Recommendations:
Literature form the Cooperative Extension
Service, suggestions from reliable garden store operators, or suggestions
from soil-testing laboratories will help guide you in the amount When applying pesticides:
Irrigation
Disposal of ChemicalsOne potentially serious source of groundwater and surface water contamination is the disposal of unused pesticides. It is tempting to flush them into sinks and toilets or to pour concentrates in the woods or on the edges of home lots. Serious health or water quality hazards may be caused by these practices. Pesticides and other hazardous chemicals greatly reduce the performance efficiency of home, community, or municipal waste treatment systems. A safe way to dispose of unused or old pesticides is to accumulate them in plastic-lined boxes or in metal or plastic pails and deposit them at a qualified and properly designed hazardous waste storage facility. Many cities and towns throughout North Carolina are now systematically collecting hazardous wastes (including pesticides) at a central point for proper disposal. Call city or county officials to ask about collection schedules. With proper storage, pesticides will keep their effectiveness for several seasons. Use them properly and completely, and you will avoid the problem of disposal.
ConclusionFortunately, you do not have to choose between
having an attractive lawn or garden and protecting water quality. The
key to achieving both goals is to use chemicals only when needed and then
use them judiciously. Reduce soil erosion by keeping soil covered with
mulches, matting, and ditch liners. Manage the application of nutrients
to keep phosphorus and nitrogen out of Contact your county Extension office whenever you have questions about lawn and garden products and their possible impact on water quality.
References and Suggested Readings
Soil Science Fact Sheets
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