Thoughtful lawn care and fertilizer use is important
to restoring and protecting our waterways.
The same nutrients - phosphorus (P) and nitrogen
(N) - that fertilize our lawns, also "fertilize" our river, lakes,
ponds and streams. Yet
our river, lakes, ponds and streams don't need fertilizing. In fact,
the Assabet River and many area streams, lakes and ponds are grossly
over-fertilized by nutrients, which come from storm water runoff
and sewage treatment plant discharges. These excess nutrients cause
aquatic plants and algae to grow like crazy in the summertime -
a condition called eutrophication. This prolific plant and algal
growth can ruin our waterways for boating, fishing and swimming
and also harm fish and other aquatic life.
How lawns can contribute to the nutrient problem
Lawns are aesthetically pleasing and provide enjoyable
places to play and relax. But they can also export significant loads
of phosphorus and nitrogen to the Assabet River, local streams,
lakes and ponds. How? During a storm, rain water (aka "storm
water") transports phosphorus and nitrogen attached to fine soil particles, or dissolved in the rain water, from your yard
to nearby waterways. Nitrate, a form of nitrogen that does not bind
to soil particles, can also leach down into groundwater, particularly
in sandy soils, and eventually
enter streams and wetlands. In dry weather, wind can also carry
nutrient-laden particles and organic matter from your yard to
Sources of phosphorus and nitrogen on the lawn
|Test your soil before you fertilize.
Most soils already have enough phosphorus to support a lawn.
Rain and wind also transport phosphorus and nitrogen
to waterways from undeveloped and uncultivated lands. Most of these
nutrients enter rivers and streams attached to soil particles or
contained in organic material such as dead leaves. It is a natural
process. However, when people apply excess fertilizer, apply
quick-release (water soluble) fertilizer, or apply fertilizer at
the wrong time, rain and wind can deliver large, unnatural quantities
of phosphorus and nitrogen to waterways, causing significant pollution
To reduce the quantity of phosphorus and nitrogen
exported from your lawn, test the soil to find out what nutrients
it needs to grow grass, apply only the type and quantity of fertilizer
indicated by the soil test, and keep both fertilizers and water
on your lawn.
Continue to ...
Managing Your Lawn for a Cleaner
Or skip to ...
Keep Fertilizer and Water
on your Lawn Where it is Needed
Professional Help and Advice
Additional Resources on
To learn about OAR's programs that target the Assabet's
issues, check out OAR Programs.