Most of us don't think of soil as a pollutant. But it is. In fact, sediment deposited by storm runoff is a major source of surface water pollution.
How many times have you ridden by a construction site on a rainy day and seen red streams running off the area? Pollution like this is defined as nonpoint-source, since it arises from many small, dispersed sources.
In Georgia, we all live in watersheds. If you manage any land -- a small, urban yard or 100 acres -- you can reduce such nonpoint-source pollution by stemming soil erosion on your property.
Soil erodes when water or wind carries off soil particles and deposits them somewhere else, such as in a stream, river or at the bottom of a bay. Often these particles are carried by runoff -- water that doesnt soak into the ground, but flows instead over the surface and runs into storm drains, streams or lakes.
Besides soil sediment, runoff can wash fertilizer and other pollutants along with it. Sediment makes up most of the pollutant carried by runoff. And most of the phosphate and pesticides entering Georgia's waters are attached to these soil particles.
Erosion in the home landscape also creates unsightly bare areas. It deposits mud and dust on driveways and walkways. Then you track it into the house.
It all starts when rain or irrigation water loosens soil particles. When there is too much water to soak into the soil, it fills surface depressions and begins to flow.
With enough speed, this surface runoff carries away the loosened soil. Runoff from roofs and paved areas can also add to erosion by directing large amounts of water quickly to nearby areas that cant absorb it fast enough.
To reduce erosion, protect the soil surface from rain. For example, a cover of plants, such as a well-maintained lawn or other groundcover or a combination of mulch and plants, will effectively protect the soil surface from rain.
Plants roots help lessen erosion, too, by holding soil in place. In some cases, though, you may have to control or redirect the runoff, too, to effectively control erosion.
Bare soil is the most obvious source of erosion. By mulching or planting bare areas, you can reduce erosion. Seed your vegetable garden with a cover crop such as rye or hairy vetch for the winter. Promptly seed and mulch bare patches in your lawn. Mulch around trees and shrubs, too, will absorb water and direct it to the root systems.
Other indications of erosion on your property include:
- Tree roots, small stones or rocks becoming exposed.
- Small rills or gullies beginning to show.
- Soil splashes on windows and outside walls.
- Stream channels widening or deepening.
- Sediment collecting in low areas or on pavement.
Another pollution problem from the landscape is leaves.
It seems strange that something as natural as tree leaves can be a pollutant. But it makes more sense when you consider that storm drains can funnel organic debris from all over your community to one small stream. It will eventually join organic debris from countless other communities on its way to our lakes, streams and rivers.
One way excessive organic matter in our water can act as a pollutant is by creating high nutrient levels. This results in algae blooms and low oxygen, suffocating aquatic life.
Besides helping you protect water quality, good landscaping techniques will give you healthier plants and a more attractive yard.