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Keep Your Soil Where it Belongs

Silt does not happen by itself

Farmers, homeowners and contractors are all responsible for making silt that clogs our streams, rivers and lakes and pollutes the Bay. Farmers who after harvesting their crops allow the soils to be fully exposed to the weather all fall, winter and spring are guilty. Homeowners who wash down their driveways and sidewalks in place of sweeping them are guilty. Contractors who bulldoze the earth to clear land for roads, homes, shopping centers and more are also guilty.
    Removing the vegetation allows exposed soil to be carried away by wind and water. The lowest point on land that water can travel is sea level. Thus, dust containing sand, silt and clay settles in the lowest points. Moving water carries soil and deposits sand as the flow of water decreases. The silt is carried farther to eventually settle to the bottom of slow-moving streams. Clay floats out into the Bay, clouding the waters and preventing bottom vegetation from growing, as well as carrying nutrients that feed algae that, when it dies, causes eutrophication.
    The early tobacco farmers were notorious for allowing their fields to remain barren after harvesting. Those farming on slopes lost tons of topsoil each year due to erosion. Most of the silt recently dredged from Rockhold Creek originated from old tobacco fields in the watershed. Even now when a sod farm starts to harvest sod, Rockhold Creek runs chocolate-brown following a heavy rain. Coloring the water is the silt in the topsoil that has washed into the creek. Most will settle to the bottom before it reaches the Bay. What enters the Bay are clay particles in suspension.
    The loss of topsoil and the siltation of our rivers and streams can be prevented by never allowing soil to stand exposed. As soon as a crop is harvested, the land should be planted either with another crop or a cover crop of wheat, rye, millet, Sudan grass or buckwheat. This rule applies to the home gardener as well as to farmers.
    When farming on slopes, contour-farming practices should be applied together with strip-crop farming. Strip-cropping plants wide strips of grass between plots of cultivated crops. The grass strips prevent the sand, silt and clay from washing away.
    Buffer zones or riparian strips of 125 to 150 feet wide of grasses or natural vegetation should be required between cultivated fields and open bodies of water. I encourage farmers to build berms of compost two feet high and two feet wide planted into tall fescue on the riparian strip. Compost is an ideal natural filter that will absorb clay and keep nutrients from flowing to the water during heavy rain.
    It should be unlawful to clean the driveway and sidewalks with water. That water carries dirt, oil, animal droppings, etc. into the storm drains. All storm drains empty into nearby streams that eventually flow into the Bay. A good push broom not only provides exercise but also pushes all of that crud onto the lawn or garden, where it becomes part of the soil. Oil will be degraded by the microorganisms in the soil.
    Before any construction begins, contractors should be required to establish a buffer zone around the construction site and install a silt fence with Filtrex filled with compost on the low side of the silt fence to capture the clays and nutrients. Compost has been proven to be an excellent filter of clays and nutrients. If the silt fence is to remain in place for more than a year, the Filtrex should be seeded with tall fescue to use the nutrients absorbed by the compost. Only clean water should be allowed to exit construction sites.
    If we all did out part in keeping soil where it belongs, our agricultural soils would be more productive, there would be less need to apply fertilizers and the water in our streams, rivers lakes and the Bay would be crystal clear and blue as it was meant to be. Progress should not be measured by polluted water or by polluted air.


Ask The Bay Gardener your questions at DR.FRGouin@gmail.com. Please include your name and address.