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Tuesday - June 22, 2010

From: West Union, IA
Region: Midwest
Topic: Erosion Control, Grasses or Grass-like, Herbs/Forbs, Shrubs
Title: Erosion control in West Union IA
Answered by: Barbara Medford

QUESTION:

Erosion control and native grasses/plants for steep, shady slope in northeast Iowa. We are building a house in northeast Iowa (near West Union in Fayette County). The road that was graded to the house site resulted in a steep (45 to 60 degree), shady slope of bare dirt on one side, about 30 feet long and up to fifteen down. What native grasses and other plants would be good to control erosion? Will erosion control blankets help?

ANSWER:

We recommend grasses for controlling erosion because of their extensive fibrous root systems that serve to hold the soil in place. However, seeding grass is not the whole process. The seeds need moisture to germinate. If the moisture comes in the form of rain, it is likely to wash the seeds down the bank before that have a chance to germinate and take root. There are two possible solutions—an erosion control blanket or pneumatic compost/seed application. The erosion-control fabric works by slowing the runoff water and allowing sediments to fall out rather than be washed away. Seeds are sown under the erosion-control material and grow up through the matting when they germinate. You can also insert plants into the soil by cutting through the matting. The roots of the plants that are growing through the erosion-control material anchor the soil to stop the erosion. If you use erosion-control blankets made of biodegrable material, they will eventually disappear leaving the plants to control the problem. Many nurseries carry this erosion control fabric.

The compost/seed application may be a bit more complicated and expensive than you had in mind since it does require a pneumatic blower, or some mechanical means, to spread the compost/seed mix. The US Composting Council offers information about suppliers of compost and compost technology, but I don't really know if this could be a do-it-yourself project. You might check with a landscaping or environmental consulting company in your area who might have the machinery to do this to learn about the feasability and expense of applying the compost/seed mixture this way. You can find the names of Landscape Professionals and Environmental Consultants in your area that specialize in native plants by searching in our National Suppliers Directory.

We will go to our Native Plant Database and find grasses and perhaps some spreading shrubs native to Iowa that should help with your erosion. These are not lawn-type mowable grasses, but more decorative prairie grasses that, being native to Iowa, will be able to cope with soil and climatic conditions. Follow each plant link to the page on the individual plant for information on expected size and sun requirements. We will be searching in our Native Plant Database for plants that can tolerate "part shade" (2 to 6 hours of sun a day) and "shade" (less than 2 hours of sun a day). We will also determine if the plants grow natively in or around Fayette County, USDA Hardiness Zone 4a to 4b.

Shade Plants for Erosion Control in West Union Iowa:

Grasses:

Andropogon gerardii (big bluestem)

Bouteloua curtipendula (sideoats grama)

Carex blanda (eastern woodland sedge)

Calamagrostis canadensis (bluejoint)

Chasmanthium latifolium (Inland sea oats)

Elymus canadensis (Canada wildrye)

Schizachyrium scoparium (little bluestem)

Sorghastrum nutans (Indiangrass)

Shrubs:

Amorpha nana (dwarf false indigo)