On Tue, 4 Dec 2012 22:07:16 +0000 (UTC), "H. H. B."
wrote:

On Mon, 03 Dec 2012 17:13:47 -0800, Oren wrote:

Grass turf. The roots help reduce erosion.

Maybe that's not so good advice if this web site is correct.
http://www.laspilitas.com/garden/howto/slope.html


Old erosion ideas that don't work.

GRASS.

snip

Interesting. That mentions seed. Grass sod was my thinking, so I
mentioned turfgrass. Varieties with a deep rooting system.

Seems like the subject is all over the place.

"...As early at 1986, a U.S. Geologically Survey funded project at The
Pennsylvania State University documented that grassed areas
established with turfgrass sod are up to 15 times more effective in
controlling runoff than seed established grass, even after three
years.

More recently, a University of Maryland team of scientists testing the
"Runoff and Sediment Losses from Natural and Man-made Erosion Control
Materials" found, "Sod offers superior performance when compared with
straw in retarding the initiation of runoff, reducing runoff rates and
reducing total soil losses. None of the man-made materials effectively
extended the time for runoff initiation."

While these and other scientific studies have documented the
effectiveness of turfgrass to control erosion, there continues to be a
debate regarding the costs and associated benefits of various methods
of turfgrass establishment. The purpose of this paper is to examine
all of the associated considerations, costs and benefits of the more
popular grassing methods so that those who are responsible for making
recommendations, or the actual decision making, will have a strong
basis in fact for that action."

....

"Turfgrass Sodding:

•Withstands heavy and prolonged rains at time of installation, without
erosion or damage; steeply sloped surfaces may have to be pegged to
soil until roots are established.

http://www.turfgrasssod.org/pages/consumer-resources/stop-erosion

As others stated shrubs, trees, etc. with a deep roots will serve the
same purpose.

In my area all the highways have rock on the slopes, no erosion.