California Vetiver Brochure 09
California Vetiver Brochure 09
California Vetiver Brochure 09
A
System
To
Mitigate
Storm
Damage
and
Control
Water
Pollution
Protection of embankments: Vetiver contour hedges may be deployed to • High tolerance to salinity (50%
protect levees and the banks of canals and lakes against soil erosion from yield reduction at 20 dS/m; lethal at
45 dS/m) facilitates the use of vetiver
wave action from lateral water movement. How does vetiver do this?
grass to stabilize coastal dunes and
Vetiver’s massive root system holds the upper 3-4 meters of soil in place
beaches.
and can not be dislodged by moving water. Vetiver roots have an average
tensile strength of 75 Mpa, which increases the average shear strength of
the surrounding soil between 30 and 40%. The effect is to stabilize the • Vetiver grass is an infertile,
levee, dam or other soil structure against scouring by water or wind. The use perennial, non-invasive plant that is
of the Vetiver System for dike stabilization on the Mekong river is incapable of migrating from its
planting site or becoming a weed.
documented in: The working life of a vetiver hedge is
http://www.vetiver.com/VNN_truong_jan2005.pdf indefinite and requires little
maintenance
Wastewater effluent polishing (China) Coastal dune stabilization (Viet Nam) Canal bank protection (Viet Nam)
What makes vetiver grass special? The answer is found in the roots, in the plant’s remarkable set of physiological and
ecological characteristics and in its inherent ability to clone itself without becoming a weed and without attracting pests.
Vetiver grass has a massive, finely structured root system that is unique among grasses. With no rhizomes or stolons
that spread to the sides, the plant’s roots grow straight down in a mass as dense as the amount of leaves it produces
above the ground. These roots penetrate 3 to 4 meters into the soil before thinning out. New roots and shoots develop
from the root crown and from nodes on the stems when the plant is buried by trapped sediment at the face of a contour
hedge. The plant continues to grow and fill in at the higher level of the newly deposited sediment, eventually forming a
terrace that helps to retain soil moisture and reduce runoff.
Vetiver also has special characteristics that are useful in managing solid waste and wastewater. Vetiver is at home in a
marsh environment: it tolerates anoxic environments and high concentrations of toxic substances such as heavy metals
and ammonia that will kill most plants. Vetiver grass may be used in constructed wetlands to “polish” pre-treated
wastewater effluents to a high quality or to intercept and treat highly toxic leachates from landfills or “brownfields” sites.
Physiological characteristics
Vetiver grass is a “climax plant,” which survives extreme ecological conditions under which other plants perish: it will
tolerate prolonged drought, fire, flood, submergence and extreme temperatures from -15°C to 55°C. In some cases it
may be the only plant to survive. In a warm climate, such as Southern California, vetiver grass is capable of recovering
quickly after being affected by drought, flooding, fire, frost and exposure to salt and adverse soil conditions.
Vetiver grass is adapted to an exceptionally wide range of pH. It can grow in soils with an acidity of 3.0 and can survive
in alkalinities with a pH as high as 10.5 to 11. Vetiver can tolerate a high level of soil salinity, soil sodicity and acid
sulfate, making it a uniquely hardy plant. For salt tolerance, refer to: www.vetiver.com/AUS_Salt%20Tolerance.pdf
Ecological characteristics
It is a general principle that plants intended for use in environmental protection or agriculture be investigated for their
potential to become weeds or intermediate hosts for pests that affect economically important crops. Because the few
seeds that vetiver grass produces are not viable and the absence of pests that affect it, the plant has been approved by
the USDA for use in the US. ”Sunshine” vetiver is the name of the Louisiana variety of Chrysopogon zizanioides. After
several years of observation, it was officially released in 1995 by the USDA Golden Meadow Plant Material Center in
Louisiana. Refer to http://plant-materials.nrcs.usda.gov/lapmc/releases.html
The South Eastern Exotic Pest Plant Council, declared in May 2001 that “Sunshine”, vetiver, i.e., Chrysopogon
zizanioides, is acceptable because of its non-invasiveness for use in the southeastern region of the US. Refer to:
www.se-eppc.org/fslist.cfm.
See also http://user.aol.com/vetivernet/vip/dnadiv.htm and http://www.vetiver.org/USA-USDA-NRCS_Sunshine.pdf
Because of its special characteristics, vetiver grass can be considered as a “nurse plant” on wastelands or disturbed
soils, where it may be the only plant that will grow in that setting. Planted as a single or series of contour hedges, vetiver
grass stabilizes the erodible ground and creates a micro-climate that favors the re-establishment of native plants. The
Vetiver System is used to remediate mine sites and to stabilize highway and railway embankments, bridges, and even to
rehabilitate rock quarries.
After native trees and shrubs have established themselves on these sites, they begin to shade the vetiver hedge,
replacing it as the stabilizing agent. Consequently, vetiver is highly regarded as a non-invasive pioneer plant useful for
land rehabilitation.
Vetiver System in California:
Infrastructure Protection, Soil
Erosion Prevention and
Comprehensive Water Pollution
Control
The leaves and stems have been Vetiver grass is not invasive, has
cut off the top. The clump itself is infertile seeds, and does not have
composed of several hundred lateral roots. Vetiver hedges remain in
individual “slips”, or sprigs, that the same place and do not move
grow side by side to make up the without human intervention. With
clump. minimal maintenance, they last for
generations
vetiver
Flume trial by USDA-ARS
in 1991 showing water
backed up 30 cm high