Technical Report on the
International Workshop on Vetiver Bioengineering Technology for
Erosion and Sediment Control and Civil Construction
19 - 21 October, Nanchang,
TVN Asia and Pacific Representative
This report concentrates on the technical aspects of the
Conference; it is complementary to the very comprehensive general
report prepared by Prof. Xu Liyu (10).
Invited Speakers: Dick Grimshaw and Paul Truong
were invited by the Chinese Academy of Sciences and Diti
Hengchaovanich by UNDP.
- TECHNICAL SESSIONS
- Fifteen technical papers were presented although most of
the papers concentrated on steep slope stabilisation,
other aspects of VGT such as factors affecting vetiver
establishment and growth were also presented. The
following are highlights presented or discussed during
- Growth patterns and factors influencing
vetiver growth in China.
Professor Xu presented a very comprehensive summary of factors
affecting vetiver growth in China.
- Soil type: wide range from rich loamy soil to wind
blown soils, saline and acidic conditions with extremely
low nutrient levels and organic matter content.
Latitude: from 10o N (Hainan) to 39oN
(Tianjing). At Tianjing mean January temperature is 4oC,
with winter minimum of -22oC. Growth starts at
temperatures between 10 and 15oC, but best
performance is in the range between 20 - 30oC
(2-3 cm/day) higher temperatures at 40oC or
higher affects growth (0.5 cm / day). Biomass production
is affected more by soil fertility than temperature.
- Tolerance: to high heat, with water logging and
- Water: Survives repeated submergence including
1.5m deep for 11 days.
- Does not thrive or survive under water at
- Elephant grass was killed when submerged.
- Tillering is affected by shading. At 23%
sunshine, 8.6 tillers were produced, in full sun,
15.7 tillers produced.
- When shading was removed, tillering recovered but
height and biomass recovered very slowly.
- Fertiliser requirement:
- Fertiliser is needed for poor soil, particularly
- Several small applications are better.
- Urea promotes best growth and tillering over
short periods only.
- Clay dipping of roots for sand dune
- Plants at 1.5 m high pruned to 0.3 m produced
18.6 tillers more than control in 40 days.
- Warm climate 2 prunings a year.
- Cold climate 1 a year.
- Most growers don't want to prune.
- VGT applications:
- Highway stabilisation.
- River and coastal bank stabilisation. Vetiver was
preferred to rock by farmers to trap silt and protect
riverbanks from rainstorm.
- Protect shoreline against sea wave, which in 1996 a
typhoon destroyed a 200m long wall when sea water level
rose to 7.5 m over sea wall. Those protected with vetiver
- Fish pond protection, so far 660 ha of ponds have been
protected by vetiver.
- VGT for Soil and Water Conservation on farm land:
- On 5 - 8o slopes, run-off was reduced by 50%
and soil loss by 67%.
- Root depth and biomass much higher than native species Eriansluis
- VGT for Wind Erosion control:
- Very effective in protecting vegetable and jojoba crops
against windstorm, averaging 14 - 17 m/sec over 125 days
- Wind speed was reduced by 59% at 5m from hedges and 79%,
2 m from hedges.
- VGT for fertility improvement
- Every 100 m hedge produced 800-1500kg fresh pruning/year.
- 4.0 - 7.5t / ha / year when planted 2m spacing.
- Corn yield improved 35%.
- Vetiver mulch lasts longer than straw mulch, after 114
days, decomposition loss for vetiver was 39% and 75% for
- Amino acid content of soil from orchards protected by
vetiver was 57.4 mg / kg higher than control.
- Water pollution control:
- Growth of vetiver grown in river water polluted by
domestic sewage, 0.8 m high and four tillers.
- Growth of vetiver grown in pond water, 0.6 m high and one
- Growth of vetiver grown in tap water 0.5 m high and zero
- Removal of nutrients from polluted river water
- After 1 week: 34% of total N and 61% of total P removed.
- After 3 weeks up to 99% of P removed
- After 4 weeks 82% of total N resulting in transparency
- Vetiver died when planted in seawater with salt content
- Field test in Tianjing showed vetiver grew well on soil
containing 0.8% of salt; and reaching 1.6m in the first
- Increase in crop yield.
- Feed for cattle, goat and fish, especially in northern
China, but not geese.
- Growing edible fungi with return up to US$ 35 294 / ha /
- Use as fuel in Yuanan.
- Handicraft in Fujian.
- Factors affecting VGT development and utilisation:
- Poor quality planting material.
- Lack of information service medium.
- Highway stabilisation
There has been a great deal of highway stabilisation work done
in Jiangxi and Fujian Provinces since 1997. The most impressive
site was on a highway near Fuzhou planted by Mrs Zhang Jing.
Several papers were presented on the application of VGT at
various provinces in China, from the high altitude Yunan
provinces, to the coastal Fujian provinces. Several major sites
were visited during the post conference tour.
- Shangrao - Fen Suigan Highway.
A paper presented by Hong et al. (2) described in
details the planning and results of this very difficult
mountainous site on the Wuyi mountain range between Jiangxi and
Jujian provinces. Despite very poor soil, with a small amount of
manure and fertilisers, a very impressive 98% of establishment
rate was achieved on this highly erodible site. Vetiver growth,
both top and root was much better than the local grass Bamao,
which is the traditional species used for road work stabilisation
in this region.
Results also indicate that vetiver growth was poorer at high
altitude. Tiller number and plant height were reduced from 4.9
tillers and 57 cm to 3.3 tillers and 43 cm respectively when the
altitude increased from 285 to 730 m above sea level. This was
attributed to lower temperature, thick fog and less sunshine
(shading) at higher altitude rather than altitude per se.
This was supported by the observation in Yunan Plateau, where
vetiver grew satisfactorily at an altitude of 1800m.
It was noted that Fusarium wilt was observed in some young
shoots, and soil temperature at 10cm deep was recorded at 17oC
in October. It was also very interesting to see that vetiver was
used to reinforce the traditional and very costly herringbone
- Wuyishan to Nanjsing Highway.
Very successful and convincing results of VGT in road batter
stabilisation. At this site, only the road itself is stabilised,
but valuable farm land at the toe of the embankment is also
protected from run off and sediment from the road. Excellent
growth was obtained after 2 years.
- Nanping to Fuzhou Highway (National Highway no. 316).
Although the soil along this lake side highway is extremely
poor and highly erodible, vetiver was established quite easily
and has successfully stabilised the very steep batters with
growth exceeding 2 m after 2 years. This is in sharp contrast
with the conventional treatment of concrete and rocks, which
often failed. A good example of this was found along this highway
where a massive slope of concrete protecting a very steep batter
was broken up and moved down the slope.
The need of appropriate fertiliser was also highlighted here.
At one site where adequate fertiliser was applied, vetiver was at
least 1.5 m tall and no erosion occurred. On the lower section of
this batter where no fertiliser was used, growth was only 0.4 -
0.5 m and severe rilling was observed.
At a few sites along this highway, after fixing some initial
erosion, the contractor replanted the slope with another grass, a
vetiver look-alike, but this local grass is poor and the ground
was hardly covered after 2 years.
The most impressive site was on a new World Bank financed
Highway linking Fuzhou and Xiamen. This site was established by
Mrs Zhang Jing, it covered about 5 ha in area with a vertical
drop of 100m. The rows were well laid out on contour lines among
concrete drainage channel. It was noted that double row planting
was used here instead of the usual single row. When fully
established this site will certainly be a showcase for VGT in
In combination with VGT, the traditional rock and concrete
structures were also used here, forming a very spectacular
combination. It would be interesting to compare the cost
difference between the two technologies.
This ring road was built about three years ago and vetiver was
planted by Dr Xia on both cut and fill slopes. Following the
planting of contour hedges, Acacia mangium was
planted in the inter row areas. Now the whole site both the cut
and fill batters are completely stabilised and covered with both
local species and A. mangium trees and grass. This
was in sharp contrast to the untreated batter (opposite the trial
site) where extensive rilling and gullying occurred.
- Old quarry rehabilitation
- A major concern in Guangzhou City was the
rehabilitation of old quarries which are located
within the city boundary. Two very large quarries
are due to be decommissioned in a few years, so
the local authority is very interested in using
VGT for their rehabilitation.
After showing the
success of quarry rehabilitation works in
Australia, the city environmental officer invited
me to visit two working quarries and an old
quarry, the latter has been successfully
rehabilitated. On the flatter area, elephant
grass was used successfully and economically for
rehabilitation purpose. However, on steeper
slopes, rock retaining walls were built to trap
and retain the debris and sediment, at the
enormous cost of US $15.30 per square metre of
retained soil. With the cost of vetiver at $0.50
/ m at most, the savings would be very
- Stream bank stabilisation
- The presentation on the use of VGT for stream
bank stabilisation (7) attracted a lot of
attention at the conference, as flood erosion is
one of the major annual disasters in southern
China, particularly in the Yantze watershed. As
highway stabilisation with VGT is now well
accepted in China, stream and channel
stabilisation is probably the next target.
- Mine rehabilitation (6)
- Vetiver was found to be the best species on a
trial established in a Zinc / Lead mine tailings
in Guangdong (5). The tailings are high in Pb,
Zn, Cu and Cd with total Pb and Zinc exceeds 3000
mg/kg and available Pb and Zinc at 100 mg/kg
(well below the threshold level of these two
Although vetiver could be
established directly on these tailings, due to
the poor nutrient status of the tailings,
additional of fertiliser and / or fresh garbage
improved growth enormously.
- Sand dune stabilisation
- In the last 30 years (1950 - 1980) 660km2
(66,000 ha) of farm land in Jiangxi Province were
lost to shifting sand dunes which move northward
at the speed of 5m/year. Therefore, dune
stabilisation is of high priority in the province
With the application of manure, vetiver
was successfully established on the sand dunes
with growth exceeding 110 cm after 7 months. The
hedges have effectively slowed the sand movement
by reducing wind velocity, which has in turn
encouraged the establishment of volunteer grasses
and herbs. The ground cover that provided by
these species further improved the effectiveness
of the vetiver hedges. Consequently, vetiver will
be used to stabilise the sandy road batter along
Poyang Lake next spring, due to its low cost and
- Effects of low temperature on vetiver growth.
- Don Miller found that vetiver grass in temperate
zones (Gisbourne, New Zealand, latitude 38
degrees South) dies after 3 to 4 years, despite
initial vigorous growth (4). Trials show that
shading of the ground surface by the growing
plant in summer can reduce soil temperature at
300mm depth by up to 60 C. Soil
temperatures below about 190 C appear
to restrict vetiver root growth. In addition a
high concentration (over 200 per square meter) of
cicada insects was found around the vetiver
roots. The interaction of low soil temperature
and insect attack appears to be causing plant
death. Annual mowing of the vetiver grass in
early summer allows a rapid rise in soil
temperature and after three years, plant health
is still good.
- Effects of plant growth retardant on vetiver
growth and tillering
- As tall vetiver plants are not always appreciated
under some applications such as golf courses and
gardens, growth retardant application was trialed
by Dr Xia Hanping to find the most effective type
and concentrations for this application. In
addition, growth retardants are known to
encourage tillering which is a bonus for planting
materials multiplication (9).
were trialed: B9 (daminozide), PP333
(paclobutrazol) and CCC (Chloro choline chloride)
at two concentrations each. Results showed that
all three promoted tillering from 11% - 53%, but
only B9 retarded growth by 6% and delayed
flowering for 10 days. On the other hand PP333
and CCC all promoted vetiver growth from 5 - 22%
and they enhanced the number of flower head up to
31%. Results indicate that vetiver reacts quite
differently from most crops in showing a high
degree of tolerance.
- Planting materials production
From his experience, Dr. Xia listed the following 12 important
points for planting material production:
- Full sun as a C4 plant, vetiver growth is
affected by shade.
- Fertile and well drained soil. Sandy loam is best. Clay
soil is not suitable.
- Fertiliser application, P and or manure.
- Pruning before planting. Prune shoots to 20-30cm and
roots to 5 -10 cm.
- Dipping roots. Dip roots in 2 - 25 ppm of 2,4,D hormones,
dilute or slurry manure.
- Oblique planting. Plant vetiver at 60o angle,
which is more convenient.
- Density: spacing 20 x 40 cm is recommended, higher
density can affect tillering.
- Plant single tillers. Although single tiller planting has
a higher mortality rate, it can produce higher tiller
number over time than three tiller strips.
- Shallow planting, 3-4 cm depth is recommended.
- Avoid pruning. Cut once or twice per year. Best to prune
it before harvesting.
- One year old plant is most appropriate for nursery
- Selling in clumps rather than tillers.
- Jiji grass - (Achnatheruum
There are 21 cultivars of jiji in central Asia of which 14 are
in western and northwestern China. These are found on a wide
range of soil types and climates (8).
Distribution in China:
Inner Mongolia, Gansu, Qinghai, Xingjiang, Shanxi, Ningxia and
- pH range from 4-9.
- Tolerant to acidity, alkalinity, salinity.
- Tolerant to drought, cold temperature.
- Tough and thick stem, deep and large root system, large
Research is being conducted by Prof. Xu and his student Mr
Wang on its seed germination characteristics and growth under
- General observation and comments
- Very big progress has been made in the application of VGT
in the last 2 years and as more successful, demonstration
sites have been established in several provinces, as far
as Yuanan, VGT is now firmly established in China. This
is due mostly to the great effort of Prof. Xu who has
enlarged his circle of influence wider and wider.
- The quality of planting material was often raised during
the Workshop, several failures in the last few years were
attributed to poor planting materials. Prof. Xu is trying
to overcome this by establishing a national standard for
the supply of planting materials.
- It was also interesting to note that two private
organisations from Guangzhou attended the Conference with
the aim of providing planting material commercially for
future use. This is a very good indication that VGT has
become firmly established in China.
- On a lighter note, a "fraud warning" notice was
also posted on the conference notice board, warning
delegates of someone pretending to be from the China
Vetiver Network, who can supply and solve any erosion
problem! With this, I firmly believe that VGT will be a
big success in China and congratulate Prof. Xu for his
- On behalf of TVN, I wish to thank the Chinese Academy of
Science, UNDP the Xiangxi Highway Bureau and other
organisations for their support and in particular Prof.
Xu, Mr Fu Heng Sheng, Chief Engineer, Jiangxi Highway
Bureau and Mr Harold Insley (Scott Wilson, Hong Kong) for
their personal support.
- Further Readings
The following papers were presented at the conference and can
be found on the TVN Homepage < www.vetiver.org>
- Grimshaw, R. China and the VGT.
- Hong, C., Ming, W. and Peng, Y. Application of contour
hedges techniques to the protection of highway embankment
in Jiangxi Province of China.
- Hong, C., Feng, W., Yu, L., and Hu. G. Experiment of
the application of vetiver to sand-fixing in subtropical
- Miller, D. Soil temperature and insect damage impacts
on vetiver growth.
- Shu, W., Xia, H. and Zhang Z. Growth of vetiver and
three other grasses on Lechang lead/zinc mine tailings: A
- Truong, P. An overview of VGT in highway stabilisation
and mine rehabilitation
- Truong, P. VGT for flood and stream bank erosion
- Wang, K. Jiji grass and its potential for soil erosion
- Xia, H. Effects of plant growth retardants on the
growth of vetiver grass.
- Xu, L. Report International Conference on vetiver
Bioengineering technology for erosion control and civil
construction stabilisation held in Nangchang, China