THE VETIVER SYSTEM

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VETIVER GRASS -THE PLANT

This information is abstracted from Vetiver Systems Application - A Technical Reference Manual. Authors - Paul Truong, Tran Tan Van, and Elise Pinners. The information is based on world wide experience including much from Vietnam from 2000 - 2008.

CONTENTS

1. INTRODUCTION

2. SPECIAL CHARACTERISTICS OF VETIVER GRASS

2.1 Morphological characteristics

2.2 Physiological characteristics

2.3 Ecological characteristics

2.4 Cold weather tolerance of vetiver grass

2.5 Summary adaptability range

2.6 Genetic characteristics

2.7 Weed potential

3. CONCLUSION

4. REFERENCES

5. LINKS

1. INTRODUCTION

The Vetiver System (VS), which is based on the application of vetiver grass (Vetiveria zizanioides L Nash, now reclassified as Chrysopogon zizanioides L Roberty), was first introduced by the World Bank for soil and water conservation in India in the mid 1980s. While this application still plays a vital role in agricultural land management, R&D conducted in the last 20 years has clearly demonstrated that, due to vetiver grass’ extraordinary characteristics, VS is now being used as a bioengineering technique for steep slope stabilization, wastewater disposal, phyto-remediation of contaminated land and water, and other environmental protection purposes.

What does the Vetiver System do and how does it work?

VS is a very simple, practical, inexpensive, low maintenance and very effective means of soil and water conservation, sediment control, land stabilizations and rehabilitation, and phyto-remediation. Being vegetative it is also environmental friendly. When planted in single rows vetiver plants will form a hedge which is very effective in slowing and spreading run off water, reducing soil erosion, conserving soil moisture and trapping sediment and farm chemicals on site. Although any hedges can do that, vetiver grass, due to its extraordinary and unique morphological and physiological characteristics mentioned lower, can do it better than all other systems tested. In addition, the extremely deep and massively thick root system of vetiver binds the soil and at the same time makes it very difficult for it to be dislodged under high velocity water flows. This very deep and fast growing root system also makes vetiver very drought tolerant and highly suitable for steep slope stabilization.

The Extension Workers Manual, or the Little Green Book

Complementing this technical manual is the slim green extension workers pocket book first published be the World Bank in 1987 and referred to on page iii as Vetiver Grass - A Hedge Against Erosion, or more commonly known the “little green book” by John Greenfield. This present manual is far more technical in its description of the Vetiver System and is aimed at technicians, academics, planners and Government officials and land developers. For the farmer and the extension worker in the field the "little green book" that can fit in to a shirt pocket is still the ideal field manual.

2. SPECIAL CHARACTERISTICS OF VETIVER GRASS

2.1 Morphological characteristics:

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Photo 1: Erect and stiff stems form a dense hedge when planted close together (India).

2.2 Physiological characteristics

2.3 Ecological characteristics

Although vetiver is very tolerant to some extreme soil and climatic conditions mentioned above, as typical tropical grass, it is intolerant to shading. Shading will reduce its growth and in extreme cases, may even eliminate vetiver in the long term. Therefore vetiver grows best in an open and weed free environment, weed control may be needed during establishment phase. On erodible or unstable ground vetiver first reduces erosion, stabilizes the erodible ground (particularly steep slopes), then because of nutrient and moisture conservation, improves its micro-environment so other volunteered or sown plants can establish later. Because of these characteristics vetiver can be considered as a nurse plant on disturbed lands.

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Photo 2: left: Vetiver grass surviving forest fire; right: two months after the fire (Australia).

 

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Photo 3: On coastal sand dunes in Quang Bình (left) and saline soil in Gò Công Province (right) (Vietnam).

 

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Photo 4: On extreme acid sulfate soil in Tân An (left) and alkaline and sodic soil in Ninh Thuận (right) (Vietnam).

2.4 Cold weather tolerance of vetiver grass

Although vetiver is a tropical grass, it can survive and thrive under extremely cold conditions. Under frosty weather its top growth dies back or becomes dormant and ‘purple’ in colour under frost conditions but its underground growing points survived. In Australia, vetiver growth was not affected by severe frost at –14ºC and it survived for a short period at –22ºC (-8ºF) in northern China. In Georgia (USA), vetiver survived in soil temperature of -10ºC, but not at –15ºC. Recent research showed that 25ºC was optimal soil temperature for root growth, but vetiver roots continued to grow at 13ºC. Although very little shoot growth occurred at the soil temperature range of 15ºC (day) and 13ºC root growth continued at the rate of 12.6cm/day, indicating that vetiver grass was not dormant at this temperature and extrapolation suggested that root dormancy occurred at about 5ºC (Fig.1).

Figure 1: The effect of soil temperature on the root growth of vetiver

2.5 Summary adaptability range

Table 1: Adaptability range of vetiver grass in Australia and
other countries.

Condition characteristic

Australia

Other Countries

Adverse Soil Conditions

Acidity (pH)

3.3-9.5

4.2-12.5 (high level soluble

Salinity (50% yield reduction)

17.5 mScm-1

Al)

Salinity (survived)

47.5 mScm-1

Aluminium level (Al Sat. %)

Between 68% - 87%

Manganese level

> 578 mgkg-1

Condition characteristic

Australia

Other Countries

Sodicity

48% (exchange Na)

Magnesicity

2400 mgkg-1 (Mg)

Fertilizer

vetiver can be established on very infertile soil due to its strong association with mycorrhiza

N and P
(300 kg/ha DAP)

N and P, farm manure

Heavy Metals

Arsenic (As)

100 - 250 mgkg-1

Cadmium (Cd)

20 mgkg-1

Copper (Cu)

35 - 50 mgkg-1

Chromium (Cr)

200 - 600 mgkg-1

Nickel (Ni)

50 - 100 mgkg-1

Mercury (Hg)

> 6 mgkg-1

Lead (Pb)

> 1500 mgkg-1

Selenium (Se)

> 74 mgkg-1

Zinc (Zn)

>750 mgkg-1

Location

150S to 370S

410N - 380S

Climate

Annual Rainfall (mm)

450 - 4000

250 - 5000

Frost (ground temp.)

-110C

-220C

Heat wave

450C

550C

Drought (no effective rain)

15 months

Palatability

Dairy cows, cattle, horse, rabbits, sheep, kangaroo

Cows, cattle, goats, sheep, pigs, carp

Nutritional Value

N = 1.1 %

Crude protein 3.3%

P = 0.17%

Crude fat 0.4%

K = 2.2%

Crude fibre 7.1%

Genotypes: VVZ008-18, Ohito, and Taiwan, the latter two are basically the same as Sunshine. Temperature treatments: day 15ºC /night 13ºC. (PC: YW Wang).

2.6 Genetic characteristics

Three vetiver species are used for environmental protection purposes.

2.6.1 Vetiveria zizanioides L reclassified as Chrysopogon zizanioides L

There are two species of vetiver originating in the Indian subcontinent: Chrysopogon zizanioides and Chrysopogon lawsonii. Chrysopogon zizanioides has many different accessions. Generally those from south India have been cultivated and have large and strong root systems. These accessions tend towards polyploidy and show high levels of sterility and are not considered invasive. The north Indian accessions, common to the Gangetic and Indus basins, are wild and have weaker root systems. These accessions are diploids and are known to be weedy, though not necessarily invasive. These north Indian accessions are NOT recommended under the Vetiver System. It should also be noted that most of the research into different vetiver applications and field experience have involved the south Indian cultivars that are closely related (same genotype) as Monto and Sunshine. DNA studies confirm that about 60% of Chrysopogon zizanioides used for bio-engineering and phytoremediation in tropical and subtropical countries are of the Monto/Sunshine genotype.

2.6.2 Chrysopogon nemoralis

This native vetiver species are wide spread in the highlands of Thailand, Laos, and Vietnam and most likely in Cambodia and Myanmar as well. It is being widely used in Thailand for thatching purpose. This species is not sterile, the main differences between C. nemoralis and C. zizanioides, are that the latter is much taller and has thicker and stiff stems, C. zizanioides has a much thicker and deeper root system and its leaves are broader and has a light green area along the mid ribs, as shown on the photos lower (Photos 5-8).

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Photo 5: Vetiver leaves, (left): C. zizanioides, (right): C. nemoralis.

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Photo 6: Difference between C. zizanioides (upper) and C. nemoralis roots (lower).

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Photo 7: Vetiver shoots, (left): C. nemoralis, (right): C. zizanioides.

Although C. nemoralis is not as effective as C. zizanioides, farmers have also recognized the usefulness of C. nemoralis in soil conservation; they have used it in the Central Highlands as well as in some coastal provinces of Central Vietnam such as Quang Ngai to stabilize dikes in rice fields, Photo 9.

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Photo 8: Vetiver roots grown in soil (lfet and middle) and in water (right).

 

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Photo 9: C. nemoralis in Quang Ngai (upper) and on Central Highlands (lower) (Vietnam).

 

2.6.3 Chrysopogon nigritana

This species is native to Southern and West Africa, its application is mainly restricted to that continent, and as it produces viable seeds its application should be restricted to their home lands (Picture 10).

2.7 Weed potential

Vetiver grass cultivars derived from south Indian accessions are non-aggressive; they produce neither stolons nor rhizomes and have to be established vegetatively by root (crown) subdivisions. It is imperative that any plants used for bioengineering purposes will not become a weed in the local environment; therefore sterile vetiver cultivars (such as Monto, Sunshine, Karnataka, Fiji and Madupatty) from south Indian accessions are ideal for this application. In Fiji, where vetiver grass was introduced for thatching more than 100 years ago, it has been widely used for soil and water conservation purposes in the sugar industry for over 50 years without showing any signs of invasiveness. Vetiver grass can be destroyed easily either by spraying with glyphosate (Roundup) or by cutting off the plant lower the crown.

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Photo 10: Chrysopogon nigritana in Mali, West Africa.

 

3. CONCLUSION

Due to C. nemoralis low growth forms and its very short root system it is not suitable for steep slope stabilization works. In addition, no research has been conducted on its wastewater disposal and treatment, and phyto-remediation capacities, it is recommended that only C. zizanioides be used for applications listed in this manual.

4. REFERENCES

Adams, R.P., Dafforn, M.R. (1997). DNA fingerprints (RAPDs) of the pantropical grass, Vetiveria zizanioides L, reveal a single clone, “Sunshine,” is widely utilised for erosion control. Special Paper, The Vetiver Network, Leesburg Va, USA.

Adams, R.P., M. Zhong, Y. Turuspekov, M.R. Dafforn, and J.F.Veldkamp. 1998. DNA fingerprinting reveals clonal nature of Vetiveria zizanioides (L.) Nash, Gramineae and sources of potential new germplasm. Molecular Ecology 7:813-818.

Greenfield, J.C. (1989). Vetiver Grass: The ideal plant for vegetative soil and moisture conservation. ASTAG - The World Bank, Washington DC, USA.

National Research Council. 1993. Vetiver Grass: A Thin Green Line Against Erosion. Washington, D.C.: National Academy Press. 171 pp.

Purseglove, J.W. 1972. Tropical Crops: Monocotyledons 1. , New York: John Wiley & Sons.

Truong, P.N. (1999). Vetiver Grass Technology for land stabilisation, erosion and sediment control in the Asia Pacific region. Proc. First Asia Pacific Conference on Ground and Water Bioengineering for Erosion Control and Slope Stabilisation. Manila, Philippines, April 1999.

Veldkamp. J.F. 1999. A revision of Chrysopogon Trin. including Vetiveria Bory (Poaceae) in Thailand and Melanesia with notes on some other species from Africa and Australia. Austrobaileya 5: 503-533.

LINKS