For centuries vetiver has been used in India both as an aromatic plant and for medicinal purposes, and as a plant used for soil conservation. The scented roots are used directly in the making of mats, baskets, fans, bags, curtains, etc., or indirectly by extraction for the distillation of the essential oil. From India the vetiver spread throughout the Tropics. One particular impetus for the spreading of the plant proved to be the Colonial Period, during which it spread both as an aromatic plant and as a hedge plant. After the Second World War and the subsequent end of colonialism, vetiver declined in importance in many countries.
Recently, many projects have been launched with the aim of increasing the use of vetiver in erosion control. Given its morphological, physiological, and ecological characteristics, as discussed in the previous chapters, it is particularly suited to the formation of hedges with a deep root system. In these countries vetiver is used to slow the run-off of the torrential rains (monsoons) and to slow and stop topsoil erosion, but only in the last decade have such farming practices been seriously considered to the point of study and a clearer definition of both the botanical and agronomic characteristics of the plant, and the technical aspects concerning its planting and cultivation. In this way not only can large enterprises with construction projects on a vast scale make use of vetiver as a plant to control soil erosion, but also, and most importantly, individual farmers who, with their own business, have to fight the process of erosion which reduces the fertility of the plots and removes soil and nutrients.
Production of essential oil
In the East, the roots of vetiver have been known for centuries for their scent which is light and pleasant. Vetiver’s essential oil, both in its raw form and in other derivative forms, is an important component in luxury perfumes, and therefore in the industry concerned, owing to the delicacy of the aroma and to the amber-scented tones.
Once uprooted the root can immediately be submitted to the distillation process after having been dried naturally, cleaned and cut up.
Vetiver’s essential oil is in the form of a viscous liquid which tends to thicken over time. The oil is characterized by its yellow colour, the exact tint of which depends on the roots used, ranging from greenish to reddish ().
If the original material is taken from young plants the scent has an earthy tone and the colour of the oil is basic green. This is not the case in older plants which are at least two years old.
The yield by distillation carried out starting with the dried roots, varies from 0.5% to 2% in weight, according to the area of origin of the material and the productivity of the distillation equipment.
The best and most sought-after oils are from Giava and from Bourbon (or Réunion); there are however other types of oil, for instance that from Haiti which is in constant productive and commercial development and oils from Brasil, India, and Africa.
Table The annual market allotment of vetiver oil.
|Countries of vetiver oil origin||12–16|
The world market in vetiver oil at the end of the 1990s was approximately 400 tons and the European Union tax-free price is around 110 ECU/kg.
The average return per hectare of oil can be considered to be around 40 kg/hectare with a gross production equal to around 4,000 ECU/ha.
The annual market allotment of vetiver oil is reported in Table The annual market allotment of vetiver oil.
With regard to the roots themselves which are not used for oil extraction and the aerial portions, there is no world market, since such products are utilized and transformed exclusively in the countries of origin. For the transformation to commercial oil local manpower is widely employed, as this process requires manual and artisan procedures. The bleached products derived from vetiver are perfect for local handicraft use.
There are several other uses of vetiver in the regions where the plant originates, which can be of economic importance in the Mediterranean areas.
The use of vetiver in the prevention of toxic contamination of water sources
Nitrate from fertilization, heavy metals, and other toxic materials from weed killers and pesticide spraying, once washed into water sources, will cause environmental pollution and contamination.
Studies conducted in a few parts of the world show evidence that vetiver hedgerows planted across slopes can reduce the rate of surface soil loss on sloping land and, at the same time, the deep and dense vetiver root system functions as a barrier, filtering soil debris and toxic substances in water, thus not allowing them to enter ground water strata.
The Indian practice of using the vetiver leaves as foodstuff has been tested in the Department of Livestock Development in Thailand.
The trials were conducted on 10 ecotypes of vetiver with the result that Kamphaengpetch 2 provided better nutritive values than other cultivars in terms of quantity of total protein, digestible dry matter and minerals. Vetiver grass cut at 4 week intervals is optimal in terms of output and nutritive value.
The study on the toxic content in the 10 vetiver cultivars reveals that the grasses have insignificant levels of nitrate and hence are not harmful to animals. Furthermore, nitrate and hydrocyanic acid elements are not found in vetiver.
Vetiver tillers and leaves are a good quality compost; in fact after 120 days the carbon/ nitrogen ratio (C/N ratio) of vetiver decreases from 91–125 before decomposition to 38.9–47.5 after decomposition. The rate of decomposition gradually declines at 60–120 days. Vetiver tillers and stems are completely decomposed to become soft, disintegrated and dark brown to black in colour.
The analysis also showed that vetiver compost gains more major nutrients from the decomposition process, i.e. nitrogen, phosphorus, potassium, calcium and magnesium on an average of 0.86, 0.29, 0.12, 0.55 and 0.41% respectively, and has a pH 7.0 value. In addition to the above-mentioned major nutrients, vetiver compost also provides humic acid.
Vetiver, owing to the fact that it is a type C4 herbaceous plant, with great efficiency in terms of energy conversion by way of photosynthesis, has a high return per hectare of dry material, usually from 20 to 40 tons per year but there is an irrigated farm in Texas where it is claimed that the return is equal to 100 tons per hectare per year.
The calorific value of the biomass varies between 15 and 18 MJ/kg, equal to approximately 60% of the calorific value of carbon (from 24 to 33 MJ/kg) and equal to approximately 45% of that of fuel oil (40 MJ/kg).
Dry vetiver leaves are used for making handicraft items such as flowers (bouquets from vetiver leaves, flower baskets), ornaments (hats and belts), household decorative items (picture frames, mirror frames, fans, tissue paper boxes, and baskets) and toys and models (human dolls, animal dolls). The aromatic vetiver roots are used for making fans, clothes hangers and are mixed with other kinds of flower scents and leaves for making perfumed sachets.
Different uses of vetiver in the Mediterranean area
In the light of vetiver’s characteristics which make it so desirable, the use of this species has been suggested for the Mediterranean basin, an extraordinary testimony to the value of the plant in the struggle against soil erosion and in the production of essential oil.
A project, lasting 30 months (from January 1994 to June 1996) and financed partly by the European Union, Directorate General VI Agriculture, Regulation 4256/88, art. 8, has been carried out in the Segura region (Murcia, Spain), one of the European regions most exposed to the phenomenon of soil erosion. This project was carried out on the “San Julian di La Hoya” farm, near to the city of Lorca. The farm is about 600 hectares in size; the main crops are almond trees in the hilly regions (the largest part of the farm) and cereals and oleaginose in the flatter areas. There are about 30,000 vetiver plants from Malaysia and US, previously grown in specially arranged nurseries, occupying an area of about 12 hectares.
The plants were employed against erosion in the following areas:
- embankments (with a gradient of around 60%) ();
- terrace borders;
- almond tree plantations (with a gradient of around 5%);
- gullies and canals;
- and areas subjected to superficial microerosion.
Plants were also cultivated for their roots in order to extract the essential oil.
In general, this pilot project has confirmed the survival rate of the plants; more than 89% of all transplants were successful even in not ideal climatic conditions. The root growth rate reached 1.7 metres in depth after 9 months and 2.6 metres 14 months after transplantation. The speed with which the tillers grew was such that after 9 months they had become, on average, about 60 in number originating from cuttings with around 5 tillers. The biomass yield was equal to approximately 40 tons/hectare of dry material 14 months after transplantation. Vetiver’s capability in soil protection was confirmed; for example when put to use in the protection of the escarpments it held approximately 20 cm of soil after only 12 months. Vetiver’s sterility was investigated; the pilot project in progress in Murcia has confirmed that the plant does not produce any inflorescence after having been cultivated for three seasons. Its resistance to winter climatic conditions was studied. Vetiver showed no signs of frost injury even at temperatures of -2 °C. Its oil producing potential was evaluated; in roots 12 and 16 months old a yield of approximately 1–2 per cent was obtained, with good quality certified by the organization responsible for certification and quality control.
The project has furthermore shown that vetiver, despite the fact that it originates in tropical and sub-tropical areas, adapts well to temperate climates. Vetiver can therefore be used to advantage in Mediterranean areas and in the numerous marginal areas of the European Union, which have been abandoned by classical farming and condemned to waste, leading either to a situation of progressive desertification or to the uncontrolled proliferation of weeds.
The results obtained can be transferred to other Mediterranean regions, allowing marginal areas to be protected without imposing on the income of the farmer, or on public funds; indeed the extraction of essential oils from roots, the exploitation of its biomass and manufactured products more than compensate for the costs of the plantations and the fight against erosion, without quantifying the agricultural, environmental and social benefits of this agricultural technique.
Selections from the book: “Vetiveria. The Genus Vetiveria”. Edited by Massimo Maffei. Series: “Medicinal and Aromatic Plants — Industrial Profiles”. 2002.