Package of Practices for Cultivation of Vetiver
Botanical Name: Vetiveria zizanioides L
The Vetiver grass (Vetiveria zizanooides) is the source of the valuable aromatic "Vetiver oil" which enjoys world wide reputation being one of the finest oriental perfumes. It is called "Khus" in Hindi and Bengali. Vetiver or Vela achamver in Tamil. As an important essential oil yielding plant of India, vetiver has been grown and extensively used in the country for several centuries. India has been exporting vetiver oil worth more than 1.5 lakhs but still there is much scope to increase the export. Its medicinal and commercial importance was known even in the earliest days of Indian civilization. The vetiver grass is a native of India and is found through out the plains and lower hills of India. Burma, Ceylon. It is systematically cultivated in Kerala, Tamil Nadu and Andhra Pradesh.
There, are basically two main types of the vetrvex grass, viz.
(1) Seedling type and (2) Non seedling type
The one that grows wild in North India is mainly the seedling type while that of the South is the non-seedling type. Besides, differences exist between the North and south Indian strains with regard to yield and aroma of the oil. The oil of some of the North India type viz. Bhartapur, Akila and Musanagar strains generally have an aroma superior to that of oil derived from South Indian grasses.
Climate and Soil:
Vetiver prefers a mild climate but can be grown under both wet and dry or arid and tropical conditions. Under temperate or warm winter hill areas, the growth of vetiver remains stunted.
The most suitable soil consists of loose sandy soils, preferably on the sloppy hills. In such soils only, the roots can be easily pulled out without much loss of thin roots. Compact and heavy soils may be avoided.
There are three different systems of planting adopted by different growers.
1) System 1:
Conical ridges, 30-38 cm high and 48 cm apart are made at the summit and the slips planted 23 cm apart on the summit.
2) System II:
The land is laid out in to beds of 30 cm high, 68 cm wide and 45 cms apart edge to edge and the slips are planted on these in two rows 22.5 cm apart, leaving 22.5 cm on either sides.
3) System III:
The beds are made 45 cm high, 60 cm wide and 30 cm apart edge to edge and two rows, 30 cm apart, are planted on these leaving 15 cm on either side. The spacing within the row is also 30 cm in this system. Trials conducted in the cinchona plantations at Anamalaie to determine the relative merits of first and second mentioned system of planting have indicated that the latter method gives a higher yield of roots. The cost of harvesting is also lesser in this method.
Vetiver can be propagated through tillers and slips. Tillers take long time for growing and therefore, slips are the better planting materials for propagations. The top of the slips are cut down before planting to prune transpiration loss, thus giving a better chance for survival of the slips.
The slips are planted in pits, five to eight cm deep made with a pointed stick. Two or three slips are planted in each hold. This is done to meet any casualties and also to get a thick stand of plants. After planting, the soil around the slips is pressed firmly and leveled. One hectare requires 1,50,000 to 2,25,000 slips with 2 – 3 slips per pit in the commonly adopted system of planting (IInd method).
The best planting time to get higher oil yield under South Indian condition is June-July. Vetiver should not be planted on shaded places as shade will exert an unfavorable influence on the development of root system.
Manures and Fertilizers:
Generally, application of groundnut cake or cattle manure or wood has a beneficial effect on the yield of roots. Fertilizer trials conducted at Research
Station, Odakkali in Kerala shows that application of 22.5 kg P205 and 22.5 K20 is optimum to get higher yield. Under North Indian conditions, vetiver clones need to be fertilized with N (20 kg/ha) to be given after two months of planting to produce higher root yield.
Harvesting is done during the dry months of the year. In general it is the practice to harvest the roots both for manufacture of articles and for distillation when the plants are about 10-12 months old. In Kerala it has been established that 18 month old plantation yield economic root yield.
Harvesting or uprooting is done with digging forks haying prongs of 45 cm length. To start with the stem portion is cut at a height of 15-20 cm and the clumps are then uprooted. About 50-60 per cent of the roots come away with the clumps leaving the rest in the soil. The clumps are beaten on a apiece of log to remove stones and earth adhering to the roots and the roots are separated with a sharp knife. As far as possible, the roots left in the soil are also collected.
The roots that possess the following characteristics have good oil content. It should
1. expose a hard surface when the skin is peeled off
2. be thick, hard, long and wiry and
3. give a very bitter taste when chewed.
The roots should not be extracted from the ground earlier than 24 month after planting if high quality oil is desired. Young roots are tender, thin, almost hair like, on pulling they break easily and stay in the ground. Besides, on distillation, they yield an essential oil with a low specific gravity and low optical rotation. The odour of these light oil is ‘green’ earthy. On the other hand, older, well developed, thicker root, yields an oil of better quality, with better odour and are more lasting. Oils derived from older roots are usually having a darker colour than the oil distilled from younger root.
Extraction of vetiver oil is produced by water distillation and steam distillation of the roots. In both these methods, the roots are first cleaned, steeped in water for about 12 hours, chopped into small pieces (5 to 10 cm long) and the distilled. Although steam distillation is more economical and gives of oil yet it is not preferred by majority of the distillers. It is because of the fact, that oil produced by steam mstitlation does not give the same colour as produced by steam distillation does not give the same colour as produced by water distillation. Distillation time varies from 12 to 36 hours.
On an average one hectare of vetiver plantation yields 5 to 7 tones of roots which on distillation yield 15 to 16 kg of oil. Roots yield 1.00 to 1.50 per cent of oil on dry weight basis: The colour of the oil is light yellow and the oil contains 65 to 75 per cent veteverol.