How to Grow Vetiver for Oil Production

How to Grow Vetiver (Vetiveria zizanioides (L.) Nash.) for Oil Production

Vetiver Crop Overview

Vetiver (Vetiveria zizanioides (L.) Nash. or Chrysopogon zizanioides) is a member of the grass family Poaceae, specifically the Panicoideae subfamily, and has deep historical and cultural roots. The word "vetiver" originates from Tamil, meaning "root that is dug up." It is commonly referred to as "Khus" or "Khus Khus" (3).

Vetiver is a robust plant that can grow up to 8 feet (2.4 meters) tall, with densely clustered, unbranched stems. The leaves, or sheaths, are smooth and stiff, growing up to 1 foot (30 cm) long and less than 5/16 inches (0.8 cm) wide, with rough edges but no odor. Its panicles are large and erect, measuring up to 12 inches (30 cm) long, with slender branches that are whorled and ascend from a naked base. The spikelets are awnless and muricate.

Vetiver can reach up to 1.5 meters (4.9 feet) in height and form clumps as broad as 1 meter (3.3 feet). Vetiver has been utilized for medicine, mat and basket production, hedgerows, firebreaks, insect repellent, scented oils, perfumes, and soaps, but it has primarily been used to prevent soil erosion. The various uses of vetiver oil, the role of vetiver in environmental protection, and good agronomic practices have been described (2). The multiple uses of vetiver oil, the role of vetiver in environmental protection, and good agronomic practices have been described (2). Although native to India, vetiver is now found across Asia, Africa, the Caribbean, the Americas, Europe, and Australia.

Vetiver Root System

Vetiver has a massive fibrous root system that can grow to depths exceeding 3 meters (9.8 feet). The roots generally grow straight down, minimizing interference with nearby crop plants (3). Typically, 92% of vetiver roots are found within 20 cm (7.9 inches) horizontally from the plant, and 88% of them are within a depth of 40 cm (15.7 inches) (4).

Vetiver Root System

Vetiver Roots and Oil Production

The vetiver roots are fragrant, and the oil extracted from the roots by hydro/steam distillation is one of the finest oriental perfumes with a long-lasting fragrance. The oil is used in the flavor and fragrance industries for the manufacture of soaps, cosmetics, perfumery, agarbatti (incense sticks), soft drinks, etc. In blended perfumes, vetiver oil acts as an excellent fixative for volatile compounds. It is known for its cooling properties and hence used in aromatherapy. Vetiver oil is in high demand due to its unique odor, for which it is used in both flavor and fragrance industries, and the inability to reconstitute this oil. The oil is known for its 'base notes' in flavors and fragrance production. Therefore, production systems must evolve for large-scale vetiver oil cultivation and distillation.

Agro-climatic Requirements

Vetiver is a hardy, versatile crop that thrives in a variety of soil and climatic conditions. As a C4 plant, it is particularly suited to warm regions. It grows in diverse climates, from the Monsoonal Tropics and rainforests of Kerala to the deserts of Rajasthan and the frost-prone foothills of the Himalayas in India. It can tolerate very wet conditions with over 3000 mm of annual rainfall, as well as dry regions with less than 300 mm of precipitation. It also endures temperature extremes, thriving in temperatures as high as 46°C (115°F) and as low as -9°C (15.8°F). Vetiver grows well in both acidic and alkaline soils.

Sowing and Transplanting

Vetiver is propagated by slips. In southern India, nurseries are typically established between February and March. Old vetiver clumps are uprooted, and the leaves are cut. The slips, which are separated by 15–20 cm (5.9–7.9 inches) long roots, are closely planted in the nursery. After the onset of the monsoon rains in June–July, the slips are transplanted at a spacing of 45x30 cm (17.7 x 11.8 inches) in flat beds, ridges, or raised beds. Approximately 70,000 slips are required to plant 1 hectare (2.47 acres) of land. Transplanting is done either on a rainy day or followed by light irrigation. Maintaining plant population through gap-filling is essential.

Fertilization and Nutrient Requirements

Vetiver planted for soil erosion control or bioremediation typically does not require fertilizers. However, for oil production, which requires a high root biomass, it is important to test the soil's nutrient status and apply fertilizers accordingly. For soils of medium fertility, a vetiver farmer may apply:

5 tonnes of farmyard manure per hectare per year,
60 kg of nitrogen (N) per hectare per year (e.g., urea),
30 kg of phosphorus (P2O5) per hectare per year (e.g., single superphosphate),
30 kg of potassium (K2O) per hectare per year (e.g., Muriate of Potash),
Secondary and micronutrients as recommended by an agronomist.

Fertilization should follow a schedule, with farmyard manure, phosphorus, potassium, and one-third of the nitrogen applied at planting. The remaining nitrogen should be applied in two-month intervals in equal portions. Integrated nutrient management, combining organic and inorganic fertilizers, produces better yields. In organic cultivation, vermicompost and bio-inoculants can be used to boost production.

Weed Management

Weeds should be controlled until the vetiver crop forms a full canopy, ensuring optimal growth.

Irrigation Needs

Vetiver is often grown as a rain-fed crop in high-rainfall regions. However, additional irrigation may be required for optimal root yields. After planting, a light irrigation is beneficial. During dry periods, 2–3 additional irrigations using surface, sprinkler, or drip methods are recommended.

Harvesting Vetiver

Vetiver is typically harvested 9–12 months after planting, depending on whether it is grown under irrigated conditions. First, the above-ground stems are cut, and the field is irrigated. The roots are then plowed deeply and collected. In heavy soils, manual digging may be necessary. Mechanical harvesting is common where labor is expensive or scarce.

How Much Vetiver Plants Yield?

Vetiver can yield 2.5 to 3 tonnes of dry roots per hectare, depending on the soil, climate, and management practices. The roots are either freshly chopped for steam distillation or soaked in water for 12 to 15 hours before distillation, which lasts for 16 to 24 hours. This process typically yields 0.6% to 1% of vetiver oil, producing 20 to 25 kg of oil per hectare.

References

Bailey, L.H. and E.Z. Bailey (1976). Hortus Third: A concise dictionary of plants cultivated in the United States and Canada. Macmillan Publishing Co., Inc., NY.
Prakasa Rao, E. V. S., et al. (2015). Vetiver Production for Small Farmers in India. Sustainable Agriculture Reviews, 17: 337-354.
Vietmeyer, N.D. (1993). Vetiver Grass: A Thin Green Line Against Erosion. National Academy Press, Washington, D.C.
Salam, M.A., et al. (1993). "Rooting Pattern of Vetiver (Vetiveria zizanioides (L.) Nash) in an Oxisol." Trop. Agric. 70: 274-275.