Vetiver grass – Natural engineering structure                       No one can deny the well-proportioned creation of nature. However, human action together with inappropriate application of technology and knowledge affect the sustainability of nature. Increased temperature, green house effect and various forms of natural phenomena are periodical warning signals from the nature.                     Such crisis leads to the attention of people around the world to apply natural methods to solve the problem and avoid the side effect. In Thailand, the main problem urgently needed to be solved relates to soil, an important factor for living things. Deteriorated soil from inappropriate utilization of soil resource and soil erosion from deforestation result in the decrease of crop yields and poverty of farmers.                     In 1991, His Majesty the King realized the potential value of vetiver grass in soil and water conservation. Researches and experiments on the benefit of planting vetiver grass were conducted. With extensive root systems, penetrating and adhering soil particles tightly, these enable vetiver grass to prevent soil erosion. It maintains soil moisture and can be grown in infertile, lateritic soil or flooding areas.                       Vetiver grass can hold soil effectively and form soil. It should be grown in continue rows. The died ones must be replaced with the new ones to avoid the gap. The line of vetiver grass will reduce runoff velocity while sediments and leaves will remain in the line of vetiver grass and become soil later. Vetiver grass also prolongs construction like road, dam and irrigation canal since it stabilizes the soil and traps the silt.                     More than 8 years has been spent by Land Development Department in order to conduct researches and experiments on the benefit of planting vetiver grass; propagation technique, plantation, agricultural benefit, environmental protection and products. It has been accepted by farmers that planting vetiver grass is the most easy, economical and suitable way to prevent soil erosion.                     In summary, results from researches and experiments mentioned above are:                     1. Among all 78 varieties of vetiver grass, only 28 varieties adaptable to different soil types and environment in Thailand have been selected. From the mentioned selected 28 varieties, it has been found that 10 ecotypes adaptive to problem area like sandy and lateritic soil are 6 ecotypes of upland vetiver (Kamphang Phet 1, Loei, Nakhon Sawan, Prachuap Kiri Khan, Ratchaburi and Roi Et) and 4 ecotypes of lowland vetiver (Kamphang Phet 2, Songkhla 3, Sri Lanka and Surat Thani).                     2. Techniques of vetiver grass propagation including root and stem cuttings, tissue culture and suitable planting have been investigated. In 2000, 100 million seedlings of vetiver grass have been propagated by Land Development Department and it is the largest amount of vetiver grass in the world. Vetiver grass varieties have been distributed to farmers and interested public as well as technology transfer. Vetiver grass should be planted in the horizontal line. The interval between plants should be 5-10 cm. according to soil suitability. The vertical interval between lines should be 1-3 m. depending on the slope and plant types. The suitable period for planting vetiver grass is during rainy season (June – August).                     3. The research on the effect of vetiver grass on soil erosion was conducted and found that planting vetiver grass can prevent soil erosion or decrease soil erosion to not more than 200 kg./rai per year. Plantation can be conducted in slope areas such as agricultural area, ditch, road shoulder area and edge of pond or reservoir.                     It has also been found that vetiver grass can make well-structured soil with increased organisms. Its leaf cuttings can be used for mulching and maintaining soil moisture, thatching, mixing with soil and cement as construction materials and mixing with polymer for furniture and equipment production. Its roots can be extracted for oil and perfume.                     The devotion of Land Development Department to continuous researches and experiments results in the receipt of the King of Thailand Vetiver awards on “Research on Methodologies for Selection, Propagation and Cultivation Techniques of Vetiver Grass and Its Application in Thailand” and leads to the fame of governmental organization and the confidence of the public requested for service.                     “Vetiver grass” is the successful method of using natural creation to solve the problem.