Vetiver Grass for Soil and Water Conservation

Vetiver grass has its natural origin in inundated areas like the basins, natural water ways, and swamps. However, vetiver cultivation experiments using selected species in different corners of the world had proven successful and revealed that vetiver can be grown practically anywhere and under adverse conditions. For instance, it can grow on plains at an altitude roughly at mean sea level, or even on mountains at an altitude of 2,000 m. above mean sea level. They can also be grown under peat, lime, saline, or low fertile soil conditions; in area with low precipitation of only 200 mm. to high precipitation of 3,900 to 5,000 mm.; or even under extreme temperatures ranging from as cold as - 9 degree celsius to as hot as 45 degree celsius.

       The Mysore ethnic group from India have been growing vetiver for the past 200 years for use as animal fodder. The application of vetiver for soil and water conservation has begun 50 years ago on the islands west of India. For over 30 years, a sugar company in Fiji has successfully grown vetiver to conserve soil and water in the sugar cane fields. Mr. Greenfield, World Bank's technical expert on soil and water conservation for Asia, discovered that steepness of the slopes in the sugar cane fields has decreased to a level of 3 to 4 m. over the past 30 years of cultivation. So it was concluded that vetiver cultivation in combination with treatment of the soil and crop rotation farming gradually created natural terraces on the land. This happens because vetiver has special characteristics capable of forming new clumps by easily developing new shoots at the internode or new rhizome above the soil. After vetiver is grown, surface soil can be protected from erosion at least 3 to 5 times than without vetiver. In addition to the new sprouts, the roots also expand and penetrate vertically thus holding the soil together.
       Another positive attribute is that vetiver is not sensitive to sunlight and can separate into new culms and produce inflorescences all year round. So vetiver will continue to grow tall which appears as if the natural steps are getting higher and higher. The process of creating and raising the natural terraces will come to an end when the slopes are adjusted to the ground level. After vetiver hedgerows are formed, the next advantage is to enhance soil fertility by developing the surface soil, which is now easy because there is greater moisture (vetiver hedgerows can preserve water between 25-70 percent). As the soil becomes more fertile, variety of crops including ground cover plants will grow abundantly. Moreover, the process of cutting the leaves to maintain the hedgerows and use as mulch will create a natural balance by enhancing the organic contents, plant nutrients, and microorganisms in the soil which make it even more fertile (leaves cut from 4-month-old vetiver generate plant nutrients for the soil on an average of N 1.29%, S 0.15%, P 0.20%, and K 1.3%, of the weight of dry grass). Furthermore, the root system penetrates more vertically than horizontally, and thus does not take up a large space to grow. For instance, vetiver hedgerows at one year old and over only require an area not wider than 1.5 m. So using vetiver for conservation purposes takes up lesser space than other soil and water conservation measures such as creating an earth embankment. For that, cash crops can be grown near the vetiver hedgerows without any problems.
       In other words, vetiver possesses certain attributes suitable for soil and water conservation purposes.


	Special Attributes of Vetiver

	1. The clumps develop an extensive, tightly knitted, and strong erecting wall. Vetiver can be grown in a long row which is comparable to a living barrier capable of resisting silts, retarding runoff, and allowing water to slowly absorb into the soil. 2. The culms above the soil possess close nodes that are developed as a result of elongation. When vetiver becomes mature to almost flowering stage, it will develop new shoots and roots. As they are buried by eroded soil, they will then grow new clumps.

       3. The culms and leaves can be cut frequently to develop new shoots and stay green and healthy.
       The cut culms and leaves are used as mulch to preserve moisture and enhance plant nutrients for the soil, similar to the process of making compost. When mature tillers with dry leaves are burnt, they will immediately develop new green shoots, thus making it unnecessary to plant new grass. The leaves from Vetiveria nemoralis can be made into thatches and sold as roofing materials. As for Vetiveria zizanioides like the Kamphaeng Phet 2 ecotype, the young leaves can be used as animal fodder for cattle but they must be cut 2-4 weeks after the previous cutting. An Indian Vetiveria zizanioides ecotype is used to feed Chinese fish. Well dried leaves of Vetiveria zizanioides can be made into a wreath, artificial flowers, as well as weaving products like hats or baskets.
       4. Root system
       Vetiver has a strong fibrous root system which rapidly penetrates deep into the soil and develops into a tightly knitted net. It holds the soil together and serves as an underground wall which not only retards waterflow but also allows it to seep into the soil. In addition, the root system helps to prevent gully erosion, both large and small sizes. The hedgerows will stop erosion caused by lower level contours which an earth embankment is not capable of.
       The roots are also capable of absorbing mineral nutrients for plants and other chemical substances like chemical fertilizers or pesticides before they flow into the water sources, thus protecting water from pollutants and maintaining the water quality.




	Vetiver cultivation to retard runoff

5. Multiplication
It is rare or almost nonexistent that the preselected vetiver ecotypes are propagated by seeds. Therefore, they will not grow into weeds that are harmful, such as the ecotypes from India and Australia. So it is safe to grow vetiver grass in orchards and other agricultural areas, especially in well-maintained farm areas like on earth banks around paddy fields in the southern provinces of Songkhla and Narathiwat where Vetiveria zizanioides is grown to hold the soil.

       6. Establishment of hedgerows
       A vetiver clump grows approximately 1 to 1.5 m. horizontally and thus will not take up a large space. It is then possible to grow cash crops close to the vetiver hedgerows.
       7. Extension work
       Utilization of vetiver grass for soil and water conservation is not difficult for farmers to apply on their own land. It is particularly easy if farmers develop a clear understanding of the benefits and seriously believe in the need to conserve soil resources for generating higher and more productive yields. This and the fact that vetiver helps to prevent erosion and siltation of water sources all contribute to creating benefits for the entire society.
       Cultivation is so simple that it can be implemented by people from diverse professions. Propagation is done by separating the shoots or culms which can be carried out frequently because vetiver growth develops very quickly.
       Vetiver can be cultivated practically anywhere because it has very few constraints. However, for severely critical conditions such as areas along the coast with high salinity or on peat soil with high acidity, the soil needs to be treated by adding limestone or lime dust before planting vetiver tillers. As for the case where sunlight is insufficient like the Pang Tong area in Muang District of Mae Hong Son Province, the problem is dealt by growing the appropriate indigenous ecotypes namely Mae Hong Son, Mae La Noi, Pang Mapha, or imported varieties namely Phra Ratchatan which is the ecotype given by His Majesty the King as well as those from Japan.
       With proper steps and careful planning such as using a suitable ecotype, the right fertilizer for a particular season, or strong tillers, the cost for cultivating vetiver will not be high but frugal enough for a farmer to implement.
       Under today's adverse environmental conditions of decreasing forest areas, the impact from this includes irregular rainfalls, violent storms, flash floods, and extremely dry weather which inevitably affect the whole country. However, vetiver cultivation for soil and water conservation, which can be done rapidly and on a wide scale, is capable of preventing flash floods and solving severe drought in farm and urban areas. Vetiver hedgerows can retard runoff under different types of topography, such as along natural watercourse and steep slopy areas.


	Methods of Vetiver Cultivation


	1. To serve as an earth embankment for soil and moisture conservation.

The steps here begin in early rainy season by ploughing the soil to prepare for vetiver cultivation along contours across the slopes. A furrow is prepared to grow vetiver at a 5 cm. inter-plant spacing; and then 1 culm or 1 to 3 shoots per hole are transplanted. Cover the base of vetiver tightly and leave a distance of no more than 2 m. of inter-row spacing vertically. Vetiver clumps will be established between 4 to 6 months or 1 to 3 cultivating seasons. In case where vetiver is grown on a dry area, the grass should be cut to 30 to 50 cm. high once every 1 to 2 months in order to accelerate the growth of vetiver clumps.




	Vetiver cultivation to serve as an embankment for soil conservation


	2. To control gully erosion and water dispersion.

Vetiver tillers for transplanting must be well established in order to effectively protect ditches from eroding and in the process, create an embankment for retaining water. The tillers should be developed in plastic bags until they grow in big clumps and are strong enough before transplanting in the ditches. The transplant hole is either dugged horizontally across the ditch or in a reverse direction of water flow. Sandbags or stones can be used to support the embankment and reinforce the hedgerows. The inter-plant spacing should be even closer than the first method with an inter-row spacing of no greater than 2 m. vertically. After an embankment is created, vetiver is planted extendingly on both sides in order to disperse water onto farm areas.


	3. To preserve moisture in orchards.

Vetiver should be grown when fruit trees are still young or even before they are planted. The spacing between the vetiver rows depends on the inter-plant spacing between the fruit trees. Vetiver hedgerows are developed along the rows of the fruit trees, leaving a space of 1.5 m. in between. Not only that the hedgerows help prevent erosion and preserve moisture, but also that the cut leaves increase the effectiveness in retaining moisture and improving soil fertility by being regularly used as mulch around the tree bases.


	4. To filter silts around pond edges.


	The first vetiver row is grown at the highest water level mark. Then one or two more rows are planted above the first, with the definite level depending on the depth of the pond edges. The inter-plant spacing is 5 cm. and vetiver is planted continuously in a row. At the initial stage of cultivation, dead tillers should be replaced in order to strengthen the clump growth. As water is approaching the pond, silts will be trapped by the hedgerows first while water is allowed to flow down into the pond. Vetiver root system will bind the soil together and prevent the pond edges from eroding. In addition, vetiver can be planted along roadsides, road shoulders, and irrigation canals as well as on slopes to cling the soil together and restore fertility to the land.

	Copyright © 1996 Chaipattana Network Webmaster. All right reserved. Reproduction of the information contained in this web site without permission is prohibited.