Case Studies
Application of Vetiver grass for gully erosion control at the northern ridges of Mount Mahomet in Cryna, Southeast Queensland, Australia (Rostedt, 2004)
Case study 1
A community-based team called Beaudesert Landcare Group has started to initiate a gully stabilisation demonstration project by using Vetiver grass. The highly erodible loamy soil has caused a very deep and narrow gully which is 6-meter-deep starting from the gully head until the creek. The operation begins by using an excavator to batter the gully slopes and southern wall in a 3:1 gradient as well as moulding a board plough as to construct three contour lines at the gully head which is then followed by placing an open jute mesh geofabrics as to cover the gully slopes.
The Vetiver was watered 600 L twice a week for 8 continuous weeks for weeks with high temperature and dry winds. The watering process stopped when the Vetiver plants had established their roots. The Vetiver plants were monitored for their growth and survival rates wherein after three weeks, the Vetiver reached up to 20 cm and subsequently 160 cm after four-months of growth.
After a year of planting, the Vetiver was found to be still holding the ground firmly even though they were flattened by the severe storm which carried about 120 mm of water every 1.5 hour. Therefore, the promising results exhibited the effectiveness of Vetiver grass in controlling soil erosion of the gully and it could be implemented in other similar conditions due to their low cost and simple application method.
Figure 1: The condition of eroded gully (left) and Vetiver grass planted after one-year at the northern ridges of Mount Mahomet in Cryna, Southeast Queensland, Australia (Truong, 2003).
Case study 2
Rehabilitation of Degraded Lands Using Vetiver Grass System in the Voi Riverbank, Kenya (Mwadime & Maghanga, 2012)
The Voi Riverbank is located in the Coast Province of Taita Taveta District in South-Eastern Kenya, where the soil contains moderate to high fertility, and fresh sediments and nutrients are regularly received during regular floods. However, the area is prone to soil erosion, causing the riverbank to collapse due to poor plant cover resulting from trees being cut down for settlements and the lack of a drainage system.
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To rehabilitate the degraded soil, Vetiver grass is used, and approximately 5 g of fertilizer is placed for each slip during planting. The Vetiver grass is first raised in a nursery for three months before being transplanted in slips along the riverbanks.
Observations are made, and between 1-4 months, approximately 75% of plant coverage is well-developed, with massive root structures that help to stabilize the soil. As a result, Vetiver grass planting has proven to be effective in protecting the riverbanks from erosion, reducing rainfall runoff, and improving the groundwater recharge, which also helps to control flooding issues.
Figure 2: The degraded soil condition before Vetiver planting (left) and 4 months after the planting of Vetiver grass (right) in the Voi Riverbank, Kenya (Mwadime & Maghanga, 2012).
References:
Mwadime, P., & Maghanga, J. K. (2012). Rehabilitation of Degraded Lands Using Vetiver Grass System: A Case Study of Voi Riverbank Stabilization in Costal Kenya. Retrieved from https://ir.ttu.ac.ke/xmlui/bitstream/handle/123456789/42/REHABILITATION%20OF%20DEGRADED%20LANDS%20USING%20VETIVER%20GRASS%20SYSTEM.pdf
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Rostedt, M. (2004). Using Vetiver for Gully Erosion Control. AU J.T., 8(2), 81-85.
https://www.thaiscience.info/Journals/Article/AUJT/10290537.pdf
Truong, P. (2003). Beaudesert Landcare Gully Stabilisation Project Cryna Road. Retrieved from