Vetiver grass for controlling sedimentation and river bank erosion

I am replying in response to Isoa Koroiwaqa's request for information on the use of Vetiver Grass in controlling sedimentation and river bank erosion, seen in the 7th November newsletter.

I have been using vetiver grass in the South West Pacific for almost 20 years and can confirm that is of great value in controlling soil erosion and reducing sedimentation. A substantial amount of work has been in Vanuatu on the island of Aneityum where extreme soil erosion in deep gullies was leaving thick deposits of red, iron rich mud on the coral reefs. The work was carried out between 1995 and 2002 and a recent visit allowed me to monitor the long term benefits. The information has been put into a presentation available on the www.vetiver.org website: http://www.vetiver.org/VAN_REEF/VAN-reef2.htm

Much useful information on the value and use of vetiver is available on the vetiver.org website but I will be happy to discuss vetiver related issues if Isoa or others are interested.

It is encouraging that vetiver is at last being used in the Rewa Valley. Vetiver was a very important component of soil erosion control on the sugar cane lands around Lautoka and Rakiraki from the 1960s until fairly recently. I spent time there in1990 and was very impressed by the terraces formed by the vetiver grass. It was effective in trapping soil particles that were moving on the cultivated slopes during intense rain and the height of the terraces indicated just how much sediment had been trapped over the previous 25 years. I understand that many of these terraces have since been ploughed out and that soil erosion is once again a problem in those areas.

Regards
Don

--
Don Miller
Agricultural Advisor

05/12/08 Pacific, Fiji, Isoa Koroiwaqa writes:
Thank you for the vertiver story from Vanuatu. I wish to ask Don if other vegetation types (trees etc) can be planted in between the row of vertiver grass and if so, what are the types of plants that can help the grass in controlling erosion. The reason is that we in Fiji and in particular in my village, we are going to trial planting a few fruit trees with the vertiver so that it not only helps in erosion control, but also a source of fruits to the families with the surplus going to the market on weekends.

Another question I wish to ask is -can the grass be plaited into mats, place mats etc, and is anyone around doing it?

Isoa Koroiwaqa
Institute of Applied Science
University of the South Pacific
Suva
Fiji Islands.

27/01/09 Pacific, Vanuatu, Don Miller writes:
Regarding combining fruit trees with vetiver grass - this has been done in several countries including Thailand, Sri Lanka and the USA. The establishment of vetiver grass will be affected by too much shading, but if the rows of vetiver are suitably spaced, and the trees are midway between the rows of vetiver, the grass will have trapped moving soil in the years before it is shaded by the fruit trees. Well established rows of vetiver grass will stay alive once they are shaded but will not grow as vigorously. If the shade is removed, particularly if by fire, the regrowth will be rapid.

Note that the best spacing for rows of vetiver grass is determined by a 2 metre vertical interval between rows. On a steep slope they will be closer together horizontally than on a gentle slope.

I have heard that many years ago in Fiji vetiver grass was used in banana plantations and that it improved their production. I will try to find the source of that information and send it to you as soon as I can.

This a brief piece placed on the Vetiver Network blogspot last year:
http://vetivernetinternational.blogspot.com/2008_10_01_archive.html

Vetiver System and Bananas - A Senegalese, Moroccan and Californian Perspective
http://vetivernetinternational.blogspot.com/2008/12/vetiver-system-and-b...