The Nutritional Needs of Vetiver in Toxic Soils��Experience from the Aneityum Erosion Control Project
Don Miller and David Price
Aneityum Island, Vanuatu
Source: Oceania_ISO_3166-1.svg: User:Tintazulderivative work: Cruickshanks - Own work, derivative of Oceania_ISO_3166-1.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30880554
Source: Google Earth
Aneityum Island, Vanuatu
Mystery Island
Erosion Control Project
Port Patrick
Local people come from the
village seen in the distance
to sell goods and food
Valuable marine reserve and
managed-breeding experimental area
source of the red sediment
~1,200 ha of actively eroding gullies
Mystery Island
“we had to wade through deep clinging red mud”
Muddy streams
Sediment polluted sand
Polluted foreshore
Thick red mud on a reef
Drying and wetting cycles
Rock rapidly breaks down
Fine surface material easily washed away
The Physical Weathering Process
25-50mm of fine surface material lost/year-1
100 years of Vetiver on Aneityum to mark coastal tracks
People eager to use it for erosion control
Introduced from New Caledonia
Some early Vetiver plantings on Aneityum failed
Lower roots black and stunted
Roots in the upper soil keeping them alive
Sad plants from early Forestry Department trial
Earlier experience with Vetiver on Atiu, Cook Islands was invaluable
Trial planting in eroding abandoned pineapple field
The same site one year later in 1993 showing�good growth due to residual fertilizer in the soil
Soil pH as low as 4.3
New Zealand soil tests returned Soluble Aluminium Saturation of 89%
Vetiver is tolerant of soluble Al but growth is
is restricted above 86% (Paul Truong, pers comm)
Acacia spirorbis
Note leaf litter under tree
Important indigenous species, tolerant of very high soluble Aluminium levels
Organic acids can form Chelate Compounds with soluble Aluminium, making the Al ions harmless
Spirorbis’ deep leaf litter gradually
decays releasing organic acids
Where Al not a problem, N, P, K and Mg still needed
Fertiliser Trials
Further fertilizer trials
Pterocarpus indicus
to support Vetiver plants
Fertiliser Regime
500gm Agricultural Lime
300gm Reactive Phosphate Rock (RPR)
100gm granulated N, P, K and Mg
per metre of Vetiver hedge
The mix was incorporated into the soft rock in the bottom of a 200mm deep trench dug on the slopes using taro spades
Lime increased soil pH and reduced Al toxicity in Vetiver root zone
Acid soil gradually made RPR available, leaching reduced
Placing the N, P, K, and Mg in trenches reduced losses
How it worked
The 89% Al saturation site where Vetiver roots were black and stunted
Chalk Hill Gully, 2001
One year old and two year old Vetiver hedges
ready for A. spirorbis planting
Chalk Hill Gully in 2001
Two year old Vetiver with
Acacia spirorbis seedlings
>100,000 Vetiver plants annually
Chalk Hill Gully, 2008
Same location as the previous slide
Terraces well developed
Soil forming
Ready for sandalwood planting
Leaf litter
Acacia spirorbis thriving
Stream draining Chalk Hill Gully
No more mud smothering beach and reef
Aneityum Erosion Control Project, 1995 – 2011
The results of this project reflect the dedication and effort of the small band of
workers who carried on with minimal supervision for 10 years, growing many
thousands of plants, carrying heavy sacks of grass and trees to remote sites and
wearing out numerous taro spades. These include Henry Kathecau, Henry Naumu, David Waniymek, Lauthep, Peter and the many other men and women who pitched in and helped make a difference to their island’s future. Thanks team.
Grateful thanks to my consulting partner, Nick Lambrechtsen, who provided huge
support by handling the paper war in New Zealand.�
Thanks also to the NZ Ministry of Foreign Affairs and Trade - NZAID for their
considerable financial support over the 8 years of the first phase. NZ Volunteer
Service Abroad, The Vanuatu Farm Support Association, Charlie Rogers and the French funded CRISP program for the brief second phase of work in 2010 - 2011.
Contact: donmillernz@gmail.com Home: +64 3 573 5118 Mobile:+64 21 189 1525
Acknowledgements