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Protection of the Terrestrial Environment

A. Agriculture

  1. Soil erosion and sediment control on sloping farmlands: Both research and field results in Australia, Asia, Africa and South America show that in comparison with conventional cultivation practices, surface runoff and soil loss from fields treated with vetiver were significantly lower and crop yield was much improved.


  2. Erosion and sediment control on floodplain: Vetiver has been used as an alternative to strip cropping practice on flood plains. This practice relies on the stubble of previous crops for erosion control of fallow land and young crops. On this experimental site, vetiver hedges that were established at 90 m interval provided a permanent protection against flood water. Results over the last five years (including several major flood events) have shown that VGT is very successful in reducing 49 flood velocity and limiting soil movement, with very little erosion in fallow strips. The incorporation of vetiver hedges as an alternative to strip cropping on floodplains has resulted in more flexibility, more easily managed land and more effective spreading of flood flows in drought years and with low stubble-producing crops.


  3. Rehabilitation of saline and acid sulphate soils: The spread of salinity in both dry and irrigated lands is of major concern in low rainfall and semiarid regions of the world. Vetiver has been used very successfully in erosion control and rehabilitation of these salt-affected lands. Acid sulphate soils constitute a major component of arable lands in many tropical countries in Africa and Asia such as Thailand and Viet Nam, where rice is the main food crop. These soils are highly erodible and difficult to stabilize and rehabilitate. Eroded sediment and leachate from acid sulphate soils are extremely acidic.


  4. Bioremedial: Vetiver has played an important role in the retention and decontamination of agrochemicals, especially pesticides, preventing them from contaminating and accumulating in the soils and crops


  5. Biological pest control: Research conducted showed that of the 79 species of insect found on the vetiver rows, only four attacked young vetiver leaves. However, due to their small population the damage was minimal. On the contrary, 30 other species found in the vetiver rows are considered beneficial insects, as they are the all-important enemies of garden, agriculture and forest pests. This indicates that an integrated pest management scheme will be put into operation when vetiver is introduced to a new environment.


B. Natural Disasters
  1. Typhoon (cyclone or hurricane): Trees take several years to develop extensive and deep root systems necessary to anchor the soil on steep slopes to prevent landslides and reduce erosion, whereas vetiver grass, when properly established, can provide the same effect within 12 months. Due to the El Niño effects, a series of hurricanes, particularly Mitch and Georges, devastated several countries of Central America in 1998, causing floods and landslides, cutting off highways and other severe infrastructure damages and killing several people. Damage assessment carried out after the typhoons revealed that vetiver provided a very effective protection against high rainfall, high wind and floods. Both civil construction structures such as roads, dams, etc, and farmlands remained stable if they were protected by vetiver.


  2. Landslide: Landslides are often caused by the lack of structural strength of the ground on steep slopes and the event is triggered by saturation during heavy rainfall periods. The problem can be exacerbated by the presence of tall trees, which top over under strong wind. Under natural conditions such as forests, deep-rooted trees provide structural reinforcement, but when deforestation is carried out for agriculture and forestry production or infrastructure construction, this structural protection is lost. The only rehabilitation method that is feasible, practical and socially acceptable is to reduce concentrated runoff, which can be effectively spread out by vetiver hedges. This involves planting overlapping short hedges to spread and divert runoff water away from the actively eroded heads. When the hedges are fully established, the concentrated flow will either spread out or be diverted to a more stable area. Rehabilitation works on the eroded land below the head can be started by using vetiver grass first and either native or eucalyptus trees later.


  3. Flood: The combination of the deep-root system and thick growth of the vetiver hedges will protect the banks of rivers and streams under flood conditions. Its deep roots prevent it from being washed away while its thick top growth reduces flow velocity and its erosive power. In addition, properly laid out hedges can be designed to direct water flows to the appropriate area.


Protection of the Social Environment

Vetiver Grass Technology has shown to have exerted a beneficial effect on the socio-economic aspects of rural life, especially in the Philippines. Due to the prolonged drought caused by El Niño in the last few years, there was no work for rural farming communities. This often led to the break-up of rural families as people moved to the cities to find work. Given the need to supply planting materials for various infrastructure projects in rural area, Vetiver Grass Technology was able to provide employment for local people propagating and planting vetiver near their villages. Therefore, product cultivation and sale provided opportunities for these people to remain in their villages instead of drifting to the big cities looking for work.


 


 

 

 

 

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