These photos are from Cuba showing in the top image agricultural lands protected by vetiver, and the lower image comparing a hedge (left)and after 10 years (right) the same hedge and the natural terrace formation behind it.
Erosion continues unabated in tropical countries. Where arable land is unprotected soil losses that often exceed 150 tons per ha are not uncommon. Erosion ultimately leads to land going out of production - often replaced by land through the deforestation process. Eroding lands and the subsequent sediment flows into the river systems result in degraded and polluted water supplies, and eventually sedimentation flows into coastal waters that impact coral reefs and fisheries. Untreated eroded wastelands result in changing hydro-graphs that result in increased and often extreme flows of water that can have large down stream environmental, social, and economic costs.
With all the evidence, little is done to prevent this damage. Prevention is not given high priority, most times the technology applied is costly and not very effective; there are high costs in subsidies and much corruption.
The Vetiver System provides a very effective and low cost way of bringing erosion losses to very low levels and at the same time reduce water losses and increase crop yields. At the recent (2010) Regional Vetiver Conference in Chile two very useful papers from Thailand and Cuba were presented that demonstrated the effectiveness of Vetiver. The Thai paper (English) (Spanish) by Pitayakon Limtong brought together research data from experiments in Thailand. The results vary - depending on site - but generally soil losses were reduced by about 90% by the second or third year, and crop (maize) yields increased by 30%. Interestingly there was very little yield difference between crops grown on man made terraces and vetiver hedgerows. The high cost of building terraces as against planting vetiver hedgerows would not merit, for an extra 0.17 tons of maize, the promotion of terrace building.
The other presentation by Claro A. Alfonso, Eduardo A. Cabrera and Pedro Porras of Cuba's Soils Institute nicely demonstrates the use of vetiver to stop erosion and complements the Thai results. Both countries are subject to extreme rainfall conditions, have high erosion rates, and need appropriate solutions.
2011 is to be International Forest Year - It should be complemented byan International Soils Year - The faster soils are lost so too will forest resources dwindle