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Vetiver Grass and Greenhouse
Gasses
(VETIVER e o EFEITO ESTUFA)
Vetiver grass, Vetiveria zizanioides, offers a way to benefit the earth's atmosphere as well as its surface environment. This tropical grass sequesters large quantities of carbon dioxide from the atmosphere -- it may, in fact, be the ideal plant for the purpose.But hedges of vetiver also stop soil erosion, rejuvenate degraded lands, keep pollutants in their place, and much more. Nobody yet knows how much greenhouse gas vetiver can remove, but is likely to surpass anything generally imagined.
A rough estimate can be gained from measurements made on a closely related grass, Andropogon guyanus.
In 1995,CIAT (a respected international agricultural research institute in Cali, Colombia) reported that this species and another deep-rooted African grass grow so widely and so prolifically in the savannas of South America that they "may remove as much as 2 billion tons of carbon dioxide from the atmosphereyearly."
Andropogon guyanus roots penetrate 1 meter into tropical soils and CIAT scientists found that the plant sequesters as much as 53 tons of carbondioxide as organic matter per hectare per year.
Vetiver roots, by contrast, are more extensive and penetrate tropical soils to depths of 5 meters and beyond. Its rate of absorbing the gas is likely to be at least twice that of its botanical cousin. Back-of-the-envelope calculations suggest that a single vetiver plant may absorb 5 kg of CO2 a year (uma simples planta de VETIVER pode absorver 5 kg de CO2 por ano).
International efforts to propagate vetiver grass are underway in more than fifty countries.
To give one example, the Chiang Rai Land Development Station in northern Thailand produces new vetiver plants at the rate of 100 million a year, which means that its annual output of plants might be removing 500 million kg of carbon dioxide. According to CIAT, that's as much CO2 as emittedby 100,000 gas-guzzling cars, each driven 20,000 km.
Vetiver's many advantages include the fact that it:
- Thrives in acid, tropical soils that now support little or nothing;
- Is adapted to widely different conditions and climates;
- Thrives in the tropics where the year-round heat fosters tremendous
- biomassgrowth;
- Produces root matter rapidly;
- "Buries" CO2 so deep as to keep it out of the atmosphere for decades ("enterra" o CO2 tão fundo, mantendo-o fora da atmosfera por décadas);
- Benefits the soil and surroundings;
- Provides multiple benefits in addition to any greenhouse-gas removal;
- Is easy to use and understand;
- Can protect roads, pipelines, natural-gas wells and other installations;
- Can stabilize spoil from mining and other industrial operations; and
- Is adapted to the most erosion prone, hunger prone and forest-depletedregions.
These days, interest in planting vetiver is widespread throughout the tropics. People want to plant it for their own benefit -- it doesn't have to be done for them. Small amounts of funding can therefore be put to immediate use without overheads or delays. The funds can produce huge multiplier effects. They can, for instance, be used to establish nurseries, which then go on producing planting materials in a self-sustaining manner into the foreseeable future.
Vetiver seems like an exceptional tool for sequestering CO2.
It can be propagated by the millions in tropical lands, and could be used to trade off against considerable volumes of emissions made elsewhere in the world. All in all, this remarkable plant has the ability to turn large amounts ofgreenhouse gases into underground solids -- all the while benefiting local soils and environments. Vetiver hedges will likely hold their stored carbon for decades. They will also benefit the lives of millions in the parts of the world that most need help.
Noel Vietmeyer. National Academy of Science (retired)
FONTE: INPECO - INSTITUTO PORTUGUÊS DE ECOLOGIA (www.inpeco.pt).
RETORNAR@