VETIVER GRASS: A THIN GREEN LINE AGAINST EROSION IN SOUTH AFRICA

Vetiver Grass: A Thin Green Line Against Erosion For developing nations, soil erosion is among the most chronic environmental and economic burdens. Many of these nations are in the tropics, where in just a few hours torrential downpours can wash away tons of topsoil from each hectare. Many others are in the drier zones, where swirling winds and flash floods (sometimes from rains so distant they are unseen) can be equally devastating. By these processes, huge amounts of valuable soil are being lost every day. Worse, the soil accumulates in rivers, reservoirs, harbors, estuaries, and other waterways where it is unwelcome, terribly destructive, and impossibly costly to remove. Erosion is thus a double disaster: a vital resource disappears from where it is desperately needed only to be dumped where it is equally unwanted. Despite much rhetoric and effort, little has been accomplished in overcoming erosion, at least when viewed from a worldwide perspective. One major reason is that there are few if any solutions that are cheap, appealing, long lived, and suitable for easy adoption over the vast expanses of the Third World that need protecting. Now, however, there may be one. In the eyes of at least some viewers, a little-known tropical grass, vetiver, might at last offer one practical and inexpensive solution for controlling erosion simply, cheaply, and on a huge scale in both the tropical and semiarid regions. Planted in lines along the contours of sloping lands, vetiver quickly forms narrow but very dense hedges. Its stiff foliage then blocks the passage of soil and debris. It also slows any runoff and gives the rainfall a better chance of soaking into the soil instead of rushing off the slope. Although there has not been much experience with this process to date, the deeply rooted, persistent grass has restrained erodible soils in this way for decades in Fiji, India, and some Caribbean nations. At least in this limited practice, vetiver appears truly remarkable. The grass itself seems not to spread or become a pest. Terraces rise as the soil accumulates behind the hedges, converting erodible slopes into stabilized terraces where farming and forestry can be conducted, safe from the evils of erosion. Farmers and foresters benefit not only by keeping their soil, but by having flatter land and more moisture for their plants. Countries benefit by having cleaner rivers, unspoiled estuaries, and more water and less silt in their reservoirs.