Vetiver hedges work with nature to curb erosion

The following is excerpted from a recent letter to Elise Pinners by John Greenfield, author of Vetiver Grass: The Hedge Against Eriosion (1990) and The Vetiver System for Soil and Water Conservation (the 2008 update of his 1987 manual), and widely regarded as the Father of the Renaissance of the Vetiver Movement:

From my 50+ years of experience starting with the Soil Conservation Service, and comparing its widely published schemes with yeomans, border listing, deep ripping, ridge and furrow, through to Fanya Juu – I noted they share one thing in common: all are constructed unnatural systems that work against nature rather than with it. They either move runoff out of the area that it fell in, or accumulate it in "puddles" or ponds that render it unavailable to crops without a lot of effort.

Compare these with the vetiver hedge properly installed across the slope or on the contour. It controls runoff, spreads it out, and allows the runoff to “ooze” through its entire length on its way down the slope, effectively watering the whole area and benefiting the plants. Vetiver hedges welcome the rain; more rain means more moisture is spread over the area. When we first discovered the world’s oldest vetiver hedges in Gundalpet, India, (where they were used to mark farm boundaries), the resulting crop in areas where these hedges crossed the slope had grown in so evenly that it looked as if it had been irrigated. Two reasons support this fact --the hedges eventually level the land because collected silt fills low areas behind the hedge, and the water spends a longer time on the surface, which breaks up surface sealing and allows the water to penetrate to depths where the moisture is needed. Since the hedges do not convey the runoff, it backs up and waits to ooze through the hedge.

When runoff is being conveyed to another outlet like a natural drainage outlet, spillway, waterway, pit or dam, it moves continually. Water from a useful rain does not remain on the ground long enough to break up surface sealing before it's lost as runoff. The more intense the rain, the faster it moves and the less moisture is stored. This pattern results in more damage to a constructed system. A constructed conservation bank can only operate safely for 300 m before it discharges the water it is conveying or storing. Otherwise the bank will overflow and burst. A vetiver hedge, on the other hand, can be run safely for kilometres because it doesn’t convey the water --it filters the water through its entire length. Since constructed systems are built from the same soil you're trying to protect from erosion, they are exposed to the same dangers of erosion and runoff as the unprotected bare ground. They are not "anchored" into the ground. In contrast, the massive root systems of Vetiver hedges anchor them to the ground.

Ridges and furrows, Fanya Juu, contour banks and their ilk are a lot of pain for very little gain. Given his plowing and planting program, the average subsistence farmer lacks the time to put them in place. Once in place, he lacks the time and labor to maintain or reconstruct them. However, once a vetiver hedge is in place, the farmer has little to worry about.

Elise, as you say in Dutch, “We get too soon old and too late smart”

Regards,

John Greenfield.