Vetiver hedges and sisal halt soil erosion, improve soil and water conservation
Practical Action
To be effectiev on sloping land, vertiver
hedges must be continuous
The field with a gentler slope is protected by
contour hedges of vertiver grass. There is no loss
of soil form water run-off.
Gully control structures
Vetiver grass strips: A number of types of andropogon grass are recommended for erosion control
(even sugar cane, which is in the andropogon family, would serve the purpose); but the most
popular is Vetiveria zizanoides, commonly called vetiver grass, Planting vetiver behind stone
banks, or by itself in continuous hedges along contour lines, is one of the easiest and most
effective ways to prevent soil erosion,
Farmers are advised to make sure the vetiver hedge is continuous, causing rain-water to seep
into the soil and offering no gaps through which run - off can flow, It usually takes two or three
growing seasons for a vetiver hedge to become dense enough to withstand heavy rains and
thoroughly protect the soil,
Vetiver hedges grow very thick and should be cut at 20-40 centimetres, or every two or three
weeks, When young, the cut grass can be used for fodder, but it performs even better as a mulch
to enrich the soil, Experts recommend piling the cuttings on the uphill side of the hedge to
encourage the formation of a natural terrace that will protect against erosion for decades - even
centuries.
Vetiver grass can be obtained from nurseries (large gullies protected with vetiver grass make
good informal nurseries), but it also grows wild in many countries. Vetiver is propagated not by
seeds but by root division, so it wiII not invade other crops.
Vetiver hedges should be planted at the beginning of the rainy season, Separate a clump of
vetiver grass, roots and all, into handfuIs called "slips". Cut off the tops of the slips so that 15 to
20 centimetres of grass remain, and plant the slips 10 to 15 centimetres apart along contour
lines. If some slips die, replace them with new ones to close all gaps in the hedge, One row of
slips is enough to produce a thick hedge.
Sisal
Sisal can also be used in place of vetiver
grass. Rows of sisal can be established on
the affected area. It can also be
established in the catchment area to
increase water infiltration and reduce the
volume and speed of run-off. Sisal has also
a dual purpose of controlling soil erosion
and that of providing fibre for the
production of craft material Iike mats, hats
and bags.
Sisal and vetiver grass can be used in
conjunction with mechanical soil and water
6 A sisal plant