John C. Greenfield (2)

Vetiver Grass: The Hedge against Erosion

John C. Greenfield

Download file: Vetiver Grass – A Hedge Against Erosion (with photos) English  

In the late 1980s, I wrote a handbook to benefit extension workers in India who were using vetiver grass (Vetiveria zizanioides) technology for the first time. This chapter is a modified version of that book, Extension Worker’s Handbook, first published in India as Vetiver Grass: A Method of Vegetative Soil and Moisture Conservation in 1987 by the World Bank and later published as Vetiver Grass: The Hedge against Erosion. The handbook, now in its fourth edition, has been edited and reprinted in many languages.

In the handbook I explain in simple terms what erosion is, how to recognize it, and how to apply the Vetiver System to help prevent it. I also introduce the concept of contour cultivation and moisture conservation, both practices essential to successful farming in rainfed areas and an essential part of the Vetiver System.

Sheet Erosion

Sheet erosion is initially the most damaging form of erosion, mainly because it often is not recognized and therefore is seldom treated. Triggered by rainfall, sheet erosion accounts for the loss of billions of tons of soil every year. As raindrops pound the ground, particles of soil are knocked loose and then carried away by the runoff. This runoff further strips unprotected areas of their valuable topsoil and becomes the muddy water that ends up in drains, streams, and rivers. Sheet erosion leads to more striking forms of erosion—rills and gullies, for example, the focus of most conservation efforts to date.

Although not as spectacular as rills and gullies, sheet erosion does leave visible marks, as shown in Figure 1a: soil collecting behind obstructions on a slope (such as the brick in example A), stones left behind by the runoff because they were too heavy to be carried away (B), or molded mounds of soil and other debris trapped under branches, twigs, or even clumps of straw (C). The reality of sheet erosion’s marks appears in Photo 2.

The effects of sheet erosion are more readily apparent in forest areas that are devoid of ground cover, and in fields or wastelands with a few standing trees, where the loss of soil exposes the roots of the trees. (See Figure 2 and Photo 2.) Water can then easily pass beneath the trunks of the trees and among their roots. After all the soil that supported them and gave them life is washed away, the trees will be washed out of the ground as well.

 

 

Trees by themselves do not prevent soil loss caused by sheet erosion; forests do, with their thick litter and low-growing vegetation. In areas where forest cover is not possible or practicable, vegetative barriers can be used to stop the loss of soil. Fibrous-rooted shrubs and grasses planted as hedges along the contour of the land slow the runoff, spread the water about, weaken its erosive power, and cause it to deposit its load of valuable soil behind the hedgerows. As a result, the runoff proceeds gently down the slope, and if the hedges have been planted at the correct vertical interval (discussed later and illustrated in Figure 23), it proceeds without further erosive effect.

The amount of soil lost through sheet erosion is alarming. Figure 3, which depicts two surviving plants whose roots prevent sheet erosion, shows how the amount can be measured. In this case a layer of soil 50 centimeters deep—as measured by the distance between the top of the plant mounds and the present soil surface—has been lost across the entire area of the field since the plants became established. The Photo 3 shows the vulnerability of the exposed roots after the soil has washed away.

 

Rainfed Farming

The traditional way of farming in rainfed areas, no matter how flat the
land may seem, is along the slope, or up and down the hill. (See Figure
4 and Photo 4.) This system encourages runoff and soil loss and thus
makes sheet erosion worse. Often more than 50 percent of the rainfall
is lost as runoff and thereby is denied to the crops; and the steeper the

slope, the faster and more erosive the runoff. Rainfall is less effective
because the water is not given a chance to soak in. By plowing along
the slope, the farmer in Figure 4 is unknowingly encouraging the
rainfall to leave his field.
Figure 4. Traditional farming in rainfed areas requires planting
along the slope or up and down the hill
Photo 4. Traditional farming in rainfed areas requires planting
along the slope or up and down the hill.
Figure 5 and Photo 5 illustrate the method advocated in this handbook—
the use of vegetative contour hedges to prevent erosion and conserve
natural moisture in the soil. Once established, such hedges need no
maintenance and will protect the land from erosion for years as they
build up natural terraces. In contrast to the planting furrows in Figure
4, those at
A in Figure 5 follow the contour of the land as laid out by the vegetative
hedges at B in the illustration. Constructed earthen embankments, or
contour bunds, have slowed erosion throughout the world since the
1930s. But this constructed method of soil conservation creates an
unnatural system of drainage and, from my experience in the field, I
no longer consider it appropriate for smallholders.
Figure 5. Farming with vegetative contour hedges prevents
erosion and conserves natural moisture in the soil.
Photo 5. Farmers who use vegetative contour hedges, which
require little or no maintenance, will protect their fields from
erosion for many years
The embankment in Figure 6a was constructed with topsoil taken from
point A, which was thereby transformed into a channel to convey the
runoff sideways. But the bank is made of the same soil it is supposed
to protect, and because its construction makes the slope steeper, over
time the bank will erode and “melt” away. Then it will have to be
replaced—at great cost to the farmer. Moreover, to collect sufficient
soil to make the bank and channel shown in Figure 6, a 5-meter-wide
strip of land must be taken out of production over the entire length of
the bank. This represents a loss of 1 hectare of productive farmland
for every 20 hectares of land treated with embankments or bunds. The
Photo 6 clearly shows a typical failure of the constructed system of
conservation in self-mulching vertisols in India.
Figure 6. With the constructed method of soil conservation, the
farmer loses a 5-meter-wide strip of land over the entire length
of the bank.
Figure 7 shows the unnatural way the land is drained by the constructed
system. All of the runoff is channeled sideways and dumped into a
constructed but unproductive waterway that no smallholder would
want running through his or her farm. This system makes the areas
below the banks too dry and the channel areas too wet for optimum
crop production.
Photo 6. With the constructed method of soil conservation,
conservation efforts failed on India’s black cotton soil
Figure 7. With the constructed system, land is drained in an
unnatural way, leaving some areas too dry and others too wet
In contrast, the vegetative method of soil and moisture conservation
uses nature to protect itself. In the system demonstrated in this
handbook with vetiver grass, only a 50-centimeter strip—or one-tenth
of the land occupied by earthen embankments or bunds—is taken out
of production. (See Figure 8.) Because the grass root divisions, or slips
as they are called, are planted in a single plowed furrow, little soil is
disturbed. And whereas earth banks have to be made with bulldozers
or by hired labor, the vegetative system requires no special tools or
labor beyond that which a farmer would already have.
The bottom illustration in Figure 8 shows what happens over time
in the vegetative system: the runoff drops its load of soil behind the
vetiver hedge, the grass tillers up through this silt, and a natural terrace
is created. The terrace becomes a permanent feature of the landscape, a
protective barrier that will remain effective for decades, even centuries.
Photo 8 shows how the terrace builds up over time.
Photo 9 shows not only the failure of a constructed bank in India but also
the failure of the cotton crop the bank was designed to protect. Before
this bank’s failure, the entire area was flooded by the constructed
system’s trapping of too much water. Because cotton cannot tolerate
poor drainage, the crop failed completely.
Photo 8. Soil build up naturally behind this vetiver
hedgerow. This photo is a cross section of a hedge and
soil profile. Note the original soil surface is shown as
the dark humic layer.
Figure 8. The vegetative system of soil and moisture
conservation uses nature to protect the soil.
Photo 10 was taken on the same day in a different location of the same
field as in Photo 9. In this situation the cotton crop thrived, protected
by a single vetiver hedge that spread the runoff out and gave the water
a chance to soak into the ground over the whole area protected by the
hedge, thus producing an excellent crop of cotton. With the vegetative
system, when the runoff reaches the hedges, it slows down, spreads out,
drops its silt load, and oozes through the hedgerows, a large portion
of the water soaking into the land along the way. (See Figure 10.) No
soil is lost, and there is no loss of water through the concentration of
runoff in particular areas. The system requires no engineering—the
farmers can do the whole job themselves.
Near Mysore in the southern Indian state of Karnataka (in the villages
and hamlets of Gundalpet and Nanjangud, for example), farmers have
been maintaining vetiver hedges as boundary markers around their
farms for more than 100 years. To keep the hedges narrow, the farmers
simply plow around the edges of the hedgerows whenever they plow
the rest of the field for cropping. The hedges are in perfect condition
and provide permanent protection against erosion (Photo 11).
Photo 9 Not only has the constructed bank failed, but the
cotton crop that the bank was constructed to protect has
also failed. Before this bank’s failure, the constructed system
trapped too much water, flooding the entire area. Because
cotton cannot tolerate poor drainage, the crop failed completely
Photo 10. Believe it or not, this field is part of the same one
shown in Photo 9, but here the cotton crop, protected by
a single vetiver hedge, has thrived. The hedge spread out
the runoff, giving it a chance to soak into the ground, which
resulted in an abundant crop of cotton.
Figure 10. With the vegetative system of soil and moisture
conservation, drainage benefits the crop. Runoff slows
down, spreads out, drops its silt load, and oozes through the
hedgerows, enabling a large portion of the water to soak into
the land along the way.
Photo 11. When the runoff drops its silt load, it builds up behind
the hedge, creating a natural terrace. The height of the terrace
in demonstrated here by the line of farmers; the one on the right
appears taller because he is standing on the terrace
Vegetative Contour Hedges
Figure 11 presents a crosssectional
view of a vetiver contour
hedge at work. The leaves and
stems of the vetiver plant slow
the silt-loaded runoff at A and
cause it to deposit the silt behind
the plant at B while the water
continues down the slope at C at
a much slower pace. The plant’s
spongy root system, pictured
at D, binds the soil beneath the
plant to a depth of up to 3 meters.
By forming a dense underground
curtain that follows the contour
of the land, the roots prevent
rilling, gullying,and tunneling.
The photo in Photo 11b shows
how the soil from the runoff
has been trapped above the
original topsoil behind the
vetiver hedge.
Photo 11b. This cross-sectional view of a two-year-old vetiver
hedge shows how about 60 cm of soil has been trapped above
the original dark band of topsoil
Figure 11. This cross-sectional
view of vetiver shows a vegetative
contour hedge at work.
The strong aromatic oil contained in vetiver makes the grass unpalatable
to rodents and other pests, and many Indian farmers report that it also
keeps rats from nesting in the area. Because the dense root system
repels rhizomes of grasses such as Cynodon dactylon, the hedgerows
prevent such grasses from entering the farm field and becoming a
weed. Another benefit of planting the hedgerows, according to the
farmers near Mysore, is that the plant’s sharp, stiff leaves keep away
snakes.
Figure12. With the vegetative system, the hedge grows
continuously, leaving no gaps for runoff to flood the crop.
Photo 12a. A vegetative system in Panama conserves soil and
moisture, protecting the crop
Photo 12b. In Costa Rica, a vetiver hedge hugs the contour of
the land, conserving soil and moisture and protecting the crop
To be effective as a method of soil conservation, the vegetative system
must form a hedge, as shown in Figure 12 and in Photos 12a
and 12b. Although under certain circumstances thick hedges can be
formed in one year, it generally takes two to three growing seasons to
establish a hedge dense enough to withstand torrential rains and protect
the soil. During the first two seasons, and sometimes the third,
the vetiver plants need protection, and any gaps in their line have to
be filled. (During the first two seasons it should also be easy to see
the silt being trapped behind the plants as they are establishing, a
phenomenon that extension workers should try to point out when explaining
the system to farmers.) Although the earth banks used in the
constructed method of soil conservation are effective immediately,
they break down over time and frequently burst open in heavy rainstorms.
Once a vegetative hedge has been established, it will neither
wear out nor require further maintenance, other than periodic trimming.
The photos in Figures 12a and 12b provide a good example of
this use of the Vetiver System.
Trimming the hedges to a height of 30 to 50 centimeters prevents them
from seeding and makes them thicken up, thereby increasing their
effectiveness in filtering runoff. In several villages and hamlets near
Mysore, the farmers trim their hedges every 2 weeks throughout the
year and feed the young palatable leaves (which are out of reach to the
rodents) to their livestock, often chopping them up and mixing them
with other fodder. They are thus ensured a year-round supply of stock
fodder regardless of rainfall.
Following the Contour
Many fieldworkers—and even research workers—lack a clear
understanding of what is meant by the contour. Figure 13a illustrates
a common misconception: that a furrow plowed along the main slope
follows the contour. This is incorrect.
A true contour embraces all slopes, major or minor; it is a line of equal
elevation around a hill. The furrows in Figure 13a, which starting from
point A, follow the main slope straight down to point C, instead of
curving around the hill; they are not on the contour and therefore will
neither conserve moisture nor prevent erosion. The true contour,
Figure 13a. With this false contour of the land, the furrows follow
the main slope straight down instead of curving around the hill.
This contour will not conserve soil or moisture
Figure 13b. With this true contour of the land, the furrows
embrace all slopes and maintain equal elevation all the way. This
contour will conserve soil and moisture.
Figure 13c. Earth banks, which must convey the runoff to a
waterway off to the side of they field, must be constructed
on the exact contour (marked with pegs at A), often making it
difficult for the farmer to follow when plowing. With vegetative
hedges, however, the contour can be averaged into a smooth
curve (line B)
pictured in Figure 13b, runs from A to B to D and continues around the
hill, maintaining equal elevation all the way.
Because constructed earth banks that conventionally are used to
control erosion must convey the runoff to a waterway off to the side of
the field, they have to be constructed on the exact contour As shown in
Figure 13c, such a line (marked with pegs at A) can be difficult for the
farmer to follow when plowing.
The vetiver hedges, however, do not have to be exactly on the contour
to provide effective soil and moisture conservation since their purpose
is to reduce the velocity of the water as it passes through them and not
to channel the water elsewhere. After the contour line has been pegged
in (see Figure 18a), the extension worker can smooth it out to make it
easier for the farmer to follow. In Figure 13c hedges and plow furrows
(crop lines) need only follow line B. The silt filtered from the runoff
will build up behind the hedges and eventually form a natural terrace.
Because the hedges run across the slope, the ends of each hedgerow
should be turned up the slope to prevent runoff from spilling around
the sides; this will encourage natural terraces to form more readily
and prevent erosion at the ends of the hedgerows, especially in steep
lands.
In Figures 14a and 14b and Photo 14 we see two farmers, A and B.
Both are good farmers, but farmer A in Figure 14a is a wise farmer; he
has protected his land against soil loss by planting vetiver hedges on
the contour, and he is using the hedgerows as guidelines to plow and
plant on the contour.
Figure 14a. On a protected farm, vegetative hedges planted on
the contour protect this land against soil loss. The hedgerows
serve as guidelines for plowing and planting on the contour,
creating furrows that will hold rainfall and store extra moisture
in the soil in anticipation of long periods of dry weather.
Photo 14. On a protected farm, vegetative hedges planted on
the contour protect this land against soil loss. The hedgerows
serve as guidelines for plowing and planting on the contour,
creating furrows that will hold rainfall and store extra moisture
in the soil in anticipation of long periods of dry weather.
Figure 14b. On an unprotected farm, plowed furrows that run
straight up and down the slope encourage the rainfall to run
off the farm, taking soil and farmyard manure for the ride and
moving so quickly that no water is soaked into the soil as a
protection against dry spells.
The furrows created in this fashion will hold rainfall and store extra
moisture in the soil, thus allowing crops to withstand long periods of
dry weather. What farmer A is doing costs no more than what farmer
B in Figure 14b is doing. All that is involved is a change in land
management.
Farmer B is a good farmer, but he is not farming wisely; he is not
thinking. By plowing just straight up and down the slope, even a very
gentle slope, he is encouraging the rainfall to run off his farm, taking
his farmyard manure (FYM) and an irreplaceable layer of topsoil
along for the ride. The rainwater runs off so quickly it does not have
a chance to soak into the soil, and thus his crops have no protection
against dry spells.
Figure 15a. When rain falls on the protected farm, the vegetative
hedges and the contour furrows protect the soil from running
off the land.
Figures 15a and 15b and Photo 15a illustrate what happens when
the two farming systems are exposed to heavy rainfall. Farmer A’s
field is protected by the vegetative hedges, and there is no loss of
soil (Figure 15a and Photo 15). The contour furrows store all the
rainwater they can hold. Any surplus rainfall runs off, but the vetiver
hedges control the flow—slowing it down, spreading the water
about—and cause the silt to be deposited. As a result, the runoff is
conducted down the slope in a safe, nonerosive manner.
Photo 15a. When rain falls on the protected farm, the vegetative
hedges and the contour furrows protect the soil from running
off the land. In this photo on India’s black soils you can see the
band of crop residue spread evenly behind the hedgerow
Figure 15b. When rain falls on the unprotected farm, the water
runs off at great speed, taking the topsoil and fertilizers with it
and eroding the soil as it moves along.
On Farmer B’s unprotected land, the rainfall runs off at great speed,
taking along his fertilizers and topsoil. The uncontrolled ride down the
slope causes unnecessary and damaging erosion (Figure 15b). Because
the runoff races by so quickly, no moisture is stored. Rainfall is only
40 to 50 percent effective, and farmer B is always complaining about
droughts. Ultimately he will have to abandon his farm because there
will be no soil left in which to grow crops. Farmer A will never have
this problem; his yields will increase over the years.
Photos 15b and 15c show the importance of land management for
moisture conservation in rainfed areas. Unlike irrigated farming, in
which farmers have complete control over their crops’ water needs,
rainfed farming is totally limited by the amount of rain that falls in the
area for the success or failure of the crops. By plowing and planting on
the average contour, rainfed farmers have a better chance of holding
the rain that falls in the field and in the
.
Photo 15b. Because rainfed farmers are limited to the amount
of rain that falls in their area for the success of their crops, they
must plow and plant on the average contour to hold the rain that
falls in the field and in the actual crop rows. The farmers also
need vetiver hedges to prevent an abundance of rainfall from
eroding the soil by spreading the runoff and giving it time to
soak into the ground.
actual crop rows, which means that the whole field benefits. In heavy
storms, when the crop rows cannot hold the rainfall, the vetiver hedges
prevent any damage from erosion by spreading the runoff out and
giving it time to soak into the ground.
Photo 15c. When farmers do not plow and plant on the average
contour, heavy rainfalls wash away the topsoil and farmyard
fertilizers. Without vetiver hedges to spread the runoff, giving
it time to soak into the soil, an abundance of rainfall erodes the
soil.
Thanks to his vetiver contour hedges, farmer A obtains an excellent
crop. (See Figure 16a and Photo 16) Because the soil has retained
ample moisture from earlier rains, his crop is benefiting from the
warm sunshine, all the grains are filling, and the crop stand shows
even growth. Farmer A will reap a high yield. In contrast, farmer B
has a disappointing harvest. (See Figure 16b.) His crop has all but
failed, and what little remains—growing in pockets where some
moisture was trapped—is being dried out by the sun. Only a small
percentage of the grain will fill, and the resulting crop is uneven.
Figure 16a. (left) On the farm with a protective vetiver grass
contour hedge, farmer A obtains an abundant crop. Figure 16b.
(right) On the unprotected farm, farmer B’s failing crop grows
only in pockets where some moisture was trapped; but the sun
will soon dry out the crop.
Photo 16. This is how an Ethiopian farmer followed Farmer
A’s approach. Excelklent maize crop planted on the contour,
protected by vetiver
Farmer B can expect a low yield. Yet he planted the same crop as
farmer A, used the same fertilizer, planted at the same time, and received
the same amounts of rainfall and sunshine. Unlike his neighbor,
however, farmer B lost most of his fertilizer, 60 percent of his
rainfall, and a layer of soil, possibly a centimeter thick, from his
farm—all because he did not plow on the contour and use vegetative
hedges to protect against erosion and help his cropland retain
moisture from the rain. If he had taken the advice of his extension
service and plowed and planted on the contour, farmer B could have
obtained the same high yields as farmer A. Photos 17a and 17b attest
to the success of crops that are protected by vetiver hedges.
Photo 17a. On a protected farm in Ethiopia, a vetiver hedgerow
protects a crop of maize.
Photo 17b. On a protected farm in China, vetiver hedgerows are
overwintering, protecting jojoba seedlings from soil and wind
erosion.
Having learned his lesson, farmer B contacts his extension worker, and
together they mark, or peg out, contour lines across the old furrows.
(See Figure 18a.) This simple process requires virtually no engineering
skills—only the use of a small hand-held level. The extension worker
stands at the edge of the field and, sighting through the level, has farmer
B move up or down the slope until the two people are standing level,
at which point the farmer marks the spot with a peg. In Figure 18a,
the contour line (X) has already been pegged out, and the farmer has
but to follow the line of pegs with his plow (as shown in Figure 18b)
to create the furrow in which to plant the slips of vetiver grass that
will eventually form a contour hedge. This is all that has to be done
to establish the vegetative system of soil and moisture conservation.
Photo 18 shows an extension worker and farmers working together to
peg out vetiver hedges on the contour.
Figure 18a. Farmer B and his extension worker peg out contour
lines along the old furrow.
Figure 18b. Farmer B plants on the contour.
Photo 18. An extension worker in Papua New Guinea pegs out
vetiver hedges on the contour.
Like any long-lived plant, however, the vetiver hedge system normally
takes two to three seasons to become fully effective. You cannot plant
a mango tree today and expect to pick mangoes next month, but it is
possible to get some immediate effect from the system by using dead
furrows as a preliminary step until such time as the vetiver grass can
be established.
The preliminary stage of establishing the vegetative system is
depicted in Figure 19a. While waiting for vetiver planting material to
be produced in the nursery, the farmer laid out the contours, prepared
seedbeds following the contour furrows, and every 5 or 6 meters
double plowed a dead furrow. The two dead furrows in the figure have
been planted on the contour to pigeon peas and intercropped with six
rows of groundnuts. The shape of each seedbed is show beneath the
crop illustration: DF marks the deeper dead furrow, PP the row of
pigeon peas it supports. Eventually, vetiver grass will be planted in
some of the dead furrows, but in the interim these furrows themselves
will provide a bit of protection against runoff. Planting the vetiver
grass will stabilize the whole system, as shown in Figure 19b, where a
vetiver hedge has taken the place of one of the dead furrows.
Figure 19a. The initial setup of vetiver hedges uses dead furrows
(DF) to support the pigeon peas (PP).
Figure 19b. To stabilize the system, the farmer has planted a
vetiver hedge in one of the dead furrows.
Establishing Vetiver Hedges
To establish a vetiver hedge, follow the step-by-step instructions that
appear on the next few pages, along with tips on handling the planting
material, advice about the best time to plant, and information about
what to expect after the grass is planted. The first step for establishing a
vetiver hedge is obtaining the planting material, usually from a vetiver
nursery. If vetiver grass is unknown in your area, check with the nearby
botanical gardens. Ask them to look up Chrysopogon zizanioides. If it
has been collected, the herbarium sheet will show what the plant looks
like, note where the specimen was found, and provide the local name
of the plant. Vetiver is found throughout the tropics and has been grown
successfully as far north as 42° latitude. Vetiver nurseries are easy to
establish. Inlets to small dams or water holding tanks make the best
nursery sites, because water en route to the dam or tank irrigates the
vetiver grass, which in turn removes silt from the water. Large gullies
protected with vetiver grass also make good informal nurseries. For
best results in establishing a vetiver nursery, the vetiver root divisions,
or slips, should be planted in a double or triple line to form parallel
hedges across the streambed. The hedgerows should be about 30 to 40
centimeters apart.
To remove a clump of vetiver grass from the nursery, as shown in
illustration A, Figure 20, dig it out with a spade or fork. The root
system is too massive and strong for the grass to be pulled out by hand.
Next, tear a handful of the grass, roots and all, from the clump (B).
The resulting piece, the slip, is what will be planted in the field (C).
In Photo 20, a Cambodian farmer has dug up a good clump of vetiver
– one doesn’t need much root. Before transporting the slips from the
nursery to the field, cut the tops off about 15 to 20 centimeters above
the base, and the roots 10 centimeters below the base (the old roots
do not regrow but act as an anchor). Cutting will improve the slips’
chances of survival after planting by reducing the transpiration level
and thereby preventing them from drying out. As shown in Figure 21a,
all that is needed to prepare the slips for planting is a block of wood
and a knife—a cane knife, machete, cutlass, or panga will do. The
finished planting piece is shown in Figure 21b.
Figure 20. The farmer digs out a
clump of vetiver grass from the
nursery (A), tears a handful of
grass and roots (the slip) from
the clump (B), and prepares to
plant the slip in the field (C).
Photo 20. This Cambodian
farmer has used a narrow
bladed spade, rather like a oil
plam fruit harvesting knife (the
latter is probaly the best tool
for the job) to dig up a plant
from a quality nursery
Photo 21a. The farmer trims the slips. Nice job, good quality
tillers
Figure 21a. (left )To prepare the vetiver for planting, the farmer
holds the slip on a block of wood and uses a knife to trim the
roots. Figure 21b. (right) The trimmed vetiver slip is ready for
planting
Although vetiver grass can be planted from single tillers (when
planting material is scarce), this practice is not recommended for grass
to be planted in the field, because it takes too long to form a hedge.
Fertilizing the slips with di-ammonium phosphate (DAP) encourages
fast tillering and is helpful both in the nursery and in the field. To do
this in the field, simply dibble DAP into the planting furrow before
planting the slips.
Figure 21c. The farmer plants the vetiver slips 10-15 centimeters
apart.
Photo 21b In Mexico, a farmer has correctly spaced planting
slips in a vetiver hedgerow.
Always plant the slips at the beginning of the wet season to ensure
that they get full benefit of the rains. Planting vetiver slips is similar
to planting rice seedlings. Make a hole in the furrow that was plowed
to mark the contour. Push the slip into the hole, taking care not to
bend the roots upward. Then firm the slip in the soil. Then 10 to 15
centimeters from the slip, along the same contour furrow, plant the
next slip, and so on. (See Figure 21c and Photo 21b)
Only a single row of slips need be planted. If planted correctly, the
slips can withstand up to one month of dry weather. Some slips may
die, however, and leave gaps in the hedge line. If possible, fill these
gaps by planting new slips. In some instances it may be possible to use
the live flower stems, or culms, of neighboring plants—simply bend
the culms over to the gap and bury them. The live stems will produce
roots and leaves at the nodes.
Figure 7-22a. If the farmer plants the slips too far
apart, it will take too long for the hedgerow to grow.
Figure 7-22b. In China, a farmer incorrectly spaced the
planting slips and the vetiver hedgerow never grew.
Of course for this or any vegetative system to work, the plant must form
a hedge; otherwise, the system cannot act as a barrier against soil loss.
Planting the slips too far apart (see Figure 22) would render the system
almost useless because it would take too long for the slips to grow
together to form a hedge. Photo 22 shows a hedge in China that was
planted in the wrong way. Even though the farmer had the extension
workers’ handbook showing the correct method for achieving a hedge
with vetiver and had advice in the field, he planted the slips too far
apart. This method of planting will never work as a method of soil
conservation, and the farmer will eventually abandon the system—not
because the system does not work, but because the farmer did not lay
it out according the instructions.
Moreover, without the extra support of a hedge to hold the soil,
fertilizer, and moisture against the vetiver grass, the plants would not
be able to survive the worst droughts. Even in arid areas that receive
less than 200 millimeters of rain a year, an effective vetiver contour
hedge could ensure its own viability. The combined effect of contour
cultivation and the hedge’s performance in slowing and spreading the
runoff is to increase infiltration of water into the soil. Thus the hedge
can help itself to what might be the equivalent of half again as much
rainfall.
For the system to provide maximum protection against erosion, the
hedgerows should be spaced apart at the proper vertical interval
(VI). The VI is the vertical distance from one hedgerow to the next
one down the slope. The actual distance measured along the ground,
called the surface run, depends on the steepness of the slope. With a
vertical interval of 2 meters, for example, the hedges on a 5 percent
slope would be about 40 meters apart, whereas those on a 2 percent
slope would be about 100 meters apart. As shown in Figure 23, the
surface run between hedgerows planted on a 57 percent slope with a
VI of 2 meters is about 4 meters. For a more comprehensive look at
the relationships among slope, surface run, and vertical interval, see
Table 7-2 at the end of this chapter. In practice, a VI of 2 meters has
generally been found to be adequate.
After the hedges have been established in the farm field, the only
care they will need is annual trimming to a height of about 30 to 50
centimeters to encourage tillering and prevent shading of the food
crops. When plowing for cropping, plowing along the edges of the
hedgerows will remove any tillers that encroach upon the field and
will thus prevent the hedges from getting too wide.
Moisture Conservation
Although measures to retain natural moisture in the soil are
essential to all rainfed-farming systems, the art of in situ moisture
conservation, as it is called, is rarely practiced and not widely
understood. There is no such thing as flat land; water runs off all
land. No matter how flat it may seem, all land must be contoured if
it is rainfed. Earth shaping, land leveling, and similar techniques are
required in irrigated areas only; rainfed areas must be contoured.
Figure 24 shows what happens when land is planted on the “flat”
without the benefit of contour furrows.
In view A, the rain runs straight off the field. View B shows the results:
because no moisture has been stored, the plants wilt and die in the sun.
View C shows the same area planted to contour furrows, with a pair
of dead furrows taking up the surplus runoff until the vetiver can be
planted. Rain caught and held in each furrow’s micro-catchment has
the chance to soak in. Each furrow can hold 50 millimeters of rainfall,
so in most storms there is no runoff. Thanks to this natural system of
Figure 23. The surface run between hedgerows planted
on a 57 percent slope with a vertical interval of 2 meters
is about 4 meters.
water storage, the plants can benefit from the sunshine, as shown in
view D. In view E, one of the dead furrows has been planted to vetiver
grass to stabilize the system.
Figure 24. When land
is planted on the flat,
rain runs straight off
the field (A), resulting
in land with no stored
moisture and plants
that wilt and die in
the sun (B). When
land is planted on the
contour, while waiting
for the time to plant
vetiver, dead furrows
take up the surplus
runoff (C), resulting
in a natural system
of water storage and
plants that enjoy both
the moisture and the
sun (D). When vetiver
grass is planted
in one of the dead
furrows, it stabilizes
the natural system
(E).
A vetiver grass hedge is the key to the in situ moisture conservation
system. Once established, it serves as a guideline for plowing and
planting on the contour, and in times of heavy storms it prevents
erosion from destroying the farmer’s field. The beauty of the plant is
that, once it has established, the hedge is permanent.
Figure 25a. This is what a system of vetiver hedges planted over
a large area would look like. Unlike a constructed system, the
Vetiver System requires no waterways and does not have to
spill into a drainage network.
Photo 25. The Vetiver System enables the farmer to plant vetiver
the full length of his field since the hedges do not convey runoff.
Figure 25 is a diagrammatic representation of what a vetiver grass system
would look like in a smallholder farming area. The Vetiver System
fits perfectly into the individual farm system, where no waterways or
earthworks exist. Most farmers have one line of vetiver roughly in the
middle of their fields, no matter what the shape; long fields may need
two lines to stabilize them. Although each field has its own line or
lines of vetiver, the entire hillside is protected against erosion because
each line protects the ones farther down the slope. Under this system,
once the hedges are established, no further protective work is needed,
and maintenance is minimal. The farmers each have their own supply
of vetiver planting material. Should a gully start to form anywhere, the
farmer obtains cuts slips of vetiver from an existing hedge and plants
it across the incipient gully to prevent its spread—permanently and at
no cost except for the farmer’s own labor.
Photo 25 shows vetiver hedges planted over a large area. Unlike a
constructed system, the Vetiver System requires no waterways, and
runoff does not have to spill into any drainage network. Because
they do not convey runoff, the hedges can be as long as any given
farmer’s field. The hedges spread out the runoff, providing moisture
conservation over the entire area. At the same time, the hedges filter
out the silt, enabling the excess runoff to flow harmlessly down the
slope.
Why Vetiver Grass Is the Ideal Plant for the Vegetative
System of Soil and Moisture Conservation
Although many grasses and trees have been tried over the years as
measures to prevent erosion, to date only vetiver grass has stood the
test of time. As made clear by the following list of its characteristics—
derived from observations of C. zizanioides throughout the world—
this truly remarkable plant is ideally suited for the vegetative system
of soil and moisture conservation. No other grass is known to rival its
hardiness or diversity.
C. zizanioides—
• When planted correctly, will quickly form a dense, permanent
hedge.
• Has a strong fibrous root system that penetrates and binds the
soil to a depth of up to 3 meters and can withstand the effects
of tunneling and cracking.
• Is perennial and requires minimal maintenance.
• Is practically sterile; because it produces no stolons or
rhizomes, it will not become a weed.
• Has a crown that is below the surface, which protects the plant
against fire and overgrazing.
• Has sharp leaves and aromatic roots that repel rodents, snakes,
and similar pests.
• Has leaves and roots that have demonstrated a resistance to
most diseases.
• Once established, is generally unpalatable to livestock. The
young leaves, however, are palatable and can be used for fodder.
(In Karnataka, India, a cultivar of V. zizanioides selected by
farmers has softer leaves and is more palatable to livestock.
This cultivar is also denser, less woody, and more resistant to
drought than some of the other available cultivars.)
• Is both a xerophyte and a hydrophyte, and once established,
vetiver grass can withstand drought, flood, and long periods
of waterlogging.
• Will not compete with the crop plants it is used to protect,
and in fact, vetiver grass hedges have been shown to have
no negative effect on—and may in fact boost—the yield of
neighboring food crops.
• Is suspected to have associated nitrogen-fixing mycorrhiza,
which would explain its green growth throughout the year.
• Is cheap and easy to establish as a hedge and to maintain—as
well as to remove if it is no longer wanted.
• Will grow in all types of soil, regardless of fertility, pH, or
salinity, including sands, shales, gravels, and even soils with
aluminum toxicity.
• Will grow in a wide range of climates and is known to grow
in areas with average annual rainfall between 200 and 6,000
millimeters and with temperatures ranging from -9º to +50º
Centigrade.
• Is a climax plant; therefore, even when drought, flood, pests,
disease, fire, or other adversity destroy all surrounding plants,
the vetiver will remain to protect the ground from the onslaught
of the next rains.
NOTE: THESE CHARACTERISTICS APPLY TO
THE NON FERTILE CULTIVARS OF C. zizanioides
ORIGINATING FROM SOUTH INDIA.
Other Practical Uses for Vetiver Grass
Apart from its success as a system of soil and moisture conservation,
vetiver grass has proved effective for a variety of other purposes.
Stabilizing terrain and structures. One of the most important uses
of vetiver grass is stabilizing the terrain and structures such as dams,
canals, and roadways.
Figure 26. Vetiver
can be used to
stabilize a paddy
field
Figure 26, for example, shows how vetiver can be used to stabilize a
typical paddy field that relies on earth banks to keep irrigation water
at the correct level. These banks (top illustration) can be worn down
by the action of wind-churned water (lap erosion) and the activities
of rats, crabs, and other hole-burrowing pests. The subsequent largescale
erosion, not to mention the loss of expensive and in some cases
irreplaceable irrigation water, could lead to loss of the crop.
Vetiver can be planted on top of the paddy banks to stabilize them
(bottom illustration). Vetiver grows well under these conditions and
does not suffer from the occasional inundation of water. In addition,
vetiver roots contain an essential oil that repels rodents. Furthermore,
because its roots grow straight down and not out into the crop, the grass
has no negative effect on the rice or its yield. Each year the vetiver can
be cut back to ground level to prevent shading of the crop.
Figure 27. (above) Vetiver
protects riverbanks by
preventing river levees from
being eroded back into the
fields.
Photo 27. (right) In Zimbabwe,
vetiver protects a riverbank.
In another example, vetiver can be used to maintain river levees by
preventing them from being eroded back into the fields. (See Figure
27 and Photo 27). It can also be used on river flats to prevent silt from
entering the watercourse from the runoff of surrounding fields.
Establishing tree crops. Vetiver’s stabilizing influence is especially
useful in steep and rolling country, where the distribution of moisture
cannot be controlled. Unsuitable for the cultivation of cereal or other
annual crops, such areas, when stabilized by vetiver grass, can be successfully
planted to perennial tree crops on the contour. Most attempts
to grow tree crops on steep hillsides are abandoned because the resulting
poor, uneven stands are not worth the cost of maintenance.
Figure 28. A vetiver grass hedge nurtures a fruit tree on a hill.
Figures 28 and 29 show a method of establishing tree crops on such
hills using contour vetiver hedges. First the contours of the hill are
pegged out. Next, by hand or with a bulldozer and ripper unit, the
farmer digs shallow V ditches along the contour lines. A row of trees is
planted close to the edge of each ditch, and vetiver grass is planted
in the ditches.
Photo 28 Vetiver hedges stabilize tree crops.
Under this arrangement of planting, the runoff between one row of
trees and the next one down the slope collects in the vetiver-lined
ditches (there is usually sufficient drainage on the slopes to preclude
the possibility of waterlogging). Thanks to the effects of such water
harvesting, the rows of trees do not have to be planted as close together
as the trees within a row. Initially, the V ditch will provide a measure
of runoff control, thereby increasing the soil’s moisture content, and
both the vetiver and the planted trees will benefit. By the time the
ditch “melts” away after a couple of years, the vetiver hedge will be
established and performing its function of increasing the infiltration of
runoff, halting the loss of soil and soil nutrients, and creating a natural
terrace.
Because the collection of runoff in the contour ditches has the effect
of doubling or tripling the amount of effective rainfall, fruit trees
planted by this method need no irrigation in the first three years of
establishment. The vetiver grass lines stabilize the whole system.
Photos 28 and 29 show the success of such systems.
Figure 29. Vetiver hedges stabilize tree crops.
Photo 29 . In Malaysia, vetiver hedgerows protect young rubber
trees on steep, stony slopes.
Mulching. After the vetiver hedges are properly established, the
farmer can cut down the vetiver grass to ground level when the dry
season sets in and use its leaves as mulch at the base of the fruit trees
to help retain stored moisture. (See Figure 30 and Photo30). The
advantage of using vetiver for this purpose is that its leaves harbor few
insects and last well as mulch. Vetiver hedges also protect the young
trees in the hot summer months by providing some indirect shade; in
the colder winter months the hedges act as windbreaks.
Figure 30. Mulch cut from vetiver hedges holds moisture for the
fruit trees, repels insects, prevents fungal disease, and outlasts
other mulches.
Photo 30. On a coffee plantation, vetiver mulch controls pests
and improves moisture availability, which is essential for high
production.
Establishing forests. Forest trees should be planted by the same
method as when establishing tree crops—on the contour and, if
possible, in V ditches bordered by vetiver hedges to stabilize them.
Where this has been done, the results have been spectacular: more
than 90 percent of the seedlings planted by this method survived the
1987 drought in Andhra Pradesh, India, whereas 70 percent of the
other seedlings died.
Stabilizing masonry walls for hill farming. In the Indian
Himalayan highlands, where farming is carried out on terraces,
vetiver grass is now being used to stabilize the masonry risers that
have been erected over the centuries. The walls pictured in the photo
in Figure 31 need all the support they can get to withstand the seas
whipped up by typhoons, and during tropical storms, to withstand
the massive damage caused by runoff from associated torrential rain
pouring over the walls, and even through the walls, from the catchment
above. The hedges in the photograph have withstood the rigors
of a typhoon that destroyed other walls in the area that were not protected
by vetiver hedges.
Without some form of vegetative support, these ancient structures
require continual maintenance. If one riser washes out during a heavy
storm, other terraces farther down the slope often suffer considerable
damage because of the domino effect. Photo 31 and Figure 31a,
depict a typical terrace system in the hills, shows the type of damage
frequently sustained. To allow for drainage between the stones, the
masonry risers are not bound together with mortar. If the walls were
solid, instead of just a small section falling out, the whole wall might
collapse and trigger a landslide that could destroy the entire farm.
Although these terraces have done an excellent job through the years,
they do exact a toll in the form of crop losses, and they require a lot
of hard work in repairs.
When we explained the Vetiver System of stabilization to the hill
farmers, they wanted to plant as many areas as possible. In a World
Bank project begun in 1986, vetiver grass was planted along the edge
of the terraces during the rainy season in the hope that its strong root
system would reinforce the masonry risers. It worked perfectly.
Figure 31b shows what the vetiver grass-protected terraces should
look like once established. The grass is planted only at the extreme
edge of each terrace so the hedges do not impede the essential
Photo 31. In the Himalayan highlands terraces are frequently
washed out by concentrated flows of run-off water.
Fig 31a. A terrace
system in the hills
can easily be washed
out during the rainy
season.
drainage between the stones. According to the farmers, what causes
most of the damage during heavy storms is the cascading of water
down the slopes and over the top of the masonry terraces, especially if
the water has a chance to concentrate into a stream. Once established,
the vetiver hedges should take most of the erosive power out of this
runoff as well as protect the edge of the terrace.
Figure 31b. Vetiver grass, planted on the extreme edge of each
terrace, stabilizes the terraces without interfering with the
essential drainage between the stones.
Figure 31c. The vetiver root system stabilizes the entire rock
face of the vulnerable masonry risers.
As shown in the close-up in Figure 31c, the masonry risers are
vulnerable because they are simply stones stacked on top of each other
and are usually 2 to 3 meters high. Because its strong root system can
easily penetrate to the bottom of the risers, vetiver grass can be used
to protect the entire rock face.
In another project in the Himalayan highlands, in areas with no masonry
terraces to halt massive sheet erosion, vetiver grass contour lines are
being established to determine whether the natural terraces that build
up behind the hedges will form a base of stable land for the production
of fuel wood and fodder crops. In China, in the provinces of Jiangxi
and Fujian, vetiver grass hedges are now being used to protect the
edges of citrus and tea terraces.
Protecting roads. Vetiver grass is also used to protect road cuttings,
as shown in Figure 32. People in St. Vincent in the Caribbean use it to
line the outer edge of the tracks to their houses. The grass has exhibited
a remarkable ability to grow in practically any soil. In Andhra Pradesh,
India, for example, it was observed growing at the Medicinal and
Aromatic Research Station at the top of a bare hill. Even though the
soils on that hill are skeletal—granite boulders had to be In the West
Indies, the plant has been used extensively for stabilizing roadsides and
has completely prevented erosion for years. bulldozed to make a plot
for the grass—and are deprived of most of the benefits from rainfall
(since they are located at the very top of the hill), and at the time
supported no other form of growth, the vetiver grass showed no signs
of stress. A plant that can thrive under these extreme conditions should
be able to do an excellent job of stabilization almost anywhere.
Figure 32. Vetiver hedges
stabilize roadsides.
Photo 32a. In Malaysia, vetiver hedgerows stabilize country
roads for minimal cost and maintenance.
Photo 32b. In Malaysia, vetiver hedgerows stabilize high-cost
highways.
Photos 32a and 32b show how vetiver grasses have been used in
Malaysia to protect roads. In Figure 32, the hedgerows stabilize the
slopes of country roads. Once the hedges are established, the roads
are fully stabilized and do not slip. The cost to establish the hedges is
minimal, and the maintenance is even less. The same Vetiver System
is used to stabilize high-cost highways, as shown in Photo 32b.
Stabilizing wasteland development. The use of vetiver grass in
wasteland development has recently been tested, and vetiver has
proved effective as the initial stabilizing plant. In the Sahel region of
Africa (in the state of Kano, Nigeria) and in Bharatpur in central India,
under the extreme conditions of constant fire and drought, V. nigritana
and V. zizanioides, respectively, have survived as the climax vegetation
for hundreds of years. When planted as contour hedges in wasteland
areas—the first stage in stabilizing such areas—V. zizanioides reaps
the benefits of any surplus runoff and harvests organic matter as it
filters the runoff water through its hedges. Because the foothills of
the Indian Himalayas are very young geologically, they are highly
erodible; planting vetiver contour hedges around these slopes and then
across the short erosion valleys will stabilize these areas. A masonry
plug at the end of the system allows silt to build up and give the grass
a basis of establishment. (See Figure 33.)
Figure 33. Vetiver hedges stabilize wasteland areas
slopes of country roads. Once the hedges are established, the roads
are fully stabilized and do not slip. The cost to establish the hedges is
minimal, and the maintenance is even less. The same Vetiver System
is used to stabilize high-cost highways, as shown in Photo 32b.
Stabilizing wasteland development. The use of vetiver grass in
wasteland development has recently been tested, and vetiver has
proved effective as the initial stabilizing plant. In the Sahel region of
Africa (in the state of Kano, Nigeria) and in Bharatpur in central India,
under the extreme conditions of constant fire and drought, V. nigritana
and V. zizanioides, respectively, have survived as the climax vegetation
for hundreds of years. When planted as contour hedges in wasteland
areas—the first stage in stabilizing such areas—V. zizanioides reaps
the benefits of any surplus runoff and harvests organic matter as it
filters the runoff water through its hedges. Because the foothills of
the Indian Himalayas are very young geologically, they are highly
erodible; planting vetiver contour hedges around these slopes and then
across the short erosion valleys will stabilize these areas. A masonry
plug at the end of the system allows silt to build up and give the grass
a basis of establishment. (See Figure 33.)
Figure 34. Vetiver hedges stabilize gullies.
The same would apply to normal gullies as shown in Figure 34. Once
established, the grass would fill and terrace the gullies with silt. In an
upland area of Fiji, as shown in Phpto 34, a gully was stabilized with
vetiver grass some 30 years before the photo was taken. In the photo,
the gully is fully stable and the hedges remain where they were
originally planted.
Photo 34. In this upland area of Fiji, some 30 years before
this photo was taken, this gully was stabilized with vetiver
hedgerows, which still remain where they were originally
planted
Stabilizing riverbanks and canal walls. Using vetiver grass to
stabilize riverbanks and canal walls is another recommended practice.
In an experiment in Tanzania, on the road to Dodoma, a road engineer
used vetiver grass to protect the wing wall of a bridge on one side of the
river and constructed the usual concrete wing wall on the other side.
Some 30 to 40 years later, the concrete wall had already collapsed into
the river, and the bank it was protecting was eroded. On the other side,
the vetiver grass was still holding the bank in perfect shape. Figure
35shows how vetiver grass can be used to protect the river approaches
to a bridge. The success of the Vetiver System is evident in Photo 35,
where newly planted vetiver hedges protect the approaches to a small
bridge in El Salvador. During the floods of Hurricane Mitch in 1998,
this bridge did not wash out.
Figure 36 shows how vetiver grass can be used to protect the banks
of a major irrigation canal. In Bangladesh, as seen in Photo 36, the
canal has been stabilized with vetiver hedgerows for decades, and the
plants do not invade the river or the fields behind the rows.
Figure 35. Vetiver hedges protect the river approaches to
bridges.
Photo 35. In El Salvador, newly planted vetiver hedgerows
protect the approaches to a small bridge.
The contour irrigation aqueducts that lead back from the main canal
around the foothills to the upper reaches of a command area suffer
from siltation and erosion as they wind their way around the slopes.
The typical problem is depicted in the top illustration in Figure 37the
concrete conduit is undercut by erosion at point A and fills with
Figure 36. Vetiver hedges protect irrigation canals.
Photo 36. In Bangladesh, vetiver hedgerows have stabilized this
canal for decades.
silt at point B. To overcome this problem, vetiver grass should be
planted parallel to the upper and lower sides of the concrete conduit.
As shown in the bottom illustration, the upper hedge will prevent
silt from entering the canal, while the lower two hedges will prevent
erosion and thereby keep the concrete structure from being undermined
by rills or gullies.
Figure 37. Vetiver hedges protect irrigation channels.
Photo 37. On a sugar farm in Zimbabwe, a vetiver hedgerow
protects an irrigation channel (behind the hedge), while other
rows protect the drain.
On a sugarcane farm in Zimbabwe, as seen in Photo 37, the left side
top vetiver hedge is protecting an irrigation channel from silting up
behind the hedge, while the other rows protect the drain from erosion
and silting and help maintain its shape.
Protecting dams. A similar approach can be taken to protect dams.
Small dams are silting up at an alarming rate throughout the world.
Once they become filled with silt, they are of no further use—and in
many cases there is no other site suitable for a new dam. If vetiver grass
is planted around the sides of the dam, as shown in the top illustration
in Figure 38, the silt carried by runoff from the surrounding hills will
be trapped before it reaches the dam. Vetiver hedges planted across the
inlets (A) of small dams on intermittent streams will protect the dams
from siltation. In time, these hedges will form stable terraces that can
be used for cropping or tree planting. In the bottom illustration, vetiver
has been planted on the walls of a dam to protect them from being
worn down by rill erosion, a problem afflicting many unprotected
earth dams around the world.
Figure 38. Vetiver hedges protect dams.
To make it easier to spot seepage along the toe, or very bottom of dam
walls and canal banks, vetiver should not be planted in those areas.
Photo 38a shows a small farm reservoir in India around which the
farmer planted vetiver grass to protect the reservoir from wave action
(lap erosion). Photo 38b shows a dam wall in Zimbabwe on which
vetiver provides complete protection and stabilization.
Photo 38a. Vetiver grass planted around the shore of a small
farm reservoir protects the reservoir from wave action.
Photo 38b. Vetiver grass planted around the shore of a small
farm reservoir protects the reservoir from wave action.
Common applications. The versatile vetiver plant has numerous
common applications as well. It makes good bedding for livestock,
because it soaks up the urine and stays dry longer. Ultimately, it
makes good compost. In countries with strong winds, vetiver grass
hedges make good windbreaks to protect young fruit and timber
trees. The grass when green also serves as a firebreak. Vetiver is used
as mulch for tree crops and as thatch for roofs of houses, sheds, and
shelters. (See Photo 39). The grass is woven into baskets, and other
habdicrads, and the leaf midribs and flower stems make excellent
brooms.
Photo 39. In Zimbabwe, vetiver grass thatch is popular. With
good thatching techniques, vetiver thatch will last for many
years.
Photo 39. Vetiver is a very god source of materialfor handicrafts.
This “bird” is made by Venezuelan ladies.
Management Tips
In the preface of the first edition of the handbook, we asked users to
give us their views and share their experiences. Below are some of
the responses we received.
General observations
• Well-grown vetiver hedges result in less runoff and improved
groundwater supplies. Dry-season stream flow improves
under the hedge system of in situ moisture conservation.
• In most instances on slopes of up to 5 percent, about 10
centimeters of silt is deposited behind the hedges annually.
• In addition to its use for soil and moisture conservation, vetiver
is being used for fodder, thatch, mulch, livestock bedding,
windbreaks, roadside protection, and brooms.
• Where hillside crop drainage is required—as in the case of
tobacco ridges on a graded slope—vetiver hedges act as an
excellent buffer against erosion if placed on the contour at
fixed intervals on the hillside.
• Most vetiver plant roots grow straight down for at least 3
meters. Other roots will grow out into the field for up to 50
centimeters, but they do not significantly affect crop growth—
probably because of the high moisture content of the soil
associated with the hedge.
• Vetiver hedges take about three years to be fully effective
under low rainfall conditions. If vetiver slips are planted 10
to 15 centimeters apart, the hedge will form more quickly.
Even where gaps exist, interplant erosion does not seem to be
a problem because the roots join together in the first year to
form a subsurface barrier.
• Where vetiver is planted along the edge of terraces, forwardsloping
terraces are better than backward-sloping terraces
because less runoff is removed by the terrace back channels.
Also because one can dispense with the back channel—and
also in some instances the front channel, where constructed—
more land will be available for cropping. The ultimate objective
should be to dispense with terracing, where possible, through
the use of vetiver hedges, so that the topsoil can remain
relatively undisturbed.
• Vetiver has been observed growing under conditions ranging
from 200 to 6,000 millimeters of rainfall annually and at 2,600
meters above sea level. It survives snow and frost (in tropical
mountain areas) and grows on most types of soil. It obviously
grows better where the soil is moist and fertile, but even under
adverse conditions it grows extremely well compared with
other grasses.
• In many countries vetiver has been infected with brown spot.
The disease does not seem to have an adverse effect on its
growth, however. A few instances of black rust have been
observed but are not significant. In India the rust seems to
be vetiver-specific and does not cross-infect other plants. In
China stem borers have attacked vetiver, but in most cases
the borer dies once it gets in the stem. Farmers generally are
unconcerned and tend to respond by selecting plants that are
more pest and disease resistant.
• Some early results from India, on both alfisols and vertisols,
indicate that rainfall runoff was reduced from 40 percent to 15
percent (compared with the control), and silt loss was reduced
from 25 tons per hectare to 6 tons per hectare (all for 2-yearold
hedges on 2 percent slopes). The time to wilting in one
demonstration on alfisols increased from 7 days to 20 when in
situ moisture conservation measures were applied.
• An interesting technique observed in China was the plaiting,
or interlacing, of vetiver leaves and stems from separate,
neighboring plants to create a temporary barrier until the full
hedge could be established.
• The cost of vetiver hedges depends on the availability and
cost of planting material. In India the initial cost of hedge
establishment is estimated at US$8 per 100 meters of hedge,
US$6 of which goes for planting materials and other inputs.
Once the live material, in the form of a hedge, is on the farm,
the cost to produce new hedges is relatively low—it may be
as little as US$2 per 100 meters. Under such conditions the
economic rate of return is more than 100 percent. Where the
slopes are less than 5 percent and the hedges are spaced about
40 meters apart, 250 meters of hedge is required per hectare
at a cost of between US$5 and US$20. (See Table 7-3 at the
end of this chapter.)
Selecting planting material
• In Karnataka, India, to date six cultivars have been identified.
One cultivar selected over the years by farmers exhibits
superior characteristics for hedge formation; fodder; and
insect, disease, and drought resistance.
• When selecting material, choose plants that exhibit resistance
to pests and diseases and that tiller well.
• Where winters are cold, select material that is more tolerant
of cold temperatures.
Establishing nurseries
• Vetiver planted densely in large gullies can be used for
replanting elsewhere. Gullies make good informal nurseries
because often they are permanently moist and have conditions
good for growth.
• Stem and root cuttings grown under plastic may be a cheap
way of vegetative propagation.
• For optimum tillering, nurseries should be fertilized (150
kilograms per hectare of nitrogen) and irrigated (especially in
very dry areas).
• Nursery plants should be cut back to about 30 to 50 centimeters
to encourage tillering.
• The best nurseries seem to be in loamy sands to sandy-clay
soils where the drainage is good and where it is easy to dig up
the plants for transplanting. We have seen excellent nurseries
(when well watered) in sandy areas near perennial rivers.
Field Planting
• As long as the vetiver is planted when the ground is wet, it
can survive a long period of drought after planting.
• On very small farms and fields where land is scarce and
where farmers are reluctant to plant across their fields,
vetiver should be planted on the field boundaries.
• On non-arable lands that are heavily eroded, vetiver should
be planted first in the gullies and around the gully heads. The
material from the gullies can then be used for planting across
the slopes in subsequent years.
• Gap filling is essential and should be done at the beginning
of the wet season. The possibility of “layering” live stems
across the gaps should be tried as a gap-filling measure.
• To encourage tillering and hedge thickening, the grass
should be cut back to 30 to 50 centimeters after the first
year. Cutting in the first year does not seem to have any
incremental impact on tillering.
• Termite infestation (attacking dead material) can be
controlled by applying 1 kilogram of benzene hexachloride
(BHC) for every 150 meters of hedge line.
• Once the vetiver has established (one month after planting),
plowing a small furrow immediately behind the vetiver
hedge line helps to capture runoff and results in better
growth of the plant.
Table 1. Slope, Surface Run, and Vertical Interval
Slope
Gradient
Surface runa
Degrees Percent (meters)
1 1.7 1 in 57.3 57.3
2 3.5 1 in 28.6 28.7
3 5.3 1 in 19.1 19.1
4 7.0 1 in 14.3 14.3
5 8.8 1 in 11.4 11.5
6 10.5 1 in 9.5 9.6
7 12.3 1 in 8.1 8.2
8 14.0 1 in 7.1 7.2
9 16.0 1 in 6.3 6.4
10 17.6 1 in 5.7 5.8
11 19.4 1 in 5.1 5.2
12 21.3 1 in 4.7 4.8
13 23.1 1 in 4.3 4.5
14 25.0 1 in 4.0 4.1
15 27.0 1 in 3.7 4.0
16 28.7 1 in 3.5 3.6
17 30.6 1 in 3.3 3.4
18 32.5 1 in 3.1 3.2
19 34.4 1 in 3.0 3.1
20 36.4 1 in 2.8 3.0
21 38.4 1 in 2.6 2.8
22 40.4 1 in 2.5 2.7
23 42.5 1 in 2.4 2.6
24 44.5 1 in 2.3 2.5
25 46.6 1 in 2.1 2.4
26 48.8 1 in 2.0 2.3
27 51.0 1 in 2.0 2.2
28 53.2 1 in 1.9 2.1
29 55.4 1 in 1.8 2.1
30 57.7 1 in 1.7 2.0
31 60.1 1 in 1.7 2.0
32 62.5 1 in 1.6 1.9
33 65.0 1 in 1.5 1.8
34 67.5 1 in 1.5 1.8
35 70.0 1 in 1.4 1.7
36 72.7 1 in 1.4 1.7
37 75.4 1 in 1.3 1.7
38 78.1 1 in 1.3 1.6
39 80.1 1 in 1.2 1.6
40 84.0 1 in 1.2 1.6
41 87.0 1 in 1.2 1.5
42 90.0 1 in 1.1 1.5
43 93.3 1 in 1.1 1.5
44 96.6 1 in 1.0 1.4
45 100.0 1 in 1.0 1.4
a. The figures for the surface run are based on a vertical interval (VI) of 1 meter. To use this table,
multiply the surface run by the VI; for example, with a VI of 2 meters on a 70 percent slope,
the surface distance between vegetative barriers = 2 x 1.7 = 3.4 meters.
Table 2. Cost of Land Treatment with Contour Hedges of Vetiver Grass
by Slope Classification and Cost of Labor
(U.S. dollars per hectare)
Slope
(percent)
Daily cost of labor
$0.50 $1.00 $1.50 $2.00 $2.50 $3.00
0–1 2.43 3.44 4.45 5.46 6.47 7.48
1–2 7.29 10.32 13.35 16.38 19.40 22.43
2–5 17.02 24.08 31.15 38.21 45.28 52.34
5–10 36.46 51.60 66.74 81.88 97.02 112.17
10–15 60.77 86.00 111.24 136.47 161.71 186.94
15–20 85.08 120.40 155.73 191.06 226.39 261.72
20–30 121.54 172.01 222.48 272.95 323.42 373.89
30–40 170.15 240.81 311.47 382.12 452.78 523.44
40–50 218.77 309.61 400.46 491.30 582.15 672.99
50–60 267.38 378.41 489.45 600.48 711.51 822.55
60–70 316.00 447.22 578.44 709.66 840.88 972.10
70–80 364.61 516.02 667.43 818.84 970.25 1,121.66
80–90 413.22 584.82 756.42 928.02 1,099.61 1,271.21
90–100 461.84 653.62 845.41 1,037.19 1,228.98 1,420.77
Note: Figures are based on a vertical interval of 2 meters.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s