In some countries, vetiver was developed or tested as an erosion control completely independent of the World Bank efforts in Asia. These experiences add new insights into the merits and wider applicability of those described in the introduction. Moreover, they are in other parts of the world and in quite different types of sites. Thus, they form a complementary set of case histories that tend both to enhance and qualify those described earlier. Six examples are discussed below
In 1989 Fort Polk faced a problem. This army base in Louisiana ("home of the Fighting Fifth Infantry, Motorized") is located at the headwaters of three scenic streams, which were filling with silt as tanks on training maneuvers ripped up the land.
The desecration of these pristine waters not only raised the ire of local communities, it threatened to bring down the heavy hand of civilian authority. Accordingly, army engineers laid check dams across the streams. That, however, did not solve the problem: after the numerous summer thunderstorms, turbid waters sluiced right over the top and muddied the streams as much as before.
Then Mike Materne, the local U.S. Soil Conservation Service agent, was brought in. By coincidence, he had just heard about vetiver. With little hope that it would do much good, he obtained some plants. (Possibly, they were remnants of some grown on Louisiana plantations before the Civil War and were still surviving, despite a century of neglect.)
His pessimism was all the more justified because the sites to be protected seemed hostile to any vegetation: the soil was down to almost bedrock ("C horizon"), the little that remained was very acidic (pH 4.0–4.2), and it contained virtually no fertility. But Materne
decided to give vetiver a try—it would be more of a survival test than an erosion-control experiment, he thought.
Accordingly, Materne grew vetiver slips in large pots in a greenhouse, and in the spring of 1990 planted them side by side on the bare and barren slopes immediately above each check dam. He wanted to establish the hedges quickly, and so he dropped a tablet of slow-release fertilizer beside each plant. His hope was that any hedges that formed might filter the turbid waters and thereby stop dirt from ever defiling the dams.
Because of the siting of the dams, some of the vetivers had to be planted into waterlogged soil (owing to a recent downpour, they were standing in water when Materne left the site). Others had to be planted into pure sand, described by Materne as "drier than popcorn." To make matters worse, a gully-washer barrelled through before the plants had a chance to establish deep roots. The speeding water knocked out some and scoured out the soil around others.
Despite all these hazards, however, most of the plants in each of the four sites, from the wettest to the driest, survived. Moreover, a few of them withstood yet another adversity when a freak fire swept through one of the plantings. It scorched and even killed surrounding pine trees, but the vetivers all survived.
In fact they did more than survive—they thrived. In 8 weeks some were almost 2 m tall. In 10 weeks they had grown together into hedges. And on one site, more than 20 cm of sediment had built up behind the thin green line of grass. Some plants held back such a load that after a storm they were temporarily bent over, almost hidden beneath a "sandbar."
By that time the hedges were so effectively filtering the runoff that the old flow of mud and silt down the streams was largely cut off. The check dams were receiving mostly clear water and were functioning as designed: temporarily holding back surplus runoff for later release into the streams.
When first hearing of Materne's proposal to plant vetiver, the local county agent vehemently disapproved, arguing that introducing an exotic plant to the watersheds might create an uncontrollable weed problem. But he was mollified—even overjoyed—when native grasses, wildflowers, shrubs, trees, and vines came crowding in behind the hedges and grew to revegetate the site. He even declared that nothing like it had been seen in the area before.
By that time it was clear that vetiver was acting as much more than an erosion trap; it was a "nurse plant" that was protecting other species and thereby giving these devastated watersheds a chance to heal themselves. Whether because of better soil moisture or the captured silt, the combination of hedges and revegetated slopes solved what had seemed an intractable erosion problem little more than a year before.
Tall, lush, and rising abruptly from the sea, St. Lucia is a prominent island of the Windward chain in the West Indies. Vetiver has been there for perhaps a century and has been reducing soil loss on the volcanic slopes for at least half a century.
Today, vetiver is seen almost everywhere. As one St. Lucian explains, "Around here, people take on to it. The first thing they do when opening a new farm plot is to plant khus [vetiver] along the tracks leading to the plot."
Much of the vetiver seen today results from government interest in the past. From the late 1920s to the 1940s, for example, the government encouraged people to plant the grass. There was no formal policy, but the colonial agent would commonly push for it when he met with large landowners to play a little poker and discuss the latest farming techniques. Farmers on the periphery of the big estates imitated the large landowners, and thus the technique spread. To help the process along, several vetiver demonstration plots were established at Mon Repos.
Today, the grass is sometimes found planted along the contours of hill slopes, where it functions much as the World Bank describes in India and Fiji. But more often, it is planted along the lower side of the swales (locally known as "drains" or "trained gullies"), which are ditches designed to carry excess water safely off the slopes. There, it reinforces the dirt walls to stop rushing runoff from bursting through.3 Householders also use it to prevent mud and water from invading their backyards.
Although vetiver is well behaved and much sturdier than other grasses, hedges that are not maintained are said to "deteriorate." As one St. Lucian notes: "The unruly portions must be trimmed and the discipline maintained."
For instance, if the edges aren't cut back, the hedge may become ragged, perhaps because a few plants are unusually rambunctious or because the soil is of uneven quality. Some hedges may break up into clumps. Also, in some old and neglected plants, the centers die out. A timely topping helps keep them "tight."
The plant is easy to trim or top. Surplus vegetation is normally cut off with a shovel or machete. However, vetiver's roots loosen the soil so well that cutting back a hedge on the downslope side can expose highly erodible dirt to the elements.
Nowhere on St. Lucia are the plants considered weeds, and seldom do they spread beyond the hedges. Seedlings are never seen, although newly planted slips sometimes washout and establish themselves down the slope, where they may look like errant seedlings. By and large the hedges seem to have little effect on neighboring crops, but plants immediately next to an old vetiver hedge sometimes exhibit a reduction in growth.
Another minor problem is that a small shrub—locally called "tibaume" (Croton astroites)—can overcrowd older hedges. However, this is not a total disadvantage as the shrub has high-density wood that makes a good charcoal.
One hazard to which the hedges are immune is St. Lucia's fearsome feral goats. These animals are so destructive that people say "all goats' mouths are poisonous." The problem is especially bad at the end of the dry season, when grasses have been grazed out and the goats have started on the trees. The animals, however, graze around vetiver, and the erosion control is unaffected.
In recent decades it is not goats but people who have destroyed many of St. Lucia's vetiver hedges. "Now everyone wants to be very modern and build a wall," says one disgusted observer. "The trouble is, it's more expensive and less effective."
Another resident notes that: "Years ago—when khus was everywhere and the slopes were forested—rivers ran year-round, but now in places they aren't running at all in the dry season because the soil is gone. People are building up on the slopes, and there is more and more water charging down in the rainy season. Everything gets mucky, but everyone wants a house!"
More vetiver, it seems, might be the solution—as it was in the past.
In 1956, the National Botanic Gardens (NBG)5 in Lucknow initiated what seemed a pointless endeavor: a major effort to reclaim a patch of usar soils. These soils, which cover nearly 7 million hectares of India, are so alkaline and salty that they have long been classified as unfit for agriculture.
However, the director of the NBG, K.N. Kaul, decided to tackle the impossible. He began his project around the village of Banthra (just outside Lucknow, on the Kanpur road), where many hectares of usar soil had been lying unused for years.
To those who saw the area, the prospect of producing anything useful appeared bleak. The soil was bare, hard, and highly eroded. Hard pans had surfaced in places, and a thick crust of sodium clay stretched as far as the eye could see. The alkalinity was extreme (as high as pH 11) and just 1 m below the surface was an impermeable layer of calcium carbonate that blocked plant roots and produced widespread waterlogging in the monsoon season. The only vegetation to be seen was sparse clumps of grasses and isolated specimens of the weed Calotropis procera with its salt-filled bladders and toxic leaves.
Administrators from the state government felt that this experiment, like all the previous ones on usar soils, was bound to fail.6 They gladly made the site available without charge. After all, what had they to lose? The people of Banthra were living in utter poverty, and many had resorted to crime to survive. Even the Banthra people themselves were less than enthusiastic, convinced that cultivating such hard and barren land would demand tractors, bulldozers, subsoilers, rollers, and other heavy machinery. They could foresee only big costs and small rewards.
However, they soon found that things were to be different. Professor Kaul planned to employ not machinery, but organic amendments and natural methods. His goal was to create a self-sustaining agriculture based on alkali-tolerant herbs, shrubs, and trees. It seemed a good idea, but at first nothing would grow at Banthra. Even the most resilient food crops died of stress and exposure. This project certainly seemed to be the failure everyone had predicted.
But then everything changed, and it was vetiver that made the difference. This rugged grass possessed an exceptional ability to withstand the heat, the drought, the salt, the alkalinity, and the waterlogging. Without even amendments or fertilizers, it could establish itself when planted directly into the usar concretion.
And vetiver did much more. As was later discovered in Louisiana, it proved to be a "first aid" plant that started the process of healing the site. Vetiver stretching in rows across the land gave other plants a chance to survive, too. It blocked the drying winds and reduced the erosion they caused. Indeed, the better microclimate and environment between the rows helped the NBG researchers establish a workable farming system. In the process, the soil began slowly to improve. This
was especially so after the researchers dug drainage systems and created ponds for collecting runoff and recharging groundwaters.
The land at Banthra is almost flat, and Professor Kaul initially thought of vetiver not as an erosion-control barrier but as a potential commercial crop. The villagers could sell the roots for essential oil, he thought. Nonetheless, the outcome exemplifies the plant's ability to survive adversity and to foster the growth of relatively less tolerant species.
That is certainly what happened at Banthra. Today it is a lovely parkland: green, shady, and beautiful. Legumes of various types now flourish, and 18 species of plants (belonging to 15 families) that had not been recorded there at the time Professor Kaul began his work are now common. The land has been transformed. It now supports a healthy mix of woodland, grassland, and cropland. As the leader of the project at the time stated with relief, "The final proof came with the accumulation of humus and eventually with the appearance of earthworms. Although this took 12–15 years, it was a good reward for the efforts we had started in the mid-'50s with 'first-aid' species like vetiver. This was indeed a day of rejoicing for us all."
In Malaysia, where the rain can fall in sheets and the slopes are steep and loose, soil losses can be among the severest in the world. Vetiver hedges would seem to be a godsend, but (at least in recent times) they were unappreciated until P.K. Yoon read about the World Bank's results in India and immediately set out to see for himself if vetiver worked.
Yoon is a scientist with the Rubber Research Institute of Malaysia, and he embarked on this venture in 1989 with less than great enthusiasm: "When I first saw a clump of rather undistinguished-looking grass, it looked so ordinary and so frighteningly similar to the horrible 'lalang' [Imperata cylindrica, a feared tropical weed] that I was thoroughly put off. However, also having seen massive erosion problems, especially on steep hills, I was prepared to have a look-see at anything that might work."
Luckily, Yoon managed to locate a vetiver clump near the city of Taiping. He carefully broke up the clump into 57 separate plants (tillers) and planted them out in individual polybags.
Vetiver proved easy to multiply. Much watering and a little slow-release fertilizer greatly boosted the growth and the production of
tillers, and topping the clumps back to 40 cm encouraged tillering even more.
At first, Yoon threw away the tops that had been cut off; however, he eventually noticed that as long as the plants were at least 3 months old, the discards included many culms. These jointed stems had buds at each joint, and Yoon found that laying the stems on damp sand and keeping them under mist caused the buds to sprout and produce new plantlets. Slitting the leaf sheath increased the success rate to the point that, after just 8 weeks, three out of every four nodes took root and began to grow. With as many as 17 nodes to a culm, this has proven a quick and efficient way to propagate vetiver without ever digging any up.
By these methods Yoon was able to convert the 57 starting plants into an amazing 16,000 tillers in just the first 7 months. Within 18 months he had distributed 200,000 plants for testing at various sites throughout Malaysia.
To see if vetiver had any chance of stopping soil loss, Yoon set up a simple demonstration at his research station at Sungei Buloh. The terrain was gently undulating (4–5° slope), and erosion had already formed a small gully. He planted slips of vetiver across the gully in five widely separated rows. After only 3 months, they had grown into hedgerows and had trapped so much topsoil that the gully had gone; in fact, what was previously a gentle slope had become level platforms, each faced by a bristly line of grass (see top of next page).
As a demonstration, it was very successful. "Every visitor we've had to date has been impressed enough to want to use vetiver on their own land," notes Yoon.
Next he set up a larger demonstration. A hillside was divided into four portions; two were planted with vetiver, the other two with cow grass (Paspalum conjugatum) and New Guinea grass (Panicum maximum ) as is normally practiced in Malaysia. At the side and bottom, corrugated-metal walls were built to deflect runoff into drums, where it could be measured and its silt content analyzed. All this was rendered useless, however, when such heavy rains fell for 2 days in October 1990 that the runoff collapsed the metal walls and washed away the drums. The vetiver planted portions remained pretty much intact; the rows of vetiver did their job, but with no control slope for comparison the precise figures Yoon had hoped for could not be obtained.
Yoon's other work concentrated on testing vetiver's ability to protect highway embankments, steep banks in housing estates, and hillsides in large new plantations. In such sites, saving a few dollars in propagation and planting costs is trivial, and Yoon grows out the plants in polybags to ensure that they rapidly produce uniform hedges when placed out on the site.
Concerned that the grass might host diseases that could affect Malaysia's crops, Yoon has surveyed the various plantings for pests. However, despite the large number of sites, there were only two serious fungal attacks—both of them in crowded nurseries.8 Moreover, the problem was easily solved: topping the plants removed the diseased parts, and the subsequent growth was normal.
An orchardist who had received some of Yoon's plants discovered an interesting application. To provide the abundant water essential to his new orchard, he excavated a series of ponds and planted the grass on the embankments. The plants grew extremely well, and they stabilized even the filled-earth sections so quickly that within 5 months the embankments were able to hold back waters 3 m deep. During the rainy weather many of the plants survived more than a month under water.
The key innovation, however, occurred when the orchardist added fish to the ponds. "He found that Chinese grass carp love to eat vetiver leaves," notes Yoon, "and he now cuts off the top of the grass and routinely feeds it to the fish. He is so pleased with this that he is digging more ponds. Also, neighboring smallholders are introducing vetiver and fish-rearing to their farms."
Young tops were readily consumed by sheep as well. Moreover, repeated cutting not only feeds the animals, it keeps the hedgerows dense and neat and in the finest condition for controlling erosion.
Yoon has also tried vetiver tops as a mulch. Farmers and gardeners in Malaysia commonly use lalang for this purpose. Preliminary observations showed that vetiver lasted much longer and did not cause any weed problem. Analysis showed that the vetiver mulch had considerable amounts of available nutrients (including nitrogen, phosphorus, potassium, and magnesium). Yoon concluded, therefore, that vetiver will be used for much more than just erosion control; it will also be a ready supply of quality mulch for suppressing weeds, conserving soil moisture, and boosting crop yields.
All these hands-on experiences have converted the former skeptic into a vetiver enthusiast: "Our work was done over a period of less than 2 years, but the results clearly show vetiver's vast potentials. They are just too tempting for anyone not to look further into it!"
Vetiver has been part of Tony Tantum's life since 1966, when he first discovered Mauritian sugarcane farmers using it to stabilize drains
in Malawi. To him, the hedges on that sugar estate in the Lower Shire Valley seemed very effective. At the time he learned that vetiver also had other uses: the culms were used as brooms, and small bundles of the roots, tied with a ribbon, were used for scenting cupboards.
In the 1980s, he moved to South Africa and found that the South African sugar industry had been using vetiver for a long time—perhaps for more than 100 years. "Hedges of the grass were put in to keep equipment from falling off the slopes," explains Tantum. "However, this was not practiced by everyone; it was pretty much limited to the French Mauritians growing sugar in Natal. They don't get along with the other sugar growers, so the technique did not spread."
Today, however, this method of erosion control is escalating. Indeed, Tantum has built a broad national base of institutional awareness of vetiver. His main resources have been Cedara College, Elsonberg College, the Institute of Commercial Forestry Research, the Environmental Authority, Natural Resources, and administrators in Transkei, QwaQwa, Bophuthatswana, and KwaNdebele. He has, moreover, generated a similar network of institutional interest in Lesotho, Zimbabwe, and Mozambique.
Tantum reports that he meets with skepticism and resistance from mechanical engineers (which is not surprising since engineered systems have dominated South Africa's erosion control for 30 years) but that most people are persuaded pretty quickly.
One convert is a North Coast farmer who was on his ninth ratoon (annual cutting) of sugarcane and preparing to replant the field when Tantum persuaded him to put in vetiver hedges. The grass would act as an "erosion safety net" when the cane was plowed out the following year, he said. But the unexpected occurred: the ninth ratoon turned out to be the farmer's highest yielding field. Perhaps the dense grass hedges were improving soil moisture to the point where an unprecedented tenth ratoon would be profitable; perhaps not. But the farmer faced a dilemma: keep the cane or replace it?
As a result of such experiences, the South African Sugar Experimental Farm is conducting a 5-hectare study of soil loss and water retention in sugarcane using vetiver.
Tantum's company, which puts in vetiver hedges under contract, has helped establish vetiver trials all over the Republic. Several are on horrendous sites. In the Western Cape, for example, the grass has been established on pure sand and on badly eroded kaolin clay. Elsewhere in the Cape, on dumps of slime residue from cement manufacture, it is doing well despite the worst drought in many years.
The trial on the pure sand was particularly impressive. It was on the coast near Camps Bay, on the road to Llandudno. Eroding road banks have long been a problem in the area. When Tantum's crew arrived,
the debris of many previous attempts—poles, wire, and plastic netting, for example—was evident. It was clear that this would be an extreme test for vetiver. The soil was barren orange grit and the steep slope faced the sea, exposed to salt spray and sea winds. The grass was planted in April 1990, and more than 90 percent of the plants survived. Within about 2 months, they started to stabilize the site.
Tantum has also established trials for several government agencies. The Department of Railways, for instance, approached him when a steep (1:1) embankment near Shongweni collapsed after a downpour of 100 mm. The embankment had supposedly been stabilized with a covering of kikuyu grass. The railways department asked Tantum if vetiver could do better. Tantum planted rows of vetiver straight into the collapsed, eroded, and unprepared surface. The soil was very poor, but no fertilizer was used. Within one month the rilling had stopped. Within 2 months residual kikuyu grass had begun to cover and stabilize the soil between the vetiver lines. However, neighboring areas (lacking vetiver) remained bare. For them, soil had to be imported and the area resodded with kikuyu grass.
In 1990, Niels Carstens of the Roads Department (Cape Provincial Administration) asked Tantum if vetiver could solve the serious erosion at the Stellenbosch flyover (Exit 22 of Highway N2 to Cape Town). The embankment here was very steep; the so-called "soil," pure white sand. Vetiver was planted in April 1990, closely spaced and without fertilizer. Virtually all the plants survived, and natural terrace formation was already visible before the end of the year.
In another trial in the Stellenbosch area (on the R44 road to Paarl), a steep road bank with very poor white clay subsoil was planted. Nothing grew there until April 1990, when vetiver was put in. Within 7 months the grass was tillering well, and the bottom hedge had built up between 70 and 100 mm of soil.
An interesting project, developed by the Institute of Commercial Forestry Research, has used vetiver hedges to stop soil loss in firebreaks, which were a major source of erosion. Thanks to the institute's work, the South African forestry industry has now accepted vetiver for this use. Also, the insurers of the industry have accepted that vetiver hedges on firebreaks are not a fire hazard. In June of each year, the hedges are treated with a contact herbicide and burned a week later. Within 2 weeks they become green belts across the firebreaks, blocking the former erosion.
Chris Nicolson, of the Institute of Commercial Forestry Research, is now developing an evergreen ground cover to fill the space between the hedges. This is a major development for the industry, and perhaps not only in South Africa because firebreaks are a source of erosion in forests worldwide.
It is no news to anyone that Madagascar has a problem with soil erosion as bad as can be found anywhere in the world. On the cultivated uplands (slopes up to 100 percent or more), minor surface rilling rapidly evolves into fierce gullying that gouges out vast areas and turns the rivers to soup. Often, this gullying starts along the elaborate networks of drainage ditches the farmers dig around their fields. These ditches are intended to carry away the runoff, but they often washout. Even when intact, they take away valuable moisture so that the mountain soils tend to quickly dry out when the rains cease.
Currently, however, the only other efforts to halt this disaster on Madagascar consist mainly of scattered reforestation projects. Their impact is often minimal because, in the absence of adequate ground cover, few of the seedlings survive and those that do grow slowly. Moreover, many end up destroyed by bushfires that recur each year.
All this was known to Thomas Bredero, the World Bank's senior agriculturist in Antananarivo. Thus, in 1988, after seeing how well vetiver performed in World Bank projects in India, he began searching Madagascar for the grass. Fortunately, French colonists had previously introduced it to produce vetiver oil. Bredero found remains of their plantations, although they were scattered and few. His main problem was how to finance and establish nurseries and demonstrations throughout the country. His first effort failed because the grower demanded gold for every vetiver plant he produced. A second was more successful, despite a seemingly never-ending drought that began just after planting. This time, a commercial farmer produced about 10 hectares of nursery, and about 90 primary schools in the Lac Alaotra area planted nurseries of 1 hectare each. As a result, farmer groups were soon being provided with vetiver slips. By late 1991, on-farm demonstrations could be found in 11 of Madagascar's 22 extension districts. It was at this point that Bredero came to be known as "Monsieur Vetivère."
However, it was clear from the outset that getting farmers to accept vetiver was not going to be easy. "There were the usual arguments—that it has no 'economic' purposes (such as improving soil fertility and cattle fodder)," said Bredero, "and that other 'economically more useful' species are available."9
But much of the opposition subsided when Bredero planted a vetiver hedge in the presidential garden. It solved an incipient erosion problem on the palace grounds and greatly pleased the president.
Madagascar's extension service now recommends vetiver for on-farm soil and water conservation in combination with other measures such as contour cultivation, dead furrows, continuous vegetative cover, and crop rotations. On slopes under 5 percent, where burning is not practiced, a grass called "kisosi" (a species of Panicum, see Appendix B) is also recommended.
In these combinations, vetiver is employed as a first line of protection, not only against erosion but also against ground fires. It complements agriculture, horticulture, and reforestation. With well-established vetiver lines, for example, many other kinds of land uses that lead to soil conservation are being developed: annual crops, perennial crops (notably fruits and fodders), and reforestation, for example.
Although at first skeptical, the forestry research department10 is now supportive. It changed its position when tests on its own sites showed that vetiver by itself slows runoff as well as a dense forest cover could.
In a number of Madagascar's rural areas, farmers have discovered for themselves vetiver's effectiveness for stabilizing dams, rice-field bunds, and irrigation works, as well as for protecting roads that can flood and wash out.
Bredero's next major challenge is to prove vetiver's usefulness in preventing the devastating gullies and ravines (known as lavaka in the Malgache language) from chewing up more land. They are so big and there are so many of them that the sandstone formations north of the capital and around Lac Alaotra constitute an alarming sight.
Bredero is now tackling the problem from two sides. First, vetiver is planted on contour lines around the upper edges as well as down the sides of the ravines to slow down and disperse runoff coming from the top of the mountains. Second, wooden poles are driven into the sand at the bottom of the ravines. The soil retained by these wooden palisades is planted with vetiver, bamboo, and fast-growing and fire-resistant trees and shrubs.11 The result is a dense vegetative cover. About 10 of these pilot-sized watershed-protection projects are now established, and early experiences seem encouraging.
The final verdict on vetiver is not yet in, but this grass just might be the answer to Madagascar's raging erosion—one of the worst local environmental problems on the planet.