|Neem: A Tree for Solving Global Problems (BOSTID, 1993)|
Neem appears to be a good candidate for planting throughout most of the warmer parts of the world. It not only grows vigorously in many types of semiarid and tropical sites, it is a multipurpose species that provides villagers with various products from which to derive an income during the years when the trees are maturing. This feature is important for motivating enthusiastic local tree planting.
Already neem is regarded as a valuable forestry species in both India and parts of Africa, but even there it could become more widely employed. It is also promising for planting in areas now suffering desperate fuelwood shortages. It is useful as a windbreak, exceptional as a city tree, and it can grow in (and perhaps neutralize) acid soils that plague much of the tropics.
This evergreen, which sheds its leaves only under extreme heat and drought (and then only for a short time), is valued for its shade. Its extended branches make it excellent for parks, roadsides villages, streets, courtyards, shelterbelts - in fact, almost any place where some relief from the sun would be appreciated.
For these and other purposes, the tree is likely to be popular. It is impressive to see how it has been accepted, even eagerly sought, by people in the Sahel. (According to forester Jean Gorse, who spent most of his career working in the Sahel: 'The propagation of neem in West Africa in the '50s and '60s must be considered as the most successful (and cheapest) rural forestry operation ever implemented in this region. This was mainly due to the 'attractiveness' of neem.")
To a large extent it is being spread there through private and commercial initiatives. Even so, the Sahel uses the tree far less than it could.
Planting neem on a large scale might also improve the declining ecosystems of many areas considered fairly hopeless. In Haiti, for example, and other countries where the tree cover has been stripped away, vast plantings of any type of tree would likely bring environmental benefits, among them fewer floods, less siltation, and reduced erosion. Neem is just one candidate for such reforestation, of course, but it is a good one.
This tree is a farmer's friend and, when people know it better, it is likely to stimulate much spontaneous planting, especially as markets for its fruits and seeds develop. On the farm and around the house neem is useful not only as a windbreak and a welcome source of shade, but its seedcake is a good fertilizer - containing (as we have noted) nitrogen, potash, phosphorus, calcium, and magnesium.
Neem is usually easy to establish. It grows best on deep, well
drained sandy soils. However,
it often fails on silty or micaceous loams and silty clays, in depressions with slow drainage, and in soils with high or seasonally fluctuating water tables.
In their first months after transplanting from a nursery, neem seedlings greatly benefit from tillage, weeding, irrigation, and one or two fertilizations.
Young plants develop fairly rapidly, at least after the first season. As a rule their girth increases 2-3 cm a year, although even faster growth is often attained.
Neem needs open sunlight for best performance, but seedlings vigorously push their way up through thorny scrub and even crop plants. (Tree planters have taken advantage of this feature in trials in West Africa. They planted neem along with pearl millet, and, after the crop was harvested. a good stand of healthy young trees remained. This made possible the establishment of a neem plantation at a relatively low cost. Neem did surprisingly well under pearl millet. Although hidden beneath the towering crop (3 m tall) for several months, it did not appear to suffer.)
The seedlings begin by emphasizing root growth. Only when roots are well established does the overhead growth become rapid. In harsh environments and on poor soils, this early emphasis on establishing extensive roots endows the tree with exceptional ability to survive adversity.
Although neem can be raised in nurseries and transplanted as seedlings, direct sowing on the site is sometimes easier and more successful. Seeds should be taken from thoroughly ripe fruits picked directly off the trees. They should be sown as quickly as possible.
Examples of some experiences with planting neem follow.
Neem has been planted in many parts of Asia: Bangladesh, Burma, Cambodia, India, Indonesia, Iran, Malaysia, Nepal, Pakistan, Sri Lanka, Thailand, and Vietnam. It has recently been introduced into Saudi Arabia, the northern plains of Yemen, and China (Hainan Island).
In India, neem grows wild in dry forests and is also cultivated in all but the highest, coldest parts of the country. It thrives best in the drier zones of the northwest, and a large number of trees are found in the state of Uttar Pradesh. It is commonly planted as a roadside tree to form shady avenues. Visitors to New Delhi cannot fail to admire the stately neems adorning the avenues, spreading from both sides a thick green canopy that shields people from the fierce sun.
Although Burma is one of the main countries where neem is native, not much about its neem trees has been recorded. Nonetheless, in recent years a German aid project has helped Burmese scientists develop a neem-seed pesticide. This one-step, formulated, methanolic extract is produced by a pilot factory in Mandalay. The product has become popular among local farmers, who use it for controlling vegetable and peanut pests. The factory also produces neem oil and sells it locally for manufacturing soap and candles.
Java has an enormous array of different types of neem trees. Some growing on a small commercial plantation have recently been found to have seeds that are extraordinarily effective against insects due to their high content of active compounds.(Information from M. Jacobson.)
Neem is fairly widespread in the country south of Lahore. In many cities giant neem trees, more than 100 years old and more than 30 m tall, grace many roads.
Neem was introduced to the Philippines only in 1978, by scientists working at the International Rice Research Institute (IRRI), By 1990, however, IRRI had distributed more that 120,000 seedlings and the tree was growing on at least eight islands. Widescale plantings for fuelwood and potential pesticide production had also been undertaken by private and governmental agencies. Owing to numerous typhoons, neem is unsuited to the northern and central regions, but in the south it grows well.
Introduced into the country more than 40 years ago, the tree has acclimated remarkably well to the hot and arid conditions. It is probably more common than date palm or any other tree as an avenue tree and can be seen in Jeddah and other cities.
In the plains where the Prophet Muhammad is said to have delivered his farewell sermon some 1,400 years ago, a city of thousands of tents springs up each year to accommodate the pilgrims. In the area, one of the hottest on earth, there is little relief from the intense heat - but relief is on the way. What is probably the world's largest neem plantation, about 50,000 trees, has recently been planted. (Ahmed et al., 1989.) The project is designed to provide shade to the 2 million Muslim pilgrims who camp there annually for the hall.
Thailand has many "Indian" neem trees (Azadirachta indica) as well
as its own species, Azadirachta siamensis, which also might have promise. It is
fast growing. At Ratchaburi, on arid rock outcroppings, 200,000 specimens
averaged 11 m tall only 6 years after planting. They were also heavily laden
Indian immigrants introduced neem to Mauritius and may also have taken it to continental Africa. It is now widely cultivated in Mauritania, Senegal, The Gambia, Guinea, Ivory Coast, Ghana, Burkina Faso, Mali, Benin, Niger, Nigeria, Togo, Cameroon, Chad, Ethiopia, Sudan, Somalia, Kenya, Tanzania, and Mozambique. In each case, it is found particularly in the drier, low-lying areas.
Because of tree planting programs of the Forestry Department and of the local people, Senegal probably has more neems than any other African country. The tree dominates towns and villages all over the country. It is used for shade and for firewood, and it has very beneficial ecological consequences, including the saving of many indigenous trees that would, in its absence, have been felled for fuel.
Neem has been growing on the plains near Ghana's capital, Accra, since the 1920s (see sidebar). The trees have naturalized, and their spread has been boosted by birds and bats that feed on the fruits and spit out the seeds while sitting in the branches. Neem is now scattered all over the area.
With their vigorous growth, the trees have become Ghana's major source of firewood. Alongside many highways and byways, it is common to see stacks of neem wood awaiting trucking to the cities.
In Accra and other centers, neem is now a common street tree and backyard shade tree. It is normally pollarded (topped) annually and the resulting branch wood hawked for fuel or building poles.
At the beginning of the nineteenth century, the Majjia Valley in central Niger was heavily wooded. But it is located in the southern Sahel, an area with highly variable and low rainfall (400-600 mm a year). The growing population - with a relentless appetite for fuelwood, fodder, and construction materials - left it bare. By the drought years of the early 1970s, wind erosion was blowing away nearly 20 tons of topsoil per hectare per year. In the rainy season, wind-blown sediment would smother farmers' seedlings, forcing them to reseed their fields over and over.
In 1975, the American relief agency CARE began planting neem windbreaks. By 1987, some 560 km of double rows of neem were established and more than 3,000 hectares of cropland protected. The trees cut wind velocity near the ground by 45-80 percent, resulting in less erosion and more soil moisture. Crop yields jumped 15 percent or more, even after accounting for the land taken up by the lines of trees.
How Neem Reached Africa
To people in West Africa these days, neem seems like an established part of the countryside. The general feeling is that it has been there since time immemorial. However, this tree is actually a recent addition to the African scene.
It was Brigadier-General Sir Frederick G. Guggisberg who brought neem to Ghana, for example. He was governor (of what was then known as the Gold Coast) from 1919 to 1927, and he introduced seeds or seedlings from India sometime during that period. The first were planted in the Northern Territories. Today, as a result, neem is found throughout Ghana and the Sahelian region.
The governor's efforts have given rise to at least two local names for neem. In Ghana, the tree is normally called "king," which is the local title for governor. In Mali, the vernacular name in the Dyula language is "goo-gay," a corruption of "Guggisberg."
Neem was first introduced to Nigeria in 1928 (probably from Ghana), where it was successfully established in the Bornu province. Several thousand seedlings from the first plantation were replanted in Sokoto, Katsina, and Kano provinces in the 1930s. Neem was also successfully established by sowing fresh seed directly into the shelter of indigenous vegetation and local food crops. There are now considerable plantations for firewood and construction materials throughout those areas of northern Nigeria.
Neem also seems to be an entrenched part of the scene in The Sudan. There, it is valued mainly as a street and amenity tree and is commonly seen at railway stations and beside mosques. Here again, however, neem is a new arrival, historically speaking. The first ones apparently were planted at Shambat in 1916. Probably, they were brought directly from India by a diligent colonial forester who appreciated their value for producing shade, fuel, wood, and oil for lamps.
Just how Senegal got its first neem is uncertain, but in the 1950s
Senegalese agronomist Djibril Sene went to India to gather neem seeds. Many, if
not most, of the neems now seen throughout the country result from his
Moreover, the obvious beneficial effect of the windbreaks - particularly as a source of cash from the sale of wood - has encouraged some farmers to start their own nurseries. Currently, more than 100 private nurseries are being tended. The long-term success of the project seems to be assured by the spread of the woodlots and nurseries into private control.
Neem is common, especially in towns and villages, in the northern regions. Sometimes it is planted in large numbers along roadsides - along the road between Maiduguri and Lake Chad, for instance. (Information from H. Schmutterer.)
Neem is part of the scene along the Niger river as far north as Timbuktu. Many of the trees are pollarded (at about 2 m height) to provide forage to cattle and goats. Many are also pruned into unusual shapes by camels.
Sudan was one of the first African countries to get neem. Today, the trees are widespread along the Blue and White Niles, in irrigation schemes, and in towns and villages.
Apparently, it was immigrants from India who introduced neem to several Caribbean nations. The tree is now grown as a medicinal plant in Suriname, Guyana, Trinidad and Tobago, Barbados, Jamaica, and elsewhere. More recent neem plantings are also found in St. Lucia, Antigua, Dominican Republic, Mexico, Belize, Guatemala, Honduras, Nicaragua, Bolivia, Ecuador, and Brazil. In most of these nations, however, the plantings are small, scattered, and exploratory. Only in Haiti, the Dominican Republic, and Nicaragua have large numbers of neem trees been planted so far.
In the last decade or so, neem has been widely planted in Haiti. In fact, this tree is now one of the leading species for reforesting this much-denuded land. For example, one project funded by USAID has planted 200,000 neem trees as part of a road beautification program using seed imported from Africa in the late 1970s. Later, neem became a popular species for planting. The trees have grown so well that today neem seed is becoming a Haitian export. Approximately 40 tons were processed for azadirachtin by an American company in 1990. Since then, other companies have also sought to buy Haiti's neem seed.
Because the tree is a tropical species, it probably cannot be grown economically in the continental United States beyond South Florida. In South Florida, however, there are four mature neem trees (two in Miami and two in Fort Myers) and 50 smaller ones (in Homestead). There are also eight trees in the futuristic Biosphere 2.(This is a $150-million. 1.2-hectare set of glass and steel greenhouses in the desert near Tucson, Arizona, in which 8 humans are sealed for 2 years. The greenhouses are isolated from all inputs such as air, water, and fuel and are filled with plant and animal life, to represent a self-sustaining microcosm of the planet Earth (Biosphere I ).)
Of course, the tree can thrive in Hawaii and other locations in the American tropics. Researchers have already begun planting it in Puerto Rico and the Virgin Islands, for example. A specimen planted at the East-West Center in Honolulu, Hawaii, in 1984 was nearly 10 m tall and fruiting heavily in 1991. And in 1989 the Hawaii State Senate passed a resolution supporting research and development of this "wonder tree."
Nineteenth century immigrants carried the tree from India to Fiji, and it has since spread to other islands in the South Pacific, even to Easter Island, which is hardly known as a place for trees. In Papua New Guinea neem was introduced at the beginning of the 1980s, mainly in the Port Moresby area.