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ENVIRONMENTAL SERVICE RENDERED BY NEEM
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NEEM IN REFORESTATION AND AGRO-FORESTRY
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BIOMASS PRODUCTION AND UTILIZATION
NEEM AND ENVIRONMENT
As
discussed above, neem has powerful pest controlling activities and medicinal
properties. More importantly, pesticides made from neem are much safer compared
to synthetic pesticides. The side-effects of the synthetic pesticides are often
not less serious than the problems themselves. They cause environmental
contamination and are a great risk of human health. As a consequence, there has
been an intense search for safer pesticides.
“The all pervasive use of
synthetics in every walk of life, be it agriculture, clothing, preservation or
health-care is now paving way for a search for eco-friendly products. All
communities, internationally, are today inclined to trust and rely more on green
technology than ever before since the advent of modern science. The era of
dependency on synthetic chemicals of the early and middle twentieth century
prompted synthesis of newer chemicals as a panacea for all diseases and
ailments. The conservative attitude of some societies, which depended on natural
products in preference to the synthetic, was often credited to inertia or
backwardness.
Happily, modern societies today, finding themselves
confounded in the web of their creation, are wiling to revert to nature for
remedies” (Govt. of India, 1996). It is in this that neem has staged a comeback
and promises to hold centre stage in the coming years.
Pesticides made
from neem are products of natural plant origin. They are biodegradable and
non-toxic. Neem products produce no ill-effects to humans and animals; they have
no residual effect on agriculture produce. For these reasons Neem is considered
as the best substitute to hazardous pesticides.
With the current thrust
on sustainable agriculture and organic farming, the use of botanical products as
pesticides has acquired greater significance. Neem is a highly suitable
candidate for environment-friendly, safe agriculture development. Azadirachtin
can be used in agriculture and public health as an eco-friendly chemical. Use of
neem products for plant protection will reduce the demand for chemical
pesticides and thereby reduce the environmental load of these synthetic
pesticides.
Synthetic pesticides are also a major source of health
problems. With the use of bio-peticides, farmers can avoid health hazards which
frequently occur both in developed and developing countries.
Neem is
extremely beneficial to save the environment from pollution; since its
in-florescence is purifying ‘with its feathery crests tossing fifty feet into
the sky’ neem is a veritable “Kalpataru” for giving healthy environs. Like other
trees, it exhales out oxygen and keeps the oxygen level in the atmosphere
balanced. Like other trees, it also brings other environmental benefits such as
flood control, reduced soil erosion and less salination. Neem can avert
environmental crisis in India and other tropical countries as it can be
successfully used for rehabilitation of degraded ecosystems and waste lands.
Neem is highly recommended for reforestation of semi-arid regions in India and
tropics of the sub-Saharan region, Asia and Central America. Neem is extremely
useful in urban forestry because it has remarkable ability to withstand air and
water pollution as well as heat. Neem also helps in restoring and maintaining
soil fertility which makes it highly suitable in agro-forestry.
Neem is a
natural resource to keep environment clean. In villages and cities as well as on
farms, it is useful as a windbreak. As a source of shade, it is excellent for
parks, roadsides etc. Because of its so many qualities, it is a common practice
in rural India to have a neem of tree within the compounds of most of the
houses. Neem is also a regarded as a valuable forestry species in India.
ENVIRONMENTAL SERVICE RENDERED BY NEEM
Neem in Indian
culture has been ranked higher than 'Kalpavriksha', the mythological
wish-fulfilling tree. In 'Sharh-e-Mufridat Al-Qanoon, neem has been named as
'Shajar-e-Mubarak', 'the blessed tree', because of its highly beneficial
properties. Although scientific studies are wanting, neem is reputed to purify
air and the environment of noxious elements. Its shade not only cools but
prevents the occurrence of many diseases.
During hot summer months in
northern parts of the Indian subcontinent, the temperature under the neem tree
is ~10° C less than the surrounding temperature; 10 air conditioners operated
together may not do the job as efficiently and economically as a full grown
neem. Restoration of the health of degraded soils and ultimate use of such
reclaimed wastelands lands through neem is another example of its value as an
environmental panacea.
About a decade ago, some 50,000 neem trees were
planted over 10 kms on the Plains of Arafat to provide shade for Muslim pilgrims
during hajj. The neem plantation has had a marked impact on the area's
microclimate, microflora, microfauna, sand soil properties, and when full grown
could provide shade to 2 million pilgrims (Ahmed 1995). It is an ancient belief
that neem growing inside the house can keep the surrounding air clean of
impurities and thereby control environmental pollution. Also, hanging neem twigs
on the door of a house is said to offer protection against pollution and
disease.
The tree is not only beautiful to look at, providing grandeur
and serenity, but also serves as a refugia to many beneficial organisms, bats,
birds, honey bees, spiders, etc. Honey-combs established on the neem tree are
singularly free from the galleria wax moth infestation. Many species of birds
and fruit-eating bats subsist on the sweet flesh of ripe fruits, while certain
rodents selectively feed on the kernel, confirming neem's safety to warm-blooded
animals. The litter of falling leaves improves soil fertility and the organic
content. Presently, little is known about the mycorrhizal associations between
neem and bacterial and fungal endophytes, but the tree seems to be a living
microcosm.
The evergreen, perennial tree can survive up to from 200 to
300 years, if not cut down. Even a highly conservative estimate of the
'environmental service' rendered by the tree @ US $ 10 per month, would give an
astonishing value of US $ 24,000 to 36,000 in its life time. Other economic uses
of neem and the benefits derived, such as biomass production, timber, seed and
honey are more tangible and quantifiable.
NEEM IN REFORESTATION AND AGRO-FORESTRY
Neem is a very
valuable forestry species in India and Africa and is also becoming popular in
Tropical America, the middle-east countries and in Australia. Being a hardy,
multipurpose tree, it is ideal for reforestation programs and for rehabilitating
degraded, semiarid and arid lands. During a severe drought in Tamil Nadu State
in June-July 1987, it was witnessed that neem grew luxuriantly, while other
vegetation dried up.
Neem is useful as windbreaks and in areas of low
rainfall and high wind speed. In the Majjia Valley in Niger, over 500 km of
windbreaks comprised of double rows of neem trees have been planted to protect
millet crops which resulted in a 20% increase in grain yield (Benge 1989). Neem,
windbreaks on a smaller scale have also been grown along sisal plantations in
coastal Kenya. Large scale planting of neem has been initiated in the Kwimba
Afforestation Scheme in Tanzania.
In countries from Somalia to
Mauritiania, neem has been used for halting the spread of the Sahara desert.
Also, neem is a preferred tree along avenues, in markets, and near homesteads
because of the shade it provides. However, neem is best planted in mixed stands.
It was probably no coincidence that Emperor Ashoka, the great ruler of ancient
India, in the 3rd century BC, commanded that the neem be planted along the royal
highway and roads along with other perennials-tamarind, Tamarindus indica and
mahua, Madhuca longifolia var. latifolia. Neem has all the good characters for
various social forestry programs.
Neem is an excellent tree for
silvipastoral system involving production of forage grasses and legumes. But
according to some reports (Radwanski and Wickens 1981), neem cannot be grown
among agricultural crops due to its aggressive habit. Others say that neem can
be planted in combination with fruit cultures and crops such as sesame, cotton,
hemp, peanuts, beans, sorghum, cassava, etc., particularly when neem trees are
still young. The neem tree can be lopped to reduce shading and to provide fodder
and mulch. Recent advances in tissue culture and biotechnology should make it
possible to select neem phenotypes with desirable height and stature for use in
intercropping and various agro-forestry systems. The alleloopathic effects of
neem on crops, if any, need to be investigated.
BIOMASS PRODUCTION AND UTILIZATION
Full grown neem trees
yield between 10 to 100 tons of dried biomass/ha, depending on rainfall, site
characteristics, spacing, ecotype or genotype. Leaves comprise about 50% of the
biomass; fruits and wood constitute one-quarter each. Improved management of
neem stands can yield harvests of about 12.5 cubic meter (40 tons) of high
quality solid wood/ha.
Neem wood is hard and relatively heavy and
religious icons in some parts of India. The wood seasons well, except for end
splitting. Being durable and termite resistant, neem wood is used in making
fence posts, poles for house construction, furniture etc. There is growing
market in some European countries for light-colored neem wood for making
household furniture (H. Schmutterer, personal communication). Pole wood is
especially important in developing countries; the tree's ability to resprout
after cutting and to regrow its canopy after pollarding makes it highly suited
to pole production (National Research Council 1992). Neem grows fast and is a
good source of firewood and fuels; the charcoal has high calorific value.
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