The astonishing resources of the physic nut tree
In Cape Verde, an interesting project has been set up on behalf
of the Ministry of Rural Development, at Loura, a village of 110 families, 25 km
from the capital. The aim of the project is to create an agro-industrial unit to
produce and process physic nuts. The physic nut tree, also known as jatropha and
the oil tree, is a shrub that had already been cultivated in Benin, Madagascar,
and the Cape Verde islands during the Second World War for the manufacture of
soap and the extraction of fuel oil from the seeds. But these activities were
abandoned in the 1950s with the boom in the oil industry. On an area of about
100 hectares, 100 000 shrubs have been planted, and experts responsible for the
initiative hope that by 1990 they will be producing around 175 tons of physic
nuts. A semi-industrial process will be used to extract 50 000 litres of oil a
year. Artisanal methods obtain only 35 500 litres and cost twice as much.
Jatrophas are an important source of energy, and the major objective of the
project is, of course, to produce fuel, sufficient to run the semi-industrial
plant and to make possible the introduction of experimental stoves into homes
and thus save fuelwood. Physic nut oil will also replace lamp oil in the home,
and residues from the agro-industrial complex at Loura will be used to run
generators. This raw material should also yield 4.5 tons of soap a year at an
expected retail cost of FF 90/kg, substantially less than imported soap, which
costs FF 115/kg.
The promoters of the project hope to create a new economic
activity for Loura with positive social and political effects, but they also
expect jatropha plantations to be an important ecological achievement. The
project is part of a reforestation programme to prevent erosion. Planted in
hedges, the shrubs can function as windbreaks to protect annual crops.
It is hoped that this initiative will be an example for other
villages of Africa, Asia, and Central America where the shrub grows.
The jatropha, indigenous to the arid regions of Brazil, is an
oleaginous shrub (Jatropha curcas) and a member of the family Euphorbiaceae. It
was introduced to the Cape Verde islands in the sixteenth century by Portuguese
navigators, but it has also been cultivated in India for several generations. It
grows both spontaneously and under cultivation in village plots, both in dry
tropical countries and in humid equatorial regions. Although it prefers cool
soils, it also grows vigorously - with almost no care - on arid escarpments, and
can adapt to long periods without rain.
The jatropha is a vigorous softwood plant, 2-6 metres tall. It
flowers twice a year; its fruit, indehiscent on the tree (i.e., it does not open
spontaneously when it ripens), is a small dark-brown spherical capsule that
contains the seeds. Propagation takes place in the rainy season by cuttings or
by seeds. The plant begins to bear fruit at three or four years and remains
productive for 30 to 50 years.
The numerous properties of jatropha seem to warrant expanding
cultivation. Indeed, the shrub is used in many tropical countries as a
windbreak, as a barrier against erosion, to make enclosures, and as fuelwood.
The fact that it adapts to ecologically deprived areas means that it can easily
be integrated in reforestation programmes. According to Georges Martin, an
authority on the species, it could be extremely useful in fighting desert
encroachment in the Sahel. Jatropha also has therapeutic properties; it is used
in Indian vedic traditional medicine and is renowned as a cathartic. All its
various parts find medical uses in western and southern Africa, Burma, Brazil,
Japan, Cape Verde, and Thailand.
A decoction of its roots can be used as a remedy for digestion
problems. Its leaves are used for skin troubles (particularly scabies and
dartres); and, in the past, Senegalese women used them to protect their hands
when applying henna to their hair.
Because the sap is a coagulant, it is used to dress wounds. And
finally, the curcas oil extracted from the seeds contains a toxic principle
which, though it cannot be used for human consumption, is known for its
purgative and diuretic effects. In addition to its medical properties, jatropha
is apparently also a molluscicide, as proven by an experiment performed in
Senegal by the Parasitological Department of the National Stockbreeding and
Veterinary Research laboratory of Dakar. According to G. Vassiliades, author of
the report on this study, the leaves, stems, seeds and kernels have the
properties required to combat aquatic molluscs, such as Lymnaea natalensis or
Bulinus guernei, carriers of human and animal disease.
But jatropha has an even more important characteristic. Its oil,
which has always been used to make soap, varnish, and dyes, and as lamp oil, is
a very efficient fuel.
In 1985, the National Botanical Research Institute of Lucknow in
India published the conclusions of its research: curcas oil mainly consists of
glycerides, and of stearic, palmitic, myristic, oleic and linoeic acids; its
molecular structure is comparable to that of colza oil; it has absolute
viscosity, determined at a temperature of 35°C and 100°C, and very
weak acidity. With all these properties, it can be used as a lubricant and
converted to replacement fuel in diesel engines. The numerous properties of this
plant definitely imply that it could be used to give new impetus to economic
activity in certain developing countries. But, as stressed by G. Martin and A.
Mayeux, engineers at the Institute for Research on Oils and Oilseeds in Paris,
in an article on energy oil crops, it is essential to continue to set up and
implement research programmes in order to create a real jatropha development