The Potential of Tapping Palm Trees for Animal Production
(PART 1)
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Christophe DALIBARD
Animal Production Officer
Feed Resources Group
FAO
ABSTRACT
Palm trees have proved to be efficient converters of solar
energy into biomass in most agro-ecological zones of the
tropical world. Most tapped palm trees gives a sap very rich
in sugar (10 to 20%). For several millennia, many species of
palm trees (including coconut) have been used for sugar
production. Highly sophisticated techniques of tapping were
developed through the centuries in Asia, Africa and America.
High yields of sugar were obtained from palms that could
continue for up to a hundred years of production. One of the
main constraints on production in recent times has been the
increasing lack of fuel needed for processing palm sap into
sugar and the price thereof. Nevertheless, since trials of
feeding pigs with fresh sugar palm sap were successfully
initiated in an FAO project in Cambodia, there has been
renewed interest in tapping palm trees for sap to be used as
feed. A thorough review of the literature has shown that
intensive pig rearing based on palm sap has already been
practised by the Indonesians for centuries and was found to be
a very efficient system for intensifying agriculture in some
highly populated islands. In today's economy, developing
animal production using palm sap as the main source of energy
in the diet looks very promising: the land could sustain
higher population densities through the intensification of
crop and animal production within sustainable integrated
systems for small farmers.
INTRODUCTION
For centuries, many palm species have been tapped throughout
the tropical world in order to produce fresh juice (sweet
toddy), fermented drinks (toddy, wine, arak), syrup ("honey"),
brown sugar (jaggery) or refined sugar. Most tapped palm trees
do not only produce sap but are multipurpose (edible fruits,
building materials, fibres, wax, etc.) and their
socio-economic importance can be critical for the rural poor.
Palm trees are also often associated with crops and pastures.
RATIONALE
Theoretically, the advantages of taking the sugars from the
sap before it goes to the fruits are obvious. These sugars are
intercepted before being used in the production of the
non-edible parts such as husk in coconut, which represents 35%
of the fruit (Rangaswami, 1977), and in the production of
edible material through chemical reactions which imply a loss,
mainly a conversion of sugar into oil as for coconut and oil
palm. It is therefore more profitable from the point of view of
edible energy production to tap a palm for the sap rather than
allowing the palm to produce fruits. Similarly, it was
demonstrated that, in the context of harvestable energy from
the coconut palm, the amount of energy harvested in the sap
(through production of ethanol) could be 5 to 7 times higher
than from the oil of the nuts (Banzon, 1984).
PHYSIOLOGY
It is possible to obtain a sugary solution by the excision of
the meristem in nearly all palms (Tuley, 1965). Basically,
starch reserves from the trunk are converted to sugar and are
transported upwards to the stem apex (Fox, 1977). Although
this is true in the case of Corypha, other explanations are
needed for palms such as coconut which does not accumulate
starch in its trunk (Reijne, 1948, cited by Van Die, 1974).
Pethiyagoda (1978) describes the upward stream as a watery
liquid containing dissolved salts absorbed from the soil, and
the downward stream as a comparatively rich mixture of food
(principally sugars) manufactured in the leaves. The sap flow
is intercepted by injuring fibro-vascular tissues of the apex
or of the inflorescence. Nevertheless, this author recognizes
that the large volume of exudate produced during tapping and
the high sugar concentration clearly indicate that the
material is drawn from stored resources and is in excess of
currently synthesised sugars. The origin of the large flow of
sap that occurs in a tapped tree is not yet clearly
demonstrated. This is also the case for Borassus flabellifer
where water from root absorption appears quite insufficient
(Kovoor, 1983). Pethiyagoda (1978) suggests that there is a
steep rise in respiration which occurs whenever there is a
rapid solubilisation and movement of materials from sites of
storage to the points at which they are needed such as during
seed germination, flower opening and fruit ripening. This
phenomenon can be fostered, heightened and sustained by
manipulative processes, the use of generally young growing
sites (merismatic tissues) and the act of freshening the
wound. Preliminary studies (not published) cited by
Pethiyagoda (1978) show a considerably increased respiration
by fragments of coconut inflorescence drawn from stimulated
spadices.
LOCATION, PRODUCTS AND TAPPED PARTS OF PALMS
Table 1 lists nearly 30 different palm species that are
traditionally tapped in parts of the tropical world. The major
part of the information was found on palms that are tapped in
the Old World, with more or less as many different tapped
species in Asia and in Africa. It has been possible to
identify only three tapped palm species in the New World
(Carnauba cerifera, Jubaea spectabilis and Mauritia flexuosa)
and very little literature seems to be available on tapping
these trees. In America and Africa, it seems that tapping
palms has been practised exclusively or mainly for wine
production, whereas in Asia the sap is used either as fresh
juice or processed into a large array of products (wine, arak,
sugar, vinegar, etc.). Table 1 also shows that there are
tapped palm species adapted to almost all agro-ecological
zones of the tropical world from tidal areas and swamps to
deserts and mountains.
Table 1: Location and management of tapped palm species
Latin name Regions and management
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Areca catechu Tropical rain forest S & SE Asia;
Improved cultivated palm [1]
Arenga pinnata Tropical rain forest into dry forest
or saccharifera SE Asia; Unimproved cultivated or
Arenga undulatifolia managed palm [1]
Beccariophoenix Central Madagascar (1,000m)
madagascariensis
Borassus aethiopium Tropical savanna Africa; Semi-wild
or wild palms [1]
Borassus flabellifer Tropical forest into savanna Asia;
Borassus sundaicus unimproved cultivated or managed
palm [1]
Borassus Along rivers Madagascar [2]
madagascariensis
Carnauba cerifera Brazil
Caryota urens Tropical rain forest Asia & S
Pacific; Unimproved cultivated or
managed palm [1]
Cocos nucifera Coastal tropical rain forest
E Africa, Asia & Pacific; Improved
cultivated palm [1]
Corypha elata SE Asia
Corypha umbraculifera Tropical rain forest S & SE Asia;
Unimproved cultivated or managed
palm [1]
Elaeis guineensis W Africa, Madagascar [2], Indonesia
[4]; Improved cultivated palm [1]
Hyphaene coriacea SE Africa
Hyphaene thebaica Semi-deserts & deserts of E Africa;
Unimproved cultivated or managed
palm [1]
Hyphaene shatan Madagascar
Jubaea spectabilis Chile
Mauritia flexuosa Tropical rain forest Peru; Semi-wild
or wild palms [1]
Nypa fruticans Tidal areas Asia; Unimproved
cultivated or managed palm [1]
Phloga polystachya Madagascar [2]
Phoenix dactylifera Semi-desert N. Africa; Improved
cultivated palm [1]
Phoenix reclinata Coast W & SE Africa [5][3][4][6]
Phoenix sylvestris Trop. rain forest to 1,500m [1];
India, Bangladesh, Ivory Coast;
Unimproved cultivated or managed
palm [1]; Bangladesh: plantations [7]
Raphia hookeri, Tropical rain forest W Africa,
R. vinifera, Madagascar [2]; Semi-wild or wild
R. sudanica, palms [1]
R. ruffia
References: [1] Johnson, 1987; [2] Decary, 1964; [3] Giffard,
1967; [4] Blanc-Pamard, 1980; [5]Cunningham, 1990; [6] Adand:S,
1954; [7] Annett, 1913.
METHODS OF PALM TAPPING
The techniques for tapping palms are numerous and can vary
drastically from one continent to another, as demonstrated by
the case of Borassus aethiopium in Africa and Borassus
flabellifer in Asia. Refined techniques of tapping the
inflorescence of the latter are compatible with production in
the long term. Destructive techniques are usually practised on
the terminal bud of B. aethiopium and are often responsible
for the death of the tree within a few months. The African oil
palm is used in Africa for producing wine mainly through two
different techniques: one is destructive (incision of stem
apex of felled palm) and is preferred in Ghana; the other is
not destructive (excision of male inflorescence) and has been
developed where economic considerations have forced the people
to preserve their palms, e.g. in eastern Nigeria (Hartley,
1977). The excision of the terminal bud of standing trees is
quite harmful since tapped palms never resume vigorous growth.
If the terminal bud is only perforated, then the trees will
show malformation in subsequent leaves, flowers and trunk
growth (Kovoor, 1983). Nevertheless, it has been observed that
multi-stemmed trees such as Hyphaene coriacea and Phoenix
reclinata in south-eastern Africa generally recoppice after
tapping, although tapped stems die unless tapping is stopped
before the apical meristem is totally destroyed (Cunningham,
1990). The very low yields of sap from these trees are
interpreted as a result of over exploitation. Cunningham
(1990) suggests that if palm size classes shifted to the
extent that there was again a high proportion of mature
fruit-bearing palms in the population, then inflorescence
tapping could be practised.
The most advanced method of tapping is that applied to the
inflorescence spadix which guarantees a high yield for long
periods without affecting the well-being of the tree. It only
entails a sacrifice of a bunch of fruit in the case of tapping
female inflorescences. Tapping the inflorescence is practised
throughout S.E. Asia on all species of tapped palm trees
(Kovoor, 1983). Two features are common in tapping:
manipulative treatment or preparation (application of
chemicals and substances of plant origin, twisting,
distortion, kneading, pounding, bruising, beating or tapping)
necessary as a prelude to copious and sustained sap flow, and
renewing the exuding wound by shaving off a thin slice of
tissue once or twice a day (Pethiyagoda, 1978). Tapping is an
art: sap yields depend on the skills of the tapper (Khieu,
1996; Coconut Research Institute, 1967).
Except for Nypa fruticans, which is trunkless and develops its
inflorescence at a height of about 1m (Hamilton and Murphy,
1988), other palm trees have to be climbed for tapping as
their inflorescences are located at the summit of their trunk
which is often over 10m high. Various methods are used to
climb the tree (six recorded by Kovoor, 1983), using
ankle-loops, aerial ropeways between trees, hoop-belt, rivetted
bamboo, mobile 4-9m long ladders and fixed ones on the upper
part of the trunks, notches in the trunk, etc.
MANAGEMENT OF TAPPED PALM TREES
The management of palm trees for sap production varies very
much according to species. Nypa fruticans, Phoenix sylvestris,
Elaeis guineensis, Raphia hookeri and Cocos nucifera can be
tapped at a rather early age, respectively when the trees are
4, 5, 6, 7 and 7 years old (Crevost and Lemari:S, 1913; Abedin
et al., 1987; Essiamah, 1992; Profizi, 1988; Levang, 1988). On
the other hand, many years are needed before tapping Caryota
urens (10 to 15), Borassus flabellifer (15 to 30) or Corypha
elata (20 to 100) (Redhead, 1989, Fox, 1977).
The number of years a palm tree can be tapped is also very
different depending on the species. Corypha elata and Raphia
hookeri flower just once. They will produce sap only for a few
months before dying (Fox, 1977; Profizi, 1988). Arenga pinnata
and Caryota urens will produce sap for several years, with
large interruptions in the case of Caryota urens as it flowers
only every two or three years (Redhead, 1989; Dissanayake,
1977). Other palm trees will produce sap for much longer
periods: 10 to 15 years for Elaeis guineensis, more than 20
years for Cocos nucifera, 50 years for Nypa fruticans and
Phoenix sylvestris and 30 to 100 years for Borassus
flabellifer (Adand:S, 1954; Levang, 1988; Magalon, 1930; Abedin
et al., 1987; Lubeigt, 1977).
Some species are able to produce sap all year round: Arenga
pinnata, Cocos nucifera, Elaeis guineensis and Nypa fruticans
(Mogea et al., 1991; Rangaswami, 1977; Tuley, 1965; Kiew,
1989). Borassus flabellifer and Phoenix sylvestris produce
only seasonally (Crevost and Lemari:S, 1913; Annett, 1913).
YIELDS OF SUGAR
Most tapped palm trees gives a sap very rich in sugar (10 to
20% according to species and individual variation). The yields
are highly variable according to the species and their
management. Under proper management, the main tapped palm
species (Arenga pinnata, Borassus flabellifer, Cocos nucifera
and Nypa fruticans)can reach yields of about 20 tonnes of
sugar per hectare (Van Die, 1974; Watson cited by Kiew, 1989).
Compared to sugarcane production (5-15 tonnes of
sugar/ha/year), the Borassus flabellifer tree can reach 18
tons/ha/year under rain-fed conditions (Khieu, 1996) and the
coconut tree 19 tons/ha/year (Jeganathan, 1974). According to
estimates, Elaeis guineensis produces much less sugar (1.2
tonne per hectare, Udom, 1987) but, as it has never been
exploited for sugar production but only for wine production,
there are good prospects for obtaining much higher yields in a
production system oriented towards sugar production.
MULTIPURPOSE USES AND ROLE IN SUSTAINABLE INTEGRATED
PRODUCTION SYSTEMS
Most palm trees have multipurpose uses. Nevertheless, they are
not always compatible. Sap production is at its maximum just
before or during fruit formation. Tapping the tree competes
with the production of the ripening fruit (Redhead, 1989).
Tapping can also stimulate fruit production: a young coconut
palm tapped during 6-12 months for sugar production will then
produce more nuts (Magalon, 1930; M.F., 1925). A technique
called sequential coconut toddy and nut production has been
developed in the Philippines at the Davao Research Centre. The
first half of the spathe is tapped and the second half is left
for fruit production as female flowers that develop to mature
nuts are situated in this lower portion. Nut and copra yields
are about 50% lower than non-tapped palms; however, this
technique has been demonstrated to be very feasible and highly
profitable for small producers (Maravilla and Magat, 1993).
Arenga pinnata can be tapped when they are between 12-15 and
more than 30 years old; then they can be cut for sago
production (Sumadi, 1988). Nevertheless, in West Java, where
sago is obtained from trees 10-12 years old, no tapping will
be done previously, farmers arguing that it would reduce the
quantity of starch in the trunk (Mogea et al., 1991). In
Eastern Nigeria, oil palms that have been abandoned as
uneconomic bunch producers usually give good economic returns
for wine production before old plantings are cleared and
replanted (Tuley, 1965).
There are various types of palm-crop associations in
Bangladesh. Phoenix sylvestris and Borassus flabellifer can
both be associated with several of the following crops: rice,
wheat, chickpea, mustard, jute, lentil, potato, linseed,
winter vegetables and sugarcane (Abedin et al., 1987).
Palm trees often have advantages compared with other crops as
far as sustainability is concerned: in parts of west Java
where Arenga pinnata is still tended in groves, soils appear
much more stable and productive of other crops than where
cassava is cultivated (Dransfield, 1977). Furthermore the
advantages of this tree are its great ecological tolerance,
its ability to grow and stabilize unproductive erosion-prone
sites such as steep dryland slopes (e.g., coffee orchards in
North Sulawesi, Mogea et al., 1991), its potential to grow on
almost any type of soil, to increase soil fertility and water
conservation, its great tolerance of accidental burning (the
only surviving tree in the Minahassa, Sulawesi after volcanic
activity), the relatively fast growth rate, the fact that it
needs almost no maintenance and usually does not suffer from
any serious pests or disease, and the wide range of secondary
or alternate products obtainable (Mogea et al., 1991).
Borassus flabellifer is often planted on paddy fields
boundaries in Cambodia and India. The effect of shading on
understorey crops are likely to be negligible due to the
small-sized crowns and to the large space (10-15m) between
trees (Jambulingam and Fernandes, 1986). Like Arenga pinnata,
this tree thrives in reputedly the poorest, infertile and arid
regions. It also suffers remarkably little from prolonged
flooding. It is extraordinarily pest and disease-resistant,
requiring limited means of cultivation if any. As it grows in
sandy plains, it is used for blocking erosion and fixing
dunes, thanks to its deep root system (Kovoor, 1983). It is
also, like Corypha elata, a fire resistant palm that is a
pioneer species on regularly burnt land such as those
exploited by the slash-and-burn technique (Ormeling (1956),
cited by Fox, 1977). It is used in Burma as a wind-break in
areas cropped with groundnut (Lubeigt, 1977). It plays a major
role in Savu and Roti islands (Indonesia) where the soil
fertility is a crucial constraint. Traditional slash-and-burn
system which is currently practised in neighbouring islands
(Timor and Sumba for example) has been replaced by
semi-permanent gardening through the use of large amounts of
old Borassus leaves that are burnt in the fields. This permits
fertile gardens to be kept in the vicinity of the houses (Fox,
1977). Borassus forests possess a potentially unique pattern
of nutrient cycling, which enables them to support relatively
productive and stable forms of agriculture as well as to
contribute to recovery of disturbed sites (Anderson, 1987).
In the Peruvian Amazonia, Mauritia flexuosa constitutes dense
populations in seasonal swamp forests on waterlogged or sandy
soils, which are generally considered as unfit for agriculture
(Kahn, 1988). Unlike sugarcane, Nypa fruticans does not
compete with other crops for agricultural land except where
total reclamation is undertaken on mangrove land (Hamilton and
Murphy, 1988).
ORIGIN OF THE DECLINE IN PALM TREE TAPPING ACTIVITY
One of the main reasons for the decline of sugar production
from palm trees is the increasing lack of fuelwood and its
increasing price. In the case of wine-producing palm trees,
the decline often occurred under religious or colonial
pressure. In Africa, some destructive techniques of tapping
were responsible for the disappearance of the trees in entire
areas. The important moves of population in the fifties
(settlers setting up coffee, cocoa, rubber trees and oil palm
plantations) were also responsible for loss of traditional
codes of managing the trees and less long term concerns. Thus
the traditional technique of tapping only male trees and
keeping females for regeneration was abandoned (Portdlres,
1964; Blanc-Pamard, 1980). In Sri Lanka, widespread
cultivation of coconut as an exported-oriented crop
drastically changed the local economy and imported sugar
became cheaper (Dissanayake, 1977). In Peninsular Malaysia,
the swamp areas were drained for coconut plantations where
Nypa fruticans was before predominant (Kiew, 1989). Fishponds
developers also found great profits in various fishpond
operations made possible by converting mangrove swamps,
including Nypa fruticans areas, for fish production
(Encendencia, 1985).
Tapping sugar palms is very labour intensive. It must be done
daily otherwise the sap flow rapidly diminishes as tissue
healing occurs and restarting the sap flow requires long and
hard work. Whenever easier and better paid jobs were
available, tapping was given up. During the colonial period in
India, Borassus tappers were recruited in the British
plantations abroad, particularly on the rubber and oil palm
estates where their skills could be easily adapted to those
required for these trees (Fox, 1977).
In many countries, in comparison to other crops or
commodities, there is a general lack of interest shown by the
decision makers about the socio-economic potential of tapping
palms. None or little research, selection of higher yielding
varieties or training and extension services are funded and
the tappers are seldom exposed to technological innovations if
they do not generate them by themselves.
...\... ====> PART 2
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FAO ELECTRONIC CONFERENCE:
LIVESTOCK FEED RESOURCES WITHIN INTEGRATED FARMING SYSTEMS
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