NOTES ON MAIN FINDINGS
Prepared by Norman Jones AGRAF and Christian Taupiac AFTES
World Bank, Washington DC
Abstract:
Prosopis sp. is known worldwide as a leguminous nitrogen fixing tree, able to
adapt to arid conditions or salines soils. It provides fodder and fuelwood but also has a
reputation as a weed and undesirable thorny tree in many circumstances. Extensive research
has been carried out in its natural range (southern and northern America) also in counties
where it is exotic (India, Mauritania, Sudan) resulting in better understanding of its
potential.
(i) on the genetics : Although the Peruvian origin seems to be one of the best, it is
proved that individual tree variation is critical, therefore clonal production from
selected trees is recommended. Priority may be awarded to thornless trees and in situ
grafting on wild rootstock may be a way to disseminate genetically improved prosopis.
(ii) on the uses : Prosopis is the only tree able to yield 2.5 tons of wood/ha/year where
nothing else can grow. On salines soils in India this can rise to 12 tons. However, in
better soil conditions other, less aggressive species would be recommended.
(iii) on the products : Prosopis timber has very good technological properties (low
shrinkage, high resistance), these and its red brown color makes it attractive for high
quality furniture and flooring. It can also be considered as a major component for food
and fodder production from its fruits/pods.
(iv) on the commercial front: There are examples of private businesses based on prosopis
wood products including furniture and flooring, fuelwood, barbeque wood chunks, charcoal
and also food and fodder products are marketed in Brazil, Haiti and Peru.
(vi) on available information : the resource person for prosopis is Dr. Peter Felker, Texas A&M University, Campus Box
218, Kingsville TX 78363 (Tel. 512 595 3966).
Like any other multi-use tree, the sustainability of projects using prosopis as a
development tool is directly related to the capacity of the local beneficiaries to
integrate this tree into their agricultural system.
Introduction
Prosopis is better known as mesquite but like many trees has various names in different
countries. It is a legume and the genus is essentially American, extending from Texas
through Mexico into South America as far as Chile, containing forty four species with only
four indigenous to Africa and Asia. Many are aggressive pioneers and because of this the
genus is considered a weed in many parts of its natural distribution and even in some
countries where it is exotic. Prosopis is a nitrogen fixing tree and this, coupled with
its pioneer habit has caused it to be introduced to many countries in Africa and Asia. It
will grow in virtually any reasonably frost free conditions and its ability to adapt to
arid conditions ensures its acceptance in many dry countries. The best known and most
widely planted species is Prosopis juliflora, in India P. cineraria is
indigenous and locally important and similarly P. africana in West Africa. The
following notes show prosopis as a valuable "tool" of immense value to poor
communities in dry areas and on problematic sites, but like all tools it is best used in
skilled hands and for specific tasks.
The Workshop
The workshop was attended by representatives from its natural range (Texas, Mexico, Peru,
Argentina) and where it has been introduced (Cape Verde, the Gulf States, Haiti, India,
Mauritania, Niger, Senegal, Sudan). Delegates from international and national development
and donor agencies attended together with representatives from a number of NGO's and
industries working with prosopis. All delegates are pro-prosopis but there are also many
around the world who consider the species a noxious weed. The following notes outline the
versatility of the genus in general terms, details on its various characters can be
obtained from the pool of specialists contacted through the workshop organizer Dr. Peter
Felker, Texas A&M University, Campus Box 218, Kingsville TX 78363 (Tel. 512 595 3966;
EM [email protected]).
The Prosopis Niche
Throughout its natural distribution prosopis has potential as a valuable timber for
furniture and flooring, it is commonly used for carving both figures and bowls. The branch
wood and off cuts are excellent fuel wood and can be converted into high grade charcoal.
Prosopis plantations can yield 2.5 t/ha/an where little else will even grow and on saline
soils in India has produced biomass of 12 t/ha/an. In recent years scientists in Peru have
worked on the use of prosopis fruits (pods) as food and fodder. As an exotic it is most
frequently planted on extremely problematic sites, exceptionally dry or in some cases
saline. In Sudan and the Gulf States it is planted to stabilize moving sand, on parts of
the Indian Gangetic plain to rehabilitate saline soils and in many countries - Haiti,
Mali, Niger, Senegal, for fuel wood and fodder on hostile sites. Many prosopis are
extremely thorny so it is planted as hedges to keep cattle either in or out.
Usable Attributes
The importance of a nitrogen fixing species with strongly pioneer characters must never be
under estimated. There are many countries in the world with extensive areas of badly
degraded lands caused by inappropriate agriculture and/or the climatic extremes of heat
and dryness. The FAO delegate pointed out that 500 million people live in dry lands
throughout the world and are amongst the poorest of all people. Many such sites are
entirely barren and under these circumstances any plant growth is better than nothing -
even if it gives only a little fuelwood, fodder or even shade. Some sites, like those
shown during the papers from Sudan and the Gulf States, need stabilization to prevent
moving sand destroying farmland or the remaining marginal sites. In Niger and Senegal
prosopis is used for hedges and also woodlots for fuel. In these countries soil
amelioration is being recognized as an additional benefit from prosopis planting. This
should not be overlooked, especially in countries where the climatic conditions will
support seasonal cropping, provided soil quality is improved.
The potential for food and fodder wherever prosopis will grow has been generally
overlooked. Many villagers collect pods and feed them to their livestock but the
Brazilian, Haitian and Peruvian delegates demonstrated there is much more value to these
valuable pods once they have been processed. Delegates were supplied with cookies and
bread made from prosopis fruits and it can be used to increase coffee volumes and even in
ice cream. The Brazilian delegate is a rancher with a thriving business converting
prosopis fruits into food and fodder products. A delegate from Haiti described the
organization of his company collecting and processing fruits for fodder which is blended
with corn, soya or cotton waste. At Piura University in Peru scientists are studying
methods for industrializing prosopis pods and their results could prove extremely valuable
for the poor, living on dry marginal lands around the world.
In Argentina and Texas prosopis timber is used for furniture making. It has an interesting
color, brown or pink when freshly cut changing to dark reddish golden brown. The physical
and mechanical properties are as good as or surpass many widely marketed hardwoods. It is
stable and heavier than teak or walnut with exceptional surface hardness making it ideal
for flooring. Since floors are usually laid using strips or small blocks even small
diameter prosopis can be used for such products. Flooring and some beautiful colonial
style furniture was displayed by the delegate representing a Texas manufacturer. Prosopis
(mesquite) flavors are popular for barbecues in the States and a manufacturer from Texas
described the manufacturing process for "mesquite cookin chunks" used to replace
charcoal. Another delegate was an American businessman representing a firm importing
prosopis charcoal from Mexico. The Haitian delegate also stressed the importance of
prosopis for charcoal, 60% of people in Port-au-Prince rely on charcoal for cooking.
Genetics
Experience with hardy often fast growing tree species which have been extensively planted
as exotics has demonstrated that studies on the genetic variation are critical to
continuing success. Species of prosopis have been transferred to many countries with
neither knowledge nor records of the genetic base of the populations. During the workshop
there was mention of similarities between the exotic populations in Mali, Senegal and
Haiti and it was suggested that this may relate to the French influence in each of these
countries in the past. Genetic studies are being carried out in a number of universities
and institutes and the delegates from Santiago University, Argentina gave an excellent
summary of their work. Prosopis species are essentially out-crossers which results in a
high degree of between tree variability providing great potential for improving selected
characters once they are genetically identified. Possibly one of the most important
observations to date is the extensive within family variation suggesting that the critical
unit for early improvement is the individual tree rather than family or provenance. Modern
forest science has utilized mass clonal production following rejuvenation as a tool to
maximize such benefits.
Next Steps
During the final session the panel appointed to review the proceedings made a number of
observations. Many stressed the need for improving cooperation between scientists working
with prosopis throughout the world and it is important that centers are identified as
reference points for researchers and anyone using prosopis for any purpose. The potential
social advantages of prosopis were highlighted as they link the basic needs of animal care
with human requirements. It was recognized that a lot more work is needed on the genetics
of the genus in order to obtain information concerning the biodiversity. One delegate
emphasized the importance of extending the thornless population because of its obvious
advantage to farm forestry. Also the novel idea of grafting improved material onto
"wild" rootstock established by natural regeneration. An operation manual is
needed written in a "how to do it" vein and in such a way as to be easily
understood and translatable into different languages. Most panel members recognize that
extension work is essential if arid countries throughout the world are to reap maximum
benefit from this hardy, valuable tree. It is very important that prosopis is planted
where it is most needed and not planted where other even more valuable species would give
better returns. Delegates were urged to go home and organize local meetings to ensure
NGO's understand the benefits possible from correctly handling prosopis.
Our Personal Views
The fascinating slides presented by the delegates were interspersed with pictures of poor
nurseries and badly treated planting stock. Planters are fortunate that prosopis is such a
hardy species. All nurseries seen had raised stock in poly-bags and presenters regularly
referred to very long nursery periods. Modern nursery research has proved two important
points, firstly, if plants are to be raised in containers some form of root training is
needed and there are containers of many sizes and shapes on the market called rigi-pots,
rootrainers, groove tubes, etc. which fulfil this need. These are placed on raised frames
and ridges inside the cells ensure roots grow downwards, when they emerge through the
aperture in the base of the container they are "air-pruned", developing growing
points inside the pot ready for immediate growth after transplanting. Secondly, the
potting substrate should be organic, however, most nurseries use whatever local soil is
available sometimes mixed with a little animal manure. Research has shown that fibrous
root systems develop best in organic mixtures so methods of composting any organic waste
must be developed. If this is scarce nursery managers must grow plants for compost
production. From the slides seen there is obviously great potential to quickly
significantly improve tree survival and growth.
Current genetic research suggests selection and propagation of individuals will provide
the best potential for improvement. Prosopis workers and planters should therefore learn
from mistakes made by rubber planters - rubber is also a tree with multiple (latex and
timber) end products. They concentrated breeding on latex, overlooking the potential of
timber. Prosopis will need breeders looking for high fruit yields, wood biomass, timber
and site adaptability. The sooner some outstanding phenotypes (trees of outstanding form)
are selected and cloned the better. Where research into selection is advanced the best
trees can be cloned and either rooted material or scions exported to countries where
prosopis is needed. Scions or budwood should also be used for grafting rootstock already
established in the field from natural regeneration to improve plant quality. In some
countries farmers could plant 100 to 200 thornless trees per hectare for timber and
interplant the rest of the area with grafted clones of heavy fruiting cultivars to provide
income from food and fodder production.
The various species of prosopis are generally hardy and easy to handle in nurseries. Only
the Indian species (cineraria) shows consistent problems related to its sensitivity to tap
root damage - a problem which can be overcome with rigi-pots. The ease of establishment is
sometimes misused resulting in prosopis being planted on sites which would be more
productive under other forest species or for purposes other than tree planting. Through
its aggressive colonization habit prosopis may spread onto valuable farm land. So care
must be taken when planning a prosopis planting program. There are also cases where
problematic sites have been planted and the resultant crop completely cleared for fuel or
other purposes leaving the site to become barren once again. Planters must ensure good
management practices are taught to villagers so that the benefits of the species are
sustainable on these poor sites.
The wood of prosopis is a good fuel, can be converted into good charcoal and also the
timber is used for many of the purposes high quality hardwoods are used. In the indigenous
prosopis forests there is potential for expanding wood industries. If techniques to
utilize small diameter woods and other methods of small wood utilization are developed a
timber industry could develop serviced by trees from marginal dryland sites outside the
natural range.
Conclusions
This was an important workshop and it is obvious that though prosopis may find its way
onto the wrong sites due to its aggressive pioneering nature its benefits on difficult
sites and in its natural habitat are many and must be harnessed. There is plenty of
valuable technical information concerning site selection, preparation and choice of the
best planting stock already available. More technical work is underway but it is important
that what is known of the benefits of prosopis is put into practice on the vast areas of
problematic sites around the world.