Managment, Use and Control of Prosopis
In 1974 Prosopis juliflora, a tropical American leguminous tree, was introduced into Yemen to combat soil erosion, and since then because of its competitiveness and adaptability it has spread rapidly to large areas.
Today over 250 ha of important agricultural lands (particularly the scarcely available irrigated area) in different regions of the country have been invaded by this species, and the rapid uncontrolled growth is likely to increase dramatically if methodologies for its use and control are not urgently introduced into the country.
Due to the very recent detection of the invasion, only limited statistical information is available, but the following numbers are sufficient to define the importance of the problem: the extent of land reported to be invaded by P. juliflora amounts to almost 70 ha in the Hodeidah Governorate, 50 ha in Hadramout, 50 ha in Lahej, 40 ha in Abyan and 40 ha in Shabwa. All these areas are at risk in terms of food security problems if additional agricultural land is invaded by the species. In the Abyan and Shabwa Governorates the invasion is very recent and severe and, although P. juliflora was successfully introduced to combat soil erosion, its recent uncontrolled spread is cause for major concern by farmers, who are confronted with harsh climatic and soil conditions and have very limited irrigated land for agricultural production.
Almost 80 percent of the Yemeni population depends on agriculture, most of which is irrigated, and P. juliflora invasion can affect the irrigation canals, where its establishment and growth impedes the correct flow of water. In the regions affected by this species, the main irrigated crops are cotton, onions, watermelons, wheat and various vegetables.
Farmers have no experience with Prosopis management and use, and consider the plant a dangerous weed. They are concerned that it will spread to other agricultural lands, affecting crop production and therefore food security. Scientists are worried about ecological changes that may occur in the natural rangelands with high risk for biodiversity maintenance and native species conservation. The actual information about the plant, its ecology, its management and its presence is insufficient and not well organized. Local governments are concerned about invasion of roadsides, water irrigation channels and other infrastructure, and there are no policy guidelines related to Prosopis management and control.
In addition to the above concerns, it should be noted that the Yemeni population increases at an annual growth rate of 3 percent while agricultural production fails to keep pace with this trend. This is affecting food security and it hence becomes of primary importance to explore alternative ways to improve food and fodder availability.
In this regard and in spite of all the above-mentioned negative aspects, P. juliflora has considerable ecological and economic potential. From the physio-ecological viewpoint, P. juliflora is a very hardy and versatile tree, well adapted to areas of unreliable and low rainfall, able to utilize low-quality irrigation water; it is also able to grow and produce on saline soils, where high salt concentrations do not allow other species to survive. Nomads and pastoralists in Yemen, as in many other countries, regularly feed their animals on P. juliflora pods, which have a high nutritional value, being rich in sugars and with a protein content of about 12 percent. The importance of pods as fodder supply increases as natural conditions become harsher, seasonally and locally.
It is well known in Latin America and India (where Prosopis is known as "Algarrobos" and "Mesquite", respectively) that pods can be processed to obtain excellent feed for ruminants and poultry, as well as various products suitable for human consumption. The most important products for human use obtained from processing of pods are: flour, used in combination with wheat flour for the preparation of bread and cakes, and "algarrobina", a syrup with a very high content of sugar (mainly saccharose).
In addition, pastoralists collect Prosopis wood for cooking and heating.
From the productive and economic viewpoint, P. juliflora can be considered a multipurpose species, as it produces timber, firewood and honey, as well as edible pods. It is widely used in its native regions and is being developed industrially in northeastern Brazil, where smallholder production is combined with centralized processing. The tree has been introduced, naturalized and planted through the drier tropics and sub-tropics for soil conservation and firewood production purposes, and it is still rarely managed as a pod-producer, despite the high nutritional value highlighted above. In short, P. juliflora should no longer be regarded as a potential weed, but properly managed and developed as a useful crop, as it can use land and water of too low a quality for common field crops, it offers farmers good opportunities for food production improvement and income generation.
The project will introduce and demonstrate techniques for the use and management of P. juliflora developed in other countries. It will establish two local pilot mills for pod processing and will train local staff in collection of information related to the species. It will also provide guidance and support to national staff in assisting farmers to adopt the introduced technologies throughout the life of the project and after its completion. Furthermore, the project will provide advice and recommendations to policy makers to adopt correct measures for Prosopis control and management and in preparing a national strategy on the above. The project will thus play a catalytic role through introduction and demonstration of pilot activities that will then be replicated and continued by trained personnel from MAI and pilot farmers with the support of involved policy makers.
The project will be especially addressed to womens groups, since women traditionally deal with food and fodder.
The project aims at supporting the Government of Yemen in developing suitable and adapted management strategies and plans for the use and control of Prosopis juliflora in local agricultural systems, with a view to improving household food security and income generation opportunities.
The project envisages the following main outputs:
Project activities got underway in the first half of 2002 and the project was completed at the end of 2003.