THE POTENTIAL BENEFITS OF AGROFORESTRY IN THE SAHEL AND OTHER SEMIARID REGIONS

This article summarises results of three related studies. The first st udy is a synthesis and analysis of available knowledge on woody plants in semi-arid regions with an emphasis on the Sahel region, investigat ing the potential 'added value' of woody plants to improve nutrient an d water availability for agricultural crop and pasture production goal s. The other two are field studies aimed to validate key issues identi fied by the synthesis study, through measurements on the influences of woody plants on water and nutrient availability, and investigations o f the relationship between soil organic matter quantity and quality an d the recovery rate of nitrogen and phosphorus from fertilisers. The f ield studies support the conclusion that processes leading to an added value of woody plants in agroforestry systems are mainly related to r educed losses of water and nutrients. Such added values are therefore lowest where they are most needed, in resource-poor environments. Spec ific farmers goals, agroecological and socio-economic conditions have to be taken into account to make optimal use of the potentials of agro forestry. The potential benefits of agroforestry systems are mainly in terms of the improved efficiency of nutrient inputs than as an altern ative for fertilisers. This has major implications for design and mana gement of agroforestry systems. (C) 1997 Elsevier Science B.V.