Implementing Agency:
Department For International Development (NRRD)

Managing Institute:
NRIL (Natural Resources International)

Contractor:
Institute of Terrestrial Ecology

Project Code: R4590 583-656-003	Start Date: Apr. 1, 1991	End Date: Mar. 31, 1994
Commitment: £204 367	Status: Completed	Type of Funding: Bilateral - TDR

Project Background:
The project is aimed at the problem of sustaining food and fuelwood production throughout the Sahel, using the system of Acacia tree fallows for soil improvement. Initial work in the Sudan showed that continuous cropping with sorghum and millet by the mechanised farming corporation (MFC) had led to exhausted soils over a period of 10 to 15 years. In the Sudan, much of the deforested land could be returned to rotational cropping with the use of tree fallows. Work on the project in the Sudan was discontinued due to the current political problems in the country. However, following initial contacts with the Laboratoire d'Ecologie Vegetale of ORSTOM, in April 1990, ITE discovered that the German overseas aid and development organisations, GTZ, had planted a series of Acacia stands in northern Senegal. As these stands were thought to be an adequate replacement for the chronosequence (time series) of stands already identified in the Sudan, the project was reviewed and transferred to Senegal in April, 1991.

Project Objectives:
The objectives of the project are: To determine the rate of improvement in soil fertility under a nitrogen fixing Acacia tree fallow, and the rate of soil deterioration with continuous cropping To determine the approximate values for the nitrogen budget of Acacia fallows, particularly the rate of nitrogen fixation To identify the factors that limit the rate of increase in soil fertility under Acacia (eg P-status , rhizobium supply etc.) and that limit the rate of soil degradation under cereal cropping (eg leaving crop residue, not burning tree stumps). To translate the scientific findings into a series of practical recommendations to be used by government agencies, and local and regional planners.