27 Hekstra. Productivity and Landuse ...

Lack of rainfall and overgrazing are generally regarded as the
main factors causing desertification of steppes and savannas.
Deserts are often considered less grazable than savannas.
Though sparse, the food quality of grasses and herbs is very
good in the desert. Quality decreases towards the savannas.
Contrary to the situation in deserts where water is the prime
limiting factor, productivity in the steppes and savannas is
nutrient limited. For agronomic improvement attention should
focus on phosphorus, nitrogen and water, in that sequence. Ex-
periments outside the Sahel, e.g. in the Mediterranean region,
are desirable to test remedial application of fertilizers.


CONTENTS:

1. Introduction 1
2. Crop cultivation in arid Africa 3
3. Limits to livestock rearing and mixed farming in Africa 8
4. Increasing rangeland productivity and exploitation 12
5. Lessons for and from the Sahel 14
References 18