ABSTRACT
The need for irrigation is commonly judged in relation to a country's climate: the adoption of irrigation being seen as a necessary technological response to permit crop production under conditions of increasing aridity. While all forms of irrigation are based on a desire to increase the water available when needed, the amounts of water required and the degrees of control achieved differ. "Total irrigation" describes regimes where the operator supplies most of the plants' water needs, whereas "supplemental irrigation" refers to situations where rainfed cultivation is augmented by the irrigator. The absence of medium-sized, commercial operators means that in many African countries, irrigation systems are polarized between a few, larger-scale government schemes and a number of very small independent irrigators. Awareness of water as a common resource shared between various production systems is fairly recent in African planning. The tremendous differences between the main types of irrigation have inhibited any sharing of experience or assistance between them.
