Pieter van der Zaag explains why irrigated areas expand only very slowly

In his interesting Viewpoint article in Water Alternatives, Bruce Lankford suggests that an African Green Revolution cannot come about without irrigation. But he does not convincingly explain why irrigated areas expand only very slowly.

Pieter van der Zaag (UNESCO-IHE Institute for Water Education) argues that grain yields have remained stagnant in Africa because of high temporal rainfall variability, significant spatial soil nutrient heterogeneity, and weak and volatile markets.