When the net revenues from the crops in the various crop sequences during the first three cropping seasons were added to those of maize succeeding the various crop sequences in the fourth season, the returns on investment ranged from −22% with speargrass fallow/maize rotation to 235% with cassava/maize rotation when no N was applied and from 29% with continuous maize to 196% with cassava/maize rotation when N fertiliser was applied (Table 6).