Extended Data Fig. 2: Total harvested area (top) and total harvested calories per ha (bottom) for maize vs. all grain crops or top five crops in each country.

Yields were converted to total calories for each crop to facilitate comparison between different crops. Maize is the majority of grain area in all five countries, although non-grain crops such as cassava and sugarcane are also important. Yields of maize show very similar trends and variation to those from the top five crops, although levels differ because of the higher calorie yield of cassava and sugarcane. The one case where maize and other crops deviate significantly is in Zambia since 2015, where reported cassava yields more than doubled in a span of a few years. We consider this more likely to be an artefact in the data than a true increase in cassava productivity.