Revisiting the link between cereal diversity and production in Ethiopia

Studies show that cereal diversity positively affects mean yields, suggesting increased crop diversity as a means of increasing production (Di Falco and Chavas 2009, Baumgärtner and Quaas 2010). In practice though, agricultural development has relied on nondiverse systems. Using the Ethiopian Rural Household Survey panel, we revisit this paradox and disentangle the effects of agroecological zones and composition of crop diversity. We find a positive effect of greater cereal diversity on cereal production, but mostly in specific agroecological zones and for households who diversify away from a particular low-productivity crop: teff. These results indicate that the scope of cereal diversity to drive increases in output may be limited. Similar to recent studies of biodiversity-ecosystem function relationships (e.g. Jochum et al. 2020), the results suggest that the composition of diverse systems can be more important than the measured diversity itself. In the case of cereal crops in Ethiopia, differences in the yields of particular cereals in the crop mix explain the diversity effect, rather than diversity alone. Since some combinations of crops add to productivity but others do not, productivity-related crop choice may not guarantee in situ conservation of crop diversity on its own. Alternative conservation solutions may well be needed for that.