"These findings support the spatial extent of pigeonpea optimality and the potential for widespread integration."—Peter et al. 2017
Peter, B. G., Messina, J., Frake, A., and Snapp, S. 2017. Scaling agricultural innovations: pigeonpea in Malawi. The Professional Geographer 70(2):239–250.
CARTOGRAPHY: Lots of vertical elements in this map, including a vertical scale bar.