Nigerian agronomist Mercy Diebiru-Ojo (R) and a worker pull out the weeds of cassava crops in a greenhouse on the campus of the International Institute of Tropical Agriculture (IITA) in Ibadan, on September 29, 2025. Mercy Diebiru-Ojo's ambitions are straightforward -- increase Nigerian yam and cassava yields by 500 percent, fight hunger and raise her country's position on the agricultural value chain from a mere grower to a processor. The first steps, at least, are already underway for the 44-year-old agronomist, who was awarded this year's prestigious Africa Food Prize for her research on yams and cassava, both major food staples in Africa. Traditionally, farmers in Nigeria -- which produces 70 percent of the world's yams -- replant chunks of yams and cassava from the previous year's harvest, to grow this year's crop. (Photo by OLYMPIA DE MAISMONT / AFP) (Photo by OLYMPIA DE MAISMONT/AFP via Getty Images)