Crop scientists from Africa are coming to central Iowa to learn ways to improve their main food source — sorghum — and to perhaps help a half-billion people to eat better. Stephanie Jacobson, spokeswoman for Johnston-based Pioneer Hi-Bred International, says the Bill Gates Foundation this week singled out the “Africa Harvest” program for a major grant. Jacobson says Pioneer is donating four-point-six million dollars in biotechnology to help improve the sorghum plant, which is widely grown on the African continent. She says the Gates Foundation is also donating nearly 17-million dollars toward the effort. Jacobson says the Gates grant will allow five researchers from Africa to relocate to Johnston to work on developing even better sorghum plants with increased levels of Vitamins A, E and other nutrients like iron, zinc, amino acids and protein, in addition to making the cooked grain easier for people to digest. She says sorghum may be something of a foreign plant to many Iowans. Sorghum grows in more arid parts of the world where drought is a severe factor that would prevent most other crops from thriving. Jacobson says it’s the main food source for about a half-billion people. She says the human body is limited in the amount of nutrition it can receive from sorghum. Through biotechnology, plant genetics researchers are working on ways to change sorghum on a molecular level to make it more easy to digest and to boost the plant’s nutritional value.