Des Moines Register 03/23/06 Dateline Iowa REGISTER STAFF AND NEWS SERVICES Professor to discuss sustainable agriculture A Harvard University professor is scheduled to speak about sustainable agriculture at two free events in early April. Calestous Juma will discuss "Reinventing African Economies: Technological Innovation and the Sustainability Transition" at 7 p.m. April 6 at the Scheman Building at the Iowa State Center in Ames. A reception will precede the talk at 6 p.m. Juma will also speak on "Shaping the New Biosociety" at noon April 7 in Room 116 of the Steiner Building at Grinnell College.