I would like to point you to this very good article from Le Monde Diplomatique, that explains how african soil is bought by private investors from The US, Europe, Asia and South Africa, in order to grow export crops, e.g. for the production of bio ethanol. The article shows how even countries whose populations suffer from food shortages invite international inverstors to buy arable land, and how 125 years after the african continent was devided by the colonial powers of that time, history repeats.

This is an interesting map from Le Monde Diplomatique that depicts how people die trying to enter the Schengen-Raum (click for higher resolution).