As Dr. Diouf points out, Africa has enormous land resources. Water is more problematic. There is a very large part of Africa that is dry and getting drier. A significant contributor to this drying process, and to the failure of much existing irrigation, is the enormous infestation of aquatic weeds in your lakes and streams. Water Hyacinth, water lettuce, water fern, Typha (my favorite - it is a GREAT crop), Phragmites and other weeds clog your rivers and reservoirs, causing flooding and aggravating drought. The huge infestation of Typha in what used to be Lake Chad is one of the dessicating influences expanding the Sahara southward. All of these weeds can be made into fuel. Some of them can be made into food. Just their clearance would free up a great deal of water for your use. Their harvest would be probably be profitable even separated from the value of their clearance, and certainly in combination. The environmental side effects would include a reduction in malaria. Harvest these nuisances. Eat what is fit for human consumption, and make the rest into ethanol.