In Africa, 28 percent of its landmass, 874 Mha, is potentially suitable for agricultural production. Of the potentially suitable agricultural land, 34 percent
comprises arid and semiarid lands (ASAL) that are too dry for rainfed agriculture. The semiarid regions have a shortened length of growing period (75-129 days) compared to the subhumid (180-269 days), and the humid (>270 days) zones. The dynamics of agroecosystems show that the farming
systems practiced have gone through diverse changes from traditional shifting farming systems to permanent and intensified arable and mixed farming systems. The changes are coping strategies to respond to the environment,
and its changing biophysical and socioeconomic circumstances..
