Simply put, it depends on what you classify as agriculture.

Slash and Burn agriculture, where plants are cut down and burned (usually right before the rainy season) to form nutrient-rich ash that seeps into the fields, has been shown to have been present in South Africa since around the 4th Century when the Bantu Expansion brought it down from central Africa.

However, the first instances of "farm life" as is traditionally pictured in Western culture (people owning land on which they grow crops for trade and food for themselves) and ideas associated with it (such as crop rotation) only have written records dating back to the 1500s.