Early hydroponic systems are believed to have been built in 600 B.C. in Babylon. These were built as stepping gardens, and used water that trickled from the top down over each layer. This form of essentially irrigation made it possible to produce food in previously incapable climates to do so. Other early hydroponic systems are believed to have been work of the Aztecs, using floating rafts to plant crops on. Such systems were used solely because crops could not be grown and harvested in the muck amid the shores. These were done by first building the rafts, and then putting a thin layer of mud from the bottom of the lake on to the top of the raft and putting them in the lake. When crops then began to grow out of the mud, the roots could penetrate
