Though the practice of growing plants in water dates back to the Hanging Gardens of Babylon in 600 B.C., hydroponics is a 20th-century term. Derived from the Greek, "hydro" means water and "ponos" means work. Hydroponics means working with water or in water, an apt description of soilless agriculture. This ancient practice has been used by many groups throughout history, from the Aztecs to the American armed forces to the National Aeronautics and Space Administration.
In the 12th century, an Aztec tribe in what is now Mexico took advantage of the nutrient-rich water of Lake Tenochtitlan. The people built rafts of rush and reed, seeded the rafts and set them afloat onto the lake. The rafts, called chinampas, were strung together, creating floating gardens. The rafts acted as anchors, and the plant roots burrowed downward, into the lake water.
In the 17th century, Johann Baptista van Helmont, a Flemish chemist, performed the willow tree experiment. Van Helmont weighed a pot of dry soil and then planted in the soil a willow tree sapling. Over five years time he watered the willow with only rainwater or distilled water. After five years he separately weighed the soil and the tree. The weight of the soil was the same. The tree, however, had increased in weight. Van Helmont concluded it was the water that nourished the tree, not the soil.
John Woodward in 1699 added small amounts of different types of soil to water and recorded plant growth and production, inadvertently creating nutrient solutions for water-based plant growth. Two German scientists, Julius von Sacks and Wilhelm Knop, developed formulae specific to the balance of nitrogen, phosphorus and potassium as nutrient solutions in water agriculture.
In a March 1, 1937, article in "Time" magazine, Dr. William Frederick Gericke of the University of California is credited as the "foremost U.S. practitioner" of a science now called hydroponics. Gericke is credited with the creation of the term, saying that it had "a strong economic and utilitarian connotation." But Dr. Gericke did more than give a name to soilless agriculture. He built upon earlier models and created a garden in which his tomato plants were anchored in an inert material, such as sawdust, and the roots immersed in solutions of water and water-soluble nutrients. It is this model on which modern hydroponics is based.
War and Space
During World War II, the armed forces built hydroponic gardens on the barren soils of the Pacific Rim islands, supplying soldiers with fresh vegetables, resolving the need to ship fresh foods long distances.
As the National Aeronautics and Space Administration (NASA) endeavors to send astronauts into space for longer periods of time and establish space stations, the need for food supply goes beyond freeze-dried packets. In the 21st century, NASA is conducting experiments in space with hydroponic gardens. NASA is looking to the future as well; hydroponics may prove to be the dominant agriculture as humans colonize the earth's moon and planets beyond.