Hydroponics

Hydroponics is the process of growing plants in a mixture of mineral nutrients and water; specifically without the use of any type of soil. The two major features of hydroponics are the use of liquid solutions for plant growth and the support of plants with porous materials, such as pebbles or gravel, which let the nutrients into the roots. Plants usually grow by using mineral nutrients from soil and non-mineral nutrients from air and water. With the use of hydroponics, plants do not get the nutrients usually taken from the soil. However, plant physiologists provide each type of plant with the correct amount of each nutrient needed to grow without soil.

There are several early examples of hydroponics, or soil-free agriculture, including the hanging gardens of Babylon and the floating gardens of China and Aztec Mexico. Early Egyptian paintings also depict the growing of plants in water.

In 1600, Belgian physicist Jan Baptista van Helmont (1579–1644) demonstrated that a willow shoot kept in the same soil for five years with routine watering gained 160 lb (13 kg) in weight. As it grew into a full-sized plant, the soil in the container lost only 2 oz (57 g). Clearly, the source of most of the plant’s nutrition was from the water, not the soil.

During the 1860s, German scientist Julius von Sachs (1832–1897) experimented with growing plants in water-nutrient solutions, calling it nutriculture. English philosopher Sir Francis Bacon (1561–1626) published the book Sylva Sylvarum, which is the earliest known book on growing plants without soil. In the eighteenth century, solutions containing mineral nutrients were first developed. In the 1860s, German botanists Wilhelm Knop and Julius von Sachs modified these solutions. Over the following sixty years, laboratory experiments were performed in growing plants without soil.

In 1929, American physician William Frederick Gericke of the University of California first coined the term hydroponics, which means water labor. Gericke demonstrated commercial applications for hydroponics. He became known for his 25-ft (7.6 m) tomato plants. Hydroponics has been shown to double crop yield over that of regular soil. It can be categorized into two subdivisions: water culture, which uses the Sachs water-nutrient solution, with the plants being artificially supported at the base; and gravel culture, which uses an inert medium like sand or gravel to support the plants, to which the water-nutrient solution is added.

Hydroponics was used successfully by American troops stationed on non-arable islands in the Pacific Ocean during the 1940s. In the late 1940s, American horticulturists Robert Withrow and Alice Withrow, of Purdue University (Indiana), designed a practical hydroponic system. Over the twenty years, hydroponic farms developed in the United States and in such countries as France, Germany, Israel, Italy, Spain, Sweden, USSR (what is now Russia), and the United Kingdom. It has also been used to produce foods in such arid countries as Saudi Arabia. In the 1970s, researcher J. Sholto Douglas worked on what he called the Bengal hydroponics system. He sought to simplify the methods and equipment involved in hydroponics so it could be offered as a partial solution for food shortages in India and other developing countries.

Successfully adopted in certain situations, hydroponics will remain in limited use as long as traditional farming methods in natural soil can support the world’s population.