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hydroponics,growing of plants without soil in water to which nutrients have been added. Hydroponics has been used for over a century as a research technique, but not until 1929 were experiments conducted solely to determine its feasibility for growing commercial crops. There are now hydroponic home gardens and commercial cropping operations in the United States and many other countries. Under hydroponics, plants can be grown closer together than in the field, thereby increasing yields, and multiple cropping (the growing of several crops in the same tank) can be practiced. In addition to conserving space, hydroponics almost eliminates weed and pest problems, and can use significantly less water than may be needed for irrigation when crops are grown in fields (an advantage where water is scarce). The cost of equipment is high and personnel must be trained. Although hydroponics is possible for most plant species, a limiting factor is the amount of physical support required. Usually the plants are held upright by wire supports or are rooted in a sterile medium, e.g., pure sand or gravel. The nutrient solutions must supply, in optimum concentrations and in correct balance, the elements, such as nitrogen, phosphorus, potassium, and other essential nutrients normally found in soil. Other names for hydroponics are soilless gardening, soilless culture, chemiculture, and water gardening. Aquaponicsaquaponics,
the growing of plants and the raising of fish by combining aquaculture with the techniques of hydroponics, usually on a small scale. Water containing fish waste matter is used as the nutrient solution for the plants being raised; the plants help clean the water that
..... Click the link for more information. combines aquacultureaquaculture,
the raising and harvesting of fresh- and saltwater plants and animals. The most economically important form of aquaculture is fish farming, an industry that accounts for an ever increasing share of world fisheries production.
..... Click the link for more information. with hydroponics.
See R. Bridwell, Hydroponic Gardening (rev. ed. 1990); R. E. Nicholls, Beginning Hydroponics (1990).
growing plants without soil in artificial mediums. In this process the root systems of the plants grow in solid substrata (without nutritive significance), in water, or in moist air (aeroponics). The plants receive nutrients from a food solution surrounding the roots.
Hydroponics permits the regulation of plant growth conditions and the creation of a feeding regimen for a root system that fulfills all the nutritional requirements of the plant. It is also possible to create the concentration of carbon dioxide gas in the air that is most beneficial for photosynthesis, as well as to regulate the air temperature and the temperature of the space around the roots, the humidity, and the intensity and prolongation of illumination.
Creating optimal conditions for the growth and development of plants helps obtain very high yields and better quality in a shorter period of time. Growing plants by the hydroponic method is less labor-consuming than soil cultivation, and the water and nutritive substances are used more economically. Application of the nutritive solution is easily automated. In hydroponics there is practically no problem with weeds.
In the USSR hydroponics is used mainly to grow cucumbers, tomatoes, and flowers and to obtain the vitamin-rich foliage of corn plants, which is used as additional fodder for young animals during the winter. The process is also used in scientific research. Of great importance for the successful growth of plants in hydroponic systems is the composition of the nutrient solution, which is varied depending on the species of the plants, their age, and the basic factors of the external environment (such as the temperature of the air and the root-medium layer and the relative humidity of the air).
The nutritive solution consists of the salts of nitrogen, phosphorus, potassium, and other elements (Ca, Mg, Fe, B, Mn, Zn, Cu, Mo). The concentration of the food solution for water cultures is about 6 millimoles per liter, for gravel cultures, about 30 millimoles per liter. For aeroponics the concentration of the solution is a little higher.
Large areas of greenhouses are used for hydroponics in the suburban areas of many cities, including Moscow, Leningrad, Kiev, and Sverdlovsk. Hydroponics is done on open ground in Armenia and Azerbaijan. Abroad hydroponics has been widely developed in Great Britain, Japan, France, Italy, and the Antilles.
REFERENCESVyrashchivanie rastenii bez pochvy. Leningrad, 1960.
Aliev, E. A., Iu. A. Diukarev, and B. V. Latenko. Vyrashchivanie ovoshchei v teplitsakh bez pochvy. Kiev, 1964.
Bentley, M. Promyshlennaia gidroponika. Moscow, 1965. (Translated from English.)
Zhurbitskii, Z. I. Teoriia i praktika vegetatsionnogo metoda. Moscow, 1968.
Z. I. ZHURBITSKII