Hydroponics, the growing of plants without soil, has developed from the findings of experiments carried out to determine what substances make plants grow and the composition of plants. Such work on plant constituents dates back as early as the 1600s. However, plants were being grown in a soilless culture far earlier than this. Hydroponics is at least as ancient as the pyramids. A primitive form has been carried on in Kashmir for centuries. The process of hydroponics growing in our oceans goes back to about the time the earth was created. Hydroponic growing preceded soil growing. But as a farming tool, many believe it started in the ancient city of Babylon with it's famous hanging gardens, which are listed as one of the Seven Wonders of the Ancient World, and was probably one of the first successful attempts to grow plants hydroponically. The floating gardens of the Aztecs of Central America, a nomadic tribe, they were driven onto the marshy shore of Lake Tenochtitlan, located in the great central valley of what is now Mexico. Roughly treated by their more powerful neighbors, denied any arable land, the Aztecs survived by exercising remarkable powers of invention. Since they had no land on which to grow crops, they determined to manufacture it from the materials at hand. In what must have been a long process of trial and error, they learned how to build rafts of rushes and reeds, lashing the stalks together with tough roots. Then they dredged up soil from the shallow bottom of the lake, piling it on the rafts. Because the soil came from the lake bottom, it was rich in a variety of organic debris, decomposing material that released large amounts of nutrients. These rafts, called Chinampas, had abundant crops of vegetables, flowers, and even trees planted on them. The roots of these plants, pushing down towards a source of water, would grow though the floor of the raft and down into the water. These rafts, which never sank, were sometimes joined together to form floating islands as much as two hundred feet long. Some Chinampas even had a hut for a resident gardener. On market days, the gardener might pole his raft close to a market place, picking and handing over vegetables or flowers as shoppers purchased them. By force of arms, the Aztecs defeated and conquered the peoples who had once oppressed them. Despite their great size their empire finally assumed, they never abondoned the site on the lake. Their once crude village became a huge, magnificent city and the rafts, invented in a gamble to stave off perverty, proliferated to keep pace with the demands of the capital city of Central Mexico. Upon arriving to the New World in search of gold, the sight of these islands astonished the conquering Spainards. Indeed, the spectacle of an entire grove of trees seemingly suspended on the water must have been perplexing, even frightening in those 16th century days of the Spanish conquest. William Prescott, the historian who chronicled the destruction of the Aztec empire by the Spaniards, described the Chinampas as "Wondering Islands of Verdure, teeming with flowers and vegetables and moving like rafts over the water". Chinampas continued in use on the lake well into the nineteenth century, though in greatly diminished numbers. So, as you can see, hydroponics is not a new concept. Many gardening writers have suggested that the Hanging Gardens of Babylon were in fact an elaborate hydroponic system, into which fresh water rich in oxygen and nutrients was regularly pumped. The world's rice crops have been grown in this way from time immemorial. And also the floating gardens of the Chinese, as described by Marco Polo in his famous journal, are examples of "hydroponic culture". Ancient Egyptian hieroglyphic records dating back to several hundred years B.C. describe the growing of plants in watre along the nile without soil. Before the time of Aristotle, Theophrastus (327-287 B.C.) undertook various experiments in crop nutrition. Botanical studies by Dioscorides date back to the first century A.D. The earliest recorded scientific approach to discover plant constituents was in 1600 when Belgian Jan van Helmont showed in his classical experiment that plants obtain substances from water. He planted a 5-pound willow shoot in a tube containing 200 pounds of dried soil that was covered to keep out dust. After 5 years of regular watering with rainwater he found the willow shoot increased in weight by 160 pounds, while the soil lost less than 2 ounces. His conclusion that plants obtain substances for growth from water was correct. However, he failed to realize that they also require carbon dioxide and oxygen from the air. In 1699, John Woodward, a fellow of the Royal Society of England, grew plants in water containing various types of soil, the first man-made hydroponic nutrient solution, and found that the greatest growth occurred in water which contained the most soil. Since they knew little of chemistry in those days, he was not able to identify specific growing elements. He thereby concluded that plant growth was a result of certain substances and minerals in the water, derived from enriiched soil, rather than simply from water itself. In the decades that followed Woodwards research. European plant physiologists established many things. They proved that water is absorbed by plant roots, that it passes through the plants stem system, and that it escapes into the air through pores in the leaves. They showed that plant roots take up minerals from eithr soil or water, and that leaves draw carbon dioxide from the air. They demonstrated that plants roots also take up oxygen. Further progress in identifying these substances was slow until more sophisticated research techniques were developed and advances were made. The modern theory of chemistry, made great advances during the seventeenth and eighteenth centuries, subsequently revolutionized scientific research. Plants when analyzed, consisted only of elements derived from water, soil and air. The experiments of Sir Humphrey Davy, inventor of the Safety-Lamp, had evolved a method of effecting chemical decomposition by means of an electric current. Several of the elements which go to make up matter were brought to light, and it was now possible for chemists to split-up a compound into it's constituent parts. In 1792 the brilliant English scientist Joseph Priestley discovered that plants placed in a chamber having a high level of "Fixed Air" (Carbon Dioxide) will gradually absorb the carbon dioxide and give off oxygen. Jean Ingen-Housz, some two years later, carried Priestley's work one step further, demonstrating that plants set in a chamber filled with carbon dioxide could replace the gas with oxygen within several hours if the chamber was placed in sunlight. Because sunlight alone had no effect on a container of carbon dioxide, it was certain that the plant was responsible for this remarkable transformation. Ingen-Housz went on to establish that this process worked more quickly in conditions of bright light, and that only the green parts of a plant were involved. In 1804, Nicolas De Saussure proposed and published, results of his investigations that plants are composed of mineral and chemical elements obtained from water, soil and air. By 1842 a list of nine elements believed to be essential to plant growth had been made out. These propositions were later verified by Jean Baptiste Boussingault (1851), a French scientist who began as a mineralogist employed by a mining company, turned to agricultural chemistry in the early 1850s. In his experiments with inert growing media. By feeding plants with water soulutions of various combinations of soil elements growing in pure sand, quartz and charcoal (an inert medium not soil), to which were added solutions of known chemical composition. He concluded that water was essential for plant growth in providing hydrogen and that plant dry matter consisted of hydrogen plus carbon and oxygen which came from the air. He also stated that plants contain nitrogen and other mineral elements, and derive all of their nutrient requirements from the soil elements he used, he was then able to identify the mineral elements and what proportions were necessary to optimize plant growth, which was a major breakthrough. In 1856 Salm-Horsmar developed techniques using sand and other inert media, various research workers had demonstrated by that time that plants could be grown in an inert medium moistened with a water solution containing minerals required by the plants. The next step was to eliminate the medium entirely and grow the plants in a water solution containing these minerals. From discoveries and developments in the years 1859-1865 this technique was accomplished by two German scientists, Julius von Sachs (1860), professor of Botany at the University of Wurzburg (1832-1897), and W. Knop (1861), an agricultural chemist. Knop has been called "The Father of Water Culture". In that same year (1860), Professor Julius von Sachs published the first standard formula for a nutrient solution that could be dissolved in water and in which plants could be successfully grown. This marked the end of the long search for the source of the nutrients vital to all plants. This was the origin of "Nutriculture" and similar techniques are still used today in laboratory studies of plant physiology and plant nutrition. These early investigations in plant nutrition demonstrated that normal plant growth can be achieved by immersing the roots of a plant in a water solution containing salts of nitrogen (N), phosphorus (P), sulfur (S), potassium (K), calcium (Ca), and magnesium (Mg), which are now defined as the macroelements or macronutrients (elements required in relatively large amounts). With further refinements in laboratory techniques and chemistry, scientists discovered seven elements required by plants in relatively small quantities - the microelements or trace elements. These include iron (Fe), chlorine (Cl), manganese (Mn), boron (B), zinc (Zn), copper (Cu), and molybdenum (Mo). The addition of chemicals to water was found to produce a nutrient solution which would support plant life, so that by 1920 the laboratory preparation of water cultures had been standardized and the methods for their use were well established. In following years, researchers developed many diverse basic formulas for the study of plant nutrition. Some of these workers were Tollens (1882), Tottingham (1914), Shive (1915), Hoagland (1919), Deutschmann (1932), Trelease (1933), Arnon (1938) and Robbins (1946). Many of their formulas are still used in laboratory research on plant nutrition and physiology today. Interest in practical application of this "Nutriculture" did not develop until about 1925 when the greehouse industry expressed interest in its use. Greenhouse soils had to be replaced frequently to overcome problems of soil structure, fertility and pests. As a result, research workers became aware of the potential use of nutriculture to replace conventional soil cultural methods. Prior to 1930, most of the work done with soilless growing was oriented to the laboratory for various plants experiments. Nutriculture, chemiculture, and aquiculture were other terms, used during the 1920s and 1930s to describe soilless culture. Between 1925 and 1935, extensive development took place in modifying the laboratory techniques of nutriculture to large-scale crop production. In the late 1920s and early 1930s, Dr. William F. Gericke of the University of California extended his laboratory experiments and work on plant nutrition to practical crops growing outside for large scale commercial applications. In doing so he termed these nutriculture systems "hydroponics". The word was derived from two Greek words, hydro, meaning water and ponos meaning labor - literally "water-working". His work is considered the basis for all forms of hydroponic growing, even though it was primarily limited to the water culture without the use of any rooting medium. Hydroponics is now defined as the science of growing plants without the use of soil, but by use of an inert medium, such as gravel, sand, peat, vermiculite, pubice or sawdust, to which is added a nutrient solution containing all the essential elements needed by the plant for its normal growth and development. Since many hydroponic methods employ some type of medium that contains organic material like peat or sawdust, it is often termed "soilless culture", while water culture alone would be true hydroponics. Today, hydroponics is the term used to describe the several ways in which plants can be raised without soil. These methods, also known generally as soilless gardening, include raising plants in containers filled with water and any one of a number of non-soil mediums - including gravel, sand, vermiculite and other more exotic mediums, such as crushed rocks or bricks, shards of cinder blocks, and even styrofoam. There are several excellent reasons for replacing soil with a sterile medium. Soil-borne pests and diseases are immediately eliminated, as are weeds. And the labor involved in tending your plants is markedly reduced. More important, raising plants in a non-soil medium will allow you to grow more plants in a limited amount of space. Food crops will mature more rapidly and produce greater yields. Water and fertilizer are conserved, since they can be reused. In addition, hydroponics allows you to exert greater control over your plants, to unsure more uniform results. All of this is made possible by the relationship of a plant with its growing medium. It isn't soil that plants need - it's the reserves of nutrients and moisture contained in the soil, as well as the support the soil renders the plant. Any growing medium will give adequate support. And by raising plants in a sterile grwoing medium in which there are no reserves of nutrients, you can be sure that every plant gets the precise amount of water and nutrients it needs. Soil often tends to leach water and nutrients away from plants, making the application of correct amounts of fertilizer very difficult. In hydroponics, the necessary nutrients are dissolved in water, and this rululting solution is applied to the plants in exact doses at prescribed intervals. Until 1936, raising plants in a water and nutrient solution was a practice restricted to laboratories, where it was used to facilitate the study of plant growth and root development. Dr. Gericke grew vegetables hydroponically, including root crops, such as beets, radishes, carrots, potatoes, and cereal crops, fruits, ornamentals and flowers. Using water culture in large tanks in his laboratory at the University of California, he succeeded in growing tomatoes to heights of 25 feet. Photographs of the professor standing on a step ladder to gather in his crop appeared in newspapers throughout the country. Allthough spectacular, his system was a little premature for commercial applications. It was far too sensitive and required constant technical monitoring. Many would-be hydroponic growers encountered problems with the Gericke system because it required a great deal of technical knowledge and ingenuity to build. Gericke's system consisted of a series of troughs or basins over which he stretched a fine wire mesh. This in turn was covered by a mulch of straw or other material. The plants were placed on this mesh, with the roots extending downward into a water/nutrient solution in the basin. One of the main difficulties with this method was keeping a sufficient supply of oxygen in the nutrient solution. The plants would exhaust the oxygen rapidly, taking it up through the roots, and for this reason it was imperative that a continuous supply of fresh oxygen be introduced into the solution through some method of aeration. Another problem was supporting the plants so that the growing tips of the roots were held in the solution properly. The American Press made their usual, and many irrational claims, hailing it the discovery of the century, in the most outlandish manner. Aftr an unsettled period in which unscrupulous promoters tried to cash in on the idea by peddling useless equipment and materials, more practical research was done and hydroponics soon became established on a sound scientific basis in horticulture. With recognition of its two principal advantages, high crop yields and it's special utility in non-arable regions of the world. In 1936, W. F. Gericke and J. R. Travernetti of the University of California published an account of the successful cultivation of tomatoes in a water and nutrient solution. Since then a number of commercial growers started experimenting with the techniques, and researchers and agronomists at a number of agricultural colleges began working to simplify and perfect the procedures. Numerous hydroponic units, some on a very large scale, have been built in Mexico, Puerto Rico, Hawaii, Israel, Japan, India, and Europe. In the United States, without much public awareness, hydroponics has become big business, more than 500 hydroponic greenhouses have been started. Dr. Gericke's application of hydroponics soon proved itself by providing food for troops stationed on non-arable islands in the Pacific in the early 1940s. The first triumph came when Pan American Airways decided to establish a hydroponicum on the distant and barren Wake Island in the middle of the Pacific Ocean in order to provide the passengers and crews of the airlines with regular supplies of fresh vegetables. Then the British Ministry of Agriculture began to take an active interest in hydroponics, especially since its potential importance in the Grow-More-Food Campaign during the 1939-1945 war was fully realized. During the late 1940s, Robert B. and Alice P. Withrow, working at Purdue University, developed a more practical hydroponic method. They used inert gravel as a rooting medium. By alternately flooding and draining the gravel in a container, plants were given maximum amounts of both nutrient solution and air to the roots. This method later became known as the gravel method of hydroponics, sometimes also termed nutriculture. In wartime the shipping of fresh vegetables to overseas outposts was not practical, and a coral island is not a place to grow them, hydroponics solved the problem. During World War II, hydroponics, using the gravel method, was given its first real test as a viable source for fresh vegetables by the U. S. Armed Forces. In 1945 the U. S. Air Force solved it's problem of providing it's personnel with fresh vegetables by practicing hydroponics on a large scale giving new impetus to the culture. One of the first of several large hydroponics farms was built on Ascension Island in the South Atlantic. Ascention was used as a rest and fuel stop by the United States Air Force, and the island was completely barren. Since it was necessary to keep a large force there to service planes, all food had to be flown or shipped in. There was a critical need for fresh vegetables, and for this reason the first of many such hydroponic installations established by our armed forces was built there. The plants were grown in a gravel medium with the solution pumped into the gravel on a preset cycle. The techniques developed on Ascension were used in later installations on various islands in the Pacific such as Iwo Jima and Okinawa. On Wake Island, an atoll in the Pacific Ocean west of Hawaii, normally incapable of producing crops, the rocy nature of the terrain ruled out conventional farming. The U. S. Air Force constructed small hydroponic growing beds there that provided only 120 square feet of growing area. However, once the operation become productive, it's weekly yield consisted of 30 pounds of tomatoes, 20 pounds of string beans, 40 pounds of sweet corn and 20 heads of lettuce. The U. S. Army also established hydroponic growing beds on the island of Iwo Jima that employed crushed volcanic rock as the growing medium, with comperable yields. During this same period (1945), the Air Ministry in London took steps to commence soilless culture at the desert base of Habbaniya in Iraq, and at the arid island of Bahrein in the Persian Gulf, where important oil fields are situated. In the case of the Habbaniya, a vital link in Allied communications, all vegetables had had to be brought by air from Palestine to feed the troops stationed there, and expensive business. Both the American Army and the Royal Air Force opened hydroponic units at military bases. Many millions of tons of vegetables produced without soil were eaten by Allied Soldiers and Airmen during the war years. After World War II the military command continued to use hydroponics. For example, The United States Army has a special hydroponics branch, which grew over 8,000,000 lbs. of fresh produce during 1952, a peak year for military demand. They also established on of the worlds largest hydroponic installations, a 22 hectare project at Chofu, Japan. It became necessary to use hydroponics in Japan because of the method of fertilization of the soil by the Japanese. It had been their practice for many years to use "Night Soil", containing human excreta as a fertilizer. The soil was highly contaminated with various types of bacteria and amoeba, and although the Japanese were immune to these organisms, the occupying troops were not. Covering 55 acres, it was designed to produce both seedlings and mature vegetables for American occupation forces. It remained in operation for over 15 years. The largest hydroponic installations up to that time were built in Japan using the gravel culture method. Some of the most successful installations have beeen those at isolated bases, noteably in Guyana, Iwo Jima and Ascention Island. After World War II, a number of commercial installations were built in the United States. The majority of these were located in Florida. Most were out of doors and subject to the rigors of the weather. Poor construction techniques and operating practices caused many of them to be unsuccessful and production inconsistent. However, the commercial use of hydroponics, grew and expanded throughout the world in the 1950s to such countries as Italy, Spain, France, England, Germany, Sweden, the USSR and Israel. One of the many problems encountered by the early hydroponics pioneers was caused by the concrete used for the growing beds. Lime and other elements leached into the nutrient solution. In addition, most metal was also affected by the various elements in the solution. In many of these early gardens, galvanized and iron pipe were used. Not only did they corrode very quickly, but elements harmful or toxic to the plants were released into the nutrient solution. Nevertheless, interest in hydroponic culture continued for several reasons. First, no soil was needed, and large plant population could be grown in a very small area. Second, when fed properly, optimum production could be attained. With most vegetables, growth was accelerated and, as a rule, the quality was better than that of soil grown vegetables. Produce grown hydroponically had much longer shelf life or keeping qualities. Many of the oil and mining companies built large gardens at some of their installations in different parts of the world where conventional farming methods were not feasible. Some were in desert areas with little or no rainfall or subsurface waters, and others were on islands, such as those in the Caribbean, with little or no soil suitable for vegetable production. Big commercial American headquarters in the Far East have over 80 acres devoted to vegetable units, to feed landless city dwellers, while various oil companies in the West Indies, the Middle East, the sandy wastes of the Arabian Peninsula and the Sahara Desert, operating in barren areas, especially off the Venezuelan Coast at Aruba and Curacao, and in Kuwait have found soilless methods invaluable for ensuring that their employees get a regular ration of clean, health-giving greenstuff. In the United States, extensive commercial hydroponics exist, producing great quantities of food daily, especially in Illinois, Ohio, California, Arizona, Indiana, Missouri and Florida, and there has been a noteworthy development of soilless culture in Mexico and neighboring areas of Central America. In addition to the large commercial systems built between 1945 and the 1960s, much work was done on small units for apartments, homes, and back yards, for growing both flowers and vegetables. Many of these were not a complete success because of a number of factors: Poor rooting media, the use of unsuitable materials, particularly in constructing the troughs used as growing beds, and crude environmental control. Even with the lack of success in many of these ventures, however, hydroponic growers the world over were convinced that their problems could be solved. There was also a growing conviction in the nimds of many that the perfection of this method of growing food was absolutely essential in light of declining food production and the worldwide population explosion. Recent surveys have indicated that there are over 1,000,000 household soilless culture units operating in the United States for the production of food alone. Russia, France, Canada, South Africa, Holland, Japan, Australia and Germany are among other countries where hydroponics is receiving the attention it deserves. In addition to the work being done to develop hydroponic systems for the production of vegetables, however, between 1930 and 1960 similar work was being conducted to develop a system to produce livestock and poultry feed. Researchers had found that cereal grains could be grown very rapidly in this manner. Using grains such as barley, they proved that 5 pounds of seed could be converted into 35 pounds of lush green feed in 7 days. When used as a supplement to normal rations, this green feed was extreemely beneficial for all types of animals and birds. In lactating animals, milk flow was increased. In the feed lots, better conversion rates and gains were achieved at less cost per pound of grain. In breeding stock the potency of males and conception in females increased dramatically. Poultry also benefitted in many ways. Egg production increased while cannibalism, a constant problem for poultrymen, ceased. Here again, however, in developing a system that would produce consistently, a number of problems arose. The early systems had little or no environmental control, and with no control of temperature or humidity, there was a constant fluctuation in the growth rate. Mold and fungi in the grasses were an ever-present problem. The use of thoroughly clean seed grain with a high germination ratio was found to be absolutley essential if a good growth rate was to be achieved. Nevertheless, in the face of these and other obstacles, a few dedicated researchers continued to work to perfect a system that could produce this nutritious feed continuously. With the development of new techniques, equipment, and materials, units became available that were virtually trouble free. Many of these are in use today on ranches, farms, and in zoos all over the world. Hydroponics did not reach India until 1946. In the summer of that year the first research studies were commenced at the Government of Bengal's Experimental Farm at Kalimpong in the Darjeeling District. At the very beginning a number of problems peculiar to this sub-continent had to be faced. Even a cursory study of the various methods which were being practised in Britain and in America revealed how unsuited they were for general adoption by the public of India. Various physiological and practical reasons, in particular the elaborate expensive apparatus required, were sufficient to prohibit them. A novel system, of which practicability and simplicity must be the keynotes would have to be introduced if hydroponics was to succeed in Bengal, or in fact ever to prove of widespread value to the people of this part of Asia. Careful appraisal of salient problems during 1946-1947 resulted in the development of the Bengal System of hydroponics, which represented an effort to meet Indian requirements. One object guided all the experiments carried out; to strip hydroponics of it's complicated devices and to present it to the peiple of India and the world as a cheap, easy way of growing vegetables without soil. Now in India, thousands of householders raise essential vegetables in simple hydroponic units on rooftops or in backyards, the Bengal System has far more than proved itself, as being usefull in the most adverse conditions. Numerous letters of appreciation from as far afield as the United Kingdom, France, the United States, Holland, Israel, Japan, Germany, Algeria, the Pacific, South and East Africa, Australia, New Zealand, Pakistan, South America, Burma, the Seychelles, Formosa, and those of the West Indies, have testified to what a large extent this object has been appreciated by the public, throughout the world. Why use hydroponics when we have plenty of land if we would only develop, and by means of better cultural practices, including manuring, improve it? And then the cry: But hydroponic yields are after all no better than those which could be obtained under ideal soil conditions! Both of these commetns call to mind a remark attributed to Charles II (King Charles II, British monarch (1660-1685)). Emphasizing the difference between himself and his brother, the Duke of York (afterwards James II), Charles is reported to have said: "Jamie would if he could, but I could if I would". Critics of soilless culture fall into these categories. They generally overlook the fact that to improve the soil of India, or of any other country, so as to make it perfect, will take 50 to 100 years. Where, after all, can ideal soil conditions be obtained? Greenhouse culture, using earth beds, is at the best a warisome and expensive affair, involving periodic sterilization and it is only under such conditions, employing glass, that anything approaching an ideal soil can be produced, even after a long period of time. And after the first crop begins to mature, alas the balance is again upset. An article in Forbes magazine, entitled, "Food Supply - Will Help from Science Come in Time?" calls hydroponics the "most spectacular current breakthrough" yet, for solving the world's food problems. An article in the Los Angeles Times, entitled, "Hydroponics: A New Chapter in Food Technology," states "...for the past several years, hydroponics has been refined to the point where it is now a commercially viable way to grow food." Reading the unresearched accounts in the media, leads on to believe that hydroponics is a recent development in scientific technology which will save the world from starvation. Yes, it may very well help save the world from a food shortage, but it is hardly a new scientific development. In fact, the first plants on the earth were grown hydroponically. More than half of all plant life today is growing with hydroponics. And the healthiest, most nutritious plants in existance are hydroponic plants. I speak of the plants growing in the body of water, which covers over 70% of the earth's surface - our oceans. There is no soil in the ocean. Plants draw all their required nutrients directly from the most complete hydroponic nutrient solution available - sea water. Among the well-known institutions which have contributed so much to the establishment of the soilless cultivation of plants as a practical proposition are, the Universities of Illinois, Ohio, Purdue and California in the United States; The University of Reading, in Great Britain, famous for it's pioneering work in new cropping techniques. Canada's Central Experimental Farm at Ottawa, as well as the internationally famous and important firm of Imperial Chemical Industries, Ltd., which undertook the adaption of hydroponics to British conditions. Other pioneers of hydroponics were the Boyce Thompson Institute for Plant Research, New York; the New Jersey Agriculture Experiment Station; the Alabama Polytechnic Institute; and the Horticultural Experiment Station, Naaldwijk, Netherlands.