Translated freely from original book by Ernst M. Salzer – Pflanzen wachsen ohne Erde, 1968
“Nature is always true, always serious, always severe; it is always right, and mistakes and errors are always the work of men.”
- J.W. Goethe, 1829
Thousands years ago, when our grandfathers – at the time freely wandering hunters and nomads – became settlers, growers of plants and keepers of animals, they formed perhaps first ideas about plant nutrition. First impulse was probably small observations, eg. That from rotting dead plants can sproute most vital life. Probably they asked themselves the puzzling question: “How and from what plants live?” There is not any uptake of nutrition visible, but still plants live, grow, flower and fruit.
First thoughts of this kind captured in writing comes from greek philosopher Aristotle (384 – 322 BC), whose teachings express opinion that problem of plant nutrient uptake was already solved. Aristotle taught that plants – considered in terms of nutritional physiology – are completely idle, because they receive their nutrients from the soil already in the final, finished (organic) form; plants in his opinion had to worry just about transport of these nutrients.
Following centuries did not bring in this area any progress for long time. Numerous herbariums, which were written during the great cultural epoch of Renaissance, had meaning only to the construction, improvement or systematics (division) of plants. Only Dutch polymath Jan Baptist van Helmont (1577-1647), called “Faust of the XVII. Century”, gave first impulse to the further development of learning about plant nutrition. Skeptical scientist conducted experiments with goal to research plant nurture. For example he filled bucket of exactly 200 pounds of carefully dried soil. Then he planted willow into the bucket, which weighted about 5 pounds. In following month and years he cared to ensure no dust gets into the soil and watered it only by rain water. Then after 5 years of experiment he found that the weight of the willow branch increased by 164 pounds, but the weight of the soil has diminished only 2 ounces (= 62,5 grams) he was astonished at first. Then from his alchemyst point of view decided that it was the water itself which supplied willow branch substances necessary for growth. He underestimated the importance of the 2 pounds of soil and he didn’t know about significancy of air as a supplier of carbon dioxide.
Quite similar observations like van Helmont did english researcher Joseph Priestley (1733-1804), which made interesting finding one day. He just didn’t know how to correctly interpret it.
It is well known that candle can’t burn long underneath airtight container. Once the oxygen, which supports combustion, is consumed from the air, candle starts to flash and flames out immediately. Priestly put under glass bell together with a burning candle a green twig and amazed found out that candle was now burning for measurably longer period of time. He assumed that green parts of the plant had to somehow influence the air. Ha had no clue about what kind of process it was, because principle of assimilation of carbon dioxide was to be found yet.
Criticism of Aristotle’s teachings which van Helmont begun continued with works of Italian scholar Marcell Malpighi (1628 – 1694) and his French peer Edne Mariotte (1620 – 1684). They both discovered that substances accepted by plants as nutrients from soil are probably subject to some chmical changes before plants use them for formation of their tissues. Numerous attempts of Stephan Hales (1677-1761) showed that in process of formation of organic plant material there is great significance of air.
This has made important and key step on the road to learning about plant nutrition based on facts. It may surprise us, that first attempt to grow plants in water solutions without soil was probably already done 250 years ago. John Woodward (1661-1728), professor of medicine at Grasham College, London, reported in 1699 on its own experiments of this kind. First he cultivated garden mint in rainwater, then in water from the Thames and finally in the murky waters of a Hyde Park canal, which he shuffled first. He determined the weight of the test plants at planting time and thein again when he removed them from the test vessels. Based on observations and results he concluded: “Plant material is not formed from water but from certain substances in the soil.” The proof was clear: the greatest increase in vegetable matter was in the third test vessel (with the largest amount of impurities). Woodward refuted this way van Helmont’s opinion, that plant’s body is grown from water. But not even he could figure out the context arising therefrom.
Jan Ingehouzs (1730-1799) introduced us to the basics of carbon dioxide assimilation and respiration of plants. Theodore de Saussure (1767-1845) and his contemporary, Rene Joachim Henri Dutrochet (1776-1847) were then able to get to get closer to today’s valid concept of formation of organic plant matter. But then came a sudden turnaround.
The suggested route unfortunately remained unnoticed. Again appeared so called “Old humus theory”, which - in short - proclaimed: The most important source of plant nutrition are not mineral compounds, but organic components, mainly humus. This misconception was managed to disprove only 150 years ago. Justus von Liebig (1803- 1873), the great German agricultural chemist, clearly stated in 1840 in his book “the application of chemistry in agriculture and physiology,” that "plant organisms, ie organic compounds, provide people and animals by means of nutrition and maintain life, but the source of plant nutrition lies purely in inorganic nature”.
Liebig proved that the amount of humus in soil when growing plants doesn’t diminish, but rather increases in time. He also showed that plants can not ever take humus insoluble in water, if it is not “pre-digested” by soil organisms, ie. if it is not decomposed to inorganic compounds (mineralized).
These findings formed the basis of today’s modern agricultural chemicals. For its further development crucial was von Liebig’s reassurance that nowadays when we are aware of the conditions of soil fertility and its ability to sustain plant life, nobody could deny that the chemistry only can be source of further advances in agriculture. Von Liebig in his research activities could rely on the results of work of various other scientists, for example, also on the work of Jean Baptiste Boussingault (1800-1887), who revitalized Woodward’s “growing plants in water solution” in an amended form as a so-called "growing in the sand ". French scholar carried on his farm in Alsace Bechelbronn experiments that brought proof that the full plant culture is possible in the soil which is completely free of humus. Wiegmann (1771-1853) and Polstorff showed in 1838 in their treatise “On the inorganic components of plants” that certain inorganic substances are essential for plant development. However, this has been pointed out very clearly also by Sprengel (1788-1859) in his book “Teachings about fertilizer.”
Thus we see that the misconceptions about nutrition plant could be repaired just in the early 19th century, largely through the work of von Liebig.
When they explained the basic features of the actual processes of plant nutrition, it could be followed by further breakthroughs in rapid succession. The history of these discoveries is also a history of growing plants without soil. Many remarkable researchers and scientists over the last 100 years tried to track down further details on plant nutrition, especially the question of which inorganic compounds plants need for their sustenance. On the clarification of this question and many of the interrelated issues still being worked on.
So called. “Growing plants without natural soil” actually first took place in 1860. In that year, professors Wilhelm Knop (1817-1901, professor and head of agricultural chemicals at Agricultural Experiment Station in Leipzig - Mockern) and Julius Sachs (1832-1897, professor of botany at Bonn - Poppelsdorf) first prepared salt solutions, which enabled to grow green plants regardless of the soil. These first successes encouraged further development of such experimental devices.
Since then, “a container with water solution” is obvious and common tool in research laboratories of agricultural institutes.
First, it was believed that the cultivation of plants without soil is suitable only for scientific research and experimental purposes. Today we are surprised with this fact, considering that science already at the end of the last century could provide the conditions for growing plants without soil on a wider scale, both for earnings and as an amateur hobby.
Connecting question of plants growing in a water solution with the complex issues of food production is closely linked with the name of the US plant physiologist prof. dr. William F. Gericke, who as associate professor of the University of California, Berkeley conducted extensive experiments in the wild and brought first report about it in 1929. He published a theory of “hydroponics” (as the parallel concept to “geoponics”, the Greek word for cultivation in soil) and made allegations that plants without soil can be grown on a large scale and that this means of growing have its importance. His experiments showed that in containers filled with nutrient solution a large variety of crops can be grown. This method of growing plants were tested in practice during the last World War, when it was necessary to supply fresh vegetables to each US troops serving on totally barren rocky islands of the seas. On these islands explosives were used to excavate hydroponic pools in bare rocks, where excessive amounts of satisfactory vegetables could be grown.
In the press releases after the Second World War mostly prof. Gericke was mentioned as a pioneer of growing plants without soil. But we must not forget that in the time when the prof. Gericke carried on his experiments, this method of growing plants was used in many places in Europe too. The most important trials were started in the Soviet Union at the initiative of D. N. Prjanishnikov under the guidance of biologist V. L. Pjatakova. The results of this experiment were practically taken advantage of by Russian polar expedition in 1937.
Growing plants without soil was introduced in Hungary in the Carpathian Mountains (led by prof. Paul Röszler) and Poland south of Lvov (led by prof. W. Piotrowszki) almost simultaneously during the years 1932-1933. At both establishments, based in higher-lying areas, there were preferably grown early vegetables and ornamental plants. These facilities are less known because they were private profit-driven enterprises.
In Germany, the oldest facility for growing plants without soil was established in the village Steinheim (in Westphalia.) It was founded in 1938 by F. Horning and since then has achieved remarkable success. For example, on the occasion of gardening show in Stuttgart in 1950, Anthuria plant was awarded prize for excellence, which was grown without soil in Steinheim.
Despite the controversy, whether it is advisable to grow plants without soil or not, which still runs today, the last twenty years led to simplifying working methods and reducing operating costs. Various cultivation methods that have evolved over time, are now spread across the globe.
Profitable large scale facilities can be found especially in overseas territories, especially in the US, then in the Dutch possessions in the Gulf of Mexico, British Guyana, on the South Seas islands and Japan. In the United States of America in addition to numerous small businesses there are about 40 large undertakings that always posses around 800-1200 hydroponic beds, with one patch averaging about 30 m2. Japanese facilities near Tokyo and Kyoto (32-ha), were originally set up the American occupation authorities and were used to supply US troops. The Japanese became familiar with the workflow, so that when they taken over the facilities, they were able to further operate them themselves.
In Europe there are horticultural enterprises for growing plants without soil for example in Switzerland, France, Denmark, Norway, Holland, Belgium, England, Sweden, Hungary, Poland and the Soviet Union. According to recent reports Italians want to rebuild production of rice seed to the method of growing without soil. After doing relevant experiments it was found that the introduction of this method saves labor and operational areas.
In Germany, besides the already mentioned company in Steinheim, which started operating in 1938, growing plants without soil is done as venture in Lemgo too. In this area carnations were grown in aqueous solution already in 1936-1939; attaining remarkable yields, 30% higher than normal. This method of growing plants in a greater or lesser extent is used in numerous other horticultural enterprises in Germany and institutions were able to achieve remarkable results. This method, however, could not be fully enforced yet, and therefore remains restricted to a relatively small amount of gardening businesses. It’s not surprising, considering the fact that most farmers today is still missing necessary knowledge. Also exaggerated news daily newspapers ran in the postwar period (eg. the title of one article was: “hundredfold harvest without hard work!”) contributed to the fact that this method of growing plants was condemned by many people as a hoax.
In following chapters we will have the opportunity to familiarize ourselves with advantages of growing plants in nutrient solutions. We will find out that hydroponics is suitable for private flower lovers and also for gardeners, because its use brings racionalization of enterprise operations and can succesfully solve many problems, including lack of labour and provision of fertilizers.
All theory, dear friend, is gray, but the golden tree of life springs ever green.
- Johann Wolfgang von Goethe
