Hydroponics: Growing Without Soil
The science of growing plants without soil has been known and used for more than one-hundred years. The word “hydroponics”, however, is comparatively new. Dr. W.E. Gericke is usually given credit for coining the word, which translated from Greek, means “working water”. The famous hanging gardens of Babylon were probably on of the first attempts to grow plants hydroponically. The work of Dr. Greicke in the 1920’s and 1930’s in California, however, is generally considered the basis for nearly all forms of hydroponics. During the 1940’s at Purdue University, Robert B. and Alice P. Withrow developed another hydroponic method. Their process was called Nutriculture. Nutriculture varied from Dr. Gericke’s method in that gravel was used as a rooting medium.
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.
How is the quality of the food today affected by the methods of Hydroponics of today?
The growing media that is used for gardening greatly effects the production of the plants. If sand is used as a medium it should be tested thoroughly for any residue that might cause infected growing medium. The sand should be cleaned at least every three of four weeks. Leaching is also a major step, it is to be done at the end of each crop cycle ( Jones 69-70). Sand that is used for the medium should have sawdust mixed with it to allow for better drainage. The sawdust also makes the sand lighter and not pact together as easy ( Bridwell 86).
Gravel is another medium, it is used more often because it is easier to clean. If gravel is used round, smooth, river-type is preferred. Granitic types are the best because of its hardness. Whatever type of gravel that is purchased must be thoroughly washed and cleaned to get rid of any calcareous on the gravel. The size is also a factor when selecting gravel. The pieces of gravel should be no smaller than a quarter inch in diameter and larger than a half inch. Crushed stone is not preferred because the sharp edges can injure the root system.
The sterilizing process is an easy, but a long and tedious job. Flood the beds with fresh water, which has enough sulphuric acid to lower the pH level to the three or four range. The solution should be left on the gravel for at least 12 hours. Flush the gravel thoroughly with fresh water. Add a fresh solution containing one quart Clorox for every one-hundred gallons of water. Leave the solution for at least six hours. After that is done completely drain and flush thoroughly with clear water at least twice. Do this again at the end of each crop cycle ( Jones 67-9).
The most common diseases for plants are the various types of fungi. A greenhouse with a controlled environment is pretty easy to prevent fungus-type diseases. The environment has to have a warm temperature, low humidity, and proper air circulation. If a long period of cold, cloudy, and humid weather occur, the temperatures can not remain at minimum levels or the plants will suffer from some type of fungus ( Jones 112).
Leaf molds are just one of many types of fungi
common in tomato plants. The fungi can be identified by small patches of spores on the leaves. These grayish spots appear on the older leaves first. On the top of the leaves will appear velvety green or brownish spots. Once these begin to form, the plant should not be moved or the spores will spread through the air to the other plants in the greenhouse. Some fungicides that can be used to control leaf molds are Maneb, Bravo, and...
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