Andrew Poulin, age 12, of Monroe, Connecticut, for his question:
What is hydroponics?
Hydroponics is a fancy method of coping with plants. It may be called soilless gardening, water culture; chemical gardening or tank farming. In any case, the trick is to coax plants to grow without dirt since plants take many of their basic nutrients from the soil, this sounds downright impossible. Nevertheless, hydroponics experts have met the challenge and succeeded at least to some extent.
When you visit the Bahamas, you may think that the vegetables served you were grown in usual farms and gardens. Maybe they were. But chances are, they were grown by hydroponics without any soil. This is because much of the local soil is merely a thin layer over the coral bedrock. There simply is not enough dirt to provide vegetables for all the hungry tourists.
Other hydroponics experts produce growing greens in Antarctica and lush vegetables in the arid sands of the Middle .East and when we go to the stars, hydroponics may provide salads and greenery.
The trick is knowing what chemicals plants normally absorb from the ground. Their roots, of course, absorb these basic nutrients dissolved in the ground water. In hydroponics, the experts mix a balanced brew of basic chemical plant nutrients and dissolve them in ordinary water. The rest is simple. The plants are arranged so that their roots dip down into the man made grocery tank.
Nobody is big headed enough to claim that we know all the chemicals needed by the plant world, or in what amounts. But plant scientists do know the main chemical: nutrients plus a list of trace elements. These are mixed in precise proportions to create a standard formula for most growing plants. Some plants need special formulas.
Naturally, the soilless plants need air. light and suitable temperature control, just as they do in nature. The big problem is to arrange them so that stems and leaves stay high and dry while the roots dip down into the liquid diet. Some hydroponics experts either anchor the roots in clean sand or gravel, allowing the enriched liquid to wash through again and again, or to seep through drop by drop. This gravel or sand culture is said to be the easiest method.
The water culture method suspends the plants above a formula filled tank. Fine netting covered with peat or sawdust is used to keep their tops high and dry and their roots in the water. A harvest of vegetables may be grown in a 100 foot long tank or a few soybeans, say, may be grown in a five gallon bottle.
All plants consume goodly helpings of six basic elements calcium and magnesium. potassium and nitrogen, sulphur and phosphorous most growers have favorite recipes for serving these in various chemical compounds. Also needed are compounds with traces of boron and iron, manganese and chlorine, copper and zinc and several others. Experts learn by trial and error which recipes work best for various plants.