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One day's harvest of Tommy Toe tomatoes, early in the season.
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Apollo tomatoes in tomato tub.
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Prize winning Savoy King cabbage.
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Prize winning Sugarloaf cabbage. Click the image to enlarge.

Question: What is the difference between Hydroponics and Organic Gardening?

Answer: With Hydroponics, plants are grown without soil and soil organisms (at least in the beginning), and the nutrient is supplied to the plant. Organic Gardening relies on soil and soil organisms, and the plants must fossick for food.

Question: Does Organic Gardening really work?

Answer: Yes! Definitely! But not for many of the reasons advanced by Organic Gardeners. For instance, many Organic Gardeners abhor the use of inorganic chemical fertilizers because "they build up and poison the soil". There is some truth in this. With Simple Sand Hydroponics, any build-up is washed out every three weeks, before new nutrient solution is added.

With Organic Gardening, all organic materials used as fertilizer must undergo bacterial action to convert the organic material into inorganic chemicals so that the tiny root hairs can assimilate them. These tiny root hairs are of a single cell structure and are covered with a semi-permeable membrane, and can take in only simple inorganic chemicals with relatively low molecular weights, dissolved in water. The chemicals used in the Starting Formulation on this site are simple inorganic chemicals. Organic chemicals of any type generally have much higher molecular weights and are too large to pass through the semi-permeable membranes of the root hairs.

Question: Why do Organic fertilizers need soil organisms to break them down?

Answer: One of the most popular organic fertilizers is fowl manure which, if allowed to sit for a few days gives off Ammonia. So fowl manure contains most of its Nitrogen in the Ammonia form. Now most plants like their Nitrogen in the Nitrate form, and soil bacteria help them by converting Ammonia Nitrogen to Nitrate Nitrogen.

Question: How do the tiny root hairs work?

Answer: The tiny root hairs work by a process called Osmosis. In a nutshell, osmosis is the flow of a liquid of lower concentration, through a semi-permeable membrane, to try to dilute a liquid of higher concentration on the other side of the membrane. In the case of roots, the liquid of lower concentration is your nutrient solution, the semi-permeable membrane is the root hair wall, and the liquid of higher concentration that is being diluted is the complex aqueous mixture of sugars and starches within the root cells themselves.

Question: What happens if I make my nutrient solution too strong?

Answer: The process of osmosis now works around the other way. The complex aqueous mixture of sugars and starches within the root hair wall is the liquid of lower concentration, which tries to dilute the liquid of higher concentration (your nutrient solution) on the other side of the membrane (the root hair wall) and the plant eventually desiccates and dies. The Moral of this story is: Do not make your nutrient solution too strong.

Question: How do Botanists know what foods plants like?

Answer: They actually analyse the plant's tissues for basic chemicals such as Nitrogen, Potassium, Phosphorus, Magnesium, Sulphur, Iron, Boron and the other trace elements. An instrument called an ICP Spectrophotometer can analyse elements down to parts per million. Since the plant is made up from "what it eats", that provides Botanists with the answer.

Question: Can animal manures be used for hydroponics?

Answer: The Author has read of animal manures being used for hydroponics, but has not seen it. Animal manures are undoubtedly a good source of Nitrogen, but what about the other essential elements? Constant analysis would be necessary to find out what Nitrogen is in the nutrient solution. As most plants prefer their Nitrogen in the Nitrate form, how are they going to get it in the relative absence of soil bacteria? Verdict: Animal manures would probably work, but they would need to be supplemented with what they lack.

Question: How about using Thrive or other complete plant foods in the hydroponic system?

Answer: Thrive is marketed as a complete plant food, yet it lacks the trace elements essential for hydroponics. It may be a complete plant food for hanging baskets, but it is not a complete plant food for hydroponics.

Question: Why do some prepared hydroponic mixes have insufficient Magnesium in them?

Answer: Plants require a surprisingly large amount of Magnesium, as can be seen in the Starting Formulation Solution #1. Magnesium is right at the centre of the chlorophyll molecule. Chlorophyll occurs in all green leaves, and in a hydroponic garden there are a lot of green leaves. As for why some mixes have insufficient Magnesium ... probably ignorance of the plant's needs.

Question: What is the importance of Iron in plant growth?

Answer: Iron is essential for all plant growth, but it must be soluble Iron. Many trace element mixes contain Ferrous Sulphate (which is soluble), and after making up into a hydroponic nutrient solution, it oxidises to the Ferric form which is insoluble and black into the bargain. Now, the plant is not going to get any Iron whatsoever.

To solve this problem, the Starting Formula uses Iron Chelate ... the Iron salt of Ethylene diamine tetra acetic acid (EDTA) as its source of Iron. If you must use Ferrous Sulphate, you must add a small amount of it every second day to keep sufficient Iron in the system. The presence of Iron catalyses many reactions necessary for plant growth. The catalyst is not consumed in the reaction, but acts more as a facilitator for the reaction. All of the trace elements in Solution #1 behave as catalysts.

Question: Can I use crushed limestone or sea shells as a hydroponic growing medium?

Answer: Limestone and sea shells are both composed of Calcium Carbonate, which will react with Phosphorus in your nutrient solution and precipitate out as insoluble Calcium Phosphate, which is not freely available to your plants. Thus, using limestone or sea shells as a medium is not a good idea.

If you think you have some limestone in your medium, here is how to test for it. Pick out a few suspicious white lumps (limestone is white, unless contaminated) and put them into a plastic cup and add a few mL of Dilute Sulphuric Acid; if it fizzes, it is probably limestone. The best course of action if the medium is contaminated with limestone, is to discard it and select a better quality medium. Alternatively, you could try washing your medium in Dilute Sulphuric Acid, and wash well after with water, and watch where you drain the washings.

This is the end of Simple Sand Hydroponics . The Author hopes you enjoyed it enough to actually build your own system.

If you need clarification on any points, please feel free to E-mail me.

The next page contains links to other Hydroponic sites. You may find some of them quite interesting.

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