While you are deciding whether to build or buy a home hydroponic unit, it would be a good idea to do a little studying about nutrients. No matter what kind of system you choose, nutrients will be an integral part of your success, because your plants must be constantly supplied with food.
Using the formulae given in this chapter, you will be able to mix your own nutrients in either large or small amounts. As in Chapter 2, however, I recommend that the novice begin with a commercially available, pre-mixed nutrient at least until a feel for hydroponics has been developed.
Nature does a lot of the work in soil gardening, although often not perfectly, or farmers would not have to use fertilizers. Almost all soil has some nutrients in it, but when you are growing hydroponically, you are taking over from nature, and in many instances it is possible for you to improve the quality of nutrients supplied.
The most common type of homemade nutrient is one made from fertilizer salts. These salts are available in bulk from agricultural agencies, plant food suppliers, some nurseries and gardening stores, and chemical suppliers. The only problem with this approach is that you usually have to buy some of these salts in twenty-five to fifty pound bags, and unless you are growing in extensive hydroponic gardens such quantities make the whole thing rather cumbersome and expensive. Even so, for the adventurous, or for the person who simply wants to know, the following information should give a good general knowledge of these materials.
Ammonium phosphate Ammonium sulphate Calcium nitrate Potassium nitrate* Sodium nitrate Potassium sulphate* Superphosphate* Calcium sulphate* Magnesium sulphate*
(Epsom salts) Ferrous sulphate* Manganese chloride Zinc sulphate Copper sulphate Boric acid powder*
Nitrogen and Phosphorus Nitrogen and Sulphur Nitrogen and Calcium Nitrogen and Potassium Nitrogen
Potassium and Sulphur Phosphorus and Calcium Calcium and Sulphur Magnesium and Sulphur
The salts marked with an asterisk are the best to work with where there are other, similar salts available, because they have superior properties, such as better solubility, cost, storage life, and stability. Potassium chloride, for example, could be used rather than potassium sulphate, but if applied for more than a few days, the chlorine in the mix could prove harmful to your plants. This is especially true since there is likely to be chlorine in your water in the first place. Magnesium nitrate could be substituted for magnesium sulphate, but it hardly seems worthwhile to use a more expensive material for the cheap and readily available epsom salts. Ferric citrate has to be dissolved in hot water, as opposed to cold for ferrous sulphate.
In addition to the three key elements of nitrogen (N), phosphorus (P) and potassium (K) that are essential to all plant growth, there should be at least ten trace elements present in your nutrient. These are: sulphur, iron, manganese, zinc, copper, boron, magnesium, calcium, chlorine and molybdenum. The following list gives the specific function of each one in plant growth.
Necessary for the production of leaves and in stem growth. An essential ingredient in building plant cells.
Required in the development of flowers and fruits and aids in the growth of healthy roots. Used by plant cells during the assimilation of the energy produced by photosynthesis. Assists in the production of plant energy and heightens the effectiveness of phosphorus. Vital in the production of chlorophyll. Aids in the absorption of nitrogen. An essential component in the energy transference process. An essential component in the energy transference process.
Needed in the production of chlorophyll. Required in minute amounts, but it is not yet known how the plant uses it.
One of the components of chlorophyll, magnesium also is involved in the process of distributing phosphorus throughout the plant.
Encourages root growth and helps the plant absorb potassium.
Required for photosynthesis. Molybdenum Assists in some chemical reactions.
There are hundreds of different nutrient formulae, but as long as the elements are present in balanced amounts, you have little to worry about. Trying to choose the best formula is a meaningless task, since many of the experts disagree. In the final analysis, your decision will probably be based on cost, availability and your own preferences. However, plants do require different nutrients on different days, at different times of the day and under different conditions. Unless you did an exhaustive test every day, it would be impossible to determine just what the plant requires at any one time. This is why it is essential to provide the plant with a balanced nutrient solution all the time and leave it up to the plant to use what it requires.
As it is used here, the term "balanced" simply means that the nutrient contains the proper ratio of elements to satisfy the maximum requirements of the plant.
Phosphorus Potassium Sulphur Iron
The ratio is arrived at by calculating the parts per million concentration of each element. Scientifically, this description may be somewhat inaccurate because of its simplicity. In fact, this may occur a few times in my discussions of the more scientific aspects of hydroponics, but I believe it is better to simplify for the novice and let the reader turn to more scientific books when he wants to experiment.
The plant will absorb what it needs through the small hairs on the ends of its roots. This selectivity makes it impossible to overfeed your plants in hydroponics. Don't forget, though, that ifyou mix too high a concentration of nutrient in the water you are using, the plant will be unable to absorb sufficient water. Salts need to dilute themselves, and if the concentration is too high, the plant will start giving off water instead of ingesting it, and the result will be a plant that dehydrates itself.
The following are three workable nutrient formulae. They are based on a 100 Imperial (120 American) gallon quantity. Each formula is translated into ounces rather than setting out complicated chemical equations based on atomic weights and parts per million.
Sodium nitrate 10 ounces
Calcium nitrate 10 ounces
Potassium sulphate 10 ounces
Superphosphate 15 ounces
Magnesium sulphate 5 ounces
Combine with trace elements and 100 gallons (120 American gallons) of water, or 1 ounce per 2 Imperial gallons.
Sodium nitrate 8 ounces
Ammonium phosphate 1-3/4 ounces
Potassium sulphate 4 ounces
Calcium nitrate 1 ounce
Magnesium sulphate 3-1/2 ounces
Combine with trace elements and 100 gallons (120 American gallons) of water, or 1 ounce per 5.5 Imperial gallons.
Ammonium sulphate Potassium nitrate Monocalcium phosphate Magnesium sulphate Calcium sulphate
9 ounces 4 ounces
Combine with trace elements and 100 gallons (120 American gallons) of water, or 1 ounce per 3.7 Imperial gallons.
The trace elements that are added to these formulae must be mixed separately. Two recipes are given below. Use a mortar and pestle to grind to a very fine powder.
These ingredients should be mixed well and stored dry. Use 1/2 teaspoon per 100 gallons (120 American gallons) of water, or dissolve 1/2 teaspoon in one quart (1.2 American quarts) of water and use one liquid ounce to 3 gallons (3.6 American gallons) of nutrient solution. Throw the rest of the quart away; be sure not to use any portion of the remainder of this quart of trace element solution. Any trace element mix cannot be kept in a liquid state and retain its quality, so don't keep this solution beyond one day.
Trace Elements No. 1
Iron sulphate Manganese sulphate Boric acid powder Zinc sulphate Copper sulphate
1 ounce 1 teaspoon 1 teaspoon 1/2 teaspoon 1/2 teaspoon
Trace Elements No. 2
This formula has two separate components. They should be mixed dry and stored separately until ready for use.
Fe 330, iron chelate Manganese chloride Boric acid powder
2 teaspoons 1/2 teaspoon 1-1/4 teaspoon
These three ingredients should be dissolved in one gallon (1.2 American gallons) ofwater. Add 5 liquid ounces to 10 gallons (12 American gallons) of nutrient solution.
Dissolve these two elements in one gallon (1.2 American gallons) ofwater and add 10 drops to the same 10 gallons of nutrient solution.
Many hydroponic gardeners will not need a hundred gallons of nutrient solution, but it is an easy matter to calculate the weight to the quantity you require based on the hundred gallon solution figures. In Formula 1, for instance, the total weight of fertilizer salts is thirty-two ounces to one hundred gallons of water. If you need twenty-five gallons of nutrient solution, you would apply eight ounces of salts plus the required amount of trace elements.
It is essential that all calculations by weight be accurate. Care must also be taken that the proper compatible "chemicals" are used and that they are properly mixed. The substances listed for each formula differ greatly, because, although the elements themselves are the same, the salts from which they are released vary in each composition. Occasionally, all the trace elements are not necessary in a separate application, for many of the salts being used contain some of the trace elements as impurities.
The two trace elements (micronutrients) chlorine and molybdenum require a brief discussion. Frequently, chlorine is not added to a trace element formula, because there is usually enough found in public works water systems. Some books mention molybdenum as a micronu-trient, others ignore it completely. The reason it is often skipped is that only .02 parts per million are required, an amount so minute that if
1/4 teaspoon 1/2 teaspoon enough is not present as a salt impurity, then the danger of adding too much to your nutrient is not worth the risk. Besides, plants have the ability to compensate for a molybdenum deficiency, should one exist.
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