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R&D Aquaponics,
PO Box 6238, Wetherill Park, 2164
Tel 61-02-9756-1833 Fax 61-02-9756-1833
email: romerja@optusnet.com.au
HYDROPONICS IS
SIMPLY FUNTASTIC!!!
Once you have started to use hydroponics it is difficult to stop. Many people think of hydroponics as being complicated and expensive, but nothing could be further from the truth. You dont need expensive pumps, timers, testing equipment or containers. It does not have to be complex and you do not have to know what the pH is or what conductivity is or how to use a pH meter or a conductivity meter, or even how to manipulate your nutrient solutions.
Some prefer the challenge of the more complicated systems.
Hydroponics is as simple or as complex as you want to make it.
Hydroponics is as inexpensive or as expensive as you want it to be.
WHY HYDROPONICS?
There are so many aspects of hydroponics and so many reasons why people use hydroponics.
For some people it is the challenge of growing plants away from soil, to others it is the taste of the fruits of their labor, to me it is convenience and minimum maintenance.
There are a number of reasons why you should consider using hydroponics such as:
* The vegetables are clean, free from grit and harmful chemicals,
* There are fewer pests and diseases.
* Plants can be grown at a convenient height for looking after them and harvesting.
* Fewer insecticides and fungicides are used.
* Weeds are no longer a problem.
* There is very little preparation before planting.
* when one crop is finished you can almost immediately start the next crop.
* You dont need a large area for growing.
* The plants are more productive.
* Herbs and vegetables can be grown just outside your back door or on a balcony.
* It requires very little water.
INTRODUCTION.
Plants are the basic source of food for all living organisms. Without plants we would not survive. Hydroponics is simply one of the techniques which can be used to grow plants. It is a technique by which water and simple natural nutrients are supplied to the roots of the plant.
In nature, the soil provides the plant with water and mineral salts and is used to anchor the plant. What differentiates hydroponics from all other techniques of growing plants, is that these natural nutrients are supplied to the plant in the proportions in which they are needed. This makes hydroponics one of the most efficient techniques for growing plants and at the same time conserves our important natural resources by using the nutrients in the most economical way.
WHAT CAN YOU GROW?
Most plants can be grown in hydroponics. This includes trees, shrubs, flowers, herbs, strawberries and most major crops. The most economical crops grown in Australia are lettuce, tomatoes, cucumbers, capsicums, strawberries, egg plants and flowers such as carnations, roses, gypsophilia, chrysanthemums, orchids also a wide range of herbs are grown hydroponically.
Plants growth rate, height and yields are determined mostly by its genetic material. Hydroponics simply allows you to get the best results from your plant.
HYDROPONIC TECHNIQUES
There are two basic techniques used to grow plants. Most people think of hydroponics as growing plants in water which contains the essential nutrients required for growth. This is only one of the systems. The other system which is widely used commercially involves the use a plant support media such as gravel, sand, volcanic rock or perlite, etc. Irrespective of the system used, an aerated nutrient solution is critical for good plant growth.
The different types of hydroponic systems are all based on different techniques for improving the degree of root aeration and supplying the essentual nutrients to the plant.
THE BASIC REQUIREMENTS FOR PLANT GROWTH.
No matter which technique is used for growing plants, the same basic requirements are the same. Plants still need light, carbon dioxide, moisture, warmth and nutrient salts. The intensity of light as well as daylenght are very important to most plants. Plants such as tomatoes and strawberries will not produce fruit unless the intensity of light is adequate. Lettuce becomes long, lanky and spindly unless they receive adequate light such as full sun.
Plant growth will be slow and the plant will not flower or produce fruit if either the temperature of the day or the night are too low. Some plants such as bulbs and strawberry plants actually require cold in order to induce flower bud formation and flowering will start as soon as the temperature starts to increase.
Irrespective of the growing technique that you use it is important to understand the growing conditions that your plants need. Most people think of cactus as liking hot, dry conditions or that Australian plants do not need a lot of water. Cactus will survive hot, dry conditions, but suddenly burst into growth and flower when they are watered and supplied with nutrients. Similarly gum trees and many Australian plants thrive and flower profusely when put into a hydroponic system and gum trees are one of the thirstiest plants that I have grown in hydroponics.
Plants grow by taking up water and the natural nutrient salts through their roots. In order to do this, the plants need oxygen in the water.
Plants breathe through their leaves taking in carbon dioxide which is then used by the plant to produce sugars by a process called photosynthesis which requires light. This process is fundamental to life on this plant.
The role of the hydroponic grower is to provide the best conditions for the growth of the plant. These include:
* Adequate light either natural or artificial.
* Warm conditions normally 22* to 28* C, day temperatures at about 5* to 10* lower at night.
* Suitable humidity of the air around the plant, normally between 60 and 70% relative humidity.
*An adequate supply of a well balanced, complete nutrient for the roots.
* Protection from strong winds and frosts.
* A gentle movement of fresh clean air across the leaves of the plant.
* Adequate oxygenated water flowing around and past the roots.
* suitable support for the plant.
These conditions apply not only to hydroponics but also to soil and other techniques for growing plants.
SYSTEMS WITH NO MEDIA
The first thing to remember is that the system is only as good as the operator. The second thing is that the plants are living and growing, and like all living things, they need care and attention. The third important factor is sanitation. Keep the area clean and tidy.
a) FLOAT SYSTEM:
This is simply using a float such as a sheet of polystyrene placed on top of the nutrient solution. The float has holes cut out to hold the plants with the roots suspended in the nutrient solution. It is essentual to pump air into the nutrient solution to replace the oxygen used by the roots and to circulate the water.
While it is not necessary, you could if you wanted to, test the nutrient solution with a pH meter and adjust the pH of the solution between 5.5 and 6.5 using a pH up (alkali) or a pH down (acid) solution. While there are other ways of testing the pH such as pH papers or pH solutions which change color, depending on the pH, they are not accurate or reliable. They are simply indicators.
While it is simpler to just follow the instructions on your nutrient bottle, you could also test the concentration of the nutrient solution by using a conductivity meter. This meter does not tell you the concentration of the individual nutrients, it will tells you the total dissolved salt concentration of the nutrient solution. You can adjust your nutrient solution by adding more water if the reading is too high or add more of the concentrated nutrient if the reading is too low. However, this assumes that you know what is the best nutrient concentration which depends on your growing conditions. Most plants require a total dissolved salts concentration of about 1500 part per million of water or about 1.5grams of nutrient in each litre of water.
If you have used a good proprietry brand concentrated nutrient and added the correct quantity to the water, then you should not need to test for conductivity or pH.
R&D AQUAPONICS has the Aqua Garden Kit which contains the polystyrene box with a lid, 1 litre of concentrated Total Growth hydroponic nutrient (a single pack complete nutrient concentrate), disposable NFT cups, which are used to hold the seedling plug and full instructions. This kit is designed to grow about 6 lettuce or two Grosse Lisse tomato plants. However, it is also used for strawberries, bulbs, herbs and a wide variety of other plants. However, the plant should be in the form of a plug which is taken from a seedling tray or as a bulb.
SYSTEM 2 N.F.T SYSTEM.
This system involves recirculating the nutrient solution as a thin film across the roots of the plant and is called the NFT system or Nutrient Flow Technique.
It is not a system I would recommend to the home grower because it needs constant attention.
It is ideal for the commercial growing of a single crop such as lettuce only. Tomatoes are also grown commercially in a similar system using much larger channels.
SYSTEM 3 SPRAY SYSTEM (Aeroponics)
This system involves spraying the roots of the plants constantly with a nutrient solution. R&D Aquaponics has an Aeroponic system suitable for 4 plants such as tomatoes, tobacco, or similar plants. For the home grower who wants the best system this is the one I recommend.
I recommend that the nutrient solution should be discarded at least every two weeks and replaced with a fresh nutrient solution. You can try nutrient adjustments but once you start then imbalances result which are difficult to correct.
SYSTEMS USING GROWING MEDIA:
The growing media is what is used to support the plant and to provide it with moisture, aeration and nutrient. These medias vary from totally organic to completely artificial (ie. plastic). What differentiates one growing media from another is its properties and characteristics.
The selection of a growing media depends on a variety of characteristics and on the type of system that you are thinking of. The properties that one looks at when choosing a growing media are:
* Cost and availability.
* Will it interfere with the pH.
* Will it interfere with the nutrients.
* Is it soluble.
* How much water and nutrients does it hold.
* Does it have good drainage characteristics.
* Is it heavy or light.
* Will it become hot in the sun.
* Is it free of diseases and pests.
Some of the growing medias that are used include:
* Sand.
* Gravel.
* Expanded clay or Leca.
* Scoria or volcanic rock.
* Pumice.
* Perlite.
* Expanded Earth
* Sawdust, Rice hulls & cocopeat.
* Vermiculite.
* Rockwool.
This list is arranged in order of water holding properties and aeration. rockwool has the highest waterholding capacity and the lowest of root aeration. Whereas coarse sand or gravel has the lowest waterholding capacity but the highest level of root aeration.
The roots of the plant hold the plant in position, but their primary function is to take in water and nutrients for the growth of the plant. The size and efficiency of the root system has a marked effect on the development of the plant and upon yields.
SYSTEM 1 TRAY SYSTEM WITHOUT RECIRCULATION.
This system is widely used by a large number of commercial growers and the home grower. It consists of a container with a drainage hole on one end and the container is filled with the growing media. The nutrient solution is then drip fed or watered into the container over the top of the growing media until the nutrient solution just begins to flow from the drainage hole. Seeds or seedlings can then be planted into the growing media.
This system is available in kit form from R & D Aquaponics and includes the container, the Total Growth Hydroponic Nutrient, the growing media mixture of perlite and vermiculite, full instructions and a moisture indicator which indicates when the tray needs more solution.
These trays are normally 600mm by 300mm by 100mm deep. While this may seem small to some people, it does offer a lot of advantages such as:
easy to move around, they can be placed at a convenient height depending on the crop being grown (tomatoes on the ground and lettuce at bench height), when the crop is finished, the old plants can be removed without disturbing the plants in the other trays, different plants can be given different nutrient concentrations, the system is very easily automated using drippers into each container.
SYSTEM 2 WICK SYSTEM.
In this system the growing media is kept moist by the growing media sucking up the nutrient solution in the reservoir below by means of a wick. Usually the plant is grown in a pot which is supported just above a nutrient solution reservoir and connected by a wick made of glasswool, rockwool, rayon, polyester or rope. The bottom of the wick is in the nutrient solution, while the top part of the wick is in the growing media.
SYSTEM 3 MEDIA SYSTEM WITH NUTRIENT RECIRCULATION.
These systems require a media that has low water holding capacity such as coarse gravel, large particle scoria (or volcanic rock), leca or expanded clay etc. In these systems we look for good drainage or good root aeration because the grower controls the frequency of watering and the amount of water and nutrients supplied to the plants.
a) The most common system consists of pipes filled with a growing media. The nutrient solution flows through the gravel and returns to the holding tank before it is again pumped back up to the system.
b) Another variation of this system is the flood and drain system in which the nutrient solution is pumped into a trough or container until the whole system is flooded to just below the top of the growing media. The nutrient solution is then allowed to drain away leaving the fresh nutrient around the roots of the plants. The flooding and draining cycle can be repeated as often as you like because it really involves washing the roots of the plant constantly with fresh nutrient solution.
c) Another variation is to use individual planter pots which may sit in a tray or bed and a stream of nutrient flows over the top of the growing media and past the roots of the plant using drippers or feeder tubes. The feeding cycle may be continuos or intermittent.
In these systems where the nutrient solution is recirculated, it is necessary to discard the nutrient solution at least every two weeks. The alternative is to constantly test both the pH and the total dissolved salts and to adjust the solution. Even when the testing is carried out, it is advisable to discard the nutrient solution about once a month or sooner. If the solution is very unstable and the pH changes rapidly, then it is advisable to discard the nutrient solution and make up a fresh solution.
A number of plants give off toxins from their root system to reduce competition from other plants (such as weeds), hence the need to discard the nutrient solution and replace it with fresh nutrient solution on a regular basis.
NATURAL NUTRIENTS.
While this aspect of hydroponics is technical, it applies to soil as well as hydroponics. The major difference is that in hydroponics we can make adjustments easily, whereas in soil it is extremely complex and difficult to make the correct adjustments. For the most part, the correct nutrient balance seldom presents a problem for the hydroponic grower because there are available a number of well formulated concentrated hydroponic nutrients available from nurseries and shops at very reasonable prices. These are available as a single complete nutrient such as the Total Growth Hydroponic Nutrient which is simple and easy to use and produces spectyacular results. R&D Aquaponics has a range of two part nutrient concentrated solutions- Oz-Manna Grow and Bloom and Dutch Formula Grow or Bloom.
The amount of nutrients used in hydroponics is very small, normally about 10 mls per litre of water, the nutrient balance and its composition is very important. The nutrient is made from naturally occurring mineral salts and there is nothing unnatural about hydroponics.
A good nutrients is the cornerstore of a successful hydroponics. It must be both complete and balanced. A nutrient is complete when it contains all the essential natural mineral salts that are required by the plant. This includes all the major nutrients such as nitrogen as nitrates or ammonium salts, phosphorous as phosphate salts and potassium salts such as sulphates, nitrates, chloides and phosphate. It must also contain calcium salts and magnesium salts and of course the salts of iron, boron, manganese, copper, zinc, molybdenum and sulphates.
It is not just a matter to have all these salts present in the nutrient but they must be in the correct proportions or ratios which will maximize the rate of growth of the plant and they must be in the proportions that are required for the particular plant. In other words, the nutrient must be balanced. While the nutrient high in nitrates may assist improved foliage growth, if the ratio of nitrogen is too high. this will lead to toxicities and if it is too low, it will lead to a deficiency.
The next criteria is that of the pH or acidity or alkalinity of the final nutrient solution. Any good nutrient formulation should have a stable pH when added to water. The pH should be on the acid side of neutral or about pH 6.2. The pH of the nutrient solution may be affected by the water supply but a well designed nutrient solution should modify the pH of the water supply so that the final pH of the nutrient solution is very close to a pH of 5.5 to 6.5. On occasions it may be necessary to add a pH down solution such as nitric acid, phosphoric acid, sulphuric acid, vinegar etc,. Sometimes it may be necessary to add a solution which will raise the pH such as potassium hydroxide, lime, bicarbonate of soda, etc,.
One of the most important aspects of hydroponics is the concentration of the nutrients in the final solution. This will depend on the plants that are being grown and on the growing conditions. Most plants will grow and flourish on a diluted nutrient solution that contains about 1500 parts per million of dissolved salts or 1.5 kilograms of salts for every 1000 litres of water used. Lettuce generally like the nutrient concentration to be lower, while tomatoes generally like it to be higher. If you have followed the instructions and added the quantity of nutrient specified then your concentration as part per million or conductivity of the solution should not need testing.
Total Growth General Purpose concentrated liquid is suitable for most plants. It is simply a matter of measuring out 10mls of this concentrated nutrient for every 1 litre of water. The final nutrient is pH stable and is normally between 5.5 and 6.5 depending on the water supply. When we started in hydroponics we believed that it should be made simple. Most suppliers of hydroponic nutrients complicate it unnecessarily by selling the nutrient concentrate as a two part concentrated nutrient in which the grower must measure out 5mls of each part for every 1 litre of water and the diluted nutrient should then be tested and the pH adjusted. The use of two part nutrients has become accepted by many growers.
The optimum range in concentration of each nutrient in solution as parts per million and the average concentration as a percentage found in a plant are as follows.
Nitrogen as nitrates 3.0%
Nitrogen as ammonium
Phossphorous as phosphates 0.3%
Potassium as salt 2.5%
Calcium as salts 2.0%
Magnesium as salt 0.4%
Sulphur as sulphates 0.3%
Chloride as chlorides 0.05%
Iron as salt 0.01%
Boron as salt 0.004%
Zinc as salt 0.003%
Copper as salt 0.001%
Manganese as salt 0.005%
Molybdenum as salt 0.00005%
LIGHT
Plants use light as energy in a process called photosynthesis in which water and carbon dioxide are combined to make sugars and amino acids.
LIGHT INTENSITY.
The intensity of the light required is probably the most misunderstood part of growing plants. The reason is simple. Our eyes can adjust quickly to the intensity of light. The plants response is much slower, it responds in various ways.
Direct sunlight is a very intense form of light. The filtered light that comes through a window is very low in intensity and is not suitable for growing most vegetables or flowers. Even the normal lights we use in our homes such as the round bulbs (incandescent) and the fluorescent lights are too low for growing most plants or for the plants to flower.
Sunlight comes from a distant source which means that the light rays are virtually parallel. Light emitted from a bulb or lamp, travel in all directions but more importantly as the distance from the lamp increases, the intensity of the light decreases very rapidly. The further you move from the source of the light, then the lower the intensity of the light.
PHOTOPERIODICITY.
This is simply the amount of daylenght. There are basically three types of plants and they require different daylenghts. Some plants produce vegetative growth when the daylenght is short and then flower and fruit when the daylenght increases. Another group of plants produce vegetative growth when the daylenght is long and flower when the daylenght is short. The third group of plants are day neutral and will produce vegetative growth and flower independent of day lenght.
A short day lenght is normally 10 to 12 hours of light per day. A long day lenght is usually 16 to 18 hours of light per day. However, if darkness is interrupted (even by a flash of light), then this is equivalent to a long daylenght (or short night length). Some plants are particularly sensitive.
TYPES OF LIGHT:
Most plants require a minimum of 3000 lux per square foot or 27,000 lumens per square. An ordinary 100watt round bulb will emit about 14,000 lumens per square meter at the source, whereas a 40W fluorescent tube will emit about 23,000 lumens at the tube when it is new. However, as you move further from the light source, the intensity of the light is reduced proportionally.
The newer high intensity discharge (HID) lights are more efficient giving a cooler brighter light per wattage rating. These come in various forms such as the metal halide, high pressure sodium and various others. These lights require a starter or ballast or transformer. The ballast may be incorporated with the reflector or it may come as a separate item.
The metal halide lights tend to give better foliage growth than the high pressure sodium light. The high pressure sodium lights tend to promote flower bud formation and flowering, but the plants tend to become more spindly and lanky and appear to be stretching for the light. The newer Son T Agro and Lucagrow lights seem to have better overall light spectrum which gives both improved vegetative growth and improved flowering. Another advantage of the Son T Agro and Lucagrow lights is that they uses the same ballast (or starter) as the high pressure sodium light, which means that a high pressure sodium light can be used at the later stages of the plants growth to improve flowering. A metal halide bulb and a sodium light bulb are not normally interchangeable because the ballast voltages are different.
The minimum wattage of these lamps required for 1 square meter of growing area is about 400 watts. It is preferable to use two 400watt lights than one 1000Watt light to do the same area and you will achieve better light distribution, better plant growth, and can have the lights much closer to the plants.
When propagating cuttings or clones or when raising seedlings, then a 75watt growing light will cover a normal seedling tray measuring 28cm * 32cm, while two fluorescent grow tubes can be used over two seedling trays. The lights are usually placed about 15cm from the top of the plants. It is usual to give these seedlings or cuttings about 16 hours of light.
REFLECTORS:
The choice of reflectors is important in directing the light where you want it. The most common reflectors are the Batwing units which are rectangular in shape and the Chinamans hat which is dome shaped. The batwing gives a more concentrated light over a smaller area while the Chinamans hat tends to give a broader light for a larger area. Normally a number of the chinamans hats are used together.
It is always advisable to cover the walls of the area with a reflective cover so that any light that strikes the wall will be sent back into the plants.
Horizontally held lamps over the top of the plants are preferable to the use of vertical lights and require less of the growing space.
WHERE DO I GET PLANTS FROM:
You can purchase plants from your local nursery as a punnet of seedlings or as a plant which has been started in a potting type mix. With seedlings it is generally advisable before planting out into hydroponics , to wash the surplus media from the roots, taking care not to damage the root system. With larger plants it is generally advisable to wash any surplus potting media from the roots of the plant and removing any old or damaged roots by gently root pruning the plant. Damaging the roots of the plant usually causes transplant shock from which the plant may never recover. The alternative is to propagate your own seedlings or plants. How you do it and what you use depends on the type of propagation.
SEED RAISING.
Seeds may often be started directly into the growing media. Most people prefer to start their seeds in a seed raising media using a seedling tray but the use of rockwool propagation blocks is preferable. Seedling trays or rockwool blocks allows you to provide better seed raising conditions and it also allows you to select the best plants for growing on.
CUTTING OR CLONES.
These may be divided into softwood or hardwood cuttings. Softwood cuttings are taken from the healthiest and most vigorous young growing shoots. Hardwood cuttings are taken from the older, more mature parts of the plant usually at autumn.
It is important that the clones do not undergo any stresses caused by low or high temperatures, dry atmosphere or winds and the growing media should be moist but not waterlogged.
If the plantlets are in rockwool or a hydroponic growing media they can be transferred to the system without removing the growing media, however, if the plantlets have been raised in a propagating soiless mix or similar, then it is advisable to remove any surplus media from the roots by gently washing the roots with water, taking care not to damage the roots.
CONCLUSION
The best advise that I can give you is to keep the system simple. Automation is good provided you can rely on it doing its job but you must check it regularly and maintain it in good operating condition.
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