The word “Hidroponia” comes from the Greek Hydro (water) and Ponos (work) which means literally “working water”. The Hidroponia is a science that studies the cultures without earth. When someone speaks of hidroponic cultures one tend to associate it with Japan, but this is not necessarily certain. Hidroponia is not a modern technology, in fact it is an ancestral technique; ancient cvilizations used it for their subsistence. For example, little is known about the fact that the Aztecs constructed a city in the lake of the Texcoco (the city of Mexico is located on a lake that is sinking), and cultivated its maize in boats or hulls with a straw framework. There are many examples like this; the Hanging Gardens of Babylonia were hidroponic cultures because they were fed on water that was flowed by channels. This technique existed in old China, India and Egypt.

It is also used commercially, being developed at very high levels in countries with serious limitations of ground and water. For example, it is a fact that hidroponia had a great weight in World War II: the North American armies in the Pacific were supplied by this technique. In the island of Hawaii, Iwo Jima; even when the United States occupied Japan, great hidroponic boats were made to supply their soldiers. Moreover, the NASA has been using it for approximately 30 years feeding the astronauts. Nowadays the spaceships travel six months or a year. The crew during that time eat cultivated vegetal products in the space.

When most people think of hydroponics, they think of plants grown with their roots suspended directly into water with no growing medium. This is just one type of hydroponic gardening, known as N.F.T. (Nutrient Film Technique). There are several variations of N.F.T. used around the world and it is a very popular method of growing hydroponically. What most people don’t realize is that there are literally hundreds of methods of hydroponic gardening. Many of the present hidroponic methods use some type of substrate, such as sand, pumice stone, sawdusts, expansive clays, coals, husk of rice, etc., to which a nutritious solution that contains all the necessary elements for the normal growth and development of the plant is added.

Taylor made

It is as simple as that. You are giving the plant exactly what it needs, when it needs it, in the amount that it needs it. When you achieve this, the plant becomes as healthy as is genetically possible. This task is almost impossible to do in the soil.

With hydroponics the plants are grown in an inert growing medium, the plants do not get anything from the growing medium. They receive only what you give them, nothing more, you have complete control over pH, nutrients and the nutrient strength. In the soil you really have no idea what the plants are getting, so gardening becomes a big guessing game.

ADVANTAGES OF THE CULTURE BY HIDROPONIA:

  • Cultures free from parasites, bacteria, fungi and contamination
  • Reduction of production costs
  • It allows the production of registered seed
  • Independence of the meteorological phenomena and stationality
  • Water saving, that can be recycled
  • Saving of fertilizers and insecticides
  • The agricultural machinery is avoided (tractors, drays, et cetera)
  • Cleaning and hygiene in the handling of the culture
  • High percentage of automatization

The Substrate

It is generally an inert solid, and it has basically 2 essential functions:

  • To anchor and to grasp the roots being protected from the light and allowing them to breathe.
  • To contain the water and the nutrients that the plants need.

The component grains of the substrate must allow the circulation of the air and the nutritious solution. They are considered good if they allow a presence of air between 15% and 35%, and 20% and 60% of water in relation to the total volume. Often it is useful to mix substrates looking for a combined work, considering the following aspects:

  • Humidity retention.
  • High percentage of ventilation
  • Physically stable
  • Chemically inert
  • Biologically inert
  • Excellent drainage
  • To have capillarity
  • Light
  • Of low cost
  • High availability

The most used substrates are the following ones: husk of rice, sand, burdens, remainders of furnaces and boilers, pumice stone, sawdusts and shavings, bricks and worn out roofing tiles (free of calcareous elements or cement), polystyrene foam (used to lighten the weight of other substrates almost solely), disturbs blonde, vermiculita.

THE IRRIGATION

In the Hydroponic cultures the use of an irrigation system to replace the water necessities of the plants is essential to provide the its necessary nutrients. The irrigation systems that can be used go from one manual to automatic with controllers of metering of nutrients, pH and automatic programming of irrigation.

An irrigation system consists of a tank for the water and nutrients, pipes of water conduction and sprinklers.

The tank must be inert and of easy cleaning, maintenance and disinfection. The criterion to select the size can vary according to the culture, locality, method of control of the nutritious solution, etc. The smaller it is, the more frequent will be the necessity to control its volume and composition.

The location of the tank will depend on the situation of the culture. In case of watering by gravity, it must have sufficient height to obtain good pressure in the sprinklers, if it is watered using a pump, the tank can be underground.

The pipes of PVC and polyethylene hoses are economic. The diameter will depend on the volume and length of the section.

Systems of irrigation

the election of one or another technique of irrigation depends on numerous factors like the physical properties of the substrate, the elements of control available, the characteristics of the operation, etc.

From the point of view of the water movement in the substrate, the irrigation systems can be classified in two great groups, water contribution of above downwards (dripping and aspersion) or of down upwards (subirrigation).

In the first case, the movement of the water during the irrigation is governed mainly by the gravity. In the second case, this movement is governed by the hair forces.

The irrigation system and the physical characteristics of the substrate are closely related to each other, and must consider one when each one is chosen.

The different types of irrigation are the following:

a) Irrigation located or by dripping:

The located irrigation consists of applying water to each flowerpot by means of a microtube provided with an exit of low volume. It is one of the most used methods.

b) Irrigation by aspersion:

In this system the water is contributed to a certain height on the culture and falls on the foliage. It´s a system that has been used much but that at the moment it is in recession.

c) Irrigation by subirrigation

The subirrigation is an irrigation technique that consists of providing the water to the base of the flowerpot. This contribution is made by means of the water filling of a tray where the flowerpots are placed. The filling can be made by elevation of the water lamina of the tray (Flow-ebb tide) or making flow water by gutters (Morel, 1990). It´s the method that´s being implanted lately.

One of the most advantageous systems is the irrigation by dripping by means of which the water is lead until the foot of the plant by means of hoses and spilled with sprinklers that let it leave with a certain volume. By means of this system the production of the cultures is increased, diminish the damages by salinity, and the fitosanitarias conditions improve.

In irrigation by aspersion the water is taken by means of pipes and emitted by sprinklers that simulate rain.

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