Lillian Liem 6S 26

Date:16-05-2004

Hydroponics

Introduction

Hydroponics is a technology for growing plants in nutrient solutions (water containing fertilizers) with or without the use of an artificial medium (sand, gravel, vermiculite, rockwool, perlite, peatmoss. coir, or sawdust) to provide mechanical support. No soil is used in hydroponic culture as compared with traditional planting methods. Besides, Hydroponics may also be called 'controlled environmental agriculture'. In a complete controlled environmental agriculture system you control: light, temperature, water, CO2, oxygen, pH and nutrients.

It is a highly efficient method of growing plants.  In soils, nutrients and water are randomly placed, and often plants need to expend a lot of energy to find the water and nutrients by growing roots to find them.  By expending this energy, the plants growth is not as fast as it could be.  In a hydroponic garden, the nutrients and water are delivered straight to the plants roots, allowing the plants to grow faster, and allowing harvesting to be done sooner, simply because the plants are putting more of their energy into growing above the ground, instead of under it

Different categories of hydroponics systems

There are several types of hydroponics systems currently in use in different parts of the world. They can be divided into two big groups. One is the roots submerge in (liquid or aggregate culture). The other one is the way nutrient solution flows in the system (open or closed system).

Liquid culture and aggregate culture is the simplest methods to set up on a small scale. The roots are hanging into the solution directly. The plant body is usually held on a piece of styrofoam placed over the nutrient solution without an inert medium. This kind of method is suitable for short plants such as lettuce and spinach. For taller plants such as tomatoes and cucumbers, they may be hung loosely with strings for support. In aggregate culture, the plant roots grow into an inert medium and are irrigated with complete nutrient solution held in a separate tank. In both methods, the solution must be aerated for aerobic respiration of the root cells.

In an open hydroponic system, the nutrient solution is distributed from a reservoir to the plant, and the excess solution is drained away as waste. On the contrary, the excess solution in a closed system is collected and reused, forming a closed loop of solution flow.

Common hydroponic systems

Flood and Drain Systems

As the name suggests, flood and drain systems work by flooding plants with an aerated nutrient solution and then draining the growing tray in order to aerate the roots and supply them with much .needed oxygen.

Flood and drain systems are very easy to use once set up. They consist of a tray, stand, pump and fittings. The tray holds the plants, the growing medium, and the nutrient solution. The pump is used to feed the plants with nutrient, and to drain the tray. The timer is used to regulate the pump and feed the system for 15 minutes every hour.

Flood and Drain systems are becoming increasingly popular by both hobbyists and professional growers alike. The method is able to supply fresh oxygen to the root system of your plants. As the tray is flooded with your nutrient solution, carbon dioxide rich air is pushed out from around the root system. When the pump is turned off, the tray is drained and oxygen rich air is drawn down to the roots. This oxygen is then used by your plants until the next cycle begins.

Nutrient Film Technique (NFT Systems)

The basic principle of Nutrient Film Technique systems are that the plant's roots are given access to a constantly running and very shallow stream (film) of nutrient solution flowing down an enclosed trough.  As with flood and drain systems, the flow of water is controlled by a pump submersed in your nutrient solution.   However, rather than flooding the plants at regular intervals, the roots of the plants have access to the stream of water which runs constantly.

To enable this plants are placed in troughs with holes cut in the lids, allowing the roots of the plant to "dangle" down into the stream of water.

Advantages of hydroponics

Hydroponics methods are usually practiced in association with greenhouses. The method, although expensive, is implemented worldwide for commercial purpose because crops are grown under totally controlled environment in greenhouses. The yield of crops increases, and the quality of crops is improved because the factors contributing to their growth such as nutrient supply, temperature, humidity, carbon dioxide level. All of these can be controlled within optimal levels. Furthermore, the effects of climates changes are minimized in sheltered environment. Growing seasons `kept under control so as to make hydroponically grown crops more attractive and tastier. The most important benefit is reduction of pollution. The use of water and nutrients becomes more efficient in closed hydroponic systems. Leaching of nutrients is prevented and wastage as well as pollution problems are minimized.