The term hydroponics refers to growing plants without soil. Eliminating contaminants that may lead to diseases, weeds, parasites, and diminished growth or productivity is the main advantage of this method. Any hydroponic system has to supply to the plants the five essential components: water, nutrients, root support, air and light. In hydroponics the plants are held in containers either with a support medium or without one. The water-nutrient solution is applied using different methods.
Water Culture System
The water culture system is the simplest form of hydroponic system, in which the plants are supplied mineral nutrients directly from a solution. A platform made of Styrofoam holds the plants and floats directly over the nutrient solution. The main advantage of this system is that the plant is always in contact with the water and nutrients, providing adequate supply. The major disadvantage of this system is the requirement of a large quantity of water as well as the inadequate supply of air and root support for the plant. This system can have a low cost and mechanization can be made depending on the magnitude of the cultivation.
Ebb and Flow System
The ebb and flow system is an aggregate culture system where a medium is used to hold the plants. The system works by flooding the medium temporarily with the nutrient solution, collecting the drained solution and storing it back in the reservoir. The process is repeated at frequent intervals, and the frequency depends on the type and size of the plants, temperature and humidity requirements. It is done using a submerged pump attached to a timer. This is the most popular hydroponic system and is suitable for seedlings, transplants and ornamental potted plants. It also is a low a cost, low maintenance system that gives the plants uniformity in growth.
The drip system is widely used and very reliable, and it requires low maintenance. In this system, the nutrient solution is delivered at the base of each plant in small drips, using a drip line. The drip line is controlled by a submerged motor fitted with a timer. This form is best suited for large scale cultivation. The disadvantages are the cost and the fact that the nutrient solution is used only once.
Nutrient Film Technique (NFT) System
The NFT system does not use any medium and so it is less expensive. The system is based on the flow of nutrient solution on the root system of the plants. The NFT system is used to cultivate plants on a mass scale in places where the soil quality is poor. The major disadvantages are the lack of oxygen around the roots, causing wilting and blossom-end rot of fruit crops. Another drawback of this system is the frequent failure of the equipments.
The aeroponic type of hydroponic system is the most advanced system in terms of technology. It uses pumps and sprayers to immerse the roots in a mist of oxygen and nutrients. No medium is not used in this system and the plants are suspended using a platform in a container, where the mist is sprayed. This system is used only in labs and not in large scale cultivation.