The below mentioned article provides a study note on the soilless growth in plant.
The practice of growing plants in nutrient-enriched water without soil is called as soilless growth or hydroponics (Gericke, 1937). However, the term hydroponics is now being applied to plants rooted in sand, gravel or other similar matter such as vermiculite or expanded clay (i.e. kitty litter) which is soaked with a recycling flow of nutrient-enriched water.
(Vermiculite is a group of low grade micas which expand and exfoliate on heating to a light water absorbent material. In exfoliated form, vermiculite is used in industries as heat and sound insulating material. It is also used in hydroponics as special “soil to sustain plants rooting system).
The plants are grown in large tanks containing nutrient solution and are supported by wire netting (Fig. 8.2A). The tanks are provided with the solution-regulating and pumping system and are placed in green houses under controlled environment.
After about a month in the greenhouse when the plants flower, they are further supported by strings attached to the greenhouse roof. Because the plants are grown in large tanks, this process of soilless cultivation is also known as tank farming. Hydroponics has achieved success in experimental stations around the world and is gradually coming into commercial use in countries like United States, Abu Dhabi etc.
According to a United Nations report on hydroponics: ‘In large areas of the tropics, water deficiency is the limiting factor in crop production, and it is in these regions that the soilless
methods hold out much promise because of the more economical use of such water as is available’.
The report adds: “In some areas, lack of fertile soil or very thin soil layers may also make soilless methods worth serious consideration’. Besides these, the other advantages of growing cucumbers, egg plants, peppers, lettuces, spinach and other vegetables hydroponically under controlled environment are:
(i) The regulation of nutrients
(ii) Control of pests and diseases,
(iii) Reduction of labour cost and
(iv) Sometimes, quicker yield.
But there are two main drawbacks of hydroponics farming. Firstly, the cost of setting up the system is very high. A typical hydroponics unit including the environmental control equipment and which encompasses three quarters of an acre costs lakhs of rupees. Secondly, it requires skill and knowledge for its operation.
The UN report says : To make a real success of the method, it is necessary to have some knowledge of plant physiological principles and even of elementary chemistry as well as sound knowledge of how to grow the crop’. However, the future of growing crops under unfavorable conditions hydroponically seems to be promising.
(In recent years, two other alternatives to grow plants hydroponically have been developed. One such alternative hydroponic system is the nutrient film growth system in which plant roots lie on the surface of a slanting trough and the nutrient solution is pumped as a thin film over the roots (Fig. 8.2B). This system ensures adequate supply of oxygen to roots and the composition and pH of the nutrient solution can automatically be controlled. This technique is often used in commercial production.
The second alternative is the aeroponic growth system (or aeroponics) in which plant roots are suspended over the nutrient solution in a nutrient mist chamber (Fig. 8.2C). With the help of a motor driven rotor, the nutrient solution is whipped into a mist that is continuously sprayed on the plant roots. Although in this technique gaseous environment around the roots can easily be manipulated, but due to greater requirement of nutrients and other technical difficulties, aeroponics is not used widely).