Hydroponics – the science of growing crops without soil in nutrient-rich solutions or a mineral-rich aqueous solvent. The word “Hydroponics” has been derived from the Greek words – “hydro” implying water and “ponics” which implies labor. Although it may sound sophisticated, the concept of going soil-less with crop productions has been around for centuries with the earliest examples dating back to the Babylonian times which include the Hanging Gardens of Babylon. This was built by, none other than King Nebuchadnezzar II himself for his beautiful wife Amyitis. Global production of rice using hydroponics technology has been around for centuries and is still persistent to this day.[i]
Using hydroponics technology, plants can have their roots exposed only to the nutrient solution. Along with this, usage of chemically inert media is very common which include gravels or perlite. Nutrients for growing crops can come from various sources like chemical fertilizers, fish excrement or even some artificially derived nutrient solutions. Based on composition, nutrient solutions can be broadly classified into two types –
1. Inorganic solutions
2. Organic solutions.[ii]
Inorganic Hydroponic Solutions: these solutions are supplemented with inorganic elements which are essential for plant growth and without which plants show mineral deficiency syndromes. These inorganic elements include nitrogen, phosphorus, magnesium, sulfur, potassium, and others which are made available directly to the roots of the plants, thereby enhancing the growth and development of plants, with the root systems being of limited growth. Because of the absence of soil, the hydroponic solutions tend to change pH and also concentrations of nutrients over time. An example is the Hoagland solution which is widely used for hydroponic cultivation of plants.[iii]
Organic Hydroponic Solutions: these solutions are obtained with the help of microorganisms which bring about degradation of organic solutions and reduce them into inorganic elements with various processes like nitrification, ammonification, etc. These microorganisms are cultured separately with multiple parallel mineralizations. This solution can then be used for hydroponic cultivation. However, organic solutions have variable chemical and nutrient composition as they are from the byproducts of animals. Also, they tend to degrade over time, resulting in foul odor. Examples include blood meal, bone ashes, etc.
WHY HYDROPONICS?
According to the United Nations, the global population is expected to reach 10 billion people through half of this century. It has been estimated that an average of about 83 million individuals is being added every year to the existing population. With the increase in population, food shortages have become increasingly common, with an estimation of about 124 million individuals facing acute shortages of food in the year 2019 itself. This can happen also because of variations in climatic conditions like flood, drought, extreme temperature conditions which have a deleterious effect on food production.
Hydroponics utilises nutrient-rich solution rather than soil, water requirement is limited, and also the plants are grown under controlled environmental conditions, such projects can prove to be beneficial for optimum crop productions in areas where the people suffer from shortages in the food supply. Such projects have been implemented by the Food and Agriculture Organisation of United Nations in various areas of the world like some African countries and Latin American countries which provide people with greater crop production as compared to the conventional method. Hydroponics technology, which is being widely used in developed countries, is based on the systems which were developed by NASA for trying to cultivate food in space by the late 20th century. The development of hydroponics of the modern-day is attributed to the German Botanist, Julius Sachs, who, in 1860 formulated the “nutrient solution” for growing plants without the need of soil by years of extensive study on essential elements which are required for the basic growth and development of plants.[iv]
TYPES OF HYDROPONIC SYSTEMS
The use of hydroponics has been on the rise because of all the advantages associated, however, many variations of the basic method are available. All these variations are now categorized under 6 basic variations, all of which have their own set of advantages and disadvantages which should be taken into consideration while adopting a particular method for cultivation.
The 6 different hydroponic systems are:
Wick System: it is the system that doesn’t require electricity and doesn’t use pumps or even aerators, hence can be easily used by most people. Plants are directly exposed to absorptive substances like that of perlite, with a Nylon wick that is wound around the plant and is then submerged within the nutrient solution. Being the simplest type, it is commonly used by many people but comes with the major disadvantage of less nutrient availability to plants.
Water culture: another simple hydroponic system, where the plant roots are directly submerged into the nutrient solution, thereby bypassing any need for nylon wick. This system has the greatest advantage as it allows the proper absorption of nutrients by plants. Also, this system utilizes a diffuser or else an air stone to introduce oxygen into the solution for use by plant roots. Due to proper absorption of nutrients, a large number of plants are well suited to this method, with the only disadvantage being the possibility of occurrence of root diseases because of filthy conditions of growing.
Ebb and Flow: also known as the Flood and Drain method, this system is very commonly used by home gardeners. This system utilizes a voluminous grow bed which is filled with medium facilitating growth like Rockwool. After the plants have been properly planted, the nutrient solution is filled in the grow bed up-to two inches below the top layer, thus ensuring that overflowing is prevented. This filling of nutrient solution is regulated by a pump which is fitted with a timer that switches it off after a while. Following this, the water is drained and made to go back to the pump. The major disadvantage is that the pump can malfunction and hence work cannot be carried out till it has been fixed.
Drip System: this system can be modified according to the plants grown, thus making it highly flexible and preferred by people who wish to make changes. In this system, the particular nutrient solution is sent to the base of the plant via a tube. This tube is fitted with a drip emitter at the end, which helps in controlling the amount of nutrient solution that reaches the plant base.
Nutrient Film Technology (N. F. T.): in this system, a growing medium is mostly not used. Instead a large reservoir, containing the nutrient solution is used, from where the pumping of the solution is done to a sloped channel such that excess solution can return into the reservoir.
Aeroponics: although the building of this system is rather difficult, this system is highly effective. Pumps are used, which are connected to mist nozzles. As the pressure builds up, the nutrient solution is directly sprayed onto the roots of the plants. The usage of correct dimensions of the reservoir becomes mandatory, as all the roots of the plants may not be accessed by the nozzle.[v]
EARLY ADOPTERS OF HYDROPONICS
Hydroponics systems have now become increasingly popular and several countries have significant production sizes. Some of the countries are:
England
United States of America
Japan
India
Australia
South Africa
Space
An estimated production size of 54 million pounds has been noted for England, while in India the production size is around 38 million pounds.[vi]
[i] Folds,
E. (2018). The History of Hydroponics. Retrieved 24 November 2020, from https://medium.com/@evanfolds/the-history-of-hydroponics-99eb6628d205
[ii] Hydroponics. Retrieved 24 November 2020, from https://en.m.wikipedia.org/wiki/Hydroponics
[iii] Johnson, L. (2015). Organic versus Inorganic:
What’s the Difference? | EZ GRO Garden. Retrieved 25 November 2020, from https://ezgrogarden.com/hydroponics/organic-versus-inorganic-whats-the-difference/#:~:text=Hydroponic%20culture%20is%20inorganic%20because,plants%20with%20smaller%20root%20systems.
[iv] Lagomarsino, V., & Senft, R. (2019). Hydroponics: The power of water to grow food – Science in the News. Retrieved 25 November 2020, from http://sitn.hms.harvard.edu/flash/2019/hydroponics-the-power-of-water-to-grow-food/
[v] 6 Types of Hydroponic Systems Explained – Sensorex. (2019). Retrieved 25 November 2020, from https://sensorex.com/blog/2019/10/29/hydroponic-systems-explained/
[vi] Top 7 Countries That Use Hydroponics (Their Production Size Revealed) | Hydroponicsspace. (2020). Retrieved 25 November 2020, from https://hydroponicsspace.com/top-7-countries-that-use-hydroponics-there-production-size-revealed/