For over ten millennia, man used the earth to produce his bread and butter. So, why soil-less farming, now? Why not use soil for farming, like it has been done for centuries? Research indicates that with the current rate of soil degradation due to chemically intensive farming and rising populations, only sixty years are left for us to use the earth for food generation. This is because it takes a thousand years to generate just three centimeters of topsoil. Soil-less plant growth also helps in water conservation. Therefore, it is very crucial right now to make a switch to more self-sustaining farming methods that depend less on external resources.
Using these technologies, people can grow food anywhere and even produce higher crop yields, without having to use pesticides, due to the lack of pests and plant diseases that generally comes with outdoor farming. This blog helps one to learn about three soil-less farming techniques – hydroponics, aquaponics, and aeroponics and how one can choose among these techniques based on what suits their location, capital, time, and requirements.
In hydroponic farming, the plant’s roots are submerged in nutrient-filled freshwater, which allows it to grow up to 50% faster than conventional farming. The water solution must contain all the essential minerals which are required for plant growth like Nitrogen, Potassium, Calcium, Magnesium, etc. The pH level should be between 6 and 6.5, and these can be regulated using pH adjustment solutions that will be available in local garden stores. Sometimes, porous mediums like vermiculite, perlite, peat moss, coconut fiber, or rock wool are used to give additional support to the roots to hold the plants upright. These medium-based systems are called aggregate hydroponics systems, whereas otherwise they are called liquid hydroponic systems. Hydroponic systems use 98% less water used in conventional farming methods and require only 25% of the area that is used for farming on earth.
Once a hydroponics system begins, the food production output is quite consistent and this makes the results more predictable. These systems have fewer elements to get used to – water, nutrients, the growing medium, and the lighting. Thus, it is easier for the farmers to take control and manage the system once it is up and running. These systems are also flexible in terms of size and area as they can range from a single unit for a family to an entire neighborhood, and since only a few additional factors come into play, any indoor space can be converted into a production unit. Another advantage is that the verifiable nutrient levels and pH values in these systems are completely under one’s control and can be increased or decreased as required.
However, there are a few drawbacks to this system. The nutrients used in the water are not organic, and though the vegetables are healthier than conventional farming, the topic is debatable. Over a period, the nutrient-filled water generates toxic salts which are harmful to the plants and the disposal of these can become a big challenge in itself since they cause harm to the environment. Hydroponic systems can also result in pythium or root rot, which affects the health of the plants. Apart from this, a constant supply of electricity is used for water pumping, lighting, and regulation of temperature, which means the process is quite energy-intensive. Solar power or other alternative energy sources can be used to cover up this drawback.
Aquaponics is a combination of aquaculture and hydroponics. Aquaculture or growing fish requires constant recycling of water when it comes to a closed tank. Hydroponics or soil-less farming requires a nutrient-filled water base. It turns out that fish waste acts as an excellent source of food for the plants and thereby the plants purify the water for the fish. Making use of this symbiotic relationship, aquaponics becomes a perfect circular system for food harvesting as well as fish harvesting, since water, a precious resource, is recirculated within the same system. Waste-water management is the highlighting aspect when one adopts this system. Red worms are also used in the system so that the fish excreta breaks down into plant nutrients even faster. Another important reason for the addition of red worms is to prevent the outbreak of E. coli bacteria which grow rapidly on the fish discharge and can cause diseases.
In terms of long-term usage, aquaponics is much more cost-effective because one need not buy expensive nutrients whose costs are ever-increasing due to the scarcity of minerals. Since the fish waste itself becomes the plant nutrients, the input includes only good quality fish food. Another advantage of the aquaponics system is that the plants grow much faster when compared to the hydroponics system and hence the food yield is much higher. Also, plant root diseases are non-existent in aquaponic systems. Aquaponic systems are biomimetic and the entire process is natural and organic. They also do not require water discharge as the same water is purified and reused in a closed system.
Aquaponic systems require more time, effort, and money to install initially when compared to hydroponics. This is because additional plumbing is required and accurate calculations are to be made to obtain the right ratio between the area that will be used for plants and the area reserved for fish. Since the entire process is natural, it might even take up to a few months for the fish to get adjusted to the pH levels and come to a point where one can predict good yields. A deciding factor for choosing this could be whether one is ready for the added responsibility of growing fish in the first place.
In aeroponic systems, the plant roots are suspended in the air with nutrient-filled mist. The seeds are planted in tiny foam pieces which receive light from one side and nutrition from the other side. Aeroponics does not require any medium – liquid or solid. Since sprinklers are used, managing aeroponics comes with handling a large number of switches and regulators. This approach can especially be useful in vertical farming. The periodic sprinkling of water helps greatly in oxygenation, as the roots are directly in contact with air. The root hairs are noticeably much longer and larger in number in plants grown using this system. The plants do not have to search for oxygen as much as they have to in a soil or water medium, since they are freely suspended in the air itself. The amount of water used is 40% less compared to hydroponic systems, and it requires 10% of the area used in conventional farming.
Aeroponic systems, however, are more expensive to set up because of the constant energy supply and energy backups that are required. They are highly dependent on the sprinkler systems and can hence fail in the case of a power failure even for a small amount of time. These systems also require regular disinfection of the root chamber to avoid root diseases. The cleaning of the vertical root chambers can be done using a mixture of warm water, 35% hydrogen peroxide, and 99% isopropyl alcohol.
How does one choose the right option?
If one has enough capital and time to invest in the beginning, aquaponics would be the best option, since it relies less on electrical energy, and the water and waste get recycled naturally within a closed loop. Aquaponics is also more suited to warm and tropical climates because sunlight is the best source of light for fish and plants. Creating artificial lighting and regulating temperatures in cool countries for aquaponics can increase the initial costs and the running costs even more.
Hydroponics is quite well-suited for cold countries since an artificial indoor environment has to be created anyway for any type of farming in a cold country. Hydroponics requires more water compared to aquaponics and aeroponics and hence can be used in a situation where saving water is not the highest priority. However, this method can be the best to start with, since it is the simplest and least expensive and one can always make a shift to any other system using the same infrastructure.
Aeroponics can be used for vertical farming and needs much lesser space compared to aquaponics and hydroponics. This can be a perfect solution for a situation where lack of space is the largest constraint of all. But out of all the three systems, this requires the maximum amount of initial investment and hence is probably not a viable option, to start with.
All these methods are much more productive alternatives compared to traditional farming. These techniques are very well suited for growing food vertically in cities and towns which are already facing high population density issues. They can be adopted for home farming as well as on larger scales. The development of these systems in neighborhoods can help in the decentralization of the food production process, thereby reducing huge transportation costs as well as decrease the involvement of middlemen who meddle with the food production costs.
By 2050, the number of people in cities and urban areas will become 70% of the total population. In a way, adopting these technologies or similar adaptions will be inevitable in the near future. Vertical farming is the only solution whether it is a people’s initiative or government initiative or preferably both. Studies also indicate that homes of 300 million people will be underwater by 2100. “Futuristic” cities like floating cities, which are already becoming a reality today, and water-and air-based farming will be the only way forward.