Vertical Farming Technology: 3 Revolutionary Methods

Image showing vertical farming technology in a lab.
Vertical farming technology might look complex, but it can be fairly straightforward.

Suppose farming has always appealed to you, but you live in a city apartment and don’t own acres of land. Therefore, you may be interested in technology allowing you to grow food within a small surface area without leaving your city.

Vertical farming technology enables growers to reduce land surface area usage, minimize energy and water consumption and make farmers independent from weather conditions. Technologies employed include Hydroponics, Aeroponics, and Aquaponics.

Read on if you are curious about how to farm without leaving your city, use 80-95% less water than conventional farmers, and grow food without pesticides while not worrying about the weather. 

Vertical Farming Technology: How Does It Work?

Traditional farmers grow food in the ground. All seeds are planted in soil on a single horizontal plane, such as a plowed field or greenhouse. Vertical farming technology allows people to grow crops in layers that are vertically stacked. These stacked crops may grow inside shipping containers, skyscrapers, and warehouses. The efficiency of vertical farming is based on the following technological forms

Hydroponics: Growing Food Without The Need For Soil

Hydroponics is the art of growing food in a nutrient-rich water solution. The big advantage is that it eradicates the problem of soil-borne pests and diseases, thus negating the need for pesticides. Crops are grown in mediums made of inert, organic stuff such as coconut coir, clay pellets, and rockwool rather than soil. The plant roots are continuously supplied with water and nutrients through an elaborate system of pipes, which forms most of the vertical farming technology.

Image showing a hydroponic vertical farm.
An example of a hydroponic farm.

Hydroponic systems have 2 main components: 

  • A reservoir containing a water-nutrient solution 
  • A plant growing tray.

Plants are grown in pots full of organic matter, such as coconut coir, Perlite, Growstones, Rockwool, or clay pellets. These provide physical support to the plant roots. Nitrogen, phosphorus, potassium, iron, calcium, zinc, chlorine, and manganese are dissolved in water and get straight to the roots. Plants are usually suspended in the air, above the water reservoir, with their roots either partially or fully submerged in it.

Growth Media In A Hydroponic System

In a hydroponic system, the growing media is used to stabilize plants and as a buffer. A good growing medium maintains an equal air-to-water ratio. The most commonly used mediums are:

  • Rockwool: A mix of granite and limestone rocks, heated to melting point and then spun into fine long fibers. It is non-degradable and porous with great water holding and aerating capacity. Its disadvantage is its high pH, which can alter the pH levels of the nutrient solution.
  • Oasis Cubes: A sheet-like floral foam used as a starting environment for seedlings. It is non-reactive, has a neutral pH, good aeration, and a large water-holding capacity. However, they crumble easily and are not reusable.
  • Coconut Fibers: Are the brown husk of coconuts, are very inert, and have a good water holding capacity.
  • Growstones: It is 99% recycled glass, lightweight, very porous, and provides good air circulation. The disadvantage is its dustiness, stickiness to plant roots, and very expensive.
  • Expanded Clay Pellets Are small, porous, and lightweight balls with a neutral pH and can provide firm support to crops. They can be reused after being sterilized and cleaned. However, they have a very low water holding capacity because of the large spaces between the pellets.

Types Of Fertilizers Used In Hydroponics

Calcium nitrate (CaNO3) is an inorganic fertilizer used in hydroponic systems to supply plants with nitrogen and calcium. For inorganic fertilizers to be good for plants and avoid plant damage and death, they must be correctly dosed, easily absorbed by the plants, and easily measured by conductivity testing.

Organic fertilizers are made of plant or animal materials or by-products. Organic fertilizers are harder to apply for hydroponics than inorganic fertilizers because they have to be partially decomposed before being absorbed by plants. Also, the nutrient solution needs to be changed frequently to avoid unpleasant odors. Organic fertilizers are not suitable for all hydroponic farms.

Air Pumps Used In Hydroponic Systems

Plants cultivated in deep-water culture set-ups can suffocate if they don’t receive the right oxygen amount. Since the roots of plants in hydroponic systems are submerged in the nutrient reservoir at all times, this may be a problem. The oxygen delivery process in most hydroponics systems consists mainly of 3 parts: air stones, air pumps, and airline tubing. This is where most of the vertical farming technology resides.

Air pumps are mostly put outside the nutrient-water reservoir, pushing air from the room and into an air stone device placed at the bottom of the reservoir. The air pump and the air stone are linked by airline tubing. Tiny oxygen bubbles are made in the reservoir when air is forced through the air stone, oxygenating the water.

Type Of Water Required In A Hydroponic System

Water containing a high level of chlorine, chloramines, and bacteria is unsuitable for hydroponic farming because it stunts the development of leafy greens like lettuce. Many hydroponic systems use distilled water, and water is purified by reverse osmosis. 

The Hydroponic Pipe Network

Pipes link the nutrient reservoir to the growing trays in which the plants grow. Water and nutrients flow through these pipes from the reservoir to the growing tray and back. PVC piping is usually used since it is white and hence does not retain heat. 

Aeroponics: Growing Food Outside A Container

Aeroponics was invented by NASA scientists seeking an efficient method to grow plants in space. They found a way to grow plants outside of a growing medium, eradicating the need for a growing container. Plants are tied to a support, and their roots are sprayed with nutrient-rich aerosol or mist

This is a very efficient farming method since it requires only a fraction of the water and space needed in traditional farms and requires no soil. It is the most sophisticated form of hydroponics because it uses so little water and doesn’t need solid materials like coconut coir or rockwool. In aeroponics farming, plants’ roots are suspended in the air and sprayed directly with nutrient-containing droplets.  

Aeroponics systems consist of a reservoir, net cups, timer, water pump, and misting nozzles. The reservoir contains a water-nutrient solution and water pump, which pumps the water into the misting nozzles through pipes. A programmed timer controls the Pumped water from the reservoir. Plants are inserted into net cups that contain holes that allow the root system to grow normally.

Image showing the underside of an aeroponic farming system.
The underside of an aeroponics system that shows the vertical farming technology.

Many crops such as leafy greens, strawberries, root crops, and tomatoes can be aeroponically grown. However, it is a new technology that requires highly skilled workers to set up. It is more expensive to maintain than other hydroponic systems. Unsurprisingly, there’s a lot of vertical farming technology involved, which can result in catastrophic losses for growers in the event of a malfunction. 

For readers concerned that VF is limited to growing leafy greens and wonder if fruit and other veggies can be grown,  they can rest assured that VF is quite diverse.  

Aquaponics: Creating A Symbiotic Environment Between Fish And Crop Farming

Aquaponics is the synthesis of hydroponics (growing plants without soil) and aquaculture (fish farming). Water containing fish excrement from a fish tank is fed into a hydroponic grow bed. Bacteria found between the plant roots and in the bed, gravel break down the ammonia from the fish waste into nitrites (NO2) and then into nitrates (NO3) in a process called nitrification. 

Plants absorb these nitrates as food. In turn, the plants and gravel in the hydroponic grow bed filter out all chemicals, gases, and chemicals harmful to the fish in the tank. The clean, fresh, and oxygenated water is recycled back to the fish tank, where the cycle begins anew. 

Aquaponics arguably has the least amount of vertical farming technology of the 3 methods. It’s simply a fish tank setup with a few extra pumps and water supplies.

You can check out this video to see an aquaponics vertical farm in action.

Controlled Environment Agriculture (CEA)

CEA is an enclosed farming method that enables weather-independent food production and ensures maximal crop growth all year round by controlling input factors such as temperature, lighting, nutrient, and water infusion. CEA includes all indoor and vertical farming technologies, such as hydroponics, aeroponics, and aquaponics.

CEA makes urban farming possible by enabling crops to be grown in city apartments and underground basements. Shorter food supply chains are now possible, as city demand for fresh produce can be met directly and locally. Since CEA is weather independent, it eliminates seasonal supply fluctuations, stabilizing market prices and thus benefiting both consumers and farmers. 

CEA is central to vertical farming technology, and uses:

Collecting Data Using Smart Sensors

By acting on a continuous data stream of critical input variables captured by smart sensors, vertical farming technology can achieve yields significantly surpassing that of even the most advanced greenhouses. The most important variables to be captured and measured are:

Differences between air temperature and plant temperature indicate whether the leaves’ stomata are open. If not, the plant cannot absorb CO2 and convert it into biomass. In the case of irrigation water monitoring, pH (acidity), EC (electrical conductivity), and iron and magnesium levels of the water can be measured to ensure maximal crop yields.

Intuitively, the plants’ light level and spectrum should be deducible from the type and number of LED lighting used. However, research has found that from the plant’s point of view, light levels can deviate as much as 2x from the objectively measured light level installed between and above the plants. This value difference mainly depends on the plant density in the growing area. To ensure optimal growth conditions, this difference needs to be continuously tracked. 

Plant growth rates can be monitored and controlled from data collected on plant size, height, weight, and color. Vertical farming technology – including cameras – collect images of the plants to track their development and compare them to data captured in previous growth cycles under similar conditions. Cameras can also help prevent future problems by detecting early-stage growth deficiencies (such as tip-burn) and diseases.

Sensors can be put anywhere within a growth layer, and data is sent wirelessly for processing. Cloud applications retrieve this data and visualize the most useful information for specialists and farmers. The sensor platform development is part of Horizon 2020 Internet of Food (H2020 IoF), a European Commission (EC) innovation project closely collaborating with Staay Food Group.

AI researchers are currently developing mathematical models to couple realized growth conditions with realized growth results in a process known as ‘supervised learning.’ This will enable vertical farming technology to predict the precise growth conditions needed to achieve optimal growth and meet specific grower needs. AI techniques like machine learning can analyze images of plant growth to detect unexpected deviations or growth deficiencies.

Using Automated-Dosing Systems To Deliver Nutrients

In vertical farming technology, automatic-dosing systems are commonly used to continuously assess the reservoir’s nutrient concentrations, pH, EC levels, and water temperature. Usually, the dosing machine is linked to the nutrient source by peristaltic pumps that pump the needed dose of nutrients and dispense them into the reservoir. 

Probes placed in the reservoir measure EC and pH levels in real-time and restart the dosing cycle if necessary. Automated dosing enables growers to control the nutrient solution without spending a lot of time fixing pH, EC, nutrients, and temperature. Also, the high level of precision in nutrient supply avoids plant shock and stunted growth, which are often consequences of unbalanced growth conditions.

Sterilization Systems For Optimal Plant Growth

To make growing pesticide-free crops all year round possible, vertical farming technology uses rigorous sterilization and disinfection. Sanitation is necessary for optimal growth and compliance with international food safety regulations. Sanitation is accomplished with UV-C sterilization, ozone sanitation, and chemical disinfectants. 

UV-C light lamps emit a specific wavelength of ultraviolet light, which acts as a germicidal. It deactivates the DNA of bacteria, viruses, and other pathogens, disrupting their ability to multiply and cause disease. UV-C light kills around 99.9% of all microbes in the treated area. Its effectiveness is very popular with Vertical farming.

Ozone sanitizers use ozone gas to purify the air in indoor farms from fungi and other microbes harmful to plants. Chemicals such as hydrogen peroxide and hypochlorite help sterilize surfaces like floors, transporting equipment, and tools such as harvesting clippers. If the latter is not cleaned, diseases can quickly spread from plant to plant. 

Irrigation Water Recapture and Recycling

Many vertical farms minimize their water use by recapturing and recycling irrigation water. Plants lose most of their water during transpiration. Vertical farming technology collects transpired water using air conditioning and dehumidifiers. After being treated and filtered, the captured water is reused in the production process.

What is the best vertical farm system?

Deciding on the best vertical farming technology system can be done according to the following criteria: 

  • Commercial viability
  • Ratio of crop yield to inputs
  • Ease and cost of start-up 
  • Technical know-how required

Aquaponics has an advantage in commercial viability since it delivers both fish and crop yields. In terms of crop yield ratio to inputs, aeroponics is the winner. Since crop roots using the aeroponics method are suspended in air and not in a water-nutrient medium such as in hydroponics, they receive more oxygen. Hence crops grow faster and bigger, resulting in higher crop yields than in hydroponics.

Aeroponic systems also use up to 25% less water than hydroponics and less space. Also, since crop roots are not continuously immersed in a nutrient-water solution, they are not as vulnerable to bacterial diseases. The downside to Aeroponics systems is that they have higher start-up costs and require more technical know-how to set up and run than Hydroponic systems. 

Due to the complex monitoring equipment required, Aeroponic systems are more vulnerable to electric power outages than hydroponic systems.

Final Thoughts on Vertical Farming Technology

Vertical farming technology is the 21st century solution to the negative impact traditional farming has on the environment. By clearing away forests and woodland in favor of growing large-scale commercial monocultures, conventional commercial farming is guilty of soil erosion, groundwater contamination through pesticide and chemical fertilizer use, and biodiversity reduction. 

By radically reducing the land space and water required and eliminating the need for soil and pesticides, vertical farming technology is far more environmentally friendly. Also, by producing food directly in cities, supply lines and transport costs can be radically reduced. Since global food shortages are more a problem of distribution than insufficient amounts grown, Vertical farming could also be a solution to the food insecurity experienced in many parts of the world. 

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