Vertical Farming

Vertical farming refers to growing crops in stacked trays or platforms. Predominantly housed indoors, vertical farms require lighting and control systems for temperature, humidity, and air circulation that are autonomous from the natural environment.

Though greenhouses are slowly adopting hydroponics, aquaponics, and aeroponics, these technologies are most closely associated with vertical farming. This is because vertical farms mostly use inert substrates in place of soil, as a means of getting water and minerals to the plants efficiently.

Vertical farming is a response to the world’s declining amount of arable land, greater demand for healthy crops, and inefficient rural sprawl. Vertical farming is the first type of food production that can viably work in urban centers, in confined spaces, without reliance on natural elements, and without polluting the soil.¹

As a predominantly urban farming practice, vertical farms have been studied to establish a possible symbiotic relationship between vertical farming and polluted streams from dense urban settlements.

One such research showed that a holistic integration of these streams into vertical farming through hydroponics and aquaponics significantly reduced carbon emissions while producing food that was substantially more organic.

Vertical-farming technologies

To better discuss vertical farming, some technologies need to be explained in further detail, showing both the potential and the limitations of vertical farming:

Hydroponics – While the two terms are not synonymous, hydroponics is closely associated with vertical farming.² The practice involves growing crops without using soil as a living, active substrate. Other substrates such as glass pebbles or inert sand may be used, but only to provide additional anchorage to plant roots. This enables plants to easily access the nutrients they need from water, without the need to first inundate soil with water. While it is possible to use soil as a substrate, it would only be for the same purpose as sand or glass: to provide anchorage.

Aquaponics – In aquaponics,³ plants and fish enjoy a symbiotic relationship: the plants each the fish excrement and then purify the water and make it conducive for fish to grow. When fish waste, which contains unionized ammonia, gets into the water, most of it is converted to ammonia.⁴ A series of bacteria then convert the ammonia first to nitrites and then to nitrates, which are absorbed by the plants. Thus, the plants effectively remove fish waste from the water with the assistance of the bacteria. The result is less use of agrochemicals, more variety of food grown, and lower costs. Another significant advantage is that, through aquaponics, it is theoretically possible to one day have a fully organic vertical farm.

Aeroponics – This is the rarest of the three “-ponic” vertical-farming technologies and possibly the newest.⁵ Introduced by NASA to see whether plants could grow in space, aeroponics has been hailed as groundbreaking in its water usage, consuming up to 90% less water than a normal farm. In aeroponics, a fine nutrient-loaded mist is delivered to plant roots at a rate that ensures sufficient absorption without wastage or malnutrition. The plants are usually anchored in a sponge or similar material. The technology is still in the early stages of development. It operates within very fine parameters, meaning that a slight variation in the mist solution could result in rapid plant deterioration.

LED technology – Vertical farms need artificial light to survive.⁶ Light-emitting diode (LED) lighting has been successfully used to grow plants in the absence of sunlight, as would be the case when trays of plants are stacked on top of each other. The advantage of LED lighting is that, after years of research, scientists have identified just the right amount of light that particular plants need to grow and how much light would be needed to speed up plant growth and health. Advanced LED lighting is still prohibitively expensive, but as more advances are made it will become more common and effective.

Another important technology that will transform vertical farming is convolutional neural networks (CNN), discussed above in the greenhouse farming section.

The expected results of CNN deployment include better awareness of plants’ natural behavior and, consequently, more refined ideas on how to manipulate these behaviors for higher yield, better resource optimization, and the production of more healthful food.

At the same time, IoT devices are being deployed in vertical farms for better management.⁷ These devices monitor humidity, nutrient quantities in the water, temperature, pH, and electrical conductivity.

Advantages of vertical farming

The most obvious advantages of vertical farming include optimizing growing conditions, saving resources, and growing food in any setting. Disadvantages include cost, inability to grow many crops essential to human and animal nutrition, and inability to integrate crucial soil elements in plant growth.

Advantages:

Continuous production – Vertical farms can insulate plants from the natural environment, especially weather patterns and soil health. This makes it possible to grow plants quickly all year round.⁸ Constant temperatures in the air and substrate, uniform airflow and humidity, and optimized lighting all ensure that the yield per unit is much higher in vertical farms than in greenhouses or open fields. By some estimates, growing crops in a vertical farm takes only as much as half the time needed to grow the same crop in a greenhouse.
No need for pesticides – Since vertically farmed plants do not interact with soil as a living ecosystem or the environment in terms of temperature, humidity, and airflow, the chances of plants being attacked by pests are negligible. Additionally, CNN technologies can map out trouble spots quickly and prescribe solutions that may not necessarily involve the use of pesticides. Ultimately, this may mean that crops from vertical farms are more healthful than crops grown in normal environments.
Resource conservation – Vertical farming does not require or support rain-fed agriculture or irrigation. Hydroponics, aquaponics, or aeroponics are the only means used to water and nourish plants. The use of these systems means massive savings in water use since some technologies use up to 90% less water than greenhouses.⁹ Another essential resource is land. Modern agriculture is mainly rural, and land is increasingly becoming too polluted to sustain agriculture. Vertical farming can be done on a quarter of the land needed for a greenhouse and can be installed even in the busiest megacity downtown. The proximity of food to eaters cuts down on storage and transport costs. While vertical farming is highly mechanized, it does not use the sort of heavy machinery that is seen in open fields, meaning lower carbon emissions vis-a-vis output.
Improved efficiency – Vertical farms are highly automated, with planting, tending, pollinating, and harvesting crops being mostly done through automation.¹⁰ Among other advantages, automation allows slight variations in conditions to be quickly detected and controlled, thereby enhancing the yield and quality of the product.

Disadvantages:

Highly capital intensive – Vertical farms are very expensive to set up. They require buildings or outfitted containers; robotics for planting, tending, and harvesting crops; machine learning to enable machines to efficiently run the farms; and a high level of automation. The need for special lighting, nourishment and temperature optimization adds to the hefty startup cost. This might mean that, in the short term, vertical farms may not be an effective source of food to feed the world until the technology further advances and becomes less costly.
Energy use – The lengths that vertical farms go to secure insulation from the natural environment result in a big energy bill. This is ironic in some ways since vertical farms pride themselves on using resources optimally. It can be argued that steep energy costs are compensated for in other areas, such as minimal water and land use.
Lack of clarity on organic status – While plants do not receive pesticides in a vertical farm, they require chemicals to grow.¹¹ These chemicals are not organic but are produced in factories, based on what researchers have determined to be the essential nutrients needed by plants. While aquaponics is trying to address these challenges, much ground still needs to be covered before these crops can rightly be stamped organic.
A limited number of crops – Vertical farms are not suitable for some crops. The massive costs to start and run a vertical farm necessitate maximum efficiency. Most parts of the kale or lettuce plant can be consumed by humans, but only a small part of a corn plant will eventually be consumed, the rest being wasted. Secondly, some crops, such as onions, cannabis, and various vegetables, get a distinct flavor or character from the soil they grow in. While they may grow faster on vertical farms, they may not acquire the same quality that healthy soil will give them.¹² Science may improve this in the future, but meanwhile, it remains a major sticking point for vertical-farm use.

Conclusion

Vertical farming has the potential to provide the world with an enormous amount of food in the future. The integration of technology, as well as fish-rearing in vertical farms, all help make farming more sustainable.

However, formidable challenges exist, such as the narrow range of plants that vertical farms can grow and the current startup costs.

Food miles, the distance that food has to travel from farm to fork, is becoming increasingly higher since the rate of urbanization continues to grow. The need to grow food close to where people live makes vertical farming an important part of the solution.[↩]
Hydroponics has reduced the need for pesticides by insulating growing plants from the environment, especially soil. Hydroponics has also led to massive savings in water use for agriculture. This is significant given that more than 70% of all clean water is used in agriculture. Despite these advantages, once a hydroponic farm wants to change the water, it is important to ensure proper disposal, failure to do so may cause soil and water pollution.[↩]
In many respects, aquaponics is a more resilient and sustainable alternative to hydroponics. The growth of fish alongside plants not only produces a more balanced diet but also minimizes the need for nitrates in nurturing plants. Aquaponics uses less water than other forms of farming, though its range of application is also limited.[↩]
This article highlights the important role that water acidity plays in keeping down levels of toxic unionized ammonia (NH3). Were the pH to go up, the level of NH3 would also increase, potentially killing off the fish and plants.[↩]
While aeroponics may result in a higher yield with fewer resources (water and space), it also needs advanced technical prowess, requires high setup costs, and allows little room for error. For instance, a momentary power failure or less-than-optimal delivery of nutrients to roots could easily ruin a whole crop.[↩]
One of the biggest advantages of LED lighting is that it emits the same amount of light regardless of time, weather patterns, and season. This gives plants growing under LED superior exposure to light. LEDs emit minimal heat, enabling vertical farms to use specific technologies for heating, while this lighting method also picks the specific light needed for plants to optimize photosynthesis (blue and red) and delivers it in the right quantities.[↩]
IoT infrastructure is essential in modern vertical farming. Vertical farming requires extensive monitoring and manipulation of growth conditions to enable plants to give the best yield possible. Sensors and other tools collect enormous amounts of data, just as in smart greenhouse agriculture. This data is then analyzed and used in machine-supported decision-making.[↩]
The capacity to provide up to 20 hours of precise amounts of multidirectional light is one instance of ensuring constant growth for plants.[↩]
Runoff water, which is allowed to drain into the environment in many instances of greenhouse and open-field farming, is instead captured and recycled in vertical farming. The same water can also be used for fish farming, as seen in aquaponics.[↩]
To grow food with the intensity that vertical farming demands, automation is necessary. Robotics using artificial intelligence (AI) can tend plants with minimal human interference, reducing labor costs and eliminating the need for a human workspace. Automation is also important in controlling plant-growth conditions, including light, temperature, and nutrients. Attendant costs to maintain robots and improve machine learning should be considered.[↩]
While organic hydroponics may seem like an oxymoron, recent research suggests that it is indeed possible to derive organic nutrients and feed them to plants, thereby achieving organic production. However, current results show slow plant growth compared to inorganic supplements, which shows that while this may be possible in the future, organic hydroponics is still elusive.[↩]
Research performed on field onions in 2005 showed that onions derived a specific flavor based on where they were grown. Tests on other crops have shown varying shelf life and quality based on the soil quality, but differences in taste are still inconclusive.[↩]

Author

Mbau Tim