Vertical farms have been gaining increased attention over the past 6 months in the UK especially with major industry moves to incorporate systems into Ocado and M&S. But what is Vertical Farming and how does it work?
Vertical farming is a version of Control Environment Agriculture (CEA), check out our previous blog post. It is the process of growing plants (mainly) in a manner where the space is optimised vertically. This means that more than one plant can be grown on the same square foot (or metre) of land space. There are two main types of vertical farming systems in general use around the world;
1) crops grown on vertical surfaces creating a wall of plants which are then placed side by side filling the available space. The crops are lit from the sides.
2) crops grown on horizontal systems such as those in the Hydrogarden V-Farm system and lit from above the plants.
Each method has its own merits and uses and companies should thoroughly review these before committing to a particular growing system.
Location and Resources
Whilst vertical farms can be located in green houses, they are more generally developed with their own environmental control and artificial lighting for each stack or level. What this means is that vertical farms are generally totally indoors and the products that are produced, are grown under completely controlled environmental conditions CEA.
When developing vertical growing systems it is difficult to utilise sunlight alone as the light will be shaded by the levels of the racking or the vertical arrangement of the racking, as shown above. Therefore the light source of choice for vertical farming plant growth would not be the sun but specifically tuned LEDs. These are highly energy efficient sources of light producing only the light that is needed for the plant.
LEDs are used because they do not radiate heat in the way a normal incandescent light bulb would, and therefore can be brought close to the top of the plant without fear of overheating the plant. This allows for the levels to be brought further together and thus to increase the lacking density of the plants to produce more plants per unit area.
Of course having only artificial lighting will increase the energy costs but this can be offset by using green energy (such as solar or wind energy) sources. Also, because sunlight is no longer present the heating and cooling needs are reduced. Particular attention to the costs of energy versus the land rental costs need to be made to ensure that the vertical farming model is going to be cost effective for the location and crop types that you are seeking to grow.
The amount of water used to water the plants, the amount of nutrients delivered to the plants and even the temperature of the room are all aspects that are completely controlled in CEA vertical farming systems. By allowing the environment to be totally controlled plants can be grown under their optimal environment conditions and so will grow well even indoors.
In fact, the use of CEA can lead to optimisation of the growing processes that produce yields and nutrition levels in the plant which far exceed those able to be grown outdoors. The control of the environment also reduces water evaporation and leads to a water use which is at least 90% less than traditional farming systems.
Since growing can be accomplished completely indoor then the location of the "farm" can be virtually anywhere - even in outer space where NASA is already doing essential research. Vertical farms can be located in existing building in towns and cities as well as being used in repurposing existing farm buildings or in megafarms.
How Does It Work?
When growing indoors the normal patterns of day/nights and the seasons of the year are not present and either have to be artificially created or avoided depending on the type of crop. The controlled environment allows for the use of different ways in which the roots of the plant can be fed i.e. soil is not the only choice and other substrates or no substrates can be chosen when using hydroponics or aeroponics systems.
When stacking plants vertically the weight of soil can lead to significant issues and so hydroponic techniques using only water and water based nutrients offer significant advantages. Instead of watering the plants and relying on the soil to absorb the water and irrigate the roots, vertical farming delivers the water/nutrients directly to the roots by means of Hydroponics or Aeroponics processes.
The soil normally performs three key functions holding the plant in place mechanically providing a means to protect the root and providing a means for the roots to be fed with water and the necessary macro and micronutrients for plant healthy growth.
In vertical farming systems the soil is replaced but, of course, the plants still need to be mechanically supported and irrigated - this is where a lot of the specialism of vertical farming methods are differentiate.
Indoor vertical farming under controlled environment agriculture conditions holds a promising place for growing crops in the future. There is still a lot to learn about this emerging industry and some obstacles to overcome but this won’t deter out efforts away from expanding vertical farming into the mainstream consumer markets.
In our next blog we will discuss the various ways in which the irrigation systems can work to ensure that plants grow efficiently and encourage good uptake of nutrients into the plants.