Urban agriculture has made it possible to move vegetable production from rural to densely populated areas, for which it uses different approaches to achieve its mission: food sufficiency. Approaches range from open-sky plantations to controlled environments. Open sky plantations, such as community gardens or roof gardens, offer social rather than economic welfare; it is the controlled environments that offer profitable productions in abandoned spaces or built in a special way. In this chapter, the advantages and disadvantages are mentioned as well as techniques that can improve the performance of this growing area of food development.
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FAO recognizes the importance of urban agriculture to solve famines in various parts of the world, in the same way it can help solve the problems of climate change, the problem of warming cities allows the reuse of resources and introduces biological diversity through the planting in or around cities of different varieties of plants and also provide sources of employment and psychological health. Urban agriculture (UA) can occur in the following production environments: community gardens, municipal gardens, roof gardens, private gardens, greenhouses and vertical farming. Of which the first four correspond to open-field agriculture and the last two to controlled areas
Agriculture in the open field and in spaces with controlled environment has become a sector with a high degree of energy consumption, where directly the production of fertilizers, pesticides, herbicides, use of machinery and pumping water from its place of origin (underground well, reservoir or natural source) consumes 6.6% that the sector uses (Chou, L. et al, 2021). Additionally, it must be considered that indirectly energy consumption has to do with the packaging of production, refrigeration and transport. To try to minimize the energy consumption of the latter, it has been thought to move vegetable production activities to the urban environment (United Nations Report on the development of water resources in the world 4, 2012), where the dense population is in permanent search of fresh vegetables being in this way that you can save on the transfer of the same, Storage and refrigeration may be less due to shorter meal times on the road and packaging may also be skipped if consumers come directly to the production center within cities.
However, it should not be lost sight of the fact that one of the main problems of urban agriculture is not only the consumption of energy but the cost of its production, adding the cost of water, which leads to an additional consumption of energy so that water is used optimally, through reducing its use to those allowed by the crop and the expenditure of energy required for its recycling, since such water cannot be discharged into the drainage of the city directly.
Energy expenditure occurs differently for each of the different types of cultivation encompassed by urban agriculture: private gardens, communal gardens, municipal gardens, roof gardens, peri-urban crops, greenhouses, and finally vertical crops. The above crops can be divided into open-air crops, as are all types of gardens, as well as peri-urban crops and crops with controlled environment such as greenhouses and vertical crops.
Agriculture in controlled environments (CEA) is a technology that allows, in closed environments and through control and recycling techniques, the growth of plants independently of the type of soil, such as arid land or the absence of it, as in hydroponics or aquaponics. Given the current circumstances of the world regarding the food issue where fewer and fewer people are dedicated to farming and migrate to large cities, climate change, desertification and overexploitation of cultivated soils, the lack of drinking water (of which 70% (Windapo & Moghayedi, 2020) it is used for planting), population growth and soil depredation, for all these reasons the classic cultivation techniques have been exceeded and are already insufficient to sustain the current and future population.
Controlled agriculture techniques allow the planting and growth of vegetables independently of the climate and in some cases without the application of pesticides, herbicides or fertilizers and being a totally closed environment the plants thus obtained result in healthy plants and suitable for human consumption. Likewise, the use of monitoring, control and recycling systems allows the use of little water (up to 90% less water than traditional techniques (Benke & Tomkins, 2017)). Also artificial lighting can be controlled to achieve optimal vegetable growth and improve taste, generally controlling nutrients, lighting and temperature of plants can improve their food properties and generate high production rates by not depending on climate and sunlight as if open-air crops do.