Protected Agriculture in Extreme Environments: A Review of Controlled Environment Agriculture in Tropical, Arid, Polar, and Urban Locations

Abstract. Many methods of protected agriculture are used to modify the growing environment of plants. Ideally, plant production would take place in regions that do not require protective structures, regions that present ideal temperatures, no harsh extremes, and sufficient but not excess precipitation. This is not the case however, as most countries, save for a select few, require various forms of controlled environment agriculture to protect crops against climatic and environmental extremes. Although the greenhouse industry has developed vast amounts of technology for the temperate climate regions of our planet, much remains to be improved in terms of protected agriculture in the more extreme climates. Tropical, arid, polar and urban locations offer contrasting environments that present various challenges for plant growth. Some challenges are specific to each location, while others are common across them. Tropical and arid climates offer high solar radiation, but present harsh temperature and relative humidity conditions. Most protected agriculture structures are relatively open in nature to ventilate and discharge heat, but are susceptible to pests and diseases. On the other hand, polar climates and urban environments often lack solar radiation and require a high level of control of the air quality. The structures used in these environments are relatively enclosed to entrap heat (polar) and to make efficient use of space. The sustainability of available technologies and energy efficiency are important themes present in all discussed climates and environments. Protected agriculture technologies offer solutions to growers in locations with extreme climates wishing to produce high yields of high quality crop, and this article presents a review of the existing challenges and of the advancements made in this field. Keywords: Arid climate greenhouse, Evaporative cooling, Natural ventilation, Protected agriculture, Tropical climate greenhouse, Urban agriculture, Vertical farming.