An Ethical Argument for the Rapid Deployment of Hydroponic Technologies

By: , Weston, CT // February 1, 2022

Global population growth, projected to surpass eleven billion by 2100, threatens the world with a myriad of challenges pertaining to the adequacy of food production. To satisfy future demand, researchers estimate that “the production of food commodities should be increased by as much as 110%” (Bello 1). Achieving this goal is a tall order for a society in which 690 million people are already undernourished (FAO). Furthermore, the expansion of food production raises concerns over the sustainability of conventional agriculture in relation to the availability of natural resources and the vitality of the environment at large. The “Green Revolution” of the twentieth century, which has enabled our ability to sustain the current global population, is largely dependent on nitrogen and phosphorus fertilizers to maintain soil fertility, as well as chemical intervention in the form of lethal pesticides to manage pest infestation resulting from monoculture farming (Tilman 5995). Not only do these practices harm pollinators, such as bees and butterflies, which are essential for fertilizing crops, but chemical fertilizers are a major source of carbon emissions contributing to climate change.1 The future demand for food under the current agricultural framework will require significant increases in chemical fertilizers and pesticide consumption, in addition to the need for more arable land and fresh water.2 However, resources available to devote to open field agriculture are finite, and in some areas close to depletion.3

1 Agriculture and land use combined account for 34 percent of total carbon emissions (Posner and Weisbach 30). 2 According to David Tilman, University of Minnesota Department of Ecology and Evolution, an analysis of past

trends suggest that a simple doubling of agricultural production would require at least a three-fold increase in fertilization rates and a doubling of irrigated land area (Tilman 5995).
3 Agriculture accounts for 70% of freshwater usage, and many aquifers have been drained beyond recharge rates (Ekins & Gupta 1).

Agriculture, as it is conducted today, requires vast open spaces; it therefore displaces large swaths of native flora.4 Having exhausted the majority of arable grasslands, humanity has now turned to the land occupied by forests. As estimated by the United Nations, the demand for arable land is responsible for 80% of deforestation to date. This has major implications for climate change given that forests act as important carbon sinks, drawing carbon dioxide out of the atmosphere (“Deforestation – United Nations”). Consequently, agricultural monocultures have displaced or threatened thousands of plant species, insect species and vertebrates, resulting in a homogenization of the world’s ecosystems (Tilman 5995). This widespread transformation of the Earth’s surface contributes greatly to habitat fragmentation and land degradation, resulting in the largest global mass extinction since the demise of the dinosaurs 65 million years ago.5 The rapid alteration of the Earth’s surface for the purpose of food production therefore constitutes a direct threat to biodiversity and the stability of the planet’s intricate ecosystems (Wilson 43, 57). These ecosystems provide services that are vital for sustaining human life.6 Non-agricultural ecosystems provide “at no cost” drinkable water, soil revitalization, pollination, natural pest management, flood control, fresh air, and commodities such as timber, fish and game (Tilman 5998). Some estimate the total economic value of these ecosystem services to be over 125 trillion dollars annually—a figure so large that it exceeds the entire gross world product.7 In short, a threat to planetary biodiversity is a threat to humanity. Conventional industrial agriculture, as it stands unchecked, imperils human survival; the very act of feeding ourselves is poised to become

4 The current “ecological footprint” arising from global agricultural activities is 17,840,000 square kilometers or “the size of South America” (Anda and Shear 8).
5 The rate of extinction has increased 877-fold since the advent of human civilization. There have only been five extinction events of this scale before in Earth’s history leading many to call this modern die-off the “Sixth Extinction” (Wilson 8, 43).

6 Diminishing biodiversity is also linked to a rise in zoonotic diseases — a concern that is particularly salient in the wake of the Covid-19 pandemic and the 3.2 million deaths to date (John Hopkins University Coronavirus Resource Center).
7 Pollinators, for example, are estimated to provide a service in excess of $351 billion annually (Ekins and Gupta 2).

our undoing. In this way, agriculture represents a profound test of the “reach and quality of human morality” (Wilson 44). We cannot detach ourselves from the ethical implications of our current system of agriculture; however, ensuring that agriculture “rest[s] on a firm ethical foundation” is not an undemanding undertaking (Zimdahl 752).

In his 2016 book, Half Earth: Our Planet’s Fight for Life, famed Harvard biologist E. O. Wilson argues that “only by committing half of the planet’s surface to nature can we hope to save the immensity of life-forms that compose it” (Wilson 3). Wilson’s Half-Earth solution is based on the premise that planetary biodiversity can be maintained (and ecosystem services can rebound) if sufficiently vast interconnected tracts of land are set aside as reserves free from human interference. As the most extensive human interaction with the land, agriculture is unavoidably implicated in the effort to protect healthy ecosystems; and any strategy that aims to realize Wilson’s vision, in full or in part, will necessarily require that some, if not a significant amount of, farmland revert to wilderness. Simply halting, let alone reversing, the expansion of modern agriculture would require nothing short of a modern agricultural revolution. In Wilson’s words, “a human effort commensurate with the magnitude of the problem” (Wilson 187).

Revolutionizing the agricultural sector will require both a reimagining and reinvention of food production. To this end, an emerging class of soilless cultivation methods, known as hydroponics, may be a large part of the solution. Hydroponic technologies, as defined by this paper, encompass a wide variety of soilless cultivation techniques and methods. Conventional hydroponics involves substituting soil for a nutrient rich solution and is often paired with artificial LED lighting in a climate-controlled greenhouse. This enables growers to precisely control plant nutrition; generate productive year-round yields; conserve land, water and labor;

and avoid the vagaries of a variable climate8. Hydroponic techniques are still evolving, and crop- yield experiments are expanding, but it is generally thought that the crops best suited for this technology include leaf crops (spinach, lettuce, salad greens), vine crops (tomato, cucumber, pepper, squash, beans), and culinary herbs (basil, parsley, chives and coriander) (Specht et al. 47). Additional categories of hydroponic technologies, which have gained traction in recent years, include aeroponics, in which nutrients are supplied directly to exposed roots via mist thereby decreasing water usage, and aquaponics, in which fish and vegetation are raised in tandem in a multitrophic culture (Birkby 2, Goddek et al. 4199, Reinhart 2). While this paper may note the potential of specific methods in particular applications, it makes little delimitation between these technologies in terms of their overall merits and instead aims to make the case for a mass rollout of hydroponic technologies generally.

The current global food system reveals an urgent ethical dilemma. How do we continue to feed ourselves while protecting the living systems which support our sustenance? Hydroponics offers a viable, concrete solution to expand food production without compromising the ecological systems upon which our civilization depends. Given the current trajectory of population growth and the environmental challenges posed by conventional industrial agriculture, it is morally imperative that we deploy hydroponic technologies as rapidly and as widely as possible. Failure to act in a timely manner is likely to result in irreversible damage to the natural environment and jeopardize the wellbeing of future generations. It is therefore

8 By far the most successful method is the Nutrient Film Technique, which involves suspending plant roots in a channel of continuously recirculated nutrient solution in the absence of a growth medium. Other popular methods of hydroponics include: 1) Wick System, a basic design in which plants are placed in a structural medium and connected to a reservoir of nutrient solution by a nylon wick; 2) Ebb and Flow System, used for early commercial applications in which the grow bed is saturated with nutrients and moisture through a pump system; 3) Drip System, in which individual plants are nourished by a continuous slow rate drip line; 4) Deep Water Culture System, in which roots are suspended directly in nutrient solution and oxygenated by air pumps (Sharma et al. 366; Khan et al. 9; Maucieri et al. 90-93).

necessary and urgent that governments, corporations, and citizens move to subsidize, launch, and promote hydroponic ventures in a bid to galvanize this fledgling industry and arrest the conversion of land for the purpose of conventional agriculture.

The Morality of Environmentalism

If the world is to emerge from the 21st century without a dramatic loss in biodiversity from habitat destruction or human life from starvation, then a radical shift in our current agenda is a moral necessity. Given humanity’s awesome power to influence life on Earth, many scholars have elected to distinguish our current geologic time from the Holocene, the geologic epoch which began following glacial retreat and the proliferation of man 10,000 years ago. They refer to this new epoch as the Anthropocene, the Epoch of Man (Wilson 8-9). Hitherto the Anthropocene has been characterized by human domination of nature and the vast repurposing of natural resources for human use. But if one is to accept the notion that humans are agents of morality, then it also follows that “the anthropocene is an epoch of ethics because it is an epoch of dominion by a moral species” (Jenkins 2). Morality is implicated because “never before has a single species wielded so much power to shape the world and affect all forms of life” (Lowe 479). In The Future of Ethics, Willis Jenkins points out that while “it is not unprecedented for a species to transform the biosphere . . . upstart bacteria did it several billion years ago, radically remaking the atmosphere and banishing previously dominant species. It is unprecedented that a species should do so knowingly” with the knowledge that its actions could imperil “the systems on which life depends” (Jenkins 2). Put bluntly, “as moral agents, we bear moral responsibility for the resulting impacts” of our actions (Lowe 480).

The morality of environmentalism, and agriculture in particular, has been needlessly complicated by debate over the motives compelling us to maintain a healthy planet that would benefit the interest of all species. The early movement toward conservation in the United States

is characterized by utilitarian ethics seeded in the aspiration for national growth and prosperity. In fact, Gifford Pinchot, the first head of the U.S. Forest Service, stated in 1905 that “‘conservation did not mean protecting or preserving nature’ it simply represented the idea that natural resources should be used wisely and efficiently” for the material interests of humankind (Nash 9). With the rise of the science of ecology in mid-century, however, a new breed of environmentalism took shape to challenge this notion and emphasize the moral dimension of environmental stewardship. The argument that nature itself has intrinsic value, and is therefore entitled to the right of protection, grew organically from roots of American liberalism, and can be understood “as an extension and new application of them” (Nash 12). The idea that humans are “moral agents” who have a duty to defend the rights of nature ran counter to the culture of unlimited economic growth and resource exploitation inherent in laissez-faire capitalism (Nash 11). A duality arose which pitted anthropocentric conservationists and biocentric preservationists against one another, despite the fact that a healthy planet served the interests of both. As distinguished philosopher, Bryan G. Norton, points out “conservation and preservation are different activities, which might result from varied and complex motives” (Norton 201). Norton criticizes the definition of conservation and preservation, which is artificially mutually exclusive because the focus is motivational and rather than purpose-oriented. He explains that “if the conservation-preservation distinction is a distinction in motives which reflect a difference in value theory” then it assumes these ideas are in opposition; but once the definition is purged of motive, then the commonality comes into focus. Norton points to the beliefs of naturalist Aldo Leopold, famed for his inspirational book A Sand County Almanac, who viewed “the dichotomy between human values and nonhuman values” as false, given that ‘to destroy species and natural systems is to harm humanity’” (Norton 206). Thus, there is potential for the alignment of purpose which avoids the quagmire of having to solve the issue of motivation.

The alignment of purpose between anthropocentric and nonanthropocentric thought is most apparent when looking ahead into the future. As Norton surmises, “Showing respect for nature, its processes of life, may just be an alternative formulation of the injunction to show concern for resource stability essential to human survival over the longest term” (Norton 220). This sentiment gives rise to the concept of intergenerational or “diachronic” justice—the idea that future generations have a right to the bounty of nature and that the current generation therefore has a moral imperative to defend what is left of the Earth’s biodiversity. Diachronic justice thus underscores the need to preemptively defuse environmental threats by adopting sustainable agricultural techniques, as well as other sustainable practices. According to authors Randall Curren and Ellen Metzger, in Living Well Now and in the Future (2017), “diachronic justice takes seriously the moral claims of future generations and seeks to better incorporate them as moral subjects in current ethical and political deliberations” (Lowe 481). In other words, sustainability, as it impacts future generations, is in itself a normative query. The fact that humanity is currently and “collectively living in such a way as to diminish opportunities to live well in the future” presents an ethical dilemma which begs immediate attention and intervention (Curren and Metzger 1). Diachronic justice mandates that we have a duty today to prevent harm from arising tomorrow and into the indefinite future. From this point of view, our current needs must be balanced against the needs of future generations; activities inconsistent with the interests of future claims must necessarily be avoided. Application of this principle to the conundrum of global food supply rules out the intensification of conventional agriculture as a viable course of action and recommends the adoption of alternative sustainable technologies such as hydroponics.

The Potential of Hydroponics

The value of hydroponic technologies collectively is that they are significantly more efficient in terms of yield and resource consumption; can be implemented in areas that traditional

agriculture cannot; can be organized in configurations that further maximize output; are insulated from most diseases and pathogens, can provide high-quality nutritious produce; and most importantly, can help minimize the environmental impact of food production by supplanting conventional industrial agriculture.

The fact that hydroponic agriculture is not dependent on soil or sunlight, and thus not limited to arable land, is revolutionary. Hydroponic farming can take place almost anywhere. Growing Underground is a UK company, established in 2012, which successfully operates a hydroponic farm growing a variety of produce in abandoned WWII air raid bunkers 30 meters under the streets of London (Gentry 194). Given that 66% of the world’s population will likely live in or near urban areas by mid-century, an agricultural method that successfully exploits the urban landscape is critical to the future sustainability of agriculture (Gentry 191).9 In Sweden, for example, the feasibility of incorporating urban hydroponic vertical farming with district heating in Stockholm and other urban centers is being studied in an attempt to create a circular system in which energy production compliments urban food production and benefits the public by providing hyper-local high-quality produce and emissions-savings from the elimination of transportation (Gentry 191-197). Vertical farming is a configuration of hydroponic cultivation in which plants are stacked in shelf-like layers that can reach several stories high. In other words, unlike soil-based agriculture, which is limited to horizontal expansion, vertical farms take advantage of available height. The possibilities with regard to the location of vertical hydroponic farms are nearly endless. Enterprising farmers have employed shipping containers, fall-out

9 The term ZFarming was introduced by a team of researchers led by Kathrine Specht of the Leibniz Centre for Agricultural Landscape Research, to encompass all the types of urban agriculture characterized by the non-use of open field farmlands (Specht et al. 35). Zfarming is emblematic of a movement toward green urban architecture which aims to creatively integrate food production with city buildings via rooftop gardens, greenhouses and indoor farms. According to Specht, “the idea behind ZFarming is to create entities linking food production with buildings with multiple use of residential or industrial waste resources to establish a small-scale resource saving system” (Specht et al. 34).

shelters, parking lot structures, rooftops, multi-storied structures (such as abandoned factories) and other properties deemed brownfields (Birkby 1-5). With hydroponics, cities can be reimagined and reinvented, as the heart of agriculture. Thus food production can be decoupled from land usage so that human welfare no longer comes at the expense of nature.

Soilless farming also has far-reaching implications for arid regions of the world. Soil is the most widely available growing medium for plants. However, soil quality varies dramatically, given climate, composition, drainage and compaction, microbial flora and ground pollution. By freeing agriculture from the bonds of soil and sunlight, agricultural production can thrive independent of these conditions. In desert climates such as Arabia, conventional agriculture is inhibited by hot temperatures, high rate of evaporation, and inadequate rainfall; thus, there is heavy reliance on irrigation, which is “responsible for the largest proportion of water consumption amounting to roughly 78% of total water utilized” in the region (Bello 2). Similarly in Mexico, low water availability has resulted in pressure on water resources in two-thirds of the country, with “agriculture accounting for 77% of the water withdrawn” (Anda and Shear 1). According to a study by José de Anda and Harvey Shear in 2017 assessing the potential of vertical hydroponic agriculture in Mexico, “because of the arid conditions prevailing in most of the country and the increasing needs of water for agriculture, most of the aquifers located in the central and northern part of the country are classified as overexploited” (Anda and Shear 3). Anda and Shear conclude that the benefits of hydroponic cultivation in arid countries like Mexico are almost immeasurable.10 Hydroponics may therefore serve to improve food security in arid regions for both current and future generations.

10 Benefits include, but are not limited to: a decrease in land conversion driven by traditional soil cultivation systems, allowing the restoration of damaged forests and reduced risk to endangered species (2583 species are endangered in Mexico); reduction of water consumption allowing recovery of aquifers, rivers and streams; reduction in fertilizers and pesticides decreasing air, soil and water pollution; reversal in the construction of dams and

Hydroponic technologies also offer major advantages over traditional agriculture in terms of yield, resource usage, and quality. One of the most common observations in the comparison between soil and soilless cultivation is the speed at which crops grow in hydroponics, and the ability to grow crops year-round. Yields are typically 20-25% higher, given that the number of plants per unit area is on average higher than conventional agriculture (United Nations, Sharma et al. 366). Survival rates also tend to be higher on average given the reduction of pests common to soil grown plants such as aphids, spider mites and fungus gnats (Treftz and Omaye 199). Researchers at the School of Sustainable Engineering and the Built Environment at the University of Arizona undertook a comparative study of the resource inputs required to grow lettuce, a standard hydroponic crop, in the state of Arizona. Their findings reveal that hydroponics is 11 times more efficient in terms of area and 13 times more efficient in terms of water usage than conventional agriculture techniques. Similar results have been found in a study by Chenin Treftz and Stanley Omaye, reported in “Comparison between Hydroponic and Soil Systems for Growing Strawberries in a Greenhouse”. They discovered that hydroponics was successful in terms of yield and survival for strawberries despite the complexity of the fruit’s root structure and stalk which require physical support (Treftz et al., “Strawberries in a Greenhouse” 195). The authors of this study ran a follow up study to explore consumer preferences recognizing that for hydroponic products to be successful, “nutritional quality and sensory attributes must be equal to or better than soil grown produce” (Treftz et al., “Sensory Attributes” 1372). The results favored the hydroponic grown fruit, with 70% of participants

recovery of impacted ecosystems; reduction in the carbon footprint due to less agriculture related emissions; increase in agricultural productivity with year-round crop production; access to fresh, safe and locally-produced produce in urban centers; job creation and technical education of workforce to manage hydroponic systems; and possible reduction in rate of emigration with quality of life improvements (Anda and Shear 9).

preferring the hydroponic strawberry over the soil-grown sample; the hydroponic berry also scored superior in the sensory category, particularly with regard to the intensity of aroma (Treftz et al., “Sensory Attributes” 1379). Although some researchers point out ambivalence in the data regarding the nutritional value of hydroponic vs soil-grown produce, the general opinion is that the “hydroponic system can elevate the content of various phytochemical compounds in crops” (Bello 10). Hydroponics can thus provide more higher quality products while simultaneously minimizing resource inputs. Whether viewed through the anthropocentric lens of human nutrition, or the nonanthropocentric lens of natural resource consumption, hydroponics appears to offer significant improvements over conventional agriculture.

Finally, although hydroponic crops can be susceptible to certain types of water-borne disease and algae overgrowth, hydroponic systems depend far less on the use of pesticide and fertilizer. Given that the use of pesticides has “increased globally by nearly 42 times with the current utilization in the amount of 2.5 million ton[s] annually”, the rapid deployment of hydroponic systems may have a significant beneficial impact on both food safety and the environment (Bello 4).

Despite the overall optimism in the literature regarding the technological feasibility of hydroponics, the technology is in its infancy and there remains skepticism regarding its ability to fulfill the promise of its hype. Whether hydroponics can help ease the strain on the natural world will depend, not only on its ability to produce edible crops in sufficient quality and quantity, but also on its ability to attract investment, attain consumer confidence, and achieve overall socioeconomic acceptance. One of the chief complaints from critics to date is that the steep expense of start-up costs which serve as a barrier to market entry. The equipment requirements are a key factor in cost, which include HVAC systems, fans, ventilation, irrigation, control systems, and specialty lighting. The average 500 sq. ft. farm can cost up to 110,000 dollars for a

base level set up not including real estate and automation (“Hydroponics Market”). But as the prospect for potential profits grow, many believe it is safe to assume that capital investment will follow.11 In addition, the barrier to market entry may in part be breached through the help of crowdfunding, wherein venture capital is raised by broad support from the community and independent investors.12

The greatest drawback to commercial scale hydroponics is the high energy demand. Energy is “by far the greatest of all operational costs . . . sometimes reaching 40%” (Manos and Xydis 12662). Given the need to control temperature, air distribution, lighting, and automation, the energy demands of some hydroponic applications also give rise to the question of sustainability. However, the ongoing push to switch global energy infrastructure away from fossil fuels and towards renewables may enable hydroponic greenhouses to achieve carbon neutrality. In fact, many hydroponic ventures have already incorporated renewable energy generation into their designs, which can also help to reduce net energy costs (Buehler 8).13

Despite these difficulties, the industry of hydroponic cultivation is growing exponentially, and is expected to reach USD 17.9 billion by 2026” (“Hydroponics Market”). Europe is considered the largest market for hydroponic produce, in which France, the Netherlands, and Spain are the three top producers, followed by the US and Asia-pacific region (Aires 55). However, it is difficult to calculate, in terms of economic value, the benefit to the environment of hydroponic technologies. While these studies offer insight into the technological

11 In their analysis of Urban Rooftop Farming (URFs), Devi Bueler and Ranka Junge, found that 26% of URFs in 2016 were primarily commercial in purpose and concluded, somewhat optimistically, that “a well-executed commercial operation has the potential to attract private investment and is therefore likely to overcome the key challenge of obtaining financing” (Buehler and Junge 2).

12 Growing Underground, discussed herein, obtained its original funding from such sources (Gentry 194).
13 Other criticisms include the gaps in knowledge, which are understandable in nascent industry. Specifically, they point to nutrient input efficiency and the “lack of knowledge about the nature of organic molecules and biochemical processes” necessary to properly nurture plants (Goddek et al. 4210).

feasibility of implementing hydroponics based on social, economic, and technological considerations, this fundamentally anthropocentric perspective neglects the ecological benefits associated with such a transition, and consequently, undersell the necessity of such a modern agricultural revolution.

The Future of Food

The future of mankind’s food supply is inextricably linked to the fate of the planet itself. On one hand, the desire to provide sustenance for people compels an expansion of food production. On the other, the desire to protect natural species necessitates a reduction of open field farming. On close inspection, there is tension among these priorities, but widen the perspective and these priorities overlap: “Human beings are not exempt from the iron law of species interdependency. . . The biosphere does not belong to us; we belong to it” (Wilson 16). Pursuing policies and technologies that benefit the Earth also stand to benefit humanity. And this sentiment is manifest in hydroponics.

Hydroponics is on its way to becoming an effective alternative to traditional agriculture. In doing so, it would both provide sustenance for an expanding population and mitigate the impact of that population on the Earth’s biosphere. However, hydroponic technologies are still nascent. Despite successful implementation in the case studies described above, and the projected economic potential of the method on a commercial scale, hydroponics is not poised to displace existing agricultural methods overnight. It would be both presumptuous and dangerous to conjecture that capitalist motivation and laissez-faire economics alone can bring about a transition toward sustainable agriculture swift enough to eschew future catastrophe. Hydroponics provides hope; but hope in the absence of action is vain. As Benjamin Lowe, National Science Foundation fellowship recipient at University of Florida’s School of Natural Resources notes in his review of Ecology, Ethics and Hope, “hope can have the unintended consequence of

demotivating people from taking action . . . it could do this by promoting a false sense of security and optimism, thus placating some and leaving them less likely to take action” (Lowe 482).

Whether motivation to act is rooted in biocentric or anthropocentric values is irrelevant given that the interests of both are served by the implementation of hydroponics. Hydroponics offers a pragmatic resolution to this ethical dilemma, not by decisively endorsing one perspective over the other, but by offering a united vision for both. As Norton optimistically speculates: “if the interests of the human species interpenetrate those of the living Earth, then it follows that anthropocentric and nonanthropocentric policies will converge in the indefinite future” (Norton 220). Hydroponics is this convergence of anthropocentric and nonanthropocentric policies. It represents a solution to both the technical challenges associated with responsibly expanding food supplies, and the ethical conundrum that agriculture itself poses. In essence, while the anthropocentric/nonanthropocentric debate remains unsettled, hydroponic technologies eschew this unproductive discussion by offering a mutually acceptable, concrete course of action. For the sake of the planet and humanity alike, it is imperative that we pursue the potential offered by hydroponics for a new, sustainable agricultural revolution.


I would like to thank all my classmates in WRI 121: The Future of Food for their comments and suggestions during my class workshop. In particular, I want to thank the members of my peer group, Katie Baldwin and Hyerin Noh, for their insights and feedback during our group conference and throughout drafting of this paper. Your assistance was invaluable. Finally, I would like to thank Professor Geheber whose first class Zoom background helped inspire and whose comments helped guide this paper to completion. Thank you all for a wonderful semester.

Honor Code

This paper represents my own work in accordance with University regulations.

– Kelvin Green

Works Cited

Aires, Alfredo. “Hydroponic Production Systems: Impact on Nutritional Status and Bioactive Compounds of Fresh Vegetables.” Vegetables – Importance of Quality Vegetables to Human Health, 2018, doi:10.5772/intechopen.73011.

Barbosa, Guilherme Lages, et al. “Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods.” International Journal of Environmental Research and Public Health, vol. 12, no. 6, 2015, pp. 6879–6891., doi:10.3390/ijerph120606879. Accessed 19 Apr. 2021.

Bello, Suraj. (2019). Hydroponics: Innovative Option for Growing Crops in Extreme Environments-The Case of the Arabian Peninsula (A Review).

Birkby, Jeff. “ATTRA Sustainable Agriculture.” Jan. 2016.

Buehler, Devi, and Ranka Junge. “Global Trends and Current Status of Commercial Urban Rooftop Farming.” Sustainability (Basel, Switzerland), vol. 8, no. 11, 2016, p. 1108., doi:10.3390/su8111108. Accessed 19 Apr. 2021.

Curren, Randall R., and Ellen Metzger. Living Well Now and in the Future: Why Sustainability Matters. The MIT Press, 2018.

De Anda, José, and Harvey Shear. “Potential of Vertical Hydroponic Agriculture in Mexico.” Sustainability (Basel, Switzerland), vol. 9, no. 1, 2017, pp. 140–140., doi:10.3390/su9010140. Accessed 19 Apr. 2021.

“Deforestation – United Nations Sustainable Development.” United Nations, United Nations, 3 Sept. 2015,

Ekins, Paul, and Joyeeta Gupta. “Perspective: A Healthy Planet for Healthy People.” Global Sustainability, vol. 2, 2019, pp. 1-9., doi: 10.1017/sus.2019.17.

FAO, IFAD, UNICEF, WFP and WHO. 2020. The State of Food Security and Nutrition in the World 2020. Transforming food systems for affordable healthy diets. Rome, FAO.

Gentry, Matthew. “Local Heat, Local Food: Integrating Vertical Hydroponic Farming with District Heating in Sweden.” Energy (Oxford), vol. 174, 2019, pp. 191–197., doi:10.1016/ Accessed 19 Apr. 2021.

Gilmour, Daniel N., et al. “Do Consumers Value Hydroponics? Implications for Organic Certification.” Agricultural Economics, vol. 50, no. 6, 2019, pp. 707–721., doi:10.1111/agec.12519. Accessed 19 Apr. 2021.

Goddek, Simon, et al. “Challenges of Sustainable and Commercial Aquaponics.” Sustainability (Basel, Switzerland), vol. 7, no. 4, 2015, pp. 4199–4224., doi:10.3390/su7044199. Accessed 19 Apr. 2021.

Gremmen, Bart, et al. “Responsible Innovation for Life: Five Challenges Agriculture Offers for Responsible Innovation in Agriculture and Food, and the Necessity of an Ethics of Innovation.” Journal of Agricultural and Environmental Ethics, vol. 32, no. 5-6, 2019, pp. 673–679., doi:10.1007/s10806-019-09808-w.

“Hydroponics Market.” Market Research Firm, Jan. 2021,

Jenkins, Willis. The Future of Ethics Sustainability, Social Justice, and Religious Creativity. Georgetown University Press, 2013.

Khan, Fraz Ahmad. “A Review on Hydroponic Greenhouse Cultivation for Sustainable Agriculture.” International Journal of Agriculture, Environment and Food Sciences, vol. 2, no. 2, 2018, pp. 59–66., doi:10.31015/jaefs.18010.

Khan, Saad, et al. “Hydroponics: Current and Future State of the Art in Farming.” Journal of Plant Nutrition, vol. 44, no. 10, 2020, pp. 1515–1538., doi:10.1080/01904167.2020.1860217. Accessed 19 Apr. 2021.

Kloas, Werner, et al. “A New Concept for Aquaponic Systems to Improve Sustainability, Increase Productivity, and Reduce Environmental Impacts.” Aquaculture Environment Interactions, vol. 7, no. 2, 2015, pp. 179–192., doi:10.3354/aei00146. Accessed 19 Apr. 2021.

Lagomarsino, Valentina. “Hydroponics: The Power of Water to Grow Food.” Science in the News, Harvard University Graduate School of Arts and Sciences, 4 Oct. 2019,

Lowe, Benjamin S. “Ethics in the Anthropocene: Moral Responses to the Climate Crisis.” Journal of Agricultural & Environmental Ethics, vol. 32, no. 3, 2019, pp. 479–485., doi:10.1007/s10806-019-09786-z. Accessed 19 Apr. 2021.

Manos, Dimitrios-Panagiotis, and George Xydis. “Hydroponics: Are We Moving towards That Direction Only Because of the Environment? A Discussion on Forecasting and a Systems Review.” Environmental Science and Pollution Research International, vol. 26, no. 13, 2019, pp. 12662–12672., doi:10.1007/s11356-019-04933-5. Accessed 19 Apr. 2021.

Martin, Michael, et al. “Exploring the Environmental Performance of Urban Symbiosis for Vertical Hydroponic Farming.” Sustainability (Basel, Switzerland), vol. 11, no. 23, 2019, p. 6724., doi:10.3390/su11236724. Accessed 19 Apr. 2021.

Maucieri, Carmelo & Nicoletto, Carlo & van Os, Erik & Anseeuw, Dieter & Havermaet, Robin & Junge, Ranka. (2019). Hydroponic Technologies. 10.1007/978-3-030-15943- 6_4.

Nash, Roderick Frazier. The Rights of Nature: a History of Environmental Ethics. University of Wisconsin Press, 1989.

Norton, Bryan G., and The University Center for Environmental Philosophy. “Conservation and Preservation: A Conceptual Rehabilitation.” Environmental Ethics, vol. 8, no. 3, 1986, pp. 195–220., doi:10.5840/enviroethics1986832. Accessed 19 Apr. 2021.

Olde, De, and Vladislav Valentinov. “The Moral Complexity of Agriculture: A Challenge for Corporate Social Responsibility.” Journal of Agricultural & Environmental Ethics, vol. 32, no. 3, 2019, pp. 413–430., doi:10.1007/s10806-019-09782-3. Accessed 19 Apr. 2021.

Olson, John. “Aeroponics: A Compliment to Hydroponics and the Food System of Space.” Global Food Health and Society, 26 Nov. 2018, global18/2018/11/26/aeroponics-a-compliment-to-hydroponics-and-the-food-system-of- space/.

Pattillo, Allen. (2017). An Overview of Aquaponic Systems: Aquaculture Components.

Putra, P. Agung, and Henry Yuliando. “Soilless Culture System to Support Water Use Efficiency and Product Quality: A Review.” Agriculture and Agricultural Science Procedia, vol. 3, 2015, pp. 283–288., doi:10.1016/j.aaspro.2015.01.054. Accessed 19 Apr. 2021.

Rinehart, Lee. “ATTRA Sustainable Agriculture.” Mar. 2019.

Sambo, Paolo, et al. “Hydroponic Solutions for Soilless Production Systems: Issues and Opportunities in a Smart Agriculture Perspective.” Frontiers in Plant Science, vol. 10, 2019, pp. 923–923., doi:10.3389/fpls.2019.00923. Accessed 19 Apr. 2021.

Sardare, Mamta. (2013). A Review On Plant Without Soil – Hydroponics. International Journal of Research in Engineering and Technology. 02. 299-304. 10.15623/ijret.2013.0203013.

Sharma, Nisha, et al. “Hydroponics as an Advanced Technique for Vegetable Production: An Overview.” Journal of Soil and Water Conservation, vol. 17, no. 4, 2018, p. 364., doi:10.5958/2455-7145.2018.00056.5.

Specht, Kathrin, et al. “Urban Agriculture of the Future: an Overview of Sustainability Aspects of Food Production in and on Buildings.” Agriculture and Human Values, vol. 31, no. 1, 2014, pp. 33–51., doi:10.1007/s10460-013-9448-4. Accessed 19 Apr. 2021.

Stojanovic, Milutin. “Conceptualization of Ecological Management: Practice, Frameworks and Philosophy.” Journal of Agricultural & Environmental Ethics, vol. 32, no. 3, 2019, pp. 431–446., doi:10.1007/s10806-019-09783-2. Accessed 19 Apr. 2021.

Touliatos, Dionysios, et al. “Vertical Farming Increases Lettuce Yield per Unit Area Compared to Conventional Horizontal Hydroponics.” Food and Energy Security, vol. 5, no. 3, 2016, pp. 184–191., doi:10.1002/fes3.83. Accessed 19 Apr. 2021.

Treftz, Chenin, et al. “Comparison between Hydroponic and Soil-Grown Strawberries: Sensory Attributes and Correlations with Nutrient Content.” Food and Nutrition Sciences, vol. 6, no. 15, 2015, pp. 1371–1380., doi:10.4236/fns.2015.615143. Accessed 19 Apr. 2021.

Wilson, Edward O. Half-Earth: Our Planet’s Fight for Life. Liveright Publishing Corporation, 2017.

Zimdahl, Robert L., et al. “Ethics in Agriculture: Where Are We and Where Should We Be Going?” Journal of Agricultural & Environmental Ethics, vol. 31, no. 6, 2018, pp. 751–753., doi:10.1007/s10806-018-9753-4. Accessed 19 Apr. 2021.

Tilman, D. “Global environmental impacts of agricultural expansion: the need for

sustainable and efficient practices.” Proceedings of the National Academy of Sciences of

the United States of America vol. 96,11 (1999): 5995-6000. doi:10.1073/pnas.96.11.5995

Treftz, Chenin, & Stanley T. Omaye. “Comparison Between Hydroponic And Soil

Systems For Growing Strawberries In A Greenhouse.” International Journal of

Agricultural Extension [Online], 3.3 (2015): 195-200. Web. 19 Apr. 2021

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