essay on hydroponic farming

What is hydroponics - and is it the future of farming?

No soil, no waste, no pesticides. So how does it work? Image:  REUTERS/Edgar Su

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Stay up to date:, future of the environment.

While industrialized farming techniques have meant a more plentiful supply of cheaper, fresher food – most notably in the developed world – they can also be a threat to the environment, promoting waste, putting too much strain on resources and causing pollution. That’s one of the findings of a report published by the Ellen MacArthur Foundation at the World Economic Forum Annual Meeting in Davos .

The report highlights the importance of cities in the production and consumption of food: “80% of all food is expected to be consumed in cities by 2050, they have to be central to this story. Today they often act as black holes, sucking in resources but wasting many of them – the final stop in the take-make-waste approach.”

Partly, this is due to the need to transport food to urban areas. That’s a process that places great importance on producing a lot of food, then packing and shipping it across sometimes vast distances, before storing and finally selling it to people. From start to finish that requires resources to be deployed at every step of a long chain of events – fuel, people, land, buildings, the list goes on.

One response to this, which is beginning to take shape, is vertical farming. Forecasts from Research & Markets claim the vertical farming industry could be worth as much as $3 billion by 2024 . Key to this approach, where food is grown in densely populated towns and cities where land is scarce, is the use of hydroponics.

The plants you don’t actually plant

Essentially, hydroponics is the process of growing plants without using soil, which might sound counterintuitive to anyone unfamiliar with the practice. The word itself is an amalgamation of two Greek words: hydro, meaning water and ponein, meaning to toil. Plants are rooted into a variety of compounds, including vermiculite, rockwool, or clay pellets – inert substances that won’t introduce any elements into the plant’s environment. Nutrient-enriched water then feeds the plant. Hydroponics offers one particular advantage over traditional growing methods. Through careful manipulation and management of the growing environment, including the amount of water, the pH levels and the combination of specific nutrients plants can be encouraged to grow faster. Air and soil temperatures can also be carefully controlled, as can the prevalence of pests and diseases.

The net effect is an increased yield and improved use of resources. A less wasteful approach to resource consumption means reduced waste, preservation of water stocks and a diminished reliance on pesticides, fertilizers and other potentially harmful materials.

Have you read?

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A holistic view of supply and demand

Around one-third of all the food produced each year ends up being wasted, according to the UN Food and Agriculture Organization. That’s approximately 1.3 billion tonnes , which equates to a loss of almost $1 trillion.

The point in the value chain at which food tends to get wasted most differs between developed and developing countries. In developing countries, losses and waste tend to occur during the earlier stages of the food value chain. Reasons for that include constraints around farming, crop management and harvesting caused by a lack of finances and expertise. Improving the infrastructure and logistics of food in developing nations can help address many of these challenges.

Perhaps less surprisingly, in higher-income countries food is generally wasted later in the process. Often that is driven by consumer behaviour and retailers’ approach to in-store discounting practices; discounts that fail to attract purchases while food approaches the end of its “eat-by” period invariably lead to waste and loss. The situation is further hampered by ineffective strategies for taking unsold food and finding other destinations for it – such as, but not limited to, homeless shelters.

Consumers in rich countries waste almost as much (222 million tonnes) as the entire net food production of sub-Saharan Africa (230 million tonnes). Meanwhile, the UNFAO says the number of malnourished people is on the rise : in 2016, it stood at 804 million but the following year had grown to 821 million.

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Hydroponic Farming Explained: A Beginner’s Guide to Modern Agriculture

Hydroponic farming has gained significant popularity in recent years due to its numerous advantages over traditional soil-based agriculture. In this comprehensive beginner’s guide, we will delve into the world of hydroponic farming, exploring its benefits, components, techniques, and future prospects.

The Benefits of Hydroponic Farming

Hydroponic farming offers a range of benefits that make it an attractive and sustainable option for modern agriculture. Compared to conventional methods, hydroponics utilizes water efficiently, requiring only a fraction of the water consumed in traditional farming. This water-saving feature is especially crucial in regions facing water scarcity.

Furthermore, hydroponic systems provide optimal nutrient delivery to plants, resulting in faster growth rates and higher yields. The absence of soil eliminates the risk of soil-borne diseases and allows for precise control over nutrient composition, ensuring plants receive the exact nutrients they need. Additionally, hydroponic systems can be implemented in small spaces, making it ideal for urban farming and maximizing land usage.

Key Components of a Hydroponic System

To understand hydroponic farming, it is essential to grasp the key components of a hydroponic system. These include a growing medium, nutrient solutions, water pumps, reservoirs, and pH control mechanisms. The growing medium, such as perlite, vermiculite, or rockwool, serves as a support structure for the plants’ root systems. Nutrient solutions, consisting of carefully balanced mineral mixes, provide the necessary elements for plant growth. Water pumps and reservoirs ensure proper circulation and delivery of nutrients, while pH control mechanisms maintain the optimal pH levels required by plants.

Types of Hydroponic Growing Techniques

Hydroponic farming offers a variety of growing techniques, each suitable for different plants and environments. Nutrient Film Technique (NFT) involves a thin film of nutrient-rich water flowing over plant roots, while Deep Water Culture (DWC) submerges the roots in a nutrient solution. Aeroponics suspends the plant roots in the air and delivers nutrients through misting, and Ebb and Flow systems intermittently flood and drain the root zone. Understanding these techniques allows farmers to choose the most appropriate method for their crops.

Nutrient Management in Hydroponic Farming

Proper nutrient management is crucial in hydroponic farming to ensure optimal plant growth and health. Essential nutrients required by plants include nitrogen, phosphorus, potassium, calcium, magnesium, and trace elements. Maintaining the correct nutrient composition and pH levels in the nutrient solution is essential for healthy plant development. Regular monitoring, adjustment, and replenishment of nutrients are necessary to achieve optimal yields and prevent nutrient deficiencies or imbalances.

Choosing Suitable Crops for Hydroponic Farming

Hydroponic farming is suitable for a wide range of crops, including leafy greens, herbs, tomatoes, cucumbers, strawberries, and even flowering plants. Leafy greens like lettuce and spinach are particularly popular due to their fast growth rates and high demand. Understanding the growth characteristics, nutritional requirements, and market demand for different crops helps farmers make informed decisions when selecting crops for hydroponic cultivation.

Setting Up a Hydroponic Farm

Setting up a hydroponic farm requires careful planning and consideration of various factors. Farmers must determine the space requirements, lighting conditions, temperature control, and ventilation for the hydroponic system. Quality equipment, such as grow lights, pumps, and timers, should be sourced from reputable suppliers. Selecting suitable crops and establishing a nutrient management routine are also essential for successful hydroponic farming.

Troubleshooting Common Issues in Hydroponic Farming

Like any agricultural endeavor, hydroponic farming can encounter challenges that require troubleshooting. Nutrient deficiencies, pH imbalances, and pest infestations are common issues faced by hydroponic farmers. Early detection, prevention measures, and appropriate corrective actions are crucial to maintaining the health and productivity of the plants. Regular monitoring, proper sanitation practices, and the implementation of integrated pest management strategies can help minimize problems.

Future Prospects of Hydroponic Farming

The future of hydroponic farming is promising, with ongoing advancements in technology, research, and commercial-scale operations. As the demand for sustainable agriculture increases, hydroponics offers a viable solution. Innovations such as vertical farming, aquaponics, and controlled environment agriculture are expanding the possibilities of hydroponic farming. Hydroponics has the potential to play a significant role in addressing food security, reducing water usage, and maximizing land efficiency.

Hydroponic farming is revolutionizing modern agriculture with its efficient use of resources, higher yields, and sustainable practices. By understanding the principles, components, and techniques of hydroponics, beginners can embark on a journey to explore this innovative method of farming. With its numerous benefits and future prospects, hydroponic farming holds tremendous potential for a greener and more productive future in agriculture.

Future of Farming – Hydroponic Farming or Traditional Farming?

As the world faces increasing challenges in agriculture, the future of farming is a topic of great interest. Traditional farming methods have been the backbone of food production for centuries, but the emergence of hydroponic farming has sparked a debate about the direction agriculture should take. In this article, we will explore the future of farming by comparing hydroponic farming and traditional farming, weighing their benefits, limitations, and potential to address the evolving needs of our planet.

Hydroponic Farming: Advancements in Agriculture

Hydroponic farming is an innovative approach that eliminates the need for soil, relying instead on nutrient-rich water solutions to grow plants. This method offers several advantages that make it a compelling option for the future of farming. Firstly, hydroponic farming requires significantly less water compared to traditional farming, addressing the issue of water scarcity in many regions. The controlled environment of hydroponic systems also allows for year-round cultivation, ensuring a consistent supply of fresh produce regardless of seasonal limitations.

Moreover, hydroponic farming optimizes nutrient delivery to plants, resulting in faster growth rates, higher yields, and better resource utilization. By providing precise nutrient solutions tailored to the specific needs of plants, hydroponics maximizes nutrient absorption and minimizes wastage. This efficiency can play a critical role in feeding the growing global population while reducing the environmental impact associated with conventional farming practices.

Traditional Farming: Preserving Heritage and Feeding the World

Traditional farming, deeply rooted in agricultural heritage, has been the primary method of food production for centuries. It encompasses a range of practices, including crop rotation, soil cultivation, and the use of organic fertilizers. Traditional farming techniques have successfully fed billions of people and contributed to the cultural and economic development of communities worldwide.

One of the key advantages of traditional farming is its adaptability to diverse environments and crop varieties. This method allows for the preservation of heirloom seeds and traditional agricultural practices, maintaining biodiversity and supporting local ecosystems. Traditional farming also relies on natural processes and interactions, promoting soil health and long-term sustainability.

Comparing Hydroponic Farming and Traditional Farming

When evaluating the future of farming, it is crucial to consider the strengths and limitations of both hydroponic farming and traditional farming:

• Resource Efficiency : Hydroponic farming excels in resource efficiency, utilizing less water, space, and nutrients compared to traditional farming. It can be a valuable solution for urban agriculture and regions with limited access to fertile land or clean water sources.
• Environmental Impact : Hydroponic farming reduces environmental impact by minimizing water usage, soil erosion, and chemical runoff. Traditional farming, on the other hand, can contribute to land degradation, water pollution, and deforestation if not practiced sustainably.
• Crop Diversity : Traditional farming supports a wide range of crop varieties and promotes biodiversity, preserving traditional and heirloom seeds. Hydroponic farming is better suited for certain crops like leafy greens, herbs, and small fruiting plants.
• Cultural and Economic Considerations : Traditional farming practices are deeply ingrained in cultural heritage and support rural communities worldwide. The transition to hydroponic farming may require retraining and adaptation, potentially impacting traditional agricultural communities.
• Scalability and Feasibility : Traditional farming can be scaled up to large agricultural operations, catering to the demands of the global food market. Hydroponic farming, while scalable, requires significant initial investment and technical expertise, making it more suitable for smaller-scale operations or specialized crops.

The Future of Farming: Integrating Both Approaches

Rather than viewing hydroponic farming and traditional farming as competing methods, the future of agriculture may lie in integrating the strengths of both approaches. The utilization of advanced technology, such as precision agriculture, vertical farming, and aquaponics, can combine the resource efficiency of hydroponics with the biodiversity and cultural preservation of traditional farming. This integrated approach can address food security challenges, promote sustainable practices, and create opportunities for diverse farming communities.

The future of farming is a complex and evolving topic, with hydroponic farming and traditional farming offering distinct advantages and considerations. While hydroponic farming excels in resource efficiency and environmental sustainability, traditional farming preserves heritage, supports rural communities, and promotes crop diversity. A balanced approach that combines the strengths of both methods, leveraging technological advancements, holds the key to addressing future challenges in agriculture. By embracing innovation, sustainability, and cultural preservation, we can shape a resilient and inclusive future for the world of farming.

Hydroponic farming is a fascinating and innovative method of growing plants without soil, offering numerous benefits such as water conservation, space efficiency, and year-round cultivation. However, like any new endeavor, beginners in hydroponic farming may encounter certain challenges and problems. In this essay, we will explore some of the common beginner problems in hydroponic farming and provide insights on how to overcome them.

• Nutrient Imbalance : Maintaining the proper nutrient balance is crucial for plant growth in hydroponic systems. Beginners may face challenges in achieving the ideal nutrient concentration and pH level in the nutrient solution. Imbalances can lead to nutrient deficiencies or toxicities, affecting plant health and productivity. Regular monitoring of nutrient levels, adjusting pH as needed, and following recommended nutrient schedules are essential to prevent nutrient imbalances. Using quality nutrient solutions and conducting routine water and nutrient solution testing can also help ensure optimal plant nutrition.
• Root Diseases and Pathogens : In hydroponic systems, where plants are grown in a water-based medium, root diseases and pathogens can pose a significant challenge. Beginners may encounter issues such as root rot, pythium, or fungal infections, which can impact plant health and survival. Maintaining proper hygiene and sanitation practices, including sterilizing equipment and using clean water sources, is crucial in preventing the spread of diseases. Additionally, maintaining proper air circulation, avoiding overwatering, and using beneficial microorganisms or organic treatments can help combat root diseases.
• Temperature and Humidity Control : Temperature and humidity levels play a critical role in hydroponic farming. Beginners may struggle with maintaining the ideal temperature range for plant growth, especially in extreme climates. High temperatures can lead to water evaporation, nutrient imbalances, and increased susceptibility to pests and diseases. On the other hand, low temperatures can slow down plant growth and affect nutrient uptake. Installing proper ventilation systems, shade cloths, and temperature control devices can help regulate temperature and humidity levels in the growing area, ensuring optimal growing conditions for plants.
• Pest and Disease Management : Pest infestations and diseases are common challenges in any type of farming, including hydroponics. Beginners may face issues such as aphids, whiteflies, or mites, which can damage plants and reduce yields. Implementing preventive measures like regular inspections, maintaining cleanliness, and using organic pest control methods can help manage pest and disease problems. Introducing beneficial insects, implementing integrated pest management strategies, and quarantining new plants can also aid in preventing and controlling infestations.
• Inadequate Lighting : Proper lighting is crucial for photosynthesis and overall plant growth in hydroponic systems. Beginners may struggle with providing adequate and appropriate lighting for their plants. Insufficient light intensity or improper light spectrum can lead to weak plant growth and poor yields. Investing in high-quality grow lights, understanding the light requirements of specific crops, and positioning lights at the correct distance from plants are essential for optimizing photosynthesis and promoting healthy plant development.
• Lack of Experience and Knowledge : One of the most common challenges for beginners in hydroponic farming is a lack of experience and knowledge. Understanding the principles of hydroponics, learning about plant nutrition, and familiarizing oneself with the specific needs of different crops are essential for success. Beginners should engage in continuous learning through books, online resources, forums, and connecting with experienced hydroponic growers. Joining local gardening communities or attending workshops and seminars can provide valuable insights and support from fellow growers.

While hydroponic farming offers many advantages, beginners may encounter challenges in nutrient management, root diseases, temperature control, pest and disease management, lighting, and a lack of experience. However, by adopting good practices, conducting thorough research, and learning from experienced growers, these problems can be overcome. With patience, perseverance, and a commitment to continuous learning, beginners can successfully navigate the world of hydroponic farming and enjoy the rewards of growing plants using this innovative method.

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No Soil. No Growing Seasons. Just Add Water and Technology.

A new breed of hydroponic farm, huge and high-tech, is popping up in indoor spaces all over America, drawing celebrity investors and critics.

AppHarvest, the nation’s largest hydroponic greenhouse, opened in January in Morehead, Ky. — one in a new breed of huge indoor produce farms that use technology to fine-tune flavor, texture and other attributes. Credit... Luke Sharrett for The New York Times

Supported by

By Kim Severson

• July 6, 2021

MOREHEAD, Ky. — In this pretty town on the edge of coal country, a high-tech greenhouse so large it could cover 50 football fields glows with the pinks and yellows of 30,600 LED and high-pressure sodium lights.

Inside, without a teaspoon of soil, nearly 3 million pounds of beefsteak tomatoes grow on 45-feet-high vines whose roots are bathed in nutrient-enhanced rainwater. Other vines hold thousands of small, juicy snacking tomatoes with enough tang to impress Martha Stewart, who is on the board of AppHarvest , a start-up that harvested its first crop here in January and plans to open 11 more indoor farms in Appalachia by 2025.

In a much more industrial setting near the Hackensack River in Kearny, N.J., trays filled with sweet baby butterhead lettuce and sorrel that tastes of lemon and green apple are stacked high in a windowless warehouse — what is known as a vertical farm. Bowery , the largest vertical-farming company in the United States, manipulates light, humidity, temperature and other conditions to grow produce, bankrolled by investors like Justin Timberlake , Natalie Portman, and the chefs José Andrés and Tom Colicchio.

“Once I tasted the arugula, I was sold,” said Mr. Colicchio, who for years rolled his eyes at people who claimed to grow delicious hydroponic produce. “It was so spicy and so vibrant, it just blew me away.”

The two operations are part of a new generation of hydroponic farms that create precise growing conditions using technological advances like machine-learning algorithms, data analytics and proprietary software systems to coax customized flavors and textures from fruits and vegetables. And they can do it almost anywhere.

These farms arrive at a pivotal moment, as swaths of the country wither in the heat and drought of climate change, abetted in part by certain forms of agriculture. The demand for locally grown food has never been stronger, and the pandemic has shown many people that the food supply chain isn’t as resilient as they thought.

But not everyone is on board. These huge farms grow produce in nutrient-rich water, not the healthy soil that many people believe is at the heart of both deliciousness and nutrition. They can consume vast amounts of electricity. Their most ardent opponents say the claims being made for hydroponics are misleading and even dangerous.

“At the moment, I would say the bad guys are winning,” said Dave Chapman, a Vermont farmer and the executive director of the Real Organic Project . “Hydroponic production is not growing because it produces healthier food. It’s growing because of the money. Anyone who frames this as food for the people or the environment is just lying.”

The technical term for hydroponic farming is controlled environmental agriculture, but people in the business refer to it as indoor farming. What used to be simply called farms are now referred to as land-based farms or open-field agriculture.

“We’ve perfected mother nature indoors through that perfect combination of science and technology married with farming,” said Daniel Malechuk, the chief executive of Kalera , a company that sells whole lettuces, with the roots intact, in plastic clamshells for about the same price as other prewashed lettuce.

In March, the company opened a 77,000-square-foot facility south of Atlanta that can produce more than 10 million heads of lettuce a year. Similar indoor farms are coming to Houston, Denver, Seattle, Honolulu and St. Paul, Minn.

The beauty of the process, Mr. Malechuk and other executives say, is that it isn’t limited by seasons. The cost and growing period for a crop can be predicted precisely and farms can be built wherever people need fresh produce.

“We can grow in the Antarctic,” he said. “We can be on an island. We can be on the moon or in the space station.”

That’s easy to picture: The farms are staffed by a new breed of young farmers who wear lab coats instead of overalls, and prefer computers to tractors.

Today, the more than 2,300 farms growing hydroponic crops in the United States make up only a sliver of the country’s $5.2 billion fruit and vegetable market. But investors enamored of smart agriculture are betting heavily on them.

In 2020, $929 million poured into U.S. indoor-farming ventures, more than double the investments in 2019, according to PitchBook data. Grocery chains and California’s biggest berry growers are partnering with vertical farms , too.

“There is no question we are reinventing farming, but what we are doing is reinventing the fresh-food supply chain,” said Irving Fain, the founder and chief executive of Bowery, which is based in Manhattan and has the indoor farm in New Jersey and one in Maryland, another under construction in Pennsylvania, and two research farms in New Jersey.

Mr. Fain said his farms are 100 times as productive as traditional ones and use 95 percent less water. Other companies claim they can grow as much food on a single acre as a traditional farm can grow on 390.

Vertical farms can be built next to urban centers, so lettuce, for example, doesn’t have to sit inside a truck for days as it makes its way from California to the East Coast, losing both quality and nutritional value . Vegetables can be bred for flavor rather than storage and yield.

The new systems are designed to produce a sanitary crop, grown without pesticides in hygienic buildings monitored by computers, so there is little risk of contamination from bacteria like E. coli, which forced large recalls of romaine lettuce in 2019 and 2020.

Still, many farmers and scientists remain unpersuaded. Mr. Chapman, of the Real Organic Project, served on a U.S. Department of Agriculture hydroponics task force five years ago, and is leading an effort to get the agency to stop allowing hydroponic farmers to certify their produce as organic. The very definition of organic farming, he and others say, rests on building healthy soil. In May, the Center for Food Safety , an environmental advocacy group, led an appeal of a federal court ruling that upheld the agency’s policy.

Although the nutritional profile of hydroponic produce continues to improve, no one yet knows what kind of long-term health impact fruits and vegetables grown without soil will have. No matter how many nutrients indoor farmers put into the water, critics insist that indoor farms can never match the taste and nutritional value, or provide the environmental advantages, that come from the marriage of sun, a healthy soil microbiome and plant biology found on well-run organic farms.

“What will the health outcomes be in two generations?” Mr. Chapman asked. “It’s a huge live experiment, and we are the rats.”

The divide between soil loyalists and ag-tech futurists is playing out on a much more intimate scale between two influential brothers: Dan and David Barber, who founded and own the organic farm Blue Hill and its restaurants in Greenwich Village and at Stone Barns in Pocantico Hills, N.Y.

In 2018, David Barber created an investment fund to support new food tech companies, including Bowery. But Dan Barber, a chef whose 2014 book “ The Third Plate: Field Notes on the Future of Food ” devotes an entire section to soil, believes that truly delicious food can come only from the earth.

“I am not buying any of it,” Dan Barber said of the hydroponic fever.

Trying to enhance water with nutrients to mimic what soil does is virtually impossible, he said, in part because no one really knows how the soil microbiome works.

“We know more about the stars and the sky than we do about soil,” he said. “We don’t know a lot about nutrition, actually.”

There is a cultural cost, too. For centuries, cuisines have been developed based on what the land and the plants demanded, he said. Regional Mexican diets built on corn and beans came about because farmers realized that corn grew better in the presence of beans, which fix nitrogen in soil.

“The tech-farming revolution is turning this equation on its head,” Mr. Barber said. It aids efficiency in the name of feeding more people, but divorces food from nature.

His brother, David, had long been skeptical of hydroponics, too. “Most of my career was about good soil leads to good agriculture and good systems and ultimately good flavor,” David Barber said.

But the environmental advantages of next-generation hydroponic food production can’t be ignored, he said. Nor can the improvements in taste over earlier hydroponic produce. “They are combining outdoor and indoor thinking, and science and history, to create something special,” he said. “There are not going to be many winners in this space, but it is going to be a part of our food system.”

Indoor farm companies view their competition as the large, industrial growers that produce fruits and vegetables bred to withstand processing and shipping — not smaller farmers using more natural growing techniques. The battle, they say, is against monoculture, not farmers who maintain healthy soil and feed their communities. Hydroponic farms can help develop new and more diverse plants, and reduce overall pesticide use.

“The only thing we are trying to do is get as good as farmers were 100 years ago,” said Mr. Malechuk, the hydroponic lettuce grower.

Indoor farming is a bet on the nation's agriculture, said Jonathan Webb, the Kentucky-born founder and chief executive of AppHarvest.

“The American farmer is already obsolete,” he said, pointing out that the United States imports four billion pounds of tomatoes from Mexico every year. “Our hope is we can get farmers back on U.S. shelves.”

Even Mr. Colicchio, who led a campaign against genetically modified food and has long been a champion of small farmers, said the two styles of farming can coexist. “We’re going to need a lot of tools in the toolbox,” he said.

Ouita Michel , a chef in Kentucky, likes AppHarvest because the company is creating jobs and growing tomatoes she is happy to use in her restaurants.

But technology, she said, will never trump the magic of soil. “Nothing will ever replace my summer Kentucky tomatoes.”

Follow NYT Food on Twitter and NYT Cooking on Instagram , Facebook , YouTube and Pinterest . Get regular updates from NYT Cooking, with recipe suggestions, cooking tips and shopping advice .

Kim Severson is a Southern-based correspondent who covers the nation's food culture and contributes to NYT Cooking . She has written four books and was part of a team that won a Pulitzer Prize in 2018 for public service for reporting on workplace sexual harassment. More about Kim Severson

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Hydroponic Farming as a Contemporary, Dependable, and Efficient Agricultural System: Overview

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With a rapidly growing global population, there is an increasing need for food on a daily basis. There is a global shortage of agricultural land as more and more regions are developed for urban use. Because of this, if we want to feed the world’s growing population, we need to find ways to produce more grains with less land. Increasing food production while utilizing less agricultural area is one of the answers provided by hydroponic farming. Because of this, this page offers a comprehensive look into hydroponics and all of its variants, advantages, and problems. Additionally, various forms of hydroponics are compared in this research, as well as an explanation of each kind depending on nutritional requirements. The nutrients film technology (NFT) was shown to be superior to all other types of hydroponics farming in terms of environmental effect, simplicity of usage, water requirements, fertilizer consumption, and other aspects after a comprehensive study.

• Hydroponic system
• Nutrients film technology (NFT)

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Rai, H.M., Singh, M.K., Mishra, A.N., Solanki, A. (2023). Hydroponic Farming as a Contemporary, Dependable, and Efficient Agricultural System: Overview. In: Goyal, D., Kumar, A., Piuri, V., Paprzycki, M. (eds) Proceedings of the Third International Conference on Information Management and Machine Intelligence. Algorithms for Intelligent Systems. Springer, Singapore. https://doi.org/10.1007/978-981-19-2065-3_17

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Hydroponics in Agriculture Research Paper

There have been changes in the climate of today that has seen reduction of the amount of rainfall we receive. Abu Dhabu, a city in the Emirates where the desert like conditions prevails, has been adversely affected by these changes. Therefore the amount of water used for irrigation has to be regulated.

Modern methods of irrigation such as use of hydroponics have been introduced to reduce the amount of water wasted in irrigation farms. The following is a case study of an experiment done in the University of Peradeniya Sri Lanka to illustrate how hydroponics saves water and energy.

The use of hydroponics gardening in growing of vegetables, fruits and other plants has been so common in the world today. Many farmers are going into this advanced technology of plant growing because they believe that plants grown hydroponically have better quality than the ones grown under the normal soil planting.

The extensive use of hydroponics systems is also attributed to the many reported problems related to soil. Scientists decided to come up with technology where the use of soil would be reduced or find an alternative for the soil in a bid to curb the many soil related problems (Tavakkoli, Fatehi, Rengasamy, & Mcdonald, 2012).

The human population of the world is also increasing and leading to a subsequent rise in challenges to plant growing and agriculture in general.

The land available for the people to conduct their cultivations has been reducing since more space is occupied by human settlement and construction of infrastructure. The hydroponics gardening system is capable of producing a large volumes of crops in a small portion of land.

With many parts of the earth experiencing a change in climatic conditions, the growing pattern of plants has also been interfered with since the amount of rain and seasons are also changing. This technology of hydroponics in plants growing can adopt the reduced rainfall amounts since it seeks to save water used by the growing plants.

Many scientists believe that this advancement in the technology of plant growing is too superior and reliable than the old methods of planting and irrigation. Despite this huge support for the hydroponics systems, there has been little research done on this field of plant growing to prove the reliability and superiority of this technology.

Due to lack of more research evidences to support the fact that hydroponically grown plants are superior, an experiment was done in the University of Peradeniya. The experiment was to illustrate the comparison of a hydroponically grown plant and a soil-grown plant.

The experiment was done on lettuce ( Lactuca sativa L.) in both the hydroponics system and soil growing conditions. The physiological measures used in this research included comparing the shoot and root ratios, rates of photosynthesis, and stomata conductance of the lettuce grown under the two different conditions.

Materials used in the experiment

Lettuce (Lactuca sativa L.) was used as the experimental crop

Amount of Water

Amount of energy.

The annual difference of water intake between the two methods is 8400/7= 1200 m 3 . The pumping system used an average of 0.17 kW to pump 1m 3 of the hydroponic solution. Therefore, this requires 204kWh of energy for 1200m 3 (1200 x 0.17).

Amount of CO 2 Emissions

According to Bandara from University of Peradeniya, the experiment shows that an average of 1200 kg of natural gas would be needed annually for 1ha farm of hydroponics.

The following formula is used to calculate the total amount of CO 2 emissions.

Total amount of CO 2 emission=Total amount of natural gas X hydrogen to carbon ratio

X CO 2 to carbon ratio

= 1200 x 12/16 x 44/12

Coir dust was used in both soil and hydroponics culture in the following sizes:

Hydroponic culture- 50x33x9 cm 3

Soil culture- 45x30x5 cm 3

Amount of minerals

Hydroponics culture- 6.0mM KNO 3 , 4.0mM Ca (NO 3 ) 2 , 1.0mM NH 4 H 2 PO 4 , 2.0mM MgSO 4 .7H 2 0

Soil culture- 1.075g N, 1.175g P, 0.375g K

This experiment was conducted in two different methods and therefore the requirement of the process would also differ at some point. The first bit of the experiment used the conventional method and thus soil culture was considered here.

The other part of this research was the hydroponics systems where there was no use of soil. The following is a brief illustration of the stages followed in each of these two processes (Hanses, 2010; West Virginia University, 2014.

Soil Culture

In this experiment, the soil to be used was first grounded to have a fine texture, and this was done to enhance penetration and proper mixing of nutrients with the soil particles. After this, 10 kg of livestock manure was mixed properly with the fine soil with a view that each plant would acquire 250 g of the manure.

Before the next stage, the test was conducted to establish the concentration of the initial minerals on the soil. It is important to conduct this test before adding the inorganic fertilizers to the soil since the calculation of used mineral nutrients by the plants would be easier.

The seedlings were transferred two weeks after the planted seeds had germinated. They transplanted in seedling trays that measure 45* 30* 5 cm 3 where they are applied with nutrients.

Hydroponic Culture

In this case, polystyrene boxes were used to hold the medium which was coir dust. Each box measured 50cm by 33cm by 9 cm where four plants were expected from each of them.

The nutrient solution was then prepared as per the stated amount of mineral required in this experiment. This hydroponics solution was then passed through the grown plants to enable them absorb the nutrients.

Random measurements of the parameters stated in this experiment were done when the plants had reached 30, 37, and 45 years. Four plants were picked randomly from both the hydroponics and soil culture for these measurements to be taken. Also, the number of leaves in the plants taken for the study was recorded.

Root lengths, dry weights and root: shoot ratios

The root lengths of the plants grown in the hydroponics were slightly higher than the lengths of the soil grown plants. These plants also had their roots being more resistant to growth as the initial lengths of their roots were close to that after the experiment.

The hydroponically grown plants recorded higher shoot dry weights as compared to those from the soil which had high root dry weights. This is one of the best ways of determining the quality of the harvest one should expect after the plants have grown to maturity. The following is a set of data collected in this experiment.

Mean root lengths, root dry weights, shoot dry weights and shoot: root ratios of hydroponically grown plants and soil grown plants

Key; RL – mean root length, RDW – mean root dry weight, SDW – mean shoot dry weight, S: R ratio – mean shoot: root ratio, H – hydroponically grown plants, S – soil grown plant

Net Photosynthetic Rates

The hydroponically grown plants recorded higher net photosynthetic rates when compared to what the soil-grown plants had in this case. There are various factors associated with the rate of photosynthesis exemplified by the plants’ efficiency of using the solar energy and the leaves’ stomatal conductance of carbon (IV) oxide.

Therefore, studying the net photosynthetic rate is also very important when analyzing the solar-energy consumption.

Transpiration Rates

Furthermore, it is the plants grown in the hydroponics system that recorded a higher rate than those plants grown in the soil-based method. This shows that the plants on the hydroponics setup absorbed more moisture from the solution (Bandara, 2008).

Hydroponics in Agriculture

This is a technology of growing plants by using solutions of mineral nutrients without the necessity of using soil as a medium. This idea was brought up when scientists found out that soil is not mandatory for plant growth through their researches.

Over the years, soil has been used because it provides the growing plants with support. In this soil, most of the mineral nutrients are also stored.

Further studies also showed that water played a major role during the absorption of these minerals because the mineral nutrients are absorbed by the plants in the form of inorganic ions dissolved in water. The important minerals are diluted in water as the plants are grown in a medium containing the solution.

The medium is where the plant would be anchored while growing. The media used in hydroponics include coconut husks, gravel, mineral wool, and expanded clay pebbles.

This advanced technology in plant growing can be used by indoor gardeners and also those who prefer growing their fruits and vegetables in the outside environment. This is possible because hydroponics can use both the natural light and the artificial ones when growing.

There are various hydroponics system plans to be used in different parts of the world in growing of vegetables, fruits and other plants. These different setups have the same idea of hydroponics growing but the difference comes in the type of medium used in the growing and the state of the nutrient solution.

This technique is categorized into two main areas depending on the media used in the categorization. The 2 categories are the solution culture and the medium culture. The solution culture is that plan where there are no solid media used in the growing process of the plants under the hydroponics technology.

Examples of hydroponics solution culture are the static solution culture, the continuous flow solution culture and the aeroponics. On the other hand, the medium culture is a hydroponics technique in which there is a medium used in growing the plant.

The plants are supported by the media while the solution containing the mineral nutrients is passed through so that growing plants can absorb them. Names are attached to these type of setups according to the medium used like the sand culture and rock wood culture.

In terms of the state in which the nutrient solution is having, the hydroponics systems are also classified into two major areas. This is the Still Solution Hydroponics and the Re-circulating Solution Hydroponics.

The former method is one where the mineral nutrients solution is static while the latter has the hydroponics solution in constant circulation. Electronic pumping machines are used to maintain the circulation of the solution in cases where the system is operating at a larger scale.

The Working Mechanism

The way in which the hydroponics systems work is quite simple. It entails passing of mineral nutrients from the nutrient solution to the plant roots through capillary action. To elaborate on the working mechanism it’s preferable to discuss the media used in this technology and the different techniques used in hydroponics.

Hydroponic Media

The following is an illustration of each of the mostly used media in growing the hydroponics:

Expanded Clay

This medium is something close to marbles which is highly porous. Clay is made into round balls and then heated at high temperatures of around 1200 degrees Celsius. This is done to make the clay highly porous and also to avoid compacting after a period of time.

It is this quality that makes it the most preferred medium by the gardeners. Apart from that, expanded clay is widely used due to its low prices. This makes it more profitable for commercial gardening due to the reduced cost of operations.

The expanded clay has a neutral pH making the gardeners sure that the plants will acquire the exact nutrients from the hydroponics solution. This medium is re-usable since it can be cleaned after being used and sterilized making it economical.

Perlite and Vermiculate

This medium is also a mineral in its state. One unique factor about this type of media is that it is overheated and in extreme cases also expanded. This makes it adapt very well in dry conditions and desert like environments. Although perlite contains more air than vermiculite, it holds little water.

This is what we get from the leftover of the outer shell of a coconut after the fibers have been removed. The coir provides a very conducive environment for the growing of plant roots. This is so because of the ability of the coco peat to exchange cations at a high rate.

With this modification, this medium of hydroponics growth can store nutrients that are not used by the plant. This would mean that no mineral nutrients would be wasted since the excess would be used in the future since they are stored.

Coco peat also has a type of fungi called trichodema which dominates in it and it is useful to the plant roots. This fungus offers protection to the roots and also enhances the growth of the roots by boosting the speed of growth. Therefore, coir is one of the best media to use in this advanced technology of growing plants.

For this kind of medium, any size of gravel is applicable. Even the type of gravel used in aquariums can be used in this case. One important condition to maintain is the constant circulation of water all through the medium. This circulation can be made efficient by use of electric pumps in the system.

A lot of advantages come along with the use of this medium. For instance, this medium is relatively cheap thus giving commercial gardeners a better way to cut down on their cost of production.

This medium is also good when boosting the quality of the fruits or vegetables being planted because it maintains a good drainage system.

Therefore, the water will be saved while as the plants get adequate water for growth. One major precaution when using gravel as the medium is maintaining the water circulation since the plant roots are prone to dry with no constant water flowing.

Polystyrene Packing Peanuts

Though this medium may be cheap and economical to use, there are restrictions that come along with using it. For example, this medium of hydroponics growth is only used in enclosed systems such as closed tubes. It is also very light in weight that the types of plants grown on it are specific. Another major disadvantage of the polystyrene packing peanuts is that the plants might take in some styrene from the medium. Eventually, this is passed to the consumers of the plant and thus set a serious health risk to them.

Techniques of Hydroponic Systems

There is a variety of hydroponics systems used to grow different types of plants. The different techniques have unique specifications that make them suitable for the growth of specific vegetables or fruits.

Despite their classification, all the techniques used in hydroponics systems are aimed at providing nutrients, water, and adequate air to the plants. The following are some of the hydroponics setups used majorly in growing vegetables in different environments.

Still Solution Hydroponics (static)

This is one of the easiest hydroponics techniques to start and develop. In this case, a person would require a container or tank where the nutrient solution is placed. The plant is put into a pot or vessel which would be immersed in a container with the hydroponics solution.

It is important to note that it is only the bottom of the vessel that is immersed in the solution. From this point, the plant in the vessel will be able to absorb the mineral nutrients up through the process of capillary action. The amount of water used must also be taken care of as the plant would need good aeration.

Therefore, the water in the vessel should be at a lower level to allow space for aeration of the plant. When setting up this hydroponics system, good quality and adequate water must be in the container to avoid adding up of water which would alter the aeration of the plant.

When starting the process, the salt concentration of the water should also be low. This is necessary because after a short period of crop’s growth, the fertilizer salts would have been concentrated in the solution.

The still solution hydroponics system has the advantage of being economical in establishing and maintaining it. For example, the type of hydroponics technology does not require electricity or pumping machines.

The Re-Circulating Solution Hydroponics

This is a hydroponics system where the nutrient solution is kept flowing through the roots of the plant grown constantly. It is exactly the opposite of how the static solution hydroponics system operates.

This technology requires a lot of investment in terms of resources and the care that the plants would be offered when growing. This is performed by either developing a pumping mechanism or creating a sloping landscape to enhance the flow of water.

One advantage of this technology is that it allows adjustments on the process while it is in progress. For example, the temperature and concentration of nutrients can be varied according to the type of plant growing and the level that it has grown in this case.

The Substrate Culture

This is a type of hydroponics system where there is a medium used by the plant when growing. In these cases, the basic medium applied excludes soil and applies a substrate that does not contain nutrients. The most preferred substrates include coconut coir, rock wool, vermiculite, and expanded clay.

These materials are used to provide physical support but not for supplying nutrients components to the crop. The medium chosen should be able to last for a long time so as the growth duration of the plant can fit in the active period of the substrate.

Apart from this, the right medium should be able to hold an adequate amount of water. This ensures that the plant receives sufficient water required for maximum growth rate. This is also the same in the air capacity of the substrate as there must be good aeration conditions for the plant to thrive.

Some substrates such as saw dust and composted pine bark are not advisable to use in hydroponics gardening. In the first place, these media are not good to use because they are not consistent in the quality they provide.

This creates problems from the gardeners due to the type of quality that their vegetables or fruits can have after all the hydroponics processes.

These substrates are also not recommended because the rate at which they decompose is high. This makes such substrates not to stay for a long time in comparison to the duration that the plant would take to grow.

This technique helps in reducing the amount of water wasted while irrigating the crops. Also, it assists the plant to get proper aeration enhancing proper growth, few disease infection, and shorter period of growth.

Once a medium is used, it is vital to replace it when planting another time even though this is an optional measure. This is performed majorly to ensure that the vegetable or fruits grown are good quality.

Moreover, replacing the substrates helps in avoiding passage of diseases to the growing plants. This again proves that hydroponics gardening is bound to produce higher quality.

An irrigation scheme is created, and the hydroponics solution is pumped through the plants as the flowing solution is collected in tanks. From this point, the collected solution is pumped back to the dripping points.

Nutrition Film Technique (NFT)

In this type of hydroponics system, there are shallow gullies constructed in a sloping manner during the first step. The plants are then planted along the gullies, and nutrient solution is flown down across the plants.

Down the gullies, the nutrient solution is collected in the set collection tanks from where the solution is pumped back. The flowing of the hydroponics solution stream down the gully is also important in making sure the solution is always aerated.

For the collection tanks down the gullies, it is preferred that one has many smaller tanks instead of a huge tank. This is important because it ensures that the farm has some supplies of the solution, even if there is a breakdown in one of the tanks.

Another advantage of breaking the collection tank into smaller ones is that it avoids spread of diseases, in case there is an outbreak in the garden.

Analysis and Discussion

Comparing the conventional and the hydroponics systems of irrigation.

Over the years, the methods of irrigation have changed from the simple systems to advanced levels of irrigating plants. These advancements in the irrigation sector are connected to the changes we experience in the world’s climate and vegetation today.

Different parts of the world are getting drier due to climatic changes and thus the need to conserve the water for irrigation and also make maximum use of it by engaging efficient methods.

Sri Lanka and many countries in the Middle East are affected adversely by these changing conditions that explain their wide participation in hydroponics and other modern irrigation systems.

While illustrating the differences between the traditional methods of irrigation and the use of hydroponics, the following factors are looked at in relation to the two methods;

Harvest Quality

According to this experiment, the crops grown in hydroponics condition are expected to have bigger fruits and leaves while their roots are smaller. On the other hand, the plants irrigated in the conventional way are expected to exhibit smaller fruits and bigger roots.

This is according to the comparison done of the dried weights of the roots and shoots. Therefore, it is apparent that the harvest expected in hydroponics has higher quality than other systems.

The hydroponics systems of gardening do not require use chemicals such as pesticides and herbicides that are usually expensive. This method also ensures there is recycling of the nutrients, and thus it makes it economical.

For the traditional irrigation methods, one would need chemicals to maintain the plants, and the nutrients are also not recycled thus the harvest would not produce high profit as it is the case in these modern irrigation systems.

The growth of the hydroponics can be done all year round since they do not depend on the seasons of the climate. In most of the cases, the plants are grown within modified environments to benefit the farmer by increasing the harvests of a year.

The traditional ways of irrigation rely on the different seasons of the year and therefore will not be possible in some seasons.

Another importance attached to the use of hydroponics is that the rate of growth of plants grown hydroponically is two times faster than that of plants grown in the conventional ways. Amount of yield also multiplies by two in this method of irrigation.

This shows that given the same space, the hydroponics system produces double of what the soil based irrigation system provides.

Water Usage and Saving

In the conventional methods of irrigation, there were be no views of controlling the use of water and avoiding its wastage. It is in these traditional irrigation methods that the water would be directed to the plants in the field without considering the evaporation rates and sipping of water into the ground.

The hydroponics technology has ensured that the irrigation water is saved and used maximally in the growth of plant and thus ensuring highest produces.

For instance, the transpiration rate of the plants grown hydroponically was higher than that of plants reared on the soil in this experiment. This shows that the plants grown on soil did not absorb enough water which implies poor usage.

In the old irrigation systems, there were large operations for the scheme to provide enough water for irrigation. In the hydroponics system, the big structures are not necessary as it requires a tank of recyclable nutrient solution that is cheap and simple to operate as well as maintain. In the experiment, the average annual usage of water in the hydroponic irrigation is estimated to be 8400 cm 3 per hectare which is half the amount in traditional irrigation method.

Energy Consumption and CO2 Emission

The farms under irrigation in UAE require irrigation systems which require a lot of energy. In this experiment the method of hydroponic irrigation used was the static solution method.

In cases where the farm need big pumping machines to pump back the nutrition solution, slightly more energy might be needed to run the system.

In this experiment, this factor is noted by the net photosynthetic rates which are affected by the efficiency of the plant in using the solar energy. The plants grown in a hydroponics system had a higher net photosynthetic rate than the soil grown ones.

This is a clear illustration that the hydroponics system enhances the consumption of the natural solar energy.

CO 2 gas emission in farms using hydroponics is also quite low. The experiment shows that approximately 3300kg of CO 2 would be emitted within one year in farms having hydroponically grown plants.

Generally, the use hydroponics system has been important to the economy and the agricultural sector due to the income retrieved from exportations and other sales made locally. This modern technology of irrigation has indeed improved the quality of harvest got from the schemes.

With hydroponics, the plants are not affected by fungi since there is proper management of the water and thus the crop would not be water-logged. The harvest quality from plants grown hydroponically is also good as the size of fruits is bigger.

This advanced irrigation method has also been proven very useful in saving the water consumed by the plants. In this method of irrigation, the farmers recycle the water they use in the process rather than wasting it to leaching and dampness on the fields.

The energy consumption and emission of carbon (IV) oxide are also handled by this farming technology. The farmer will attain a reduced consumption of energy in the farm in case he/she has adopted any of the techniques of hydroponics systems that do not involve a lot of pumping activities.

In this light, the CO2 emission would also be reduced since the usage of machines in the farm would be limited. Therefore, the use of hydroponics saves water, energy and emission of CO2.

Recommendations and Concerns

Similar to many countries in the Middle East and the surroundings of Sub-Saharan deserts, UAE is experiencing a big challenge of managing the limited water available. This has forced the UAE government to adopt policies that would help to provide adequate water for the people and the irrigation scheme.

The economy is also one crucial factor that this government has to put into consideration as the prices of resources rise alongside the population size. When all these considerations put together, adopting the hydroponics technology is a good idea.

Therefore, this study recommends the implementation of this technology in irrigation projects aimed at being efficient and economical.

Future Work

In Abu Dhabi, the planting of palm trees is one activity that many stakeholders of the Emirates economy take seriously. In the Emirates of Abu Dhabi, the climatic condition that has many desert-like characteristics is good for palm tree planting.

Palm trees make up a big percentage of fruit plants in Abu Dhabi and therefore putting in place this economical irrigation method in its plantation would save the government in this business city a lot of resources in terms of water and energy.

Hydroponics has proven to be so efficient in irrigation and provision of quality agricultural products for national and international consumption. Moreover, the technology also saves water, energy, and the environment making it a good tool to be used in enhancing sustainable practices in agriculture.

Therefore, if investments are made on this area, there are high chances of developing the production of food through this modern technique. This will lead to adequate supply of food for people through cheap and qualified standards of growth.

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LifeEssay Biology. (2014). What are the advantages and disadvantages of hydroponics farming? Web.

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Mathew, T. (1987). Society for Soil and Water Conservation. Simple methods of localized water conservation. Areeplachy, Kerala, India , 34-42.

Olivia’s solution. (2014). Advantages & Disadvantages of Hydroponics! Retrieved from Olivia’s solution. Web.

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Tavakkoli, E., Fatehi, F., Rengasamy, P., & Mcdonald, G. (2012). A comparison of hydroponics and soil-based screening methods to identify salt tolerance in the field in barley. Journal of Experimental Botany, 63 (10), 3853-3867.

Tinker, P. B. (1997). Solute Movement in the Soil-Root System. Oxford: Blackwell Scientific Publishers.

Wang, A. (2005). Synthesis and properties of clay-based superabsorbent composite. European Polymer Journal , 1570-1595.

West Virginia University. (2014). BPC profiles: Mountain State Hydroponics . Retrieved from Davis College of Agriculture, Natural Resources and Design. Web.

Zhao, Y. (2009). Study on precision water-saving irrigation automatic control system by plant physiology. Industrial Electronics and Applications. ICIEA 2009. 345-370.

Zhenmin, Z. (2009). Influence of irrigation water-saving on groundwater table in the downstream irrigation districts of yellow river. Natural Computation , 305-412.

• Chicago (A-D)
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IvyPanda. (2024, February 7). Hydroponics in Agriculture. https://ivypanda.com/essays/hydroponics-in-agriculture/

"Hydroponics in Agriculture." IvyPanda , 7 Feb. 2024, ivypanda.com/essays/hydroponics-in-agriculture/.

IvyPanda . (2024) 'Hydroponics in Agriculture'. 7 February.

IvyPanda . 2024. "Hydroponics in Agriculture." February 7, 2024. https://ivypanda.com/essays/hydroponics-in-agriculture/.

1. IvyPanda . "Hydroponics in Agriculture." February 7, 2024. https://ivypanda.com/essays/hydroponics-in-agriculture/.

Bibliography

IvyPanda . "Hydroponics in Agriculture." February 7, 2024. https://ivypanda.com/essays/hydroponics-in-agriculture/.

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Hydroponics: A Versatile System to Study Nutrient Allocation and Plant Responses to Nutrient Availability and Exposure to Toxic Elements

Nga t. nguyen.

1 Division of Plant Sciences, C.S. Bond Life Sciences Center, University of Missouri, Columbia

Samuel A. McInturf

David g. mendoza-cózatl.

Hydroponic systems have been utilized as one of the standard methods for plant biology research and are also used in commercial production for several crops, including lettuce and tomato. Within the plant research community, numerous hydroponic systems have been designed to study plant responses to biotic and abiotic stresses. Here we present a hydroponic protocol that can be easily implemented in laboratories interested in pursuing studies on plant mineral nutrition.

This protocol describes the hydroponic system set up in detail and the preparation of plant material for successful experiments. Most of the materials described in this protocol can be found outside scientific supply companies, making the set up for hydroponic experiments less expensive and convenient.

The use of a hydroponic growth system is most advantageous in situations where the nutrient media need to be well controlled and when intact roots need to be harvested for downstream applications. We also demonstrate how nutrient concentrations can be modified to induce plant responses to both essential nutrients and toxic non-essential elements.

Introduction

Plants are among the few organisms that can synthesize all the required metabolites from inorganic ions, water and CO 2 using the energy captured from the sun 1 . Hydroponics is a method of growing plants that takes advantage of this fact by providing all of the nutrients, in their inorganic form, in a liquid solution with or without solid media. Hydroponic systems have been extensively used by scientists for exploring nutrient requirements and also the toxicity of some elements in Arabidopsis and other plant species 2-5 . For instance, Berezin et al. 3 , Conn et al. 4 , and Alatorre-Cobos et al. 2 used hydroponic systems and several plant species including tomato and tobacco, to generate sufficient plant biomass for mineral analysis 2-4 . Industrial applications of hydroponics have also been developed for crops such as tomato and lettuce 6 . Here, we outline the use of hydroponics in the context of research, possible variations in available methods, and finally present a system that can be easily scalable and useful for research laboratories interested in studying plant mineral nutrition.

Hydroponic systems allow for easy separation of root tissue and precise control of nutrient availability

Hydroponics offers several advantages over soil-based systems. When removed from soil, root tissue is often mechanically sheared causing loss of tissue or damage. This is particularly true for fine root structures such as lateral roots and root hairs. Hydroponic systems that do not utilize an inert particulate media allow a less invasive separation of root and shoot tissues.

In soil systems, nutrient bioavailability changes throughout the soil matrix as nutrients bind to soil particles creating micro-environments within the soil. This heterogeneity could add an extra level of complexity in experiments needing a precise control on the external concentration of nutrients or other molecules. In contrast, the hydroponic solution is homogeneous and can be easily replaced throughout the course of the experiment.

Variants of hydroponic systems

All hydroponic cultures rely on a nutrient solution to deliver essential elements to the plant. In addition to the nutrients, the roots also need a steady supply of oxygen. When roots become anoxic they are unable to take up and transport metabolites to the rest of the plant body 7 . Hydroponic systems can be classified based on how they deliver oxygen and other nutrients to the roots: oxygen delivery by saturating the solution with air (classical hydroponics), by not submerging the roots at all times, or by allowing the roots to be completely exposed to the air (aeroponics) 8 . In hydroponics, nutrient solution can be saturated with air prior to its use and changed frequently, or air can be continuously supplied in the solution over the life cycle of the plant 9 . Alternatively, plants may also be grown on inert media ( e.g. , rockwool, vermiculite, or clay pellets) and subjected to wet-dry cycles by dripping solution through the media or periodically submerging the substrate in the nutrient solution 10 . In aeroponics, roots are sprayed with the nutrient solution to prevent desiccation.

Disadvantages of hydroponic systems

Although hydroponic cultures offer clear advantages over soil-based systems, there are some considerations that must be acknowledged when interpreting the data. For instance, hydroponic systems expose plants to conditions that may be seen as non-physiological. Therefore, phenotypes or plant responses detected using hydroponic systems may vary in magnitude when plants are grown in alternative systems ( e.g., soil or agar-based media). These considerations are not unique for hydroponic systems; differential responses can also be observed if plants are grown in different types of soil 11,12 .

The following protocol provides step-by-step instructions on how to set up a hydroponic system in a laboratory. This protocol has been optimized for Arabidopsis thaliana ( Arabidopsis ); however, similar or in some cases identical steps can be used to grow other species.

1. Seedling Nursery

• Pour seeds (40-50 mg) into 1.5 ml centrifuge tubes. (See Figure 1 for appropriate seed volume, ~ 50 µl). Label each tube with pencil (ink may fade away during sterilization). Place each labeled tube, cap open, into a desiccator 13 .
• Place the desiccator in an active fume hood and close the desiccator's valve.
• Aliquot 100 ml of bleach (NaClO 6.15%) into a 250 ml beaker and then place it in the desiccator.
• Quickly add 3 ml of 12 M hydrochloric acid to the bleach using a transfer pipette. Quickly close the lid of the desiccator as the reaction proceeds rapidly. Allow the sterilization to proceed for 4 hr (marking a tube with ink and seeing the ink fade away helps to visualize that a sufficient amount of chlorine gas has been generated). CAUTION: Chlorine gas is toxic; handle its residues with extra safety precautions in a functional fume hood. Contact local authorities or visit the webpage of the Environmental Health and Safety Department - University of Missouri (ESH-MU) 14 for chemical safety and guidelines for using a fume hood: https://ehs.missouri.edu/chem/.
• Fifteen minutes before sterilization is complete (3.75 hr), turn on a laminar flow hood and clean the surface using 70% ethanol.
• After 4 hr of sterilization open the valve, briefly remove the lid of the desiccator inside of the fume hood, remove the bleach, and dispose it according to institutional procedures. This step will release a large portion of the chlorine fumes. Seal the sterilization chamber and bring it to the laminar flow hood. Open the lid widely and aerate the sterilized seeds for approximately 40 min. After this time, use the seeds immediately or store in a dry place. Note: Vapor-phase sterilization of seeds is recommended but other methods such as alternate washes with ethanol, bleach and water as described in Alatorre-Cobos et al. 2 are equally efficient.
• Add 450 ml deionized water (DI water), 0.55 g MS media plus vitamins, 0.3 g MES (4-morpholineethanesulfonic acid hydrate), and a magnetic stir bar into a 1 L glass beaker.
• Dissolve and adjust pH to 5.7 using NaOH and then add 3.5 g phytoagar. Keep stirring the solution for 5 more minutes.
• Pour the whole solution into a graduated cylinder and add DI water up to 500 ml. Autoclave this 500 ml solution, with the magnetic stir bar inside, using a 1 L autoclavable bottle.
• After the solution has been autoclaved, stir the solution for 7-10 min using the magnetic stirrer in the bottle.
• After the media has cooled down to 50-60 °C, pour the media into plates under sterile conditions and let it solidify. Plates can be stored for later use in the cold-room.
• Turn on the laminar flow hood 15 min prior to use and clean the surface with 70% ethanol. The following items are required: sterile seeds, filter paper, toothpicks, micropore tape and ¼ MS plates.
• Place the sterile seeds on a sterile filter paper. Slightly wet one end of a sterile toothpick (with sterile water or by poking the ¼ MS media). Use this moisturized end to pick the seeds from the filter paper and then lay them onto the media surface.
• Spread the seeds across the plate at a density of approximately 1 seed per cm 2 ( Figure 2 ). Then use micropore tape to keep the plate lid attached to plate body. This type of tape helps to prevent contamination while allowing gas exchange between the air and the microclimate inside the plate.
• Before germination, stratify seeds by keeping the plates two days in the cold room covered from light.
• After stratification, place the seeds in a growth chamber or in a place with optimal growth conditions (23 °C, 16 hr light/8 hr dark and 60% relative humidity for Arabidopsis ). Seedlings will be ready for hydroponics 10-12 days after germination. Note: During germination there may be significant condensation under the lid of the plate, to prevent drowning, the excess water should be discarded under sterile conditions in a laminar flow hood.

2. Hydroponic Setup and Transplant Process

• Prepare the stock solutions of each macronutrient in different bottles ( Table 1 ) and all micronutrients except Fe-EDTA in a sterile bottle (sterilize by filtration using 0.22 µm membranes). Always add Fe-EDTA at last when mixing the solution. Prepare a 10x nutrient solution in advance of the experiment but autoclave and store at 4 °C. Use or change the nutrients only when the nutrient solution has reached room temperature.
• Make an incision in the foam, running along its length using a razor blade (see Figure 3 ). Prepare one plug per plant.
• Liquid-autoclave foam tube plugs soaked in DI water.
• Cut the foam panel into smaller boards, making sure that the width and length of foam boards are 0.5-1.0 cm less than size of the container (see Figure 4 ).
• Use a cork borer to create holes on the foam board. The density of the plants should be evenly distributed, ideally 1 plant per 10 cm 2 . This density will keep plants neatly separated from each other; higher densities however are possible and will not preclude the success of the experiments. Make sure the size of the holes matches the size of the plugs (see Figure 4 ).
• Fill the containers with the nutrient solution. Make sure that the depth of the solution is enough for root development (at least 5 cm). Then carefully place the foam boards onto the solution's surface.
• Set up the air-pump system to provide oxygen into the solution (see Figure 5 ). Note: Fill in the hydroponic container with nutrient solution the same day seedlings are being transplanted. Covering the sides of the container from light will help to prevent algal growth.
• Use small tweezers to gently pull each seedling out of the medium plate and lay the root along the incision of the foam tube plug. Carefully plug the foam tube holding the seedling into the foam board then place the board back to the hydroponic container. See Figure 6 for appropriate manipulation.

3. Hydroponic Experiments

• To replace the nutrient solution, prepare fresh hydroponic solution as described in step 2.1. Remove the foam board containing plants from the hydroponic container and place it in a temporary container filled with water or hydroponic solution.
• Discard the old solution, rinse the container briefly three times with DI water. Add the freshly prepared hydroponic solution into this container and gently place the foam board with plants back into the hydroponic container. Replace the hydroponic solution twice a week.
• Adjust the composition of the hydroponic solution shown in Table 1 to modify the final concentration of an element of interest. For example, to induce iron (Fe) deficiency, modify the hydroponic solution to decrease the concentration of Fe-EDTA. Include a set of control plants grown on full (or replete) hydroponic solution, without any modification, for comparison.
• To manipulate the nutrient solution with a toxic element, first prepare an independent stock solution of the desired toxic element, preferably 1,000x concentrated. Use a pipette to spike the hydroponic solution with the toxic element at the desired final concentration using the 1,000x concentrated stock.
• For example, in order to make 3 L of hydroponic solution containing 20 µM of cadmium, prepare a 0.5 M CdCl 2 stock, and add 120 µl of the 0.5 M CdCl 2 stock into the 3 L hydroponic solution. Include a control set of plants grown on hydroponics without CdCl 2 for comparison. CAUTION: Toxic elements such as cadmium, arsenic and lead are very dangerous for human health and the environment. Please contact local authorities or visit the webpage of the EHS-MU (https://ehs.missouri.edu/train/chemical.html) 14 for environmental and health safety guidelines prior to conducting experiments.
• As almost all the material used to prepare the hydroponic set up can be reused, clean the different parts with diluted bleach (NaClO 0.6%).
• After rinsing with bleach, rinse all materials thoroughly with DI water. Keep containers, foam boards, and aquarium bubble stones in a dry place for future use. Foam plugs are ready for reuse after removing the roots and being autoclaved.

Representative Results

In this section, the results of two types of experiments, using the hydroponic system described here, are presented. In the first experiment, the nutrient solution was modified to obtain different concentrations of zinc. We also modified the nutrient solution by adding non-lethal concentrations of the toxic element cadmium ( Figure 7 ). In the second experiment, we used inductively coupled plasma optical emission spectrometry (ICP-OES) 1 to measure the elemental composition of roots and leaves of plants grown in the hydroponic solution containing cadmium ( Figure 8 ). This experiment illustrates the advantages of obtaining roots and leaves separately.

Experiment 1

Arabidopsis seedlings (Col-0) were grown in the hydroponic system described in protocol steps 1 and 2. Plants were allowed to grow for a total of 3 weeks before being treated with different zinc concentrations ( Figure 7A-B ) or a non-lethal concentration of cadmium ( Figure 7C ). Six days post treatment, plants grown at high zinc concentrations (> 42 µM) showed delayed growth due to Zn toxicity, while plants without extra zinc added also show delayed growth compared to plants grown with 7 µM Zn 2+ . Figure 7 also shows the reduction in shoot growth, root growth, and chlorotic leaf symptoms typical of plants exposed to cadmium ( Figure 7C ).

Experiment 2

Col-0 plants were grown as described in steps 1 and 2. After two weeks, the non-modified (replete) solution was replaced with 80 ml of hydroponic solution containing 20 µM Cd. After 72 hours, root tissues were washed by transferring the whole foam board with plants to a new vessel containing 80 ml of Tris 20 mM (pH 8.0) and 5 mM EDTA. This solution will remove the heavy metals bound to the surface of the root. Plants were incubated in the EDTA-containing solution on a rotary shaker for 5 minutes. EDTA solution was then replaced by 80 ml of DI water and plants were incubated on the rotary shaker for an additional 5 minutes. This rinsing step with DI water was repeated twice. After rinsing the plants with DI water, leaf and root tissues were harvested independently and processed for ICP-OES 1 . Figure 8 shows that the elemental composition of leaves is different from roots, where macronutrients (Ca, K, and Mg) in leaf tissue are present in higher concentration compared to roots. On the other hand, micronutrients such as Zn and Fe are preferentially accumulated in roots. The concentration of the non-essential element cadmium was found to be higher in roots compared to shoots.

Figure 1. Vapor-phase sterilization of Arabidopsis seeds. ( A ) Amount of Arabidopsis seeds per 1.5 ml centrifuge tubes. ( B ) Tubes containing seeds with caps open in the tube rack holder ready for sterilization, one tube with an ink-marked on the cap is included. ( C ) Sterilization set up inside a desiccator, lid and valve closed. ( D ) The ink-mark on the lid of a tube included in the seed sterilization process with strong color of ink-mark before and after sterilization. Please click here to view a larger version of this figure.

Figure 2. Seed plating step. ( A ) Seeds are placed on sterilized paper before plating. A sterilized toothpick is also required for this step. ( B ) Slightly wet the end of the toothpick with the media or water on the side of the medium plate. ( C ) Seeds are moved to ¼ MS plates. ( D ) An ideal density of seeds is ≈1 seed/cm 2 . Please click here to view a larger version of this figure.

Figure 3. Foam plug used to hold seedlings in the nutrient solution . An incision on half of the foam tube plug helps holding the seedling during transplanting from plates to hydroponics. Please click here to view a larger version of this figure.

Figure 4. Foam board preparation. ( A ) Check the size of the template foam board with the container size before preparing foam boards in large quantities. Two small perforations made at center of the foam board make it is easier to hold and handle the foam using tweezers. ( B- C ) A cork borer is used to create holes on the foam board. ( D ) Check the proper fit between the foam tube plug and holes created on the foam board. Please click here to view a larger version of this figure.

Figure 5. Air-pump setting for hydroponic experiment from top-view (A) and side-view (B). The numbers indicate: 1 - pump supplying air; 2 - plastic tubing connecting the air pump with the valve system to control the air-flow; 3 - the valve system; 4 and 5 - plastic tubing connecting the valve system with bubble stones for aeration; 6 and 7 - bubble stones (sold for fish tanks). Please click here to view a larger version of this figure.

Figure 6. Transferring seedlings to the hydroponic system. ( A ) Use tweezers to take a seedling out of the medium plate. ( B ) Place the seedling root along the incision on the foam tube plug. ( C ) Insert the foam tube plug into the foam board. ( D ) A completed foam board setting with seedlings ready to be placed on the nutrient solution. Please click here to view a larger version of this figure.

Figure 7. Nutrient solutions can be modified to test deficiency or toxic effects of elements. 4 week-old hydroponically grown Arabidopsis 6 days after treatment: ( A-B ) plants grown with 0, 7, 14, 21, 28, 35, 42, and 50 µM of Zn. Plants grown at high Zn concentrations (> 42 µM) show delayed growth (toxicity) while plants without Zn added also show delayed growth (nutrient deficiency) compared to plants grown with 7 µM Zn 2+ . ( C ) Plants grown in the absence (left) or presence of 20 µM Cd in the nutrient solution (picture was taken after 6 days of Cd exposure). Cadmium exposure induces chlorosis and reduces growth. Please click here to view a larger version of this figure.

Figure 8. Elemental composition of roots and shoots from plants grown hydroponically. Shoots contain more macronutrients (Ca, K, Mg) compared to roots while the essential micronutrients zinc and iron are more concentrated in roots. Similarly the non-essential element cadmium is preferentially accumulated in roots. Error bars represent the 95% confidence intervals (n = 14, shoots and n= 9, roots). Please click here to view a larger version of this figure.

Table 1. Effective concentration of nutrients in the hydroponic solution.

The health of seedlings used for hydroponics is one of the major factors contributing to the success of a hydroponic experiment. Sterilization of instruments, seeds, and culture media also play an important role in reducing the risk of contamination and provide a good start for the plants before they are transplanted into the hydroponic system. A working environment with facilities such as an autoclave, fume hood, cold-room (4 °C), and growth space with controlled conditions (light intensity and temperature) is necessary for a good experimental set up.

The freshness of the nutrient solution also determines the plant health and in turn determines the success of a hydroponic experiment. Since water evaporates faster under direct lighting, the concentration of salts will change due to a reduction of total solution volume; therefore it is best to change the hydroponic solution at least twice a week. However, if large, deep containers equipped with an air pump system are used it may not be necessary to replace the nutrient solution for experiments that are short in duration. Note that in the case of Arabidopsis we used Magenta vessels (77 mm width x 77 mm length x 97 mm height) but other, larger containers can also be used to accommodate larger plants.

For researchers interested in plant nutrients, hydroponic experiments provide a unique setting to test plant phenotypes and responses to different nutrient availability 17 . By manipulating the concentrations of the elements of interest, researchers can set up different experiments to test the effects of sufficiency, deficiency, or toxic concentrations of essential and non-essential nutrients. Compared to the soil-based system, the hydroponic system provides a more homogeneous nutrient medium to the plants with less risk of soil-borne diseases. In addition, both root and shoot tissues can be harvested and separated easily for further analyses on specific plant tissues.

In the representative section, we introduced two examples in which a simple hydroponic system was used for more detailed studies on plant nutrition. In the first example, by growing plants on a zinc concentration gradient, we were able to illustrate the level of control that can be achieved on nutrient composition using this hydroponic system. Plants grown with 7 µM Zn grew much more vigorously compared to plants grown in 50 µM Zn, while plants grown without extra Zn added were stunted compared to plants grown with 7 µM Zn. This was in part due to the length of time the plants were allowed to grow under sufficient conditions; earlier removal of Zn from the media is likely to induce stronger zinc-deficiency symptoms. Applying the same principle, we were able to induce toxicity using the non-essential metal, cadmium, which is known to impair plant growth.

In the second example, the elemental composition of Col-0 roots and shoots treated with 20 µM Cd for 72 hr was determined by ICP-OES. We found differences in all detected metals between roots and shoots. Macro-elements were found in higher concentrations in the shoots relative to the roots, while iron and zinc were found more abundant in roots. Cadmium followed a pattern similar to iron and zinc, being more concentrated in roots compared to shoots. These data reinforce the idea that leaves and roots provide different information about the ionome status of the plant and therefore both tissues need to be analyzed separately to understand mineral nutrition and composition at the whole plant level. Besides ICP-OES several spectroscopic methods such as Atomic Absorption Spectroscopy (AAS) or Inductively Coupled Plasma Mass Spectrometry (ICP-MS) can also be used to measure the elemental composition ( ionome ) of plant tissues 18-20 .

In a hydroponic experiment, the symptoms and phenotypes of plants responding to different nutrient conditions represent the beginning of what could be extended into more elaborated analyses such as gene expression (transcriptomics) and protein abundance (proteomics). These -omic techniques are keys to integrate plant metabolism by considering processes in a tissue-specific manner.

Disclosures

The authors declare that they have no competing financial interests.

Acknowledgments

This research was supported by the University of Missouri Research Board (Project CB000519) and the US National Science Foundation (IIA-1430428 to DMC). Nga T. Nguyen was supported by the Vietnam Education Foundation Training Program (Exchange visitor program No. G-3-10180). We also thank Roger Meissen (MU Bond Life Sciences Center) for his assistance and expertise during the video recording and editing sessions.

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Hydroponic Farming As A Solution To Systemic Food Insecurity

As many communities around the country struggle with food insecurity, hydroponic farming has been introduced as a viable solution.

Many low- and moderate-income (LMI) communities are challenged with a lack of access to grocery stores and local, nutritious food within reasonable proximity. Residents of these communities are left to survive on unhealthier diets. This is a systemic issue disproportionately affecting people of color, who are more likely to live in places shaped by decades of disinvestment and neglect.

“In the 1940s through the 1960s, redlining, racial covenant, and mortgage discrimination led to white flight and decades-long disinvestments in the urban communities where people of color remained,” said Chih-Wei Hsu, a research associate at Inclusive Action in The City, a Los Angeles nonprofit community development organization . 

Redlining – the systemic discriminatory practices that walled communities of color out of public and private investment for decades – is often understood as a housing market issue. But its harmful tentacles extend to other corners of economic life as well, including a community’s food resources.

“This results in not only suffering public services but also the grocery companies’ disinterest in building store locations in these neighborhoods and pulling out their existing stores,” Hsu said.

Hunger, public health and housing justice each have large and dedicated groups of policymakers and activists who work hard to make progress in their issue spaces. These three silos can each benefit from collaborating to increase food security in the kinds of communities Hsu described – and by finding creative, high-impact solutions.

One such tool is the hydroponic farm. Hydroponic farming is a practice of indoor farming that can be conducted almost anywhere in the world, including in cities and LMI neighborhoods within them.

A Problem With Deep Roots

Residents of city environments experience systemic food insecurity due to a combination of financial and locational issues. Not only do cities lack space for traditional farming, but residents often live outside of reasonable proximity to a grocery store. Hydroponic farms in cities can give communities power over their own food.

Hydroponic farms are indoor farms that use LED lighting along with mineral and nutrient based water to mimic the necessary elements needed to grow plants. The LED lights act as UV rays and the nutrients and minerals within the water replace the need for soil, allowing the entire process to be conducted indoors. These farms use a vertical planting system, meaning crops are grown on top of each other rather than in horizontal rows seen in traditional farms. This allows for more crops to grow locally in a more concentrated space.

This style of farming has potential to thrive in urban areas year-round. I personally come from Boston, a city environment that entirely lacks a space for farmland. Despite this, I spent three years in high school working on a farm; a hydroponic farm, that is. 

Hydroponic farms are able to produce higher yields than traditional farms . The plants receive all nutrients through water, allowing them to spend more time growing upward, rather than extending their roots through soil in search of food. Hydroponic farms use a fraction of the water needed for a traditional farm.

Almost 19 million Americans in low-income communities are more than a mile from their nearest grocery store. Many LMI residents of urban centers have no access to high-quality fresh produce – and what access they do have involves inflated prices and goods shipped in from far away. Locally grown food is more likely to generate positive economic feedback loops in these communities. 

Real World Application

I got to see the impact of hydroponic farming up close as a teenager. My high school was able to purchase a hydroponic farm from Freight Farms with funds from a grant, enabling us to grow herbs and vegetables right in the center of Boston throughout all four seasons.

Freight Farms converts shipping containers into hydroponic farms. The shipping container design allows for a high concentration of plants, as well as the ability to build upward rather than outward.

Freight Farms is just one of many companies specializing in vertical and hydroponic farms. Many share the goal of making farming more sustainable in the face of climate change. 

Across the country, organizations that specialize in hydroponic farming are aiming to provide fresh produce to individuals and families in low-income communities. A non-profit called Manna House in Huntsville, Alabama, grows produce in a 15,000 square foot hydroponic garden. Their mission is to provide struggling families in the area with healthier food.

Yellow Hammer Farms in Birmingham, Alabama, provides city residents with fresh hydroponic produce grown in their own neighborhood.

Bringing hydroponic farms to cities with the goal of providing low-income residents with healthy food is something cities across the United States could implement to combat food insecurity. Thousands of families feel the detrimental effects of hunger and unhealthy diets every year. As climate change continues to reshape our planet and future, these problems will only worsen. Hydroponic farming has potential to be the future of agriculture, able to provide locally grown food in any area of the world, while using less natural resources to do so.

As my classmates and I learned first-hand, all it takes for a community to take control of its own food future is a bit of financing on the front end to acquire and launch a local hydroponic farming facility. In our case, it took grant funding to make that possible. Lawmakers and other stakeholders working toward solutions to combat lasting systemic oppression of people of color should support such projects by making those start-up funds more widely available. Solutions like these can move us closer to a future that enables people in all communities to thrive.

Kyle Kelley is an intern at NCRC.

Photo by Petr Magera on Unsplash

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