When you think about agriculture, you probably imagine a few basic things in your mind. Huge stretches of flat land, massive harvesting machines, the heat on your skin from sunlight and, perhaps most importantly, soil. This image in your mind is a common one. Humans have been tilling, seeding, and farming land since the dawn of civilization, and modern industrial farm techniques tend to dominate our conception of agriculture. 

However, in recent years, another method of farming starts to come into our sight. One that requires less water, and surprisingly, no soil! The amazing method is called hydroponics, and though its implementation may sound far-fetched and more akin to science fiction, what other options does NASA have for farming in space? 

The first space salad 

In 2015, fresh leafy greens were on the menu for NASA astronauts on the International Space Station (ISS) for the very first time. They had been produced hydroponically on the ISS—the result of decades of work on alternative methods of cultivating food that would be viable in a low-gravity environment. Beyond its use on the ISS, scientists have been keen to understand how controlled environment agriculture (CEA) can be part of a controlled or closed ecological life support system (CELSS) for deep space missions in extra-terrestrial colonization. With all these stunning advancements, there was a reason the lead character of Andy Weir’s breakthrough novel, The Martian, was an astronaut botanist. 

According to the food scientists at NASA, one of the significant challenges to astronaut health and well-being on lengthy missions through space is maintaining enough food variety for a balanced, nutritional diet. Not only does this food need to last for extensive periods of time, but it also must maintain its nutritional value for that duration. Hydroponic farming is an exciting solution to this problem, growing fresh pick-and-eat produce that can fill an individual’s dietary needs, as well as providing some rare comfort. (NASA Kloeris, 2016). 

While this is an amazing development for the future of space travel, are we missing out on potential applications of hydroponics on Earth? 

Ancient roots for a modern word 

The word “hydroponics” comes from the Greek root "hydro" meaning water and "ponos" meaning labor. This method of farming does not use soil, but only nutrient solutions made from water and concentrated minerals. Some hydroponic farming methods use a growing medium or substrate (such as rock wool or clay pebbles) to provide a plant’s root system with something to attach to and support its weight. (Soto, 2020) 

While hydroponic farming may sound like a space-age invention, the earliest archaeological evidence of hydroponics dates back to the Hanging Gardens of Babylon which were built around 600BC. (Folds, 2018) Nonetheless, formal research and publications on modern hydroponics did not begin until the 17th century with Francis Bacon's work ‘Sylva Sylvarum’ on water culture. (Singer, 2021)

Plants in space 

Having zero gravity means that soil-based farming is not actually possible in space. Reasons for this include weight limitations, floating particles, and the risk of growing germs. An environment in space is a highly controlled one, and any unknown or loose particles can easily create troubles to an astronaut’s hard work, and even put them in catastrophic danger. 

Hydroponic agriculture as an alternative appears to be a perfect solution to these varied issues. Although the hydroponic farming approach did not originate from low-Earth orbit missions, its development in the space program has further advanced the practice. 

Like much of what NASA does when they turn their minds towards a problem, even existing solutions are improved and enhanced. Hydroponics is no exception in that regard. Modern hydroponics is a much more advanced and efficient process than its ancient predecessor methods. 

Bringing space science down to Earth 

All that said, there are several reasons why advancements in hydroponics should be brought back down to Earth. One of them is water conservation. The use of water in modern industrial agriculture is the largest consumer of freshwater resources on the planet. It accounts for 70% of the freshwater used by humans per year. (USGS, 2021) To that effect, precision farming technology has enabled farmers to assess soil moisture and irrigate more accurately, but a NASA spin-off technology in hydroponic farming can still go far beyond that. 

In joint US Government research study of hydroponics and plant water conception, a leaf sensor was used to measure leaf thickness using electrical impulses that could determine water content. At a U.S. Department of Agriculture research farm (National Science Foundation, 2010), researchers found that the plants did not require the amount of water that modern irrigation schedules called for. Crops attached to leaf sensors used 25 percent less water compared to when they were watered under standard irrigation practice. (O'Brien, 2010). 

Because of hydroponic research, we now know plants are not as thirsty as we once thought. 

Solutions for nutrient solutions 

Another product of hydroponic studies is increased efficiency in water use through the proper recirculating of nutrient solutions. An important aspect of hydroponics is the use of nutrient based solutions—this is a mix of concentrated nutrients that are vital to the plant’s growth. By injecting this into the plant’s water, it helps the plant to absorb vital minerals and grow in the same way a rich soil would. 

In these studies, a process analyser used ultraviolet spectrometry and specialized software to detect dissolved nutrients, organics, and metals in hydroponic solutions. (NASA, , 2010). Since different plants absorb nutrients in a solution at different rates, reports would inform growers when the concentration of some nutrients in a hydroponic solution drops below standard and needs to be replenished. This approach facilitates both effective water uses and optimal growth for plants. 

The human impact 

Another important application of hydroponic farming on Earth is meeting the need of an ever-growing, and ever-hungry population. According to the United Nations World Population Prospect, the world population is projected to reach 9.8 billion by 2050 from 7.6 billion in 2017 (UNSEDA, 2017). Food production is expected to increase anywhere between 59% to 98% to feed this growing demand. 

This means, that in the next four decades we will have to produce as much food as we have had in the past 8,000 years!

In a hydroponics farming environment, plants grow faster and more prominently, while using fewer resources than their soil-based counterparts. This is so because they can absorb nutrients more quickly and directly from the nutrient solution. Even a small root system can deliver the nutrient, and the plants can focus on growing upwards. 

Studies across the world have shown that crop yields from hydroponics can exceed record yields on Earth. Studies show that the growth of wheat and potato have been remarkably successful., though other vegetables have reacted well to hydroponic farming, too (Agriculture for Space: People and Places Paving the Way, 2017). 

Furthermore, there are no seasonal limitations on hydroponic growth, as the whole system is in a controlled environment without influence from weather or need for crop rotation. 

For example, the Biomass Production Chamber (BPC) at the Kennedy Space Centre worked almost non-stop for over 1,200 days from 1988 to 1996. With the superior growth rate and year-round "season," researchers produced, “five crops of wheat (64-86 days each), three crops of soybean (90 to 97 days), five crops of lettuce (28-30 days), and four crops of potato six tomato harvests per year.” A strong growth factor when compared to the minimal resources required for the production (NASA’s Biomass Production Chamber, 1996). 

Moreover, yielding loss due to pests, parasites, or soil-related diseases is also minimized, as the environment is controlled with minimal points of entry for unwanted influences. 

Soil loss and a loss for humanity 

According to the Global Land Outlook (GLO), a report launched by United Nations Convention to Combat Desertification (UNCCD, 2017), 15 billion trees and 24 billion tons of fertile soil is lost each year to ensure human security and well-being. This soil is lost through human actions focused on maintaining several key aspects of society, particularly food security, employment, and migration. Without a doubt, these are among the most critical aspects of modern human life, but these statistics are alarming. 

Soil protection is a vital topic to food production and environmental conservation. A call to develop and employ sustainable methods for the effective use of land is urgently needed to slow the rate of soil degradation and maintain the crop production necessary for the Earth’s ever-expanding population. 

Hydroponics, the future, & commercial markets 

The hydroponic approach to farming is not limited to experimental use on Earth. According to Globe Newswire, the hydroponics market size worth is expected to reach $22.2 billion by 2028. There are major players all over the world in the sector for hydroponics who are using technologically advanced and sustainably Controlled Environment Agriculture methods to grow nutritious vegetables. Through hydroponics, they can contribute to building a more secure local food supply system to feed an ever-growing world population. 

While astronauts and scientists continue to explore how to create a self-sustaining bioregenerative system for living in space, there is just as much to learn about living a sustainable life on Earth. With the increasing efficiency of hydroponics, we may be well on our way to a future where we can produce food in greater amounts and with minimum input, reduce waste, and minimize our dependence on external factors such as the environment, all while matching the pace of increasing food demand. All said, be prepared to witness an unprecedented revolution in agriculture. It is coming soon to a planet near you!