As the world population nears 10 billion by 2050, overall food demand is expected to increase by over 50%, according to the World Resources Institute. Climate change will make feeding that population more difficult in some regions.
Increased heat stress, rainfall intensity, flooding and drought could reduce crop yields and leave once arable land unusable, leading to food insecurity, according to the Environmental Protection Agency.
To grow more food with less land, some farmers and scientists have pointed to the potential of hydroponics, a method of vertical farming.
Hydroponic farming involves suspending plants in a water solution with each essential nutrient necessary for a plant to grow, removing the need for soil. This way, plants can be stacked on top of one another in a climate-controlled greenhouse almost anywhere, instead of taking up acres of fertile land.
“As kids we are taught soil has all these purposes. It stabilizes the plant, it provides nutrients to the plant, it provides water to the plant,” said Lee Rouse, a former Louisiana State University Agricultural Center horticulture extension agent. “But what’s interesting is that none of that’s actually true. You don’t need to have soil to do any of that.”
Hydroponics vs. Traditional Farming
Rouse, a Baton Rouge native, studied hydroponic systems as an LSU graduate student.
As a horticulture extension agent for East Baton Rouge Parish, Rouse was tasked with translating academic research to the public and commercial farming industry.
“Originally what [hydroponics] was used for was by scientists trying to determine what elements were essential for plants. We now know there’s 16 essential nutrients that every plant on earth needs to go from seed to seed, from generation to generation,” Rouse said.
At his hydroponic field days, Rouse would explain the nuances of the vertical farming systems he has used to grow foods ranging from leafy greens like lettuce and basil to fruits like strawberries.
He said he envisions a future in which hydroponics can be used to give abandoned buildings a new, more efficient purpose.
“One way it could have some reversable effects on global warming is, if you take that building and instead of turning it into a hotel, you take one acre of land, 20 stories tall, and now you can grow 20 acres of food on that without actually deforesting 20 acres,” he said. “It would take 20 acres of flat earth to make the same food crop, so why don’t we just reforest that? Over time this could have a long-term effect on carbon emissions.”
Another advantage of hydroponics is the ability to grow more food in a localized area without the need to transport as many materials. Transportation of food materials results in carbon emissions from trucks burning fossil fuels.
“The big mitigation potential that a lot of people are focusing on is this idea of localization of food product,” said Robert Newell, associate director of the Food and Agriculture Institute at the University of the Fraser Valley in British Columbia, Canada. “When you reduce transportation distances, you’re really reducing the need for greenhouse gas emissions.”
Newell researches the potential to produce animal feed by growing plants atop a mesh platform and using a sprinkling system to deliver nutrients.
He said localization of food production using hydroponics could also offset transportation costs because, “you’re creating more biomass and with a minimal land footprint.”
“You’re getting more bang for your buck,” he said. “What it translates to is, rather than having to transport two trucks of material, you transport fewer.”
Rouse said previous attempts at hydroponics were centered around this idea of localization, specifically its use during World War II. American soldiers stationed in the Pacific used hydroponics to grow food in areas where supplies were limited.
“Some of the very rocky parts where they’d land in ships didn’t have soil, and it was very difficult to get food. It definitely kept food in production where they didn’t have to be shipped in on a regular basis,” he said. “You can grow it locally and in very poor climates, like in Las Vegas or Pacific islands. and have the same product. Why waste fossil fuels on shipping the product?”
Rouse said there are major limitations that have held hydroponics and other methods of vertical farming back from being widely adopted.
“The upfront cost is huge,” Rouse said.
Small hydroponic farms spend on average 6% of total spending on nutrients, seeds and growing mediums. The rest of the cost goes to maintaining a sensitive growing environment within a polycarbonate or glass greenhouse, according to Pure Green, a hydroponic supply manufacturer in Arizona.
These greenhouses are energy intensive. Large hydroponic farms with more than 10,000 square feet of crops spend an estimated 25% of total spending on energy to simply power climate control systems.
If the energy demand to supply vertical farms is greater than the reductions in greenhouse gas emissions they bring, large-scale adoption of the technology would do more harm than good, Newell said.
“In a place like Alberta, [Canada], what you’re doing is you’re actually using more of a fossil fuel-based energy system, and it turned out that growing with green versions of conventional methods was more climate change advantageous [than hydroponic systems],” he said.
Experts are quick to note that there is no silver bullet to food insecurity and the many ramifications of climate change on agriculture. Rouse and Newell are more comfortable calling hydroponics a potential adaptation.
“Unfortunately, I don’t think hydroponics are going to reverse climate change. But if we stay on the projected course and nothing changes and we are degrading land and it’s becoming unfarmable, then hydroponics is a good back up plan for that,” Rouse said.