Jaclyn Fiola reached down to a cluster of seedlings growing in black pots and checked the chlorophyl levels of the recently sprouted radishes in one of Virginia Tech’s greenhouses.
The meter showed that all was normal.
That usually isn’t significant, but these are no normal plants.
The School of Plant and Environmental Sciences’ soil judging team is working with NASA to grow vegetables in lunar soil simulant for the “Plant the Moon” challenge, a global experiment to see who can grow the best crops in a lunar environment.
“Working on this challenge allows the students to work toward solving a problem that must be addressed before people could inhabit the moon,” said Fiola, a horticulture Ph.D. candidate and coach of the team.
The experiments can impact plant growth on this planet, too. As the climate changes and the population grows, food will need to be produced closer to the people who need it, and in potentially challenging growing environments.
The students sifted the lunar soil simulant through their gloved fingers. The simulant, which is so low in clay that it’s basically finely ground up rocks, almost looks like flour. It’s primarily anorthosite, a feldspar mineral. It felt different, other-worldly. It’s coarse and rough, but isn’t quite like sand. It’s sharper and not uniform.
An unusual source of nutrients
The powder is far from an ideal material in which to grow plants, especially in greenhouse pots. The challenges were immediate. Compaction and waterlogging presented themselves right off the bat.
“The material had no organic matter and no available nutrients for the plants,” said Clare Tallamy, a sophomore from Leesburg, Virginia. “We considered that when choosing our treatments. We targeted decreasing the pH in the soil and then also adding organic matter to it.”
While on a call with Professor Greg Evanylo, a solution to the team’s organic matter problem presented itself — treated human waste, biosolids that would be readily available on an inhabited lunar surface.
“It solved two problems at once,” Fiola said. “We need to be cognizant of transportation of materials to the moon and keep those to an absolute minimum. Biosolids would be created on the surface and present a great growing material.”
With help from Blue Plains Advanced Wastewater Treatment Plant, a bright orange bucket full of treated human waste arrived.
“The students were a little apprehensive at first, but they dove in,” Fiola said. “They stuck their hands into the bucket and textured biosolids just like we would soil. You just wash your hands well after.”
Biosolids decrease the pH as well, so it creates the acid needed for plant growth. An easy way to decrease the pH would be to use fertilizer, but the team felt that was an easy way out and decided to use powdered vinegar to facilitate vegetable growth instead.
“NASA limited us to 50% added material to the lunar simulant, which was a challenge,” said Kathlynn Lewis, a senior from Charlottesville, Virginia.
The team added sand to the mixture, which doesn’t do much in terms of nutrients but did help improve the consistency of the mixture in the end.
“The idea was to prove that using a specific particle size would help,” Lewis said. “As long as you have something that is of that size and solid, it’s going to do approximately the same thing, and sand is relatively inactive in the soil.”
Radishes were chosen because the team wasn’t quite sure how the mixture’s compaction properties would work and because people can eat the roots and the vegetation, meaning nothing gets wasted.
“Agriculture on other planets can help us to grow here on Earth because we face some of the same issues,” Fiola said. “High pH and low nutrient soil are something we face more and more often. We need to come up with innovative solutions to these challenges. These innovations are certainly better for the environment than just adding fertilizer, which is what we’ve always done.”
Not everything directly applies, as there are unique challenges with lunar simulant — such as the gravity difference and transportation challenges — but the knowledge of how to quickly add organic matter to less-than-hospitable soil does translate to this planet.
Awards for the challenge will be announced at the Global Summit attended by NASA officials and scientists.