Scientists show how to turn lunar soil fertile for agriculture

If humankind is ever to
establish long-term bases on the moon, there will be a need for
a regular source of food. It is not practical, however, to think
you can plant corn or wheat in plain lunar soil in greenhouses
on the moon and expect a bumper crop – or any crop at all.
But scientists are taking steps toward making moon
agriculture a real possibility. Researchers said on Thursday
they have found a way to turn inhospitable lunar soil fertile by
introducing bacteria that enhance the availability of
phosphorus, an important plant nutrient.
They performed experiments growing a relative of tobacco
using simulated moon soil, more properly called lunar regolith,
in a laboratory in China. They found that such soil treated with
three species of bacteria produced plants with longer stems and
roots as well as heavier and wider clusters of leaves compared
to the same soil without the microbes.
The action of the bacteria, the researchers said, made the
soil more acidic. This resulting low pH environment caused
insoluble phosphate-containing minerals to dissolve and release
the phosphorus in them, increasing phosphorus availability for
the plants.
“The importance of these findings is that we may be able to
use these microbes to turn the lunar regolith into bio-friendly
substrate for plant cultivation in future lunar greenhouses,”
said researcher Yitong Xia of the China Agricultural University
in Beijing, lead author of the study published in the journal
Communications Biology.
In a study published last year, researchers in the United
States grew a flowering weed called Arabidopsis thaliana in 12
thimble-sized containers, each bearing a gram of actual moon
soil collected during NASA missions more than a half century
ago.
Arabidopsis, also called thale cress, is a plant widely used
in scientific research. In that study, Arabidopsis did grow, but
not as robustly in the lunar soil as in volcanic ash from Earth
used for comparative purposes, suggesting that lunar soil could
use a little help to become more fertile.
The new research involved benth, scientific name Nicotiana
benthamiana, another plant often used in research.
The study used simulated regolith rather than the real thing
because genuine lunar soil, as one might imagine, is in short
supply on Earth. The researchers used volcanic material from the
Changbai mountains of China’s Jilin Province to create soil with
similar chemical and physical properties to lunar regolith.
The three bacteria used in the study were: Bacillus
mucilaginosus, Bacillus megaterium and Pseudomonas fluorescens.
The researchers tested other bacteria as well, but those did not
produce the same beneficial effects.
“Considering the huge scientific and economic potential of
the moon, we will need to set up manned lunar bases in the
future. But how can we provide food, oxygen and water for the
crew members? Of course we can carry them to the moon by
rockets, but that is economically unsustainable. A greenhouse
for plant cultivation on the moon could greatly reduce the need
of Earth-moon transportation,” Xia said.
A plant cultivation system on the moon could help meet
long-term food and oxygen requirements for human crews, Xia
added. Plants produce oxygen as a byproduct of photosynthesis,
the biological process in which they turn sunlight into energy.
“We have several ways to grow plants on the moon, including
transporting horticultural soil to the moon, building up a
hydroponic system (growing plants without soil) or using soil
substitute like hydrogels (gels whose liquid component is
water). Those methods do not need lunar soil, but all of them
would consume huge carrying capability on rockets, making these
plans very expensive,” Xia said.
“In contrast, our technique, which is a kind of in-situ
resource utilization, applies microbial improvement to the lunar
soil, making it more fertile and capable for plant cultivation,”
Xia added. “Our study achieved the same goal with much less
consumption of carrying capability comparing with other plans.”