Mars offers rather inhospitable living conditions. Farming as we know it on Earth is difficult there, but perhaps not impossible: soil bacteria could help a future Martian colony set up agricultural fields.
Terrestrial soil bacteria can improve plant growth in Martian soil. They would provide them with vital nitrogen, which is not available in the Mars Regolith, American researchers report in the journal “Plos One“ . The bacterium could be an inexpensive way to make the Martian soil more fertile in the event of a long-term colonization to enable local food production. Regolite is the name given to the loose material that forms through the weathering of the parent rock of rock planets or, for example, on the moon.
Given climate change, possible epidemics or other events that could wipe out humanity, it is unlikely that humans will have a “one-planet species” can remain, write the researchers collaborating with Franklin Harris of Colorado State University (USA). For this reason, it is necessary to develop methods that enable alien farming on other celestial bodies, such as Mars. The harsh conditions on Mars make a possible arable farming very difficult.The surface material of Mars lacks many of the nutrients that plants on Earth need to grow, such as nitrogen for example. In addition, the atmosphere is thinner, the radiation stronger and the temperatures more extreme.
Lack of nitrogen
In their study, the researchers tackled the problem of nitrogen deficiency. They planted yellow sweet clover (Melilotus officinalis) in both conventional soil and man-made regolith. They then added nitrogen-fixing bacteria (Sinorhizobium meliloti) to half of the cultures. Such nodule bacteria can be found on the roots of many plant species on Earth, such as peas, beans and clover. They are able to bind nitrogen (N) from the atmosphere and then make it available to the plants in soluble form. The bacteria live by substances they receive from the plants.
The addition of bacteria improved plant growth, especially in the soil, but also in the regolith. The shoots of plants in the soil with bacteria were 2.5 times longer than those without, and the biomass of shoots and roots more than doubled. In fact, the plants also interacted with the bacteria in the regolith and formed corresponding nodules on their roots. However, the number of nodules in the regolith was significantly lower than in the soil: an average of 14.5 compared to 63.
Need further research
The researchers could not find the nitrogen in the regolith, presumably the growing plants had used up all the nitrogen themselves. In addition, no rotting of the plants occurred in the short period of the experiments. The nitrogen remained in the roots and did not end up in the environment.
“This work will improve our understanding of the interactions between plants and microbes and will help make the regolith on Mars more similar to the terrestrial soil.” the researchers write. For the development of useful “astro farming techniquesHowever, many more studies are needed.
According to analyzes by the Mars rovers, the regolith lacks many other micronutrients such as copper, boron and molybdenum in addition to nitrogen. To what extent and how Mars’ thin atmosphere affects plant growth is still unclear. In addition, the atmosphere receives only a fraction of the nitrogen available in the Earth’s atmosphere for nitrogen-fixing bacteria – 1.2 versus 78 percent.
#Clover growth in Mars-like soils boosted by bacterial symbiosis @plos @PLOSONE https://t.co/Ki5NlCBKe0
— Phys.org (@physorg_com) September 29, 2021
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