Exploring the moon and establishing a sustainable human presence on it has been a long-standing goal for scientists and space agencies around the world. If humankind is ever to establish long-term bases on our celestial neighbor, there will be a need for a regular source of food.
However, one of the key challenges to achieve this is the lack of fertile soil for growing plants. In a recent study, scientists have found a way to turn inhospitable lunar soil fertile by introducing bacteria from Earth.
Agriculture in Lunar Soil
Previous studies have shown that lunar soil possesses different elements that are important for plant growth. This has raised hopes that establishing greenhouse farms on the moon can make use of local resources to help lunar bases sustain life, instead of carrying huge amounts of soil or bulky hydroponic systems from Earth.
According to Yitong Xia of China Agricultural University in Beijing, the advantage of growing plants on the moon is not limited to providing food for the astronauts who will establish colonies in the lunar base. Crop production will also help in refreshing the air as plants provide oxygen, purify water, and even provide emotional comfort for the settlers.
Prior studies, however, revealed that lunar regolith is bad at hosting crops. It lacks carbon and nitrogen compounds needed for plant growth. Aside from this, the vital elements that it possesses, like phosphorus, are mostly locked within insoluble compounds that plants might find difficult to absorb. This means that if plants are grown directly in lunar soil, their growth would be limited, and they would die early.
Transforming Lunar Soil Into Fertile Ground
In a recent study, Xia and his fellow researchers explored ways to make moon soil more fertile. Microbes on Earth helped make our home planet more habitable over billions of years by physically and chemically converting hard rock into porous, biologically active soil. The research team suggests that carrying Earth microbes to the moon to liberate insoluble elements would prove much easier than flying tons of fertilizer elements from Earth.
To confirm their theory, the team experimented with Chinese volcanic powder with composition that is similar to samples collected by the Apollo 14 mission in 1971. They investigated the ability of five species of bacteria to convert insoluble phosphorus in the simulated lunar soil into a soluble form that can be used by plants. These are also the same species in microbial fertilizers of agriculture.
Samples of simulated lunar soil were mixed with microbes in a sugary broth for 21 days. The researchers discovered that three species of bacteria more than doubled the amount of phosphorus within 10 to 21 days. Apparently, the microbes helped make the soil more acidic by liberating the phosphorus from the compounds it was trapped within.
In the next part of the study, the team grew Nicotiana benthamiana, a relative of tobacco, in a simulated lunar soil which was treated with three species of bacteria for 18 days. It was found that after 24 days of growth, the levels of chlorophyll in plants with these live bacteria were about twice the level in plants grown in simulated lunar soil with dead bacteria.
Additionally, plants grown in simulated lunar soil with three bacteria species for 18 days had longer stems and roots after six days of growth. They were also heavier and had wider clusters of leaves after 24 days of growth, compared to plants grown in simulated lunar soil with dead bacteria.
In the future, the researchers plan to mix these bacteria with algae or compost to see how they could further improve plant growth.
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