American scientists conducted a series of experiments on growing chickpeas in a simulation of the lunar regolith using manure and arbuscular mycorrhiza. The results showed that the mixture helped plants bloom, but all samples lacked chlorophyll.

There aren’t enough technological ships to conquer space. To successfully colonize other planets, humans will need to learn how to produce resources outside Earth, as resupplying from their own planets will likely be unprofitable and difficult. Plants in space can become a source of oxygen and nutrients for astronauts, thus reducing the consumption of food reserves and extending flight times.

Watercress can hardly be grown in lunar soils, and the addition of certain types of soil bacteria significantly increases the yield of crops grown in the lunar regolith. A new study published on the website bioRxivshowed the sheep chickpeas (Cicer arietinumgrown in a simulated lunar regolith) successfully survives for two weeks. This result was achieved thanks to soil renewal with arbuscular mycorrhizal fungi and fertilizers.

Lunar regolith does not retain water well and lacks the soil microbiome necessary for nutrient processing and nitrogen fixation, without which plants cannot develop properly. In experiments with simulations of Mars and lunar soils, the former always won by a large margin. The germination rate in such an environment is therefore much lower than, for example, in the Martian regolith.

To use lunar soil to grow crops, it must be fertilized; Such experiments are performed on lunar insufficiency simulations (LRS) that replicate the geochemistry, mineralogy, and particle size of the original soil. American researchers decided to improve the properties of lunar soil with the help of arbuscular mycorrhiza and vermicompost (VC), a fertilizer rich in nutrients, minerals and microbiomes.

Arbuscular fungi reduce the bioavailability of heavy metals, preventing their absorption by the host plant. They also produce glomalin, a glycoprotein that binds mineral particles together and makes soil more stable.

The researchers conducted experiments on growing chickpeas in the LRS for 120 days and at a temperature of approximately 23 degrees Celsius. Chickpeas were grown in eight pots: half were treated with arbuscular fungus, the other half were not. Samples were mixed with vermicompost in different proportions: 25% VC+75% LRS/50% VC 50% LRS/75% VC+25% LRS/100% LRS.

Scientists observed that the soil compacted in the first week, and on the 16th day, all the seeds sprouted. Increased LRS composition was associated with increased stress symptoms; The sample without vermicompost showed the highest growth at the germination stage. Previous studies have shown that this behavior leads to premature aging of the plant. Researchers explained this as a response to stress.

In the tenth week, the untreated group with mycorrhiza began to fade, while the treated group began to bloom. These chickpeas lived (aged) on average two weeks longer than plants with 100% LRS concentration. Crops matured in 120 days instead of the normal 100 days. However, all plants showed signs of chlorophyll deficiency. The result, the scientists noted, suggests that arbuscular mycorrhizal supplements and a mixture of lunar soil and fertilizer may help increase the suitability of the lunar regolith for plant growth.