We’ve previously written about the challenges presented by trying to grow crops in Mars like conditions. What we discover from these challenges have the potential to increase our growing potential on earth as well as prepare for the possibility of living on another planet.
An article in Science Daily discussed an ongoing experiment by the Wageningen University and Research Centre. The article is based on, we presume, a press release or similar as there is no mention of a published paper.
The article cites the results of the second round of an experiment using soil simulating that which may be found on Mars or the Moon and comparing the growth of different food crops in that soil with the same crops grown in normal compost soil. The researchers found no statistical difference between the experiment group and compost grown crops in their latest experiment.
However, the researchers mention that a previous similar experiment failed, with all crops grown in the extraterrestrial soil having died. This time they added chopped grass to the extraterrestrial soil and grew the plants in flat trays instead of small pots.
If both of these changes were made to all experimental species, the advantage provided by one or the other variable cant be distinguished. The article talks about a problem with watering being fixed as a result of the changes, but this could have been due to either variable (flat trays losing less water than pots or organic matter improving soil structure and water holding capacity) or a combination of both. Further, the addition of organic matter in itself will improve the potential for the crops to grow independent of water retention.
This issue may be clarified in a subsequent paper, but could be quite important. If the improvement is due to water retention alone and the improvement was found in experimental crops grown in a flat tray without organic matter being added, this may be of more significance than the improvement being due to the addition of organic matter. If the improvement is independent of the addition of organic matter, the ability of the extraterrestrial soil to produce food without addition is of great advantage to any future expedition. However, if organic matter is required independent of the type of vessel the crop is grown in, then we have a problem.
Organic matter, at least in the quantities required to grow crops, will be self limiting on another celestial body. Even if the first pioneers started with significant organic matter to grow crops, the recycling of that organic matter (using crop residues, food waste, faecal waste etc) will not replace what they started with when they grow subsequent crops. As the organic matter dwindles, making the assumption that the chopped grass added in this experiment was the variable that had the most effect on the survival of the crops, so will the crop growth and food producing ability reduce. Eventually, experiment one will repeat itself, and crops will either die quickly or fail for initiate.
This seems like a small point overlooked that may have significant consequences on what we learn from this experiment. The Wageningen University and Research Centre looks like does some really interesting, well thought out work, and perhaps a proper recital of the methods and materials in a published paper would show these concerns unfounded.