The research was conducted by the Wageningen University & Research centre in the Netherlands, and is the second phase of a program of experimentation. Initial studies hit some bumps in the form of watering issues, container problems, and the lack of organic nutrients. The new experiments, using better containers and adding manure as organic nutrition, have been much more successful.
The Moon/Mars soil simulants are approximated by chemical analysis using soils from Earth which are pretty close to Moon and Martian soils, if not exact, in chemical composition.
This is where the nitpicking starts. I’m a qualified horticulturalist. The first thing I did, naturally, was check out soil chemical composition. Before anyone starts an argument about composition, let’s remember that soil composition varies hugely on Earth from location to location. The Moon/Mars soil simulants may seem arbitrary, but they are ball park relative to observed soil compositions. Mars in particular has a gigantic reservoir of volcanic soils, caused by monster eruptions in its early history. Pretty drastic variation in composition is likely.
The first thing you see in the profile of Mars soils is a table (PDF doc) of component elements. Top of the list in percentage is silica dioxide, aka sand. Aluminum and titanium oxides are also strong. (Aluminum oxide is also very common on Earth.) Other major oxides include iron, calcium, magnesium, potassium and sulphur. These are core nutrients for terrestrial plants. The ratios of these elements are relatively low, and there are some anomalies, but again, ballpark.
These soil simulants come from Hawaii and Arizona desert. They’re pretty much what you’d expect. They’re definitely not great soils, but they have a lot of useful elements in them. Add organic nutrients, and they’d be OK on Earth.
What about soil biota?
I’m not going to knock the value of this work. It’s necessary, and needs to be done well. I am, however, going to express some reservations. One of the most critical points about these experiments is lacking from the information I’ve been able to find – What sort of soil biota are present in the mix growing these crops?
Plants don’t just “access” nutrients. Biota turns those nutrients in to usable forms for plants. In modern horticulture, you add biota to nutrients to improve crop yield and support soil chemistry dynamics.
In alien soils, however similar, supporting biota are unlikely to be present. Arguably there may be something similar, somewhere, but not on Mars or the Moon. If we’re serious about growing crops in these places, we should be checking out the issues for maintaining biota support, too.
Another, potentially crucial issue, is having biota which are well adapted to survive in these environments, and able to deal with local gravity, air pressure, and other environmental factors. Organic chemistry on Mars and the Moon can’t be the same as on Earth. There are too many new factors. Apparently healthy biota which lose the ability to reproduce in alien environments over generations, for example, could be catastrophic if colonies are dependent on these crops.
(Note in passing — it’s unclear whether these simulants reflect potential issues for soil organisms like Martian micro dust. The particles in these studies are measured as quite small, but are they small enough to duplicate the savagely “homogenized” Martian dust? The real Mars dust could be a significant issue for soil biota.)
Reliability of soil organisms – Major issue
How do microorganisms manage in these tough environments? They could change their soil chemistry behaviors to different modes. If for example the 20th generation of soil biota adapt to Martian soils, they could pick up some unexpected characteristics, too. The organisms which support growing peas, legumes, are nitrogen fixers. What if nitric acid is their new product, not organically accessible nitrogen? What if they adapt to produce a much better method of getting nutrients for themselves which doesn’t deliver the right nutrients for the plants?
This is a big deal — what will soil biota do, when actually confronted with alien soils? Development of enzymes and chemical capacities to get nutrients from soils is what soil biota do best. Soil biota are highly responsive to even minor changes in environmental conditions. They can simply hibernate, go elsewhere, or die out, depending on the state of the soil. They can also adapt, and in some cases form new sub-species, as a result. For the biota on other worlds, new capabilities may be better survival options than simply retaining their Earthly abilities.
I realize that this is the earliest stage of research, and that some of these questions can’t have answers yet. The major issue for research is soil chemistry reliability on other worlds. I’d suggest that generational research could be highly productive, fascinating, and a useful safeguard against “surprises” from alien soils.
Isaac Asimov wrote a fabulous story called Mother Earth, in which he, a biologist, explored the dietary ramifications of growing Earth plants on other planets as a critical part of the story line. The results were pretty startling, and very relevant to this work. The bottom line was that things grown on other worlds will develop significant differences from terrestrial foods. What you eat, in effect, is what you’re going to turn in to.
Buy Martian soil simulants online? You can, but handle with care
One totally unexpected thing I found while pottering around looking for information on this subject (a thankless task cluttered with publications of varying vintages and accuracy) was that you can actually buy these soil simulants online. A company called Orbital Technologies is selling Mars soil simulants, up to 50lb. at a current price of $500.
I don’t know if this company is directly associated with this research or not. They do have a very diverse range of associations with similar projects, including growing the first flower ever grown in space on the International Space Station, a zinnia, in their Orbitec Veggie program.
****If you’re interested, also note that the Dutch researchers have provided a safety sheet for handling these materials. Please be advised that the high silica content in the Martian soils is no joke. It is potentially hazardous. No significant risk other than irritation is cited in the safety sheet, but on principle, wear a mask, and take usual sanitary precautions when handling.
I’m just looking forward to buying real Martian soil… For my experiments… Nothing to worry about, folks…. The galaxy needs carnivorous potatoes.
Afterthought – Another issue is the presence or absence of fungi, which are precursor breakers-down of materials on Earth. You’d assume fungi are present in manure, but which fungi, and how they adapt, is also relevant.
