Gardening in an Alien Biosphere

Question

Take a world with the same physical characteristics as Earth, but where biochemical development has "rolled the dice" differently in some cases.

• The simple chemistry are the same compounds in slightly different proportions. The air consists mostly of nitrogen, oxygen, argon, carbon dioxide. The water is ordinary H₂O, with dissolved salts in the oceans and the trace organics one would expect from the ecosphere (see below). Sand and rocks are made from silica and carbonates, mostly.
• There is carbon-based life which looks much like life on Earth. Simple organic compounds like ethanol or butane are the same. The differences are in the more complex compounds.
  • Some sugars, amino acids, and the like have a different chirality.
  • The genetic code uses "unnatural" base pairs (natural on the world, of course).
• Life includes something like photosynthesis-based flora and mobile fauna. Details differ, of course.

What are the problems if humans want to raise crops and lifestock on this world outside a sealed greenhouse?

It seems obvious that humans could sterilize soil and bring it into a greenhouse, but that is not necessarily easier than raising crops in a space station.

Answer 1

With an alien world, alien biogenesis and presumably billions of years of alien evolution the local flora and fauna might resemble their Earth counterparts to some extent but their biochemistry would be scrambled compared to that from Earth.

Chance has a big part to play in evolution and with slightly different starting conditions the result would in all likelihood be biochemically different. Hard to say how different but such life would probably rank somewhere between inedible and toxic.

In basic terms all metabolic pathways are scrambled. Lots of common small molecules, but the larger molecules would mostly be different and their are millions of them in the biosphere this is just a small part: https://www.sigmaaldrich.com/technical-documents/articles/biology/interactive-metabolic-pathways-map.html

The alien life would be well adapted to the alien conditions, Earth life would not. There would be serious difficulties with weeds, although with research it should be possible to find something that was deadly to the native life but didn’t harm Earth life. It might take time to find it, it would probably need to be reapplied regularly and some of the “weeds” might become resistant to it.

There could be physical as well as chemical difficulties – perhaps the air is fall of a million fold more spores than on Earth that clog lungs – but there might not we don’t know.

Letting livestock anywhere near the native flora would probably not end well as Earth based fauna are adapted to Earth and would be tempted to eat whatever they perceived to be edible which would almost certainly be a mistake.

For things like wood there would probably be little immediate danger as it would probably primarily be an inert primarily structural element, but saw dust might well be toxic.

Answer 2

The "bricks" are the same, as you state. This means that, with a proper bacterial ground, "our" plants can grow, for example by having nitrogen fixing organisms. This would mean that the colonists would have to take with them not only seeds, but also sample of the grounds to be sure that all the needed microorganisms can be present.

Probably a sterilization of the ground before planting would give better chances to "our" organisms, since it would take out competition for the bricks.

For the rest I would exclude cross pathogenic effects: since the DNA basis are different, a cross infection would not find a way to propagate because the instructions of the infector would not be executable by the infected.

That however does not rule out toxic effects by alien molecules.