Plant Nursery In Space?

If you think the cost and complexity of creating useable air and water for a
space colony of 10 million is daunting, consider what it would take to
generate the food for 10 megafolks.

The chemical components of a nutritious diet are orders of magnitude more
complex than H2O to drink and N2/O2/Ar to breathe. Nutritionists are so
stumped by the task of determining what chemicals in a vegetable are
necessary for proper nutrition, they have invented the vague construct
"phytochemicals," which can be defined as "the other stuff in plants that
are necessary in trace amounts for proper human health, but which we haven't
even been identified yet." The phrase you often hear is, "sure a
multivitamin is a good idea, but if you allow it to substitute for fruits
and vegetables, you're depriving your body of phytochemicals."

Howard Garrett, an organic gardening expert here in the Dallas area, points
out that food crops grown in depleted soil fertilized with the old-school
NPK fertilizers (mainly Nitrogen and Phosphorous) are likely to lack
phytochemicals usually obtained from a more natural, organically-fertilized
soil. There seems to be a growing consensus that NPK-fertilized plants are
badly nourished and often fail to thrive.

To answer a question posed here earlier, my impression from reading Garrett
and others is that pure mineral sand with no nutrients in it can be
converted to healthy soil with compost (rotting vegetable matter and some
animal waste) and a small seeding of soil, and a little time. I would
envision soil creation in space to start with sand from regolith or other
sources, a wheelbarrow full of soil from earth, and a few growing seasons'
recycling. Mix the soil with an equal volume of sand, plant a diverse mix
of seeds, let it grow one season, take it all to a compost heap for a few
months, and when you're done you'll have 3-4 times the volume of soil to
expand the process with the next season. The initial soil from earth should
bring enough of the right bugs. The biosphere botanist discovered a new
perspective on the gas exchange processes that take place in that initial
phase, when not much oxygen creation is taking place. But I'm confident
that more research will reach a broader understanding of the inputs and
outputs of the process in space. You do notice the news reports of plants
being grown aboard the ISS, the shuttle and before that on MIR, right?

>I agree that a heavy-industry system for air/water recycling for a
>10-million people city would be huge and expensive, but perhaps the
>potential cost inherent to the risk of using a ecosystem for doing the job
>is still higher.
>
>Lucio Coelho
>

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