[WalterBright]

All the biomass would have to be recycled back into water and food.

The gating thing may be if lunar dust is workable as raw material for soil or not.

[Beached]

there are experiments with moon simulant and mars simulant. both show that with proper prep, regolith is a sufficient grow medium. just as is, it sucks, but if you wash, and then fertilize, it will work. and then after the initial prep, you treat it like you would other soil.