Manufacturing soils would be a challenge because of the organic and microbacterial contents. As a matter of fact, soils renew themselves, but they need be used intelligently and sustainably.
Less of a challenge than you might think. You'd need to take the mineral substrates, grind them to the required size and mix it with ground up waste organic material (we hardly eat the entire plant of most produce, and there's the literal tons of sewage plant biosludge any population of size will produce) and a literal ton of finely distributed soil on top. Then just let it cook for a while.
Employing microbial life for our own purposes is something we've done for literally thousands of years, and 'make nice conditions, sprinkle seed culture on top and let it sit' is exactly how we've done manure piles, compost heaps, mushrooms, cured meats, leavened bread, antibiotics and alcohol.
The real problem would be getting things started. Once a system to supply everything is in place, it'll keep going.
ORIGINAL: MiletkirThe other limiting factor is indeed water, but, as you say, it's perhaps easier to imagine how to remedy water shortages in the future. So water may be abstracted within food.
And that's my point. Food can serve as an abstraction for a number of important things that are essential to the economy / society. Actually, food can be a very active part of colony happiness, growth and even trade.
It's more that water is an easier problem to solve because potable water is chemically much less complex. Food is definitely a key component of general life, but it's a fair question as to whether or not it'd be an interesting component of gameplay for Distant Worlds 2.
It's already got a pretty large number of resources to track.
ORIGINAL: MiletkirThe way I would grossly see a layered economy structured:
Of course, everything could be connected to trade, but luxury resources would have the strongest impact on it.
Personally I'd gate things a little differently, and base it on colonial development. The game has enough resources to go around already and adding to that is unlikely to be very helpful. I'd put it down as 'produce' and 'fine foods', with fine foods a luxury resource that requires produce and a medium or higher development colony to create.
Trying to be more complex than that would require a fundamental rework of the economy, both to avoid the entire thing collapsing and to ensure that intermediate goods are properly integrated in the rest of the economy.
I mean, if you are tossing electronics, fuel, alloys and fire arms around as resource concepts you need to figure out what they are made of, where they are produced, and where they are relevant for ship construction. You can't have half a dozen resources or more resources exclusive to colony mechanics and accept their raw materials for every other construction purpose.
It's one thing when you do that for food and abstract food demand for military purposes away as 'so many orders of magnitude less demand compared to the millions a single point of cargo feeds normally it's abstracted into the running costs', but when food, electronics, fire arms, fuel, alloys and medical supplies all show up I will expect them to be relevant somehow beyond being a resource sink and gating for colony mechanics.
I'd want them to show up in the ship, station, building and army construction and maintenance requirement lists as material requirements, even if it's just for higher tier components.