Purpelia wrote:
And even if he did say that, my point is to think outside the box and come up with ways to make urban farming more practical by spreading it out as wide as possible rather than be constrained by growing it inside the city itself. You would grow as much outside the city as possible and grow what grows realistically inside of a city.
You are going to make me pull out a quote. That's a battle you can't win.
Silver Commonwealth wrote:Could urban farming be realistically implemented on such a scale,
that it could sustain cities with food? (Of course, with all the setbacks, and obstacles during the program.)
Case in point.
"That it could sustain cities with food", not that could all of the food be grown in the city including the feed for the animals and everything else. This is an important difference; the caviet was just farms that could sustain cities with food, not that everything was grown inside the city.
But even so, you can grow things like mushrooms without any sun at all, feed it to cows in feedstock, and then eat it, all without any sunlight at all. You can grow things like duckweed in aquaponics which, while technically edible for humans, is better for animals to eat, and then eat the animals whom you fed the duckweed, which grows like a weed. You don't have to necessarily grow food crops, you can grow really shitty but easy to grow foods in the city, give it to an animal, and then eat the animal. This is more efficient then trying to make artificial meat for example, and converting your algea or grass in to a burger. While a clump of grass may technically have more energy in it before a cow turns it in to milk or meat, humans can't process grass, or algae or the like in their digestive systems very well, and it lack things like vitamin B12 and protein. But an animal can process it for them, and then they can eat products from the animals. The digestive system of a cow is more efficient than a human, and it's more efficient to grow feed for cows and then eat the cow than grow feed for humans and eat the feed. It also produces things like vitamins and minerals.
Using power to grow non food crops and than have those be converted into calories by animals is inherently less efficient than growing things and eating them. It's simply a fundamental fact dictated by a little tiny insignificant law called conservation of energy.
It's not necessarily more efficient when growing crops to let humans eat them instead of animals. Yes you waste energy feeding food to a cow and then eating a cow, but it's still more efficient in the long run when you consider humans can't eat what cows eat anyways.
So you don't grow what cows eat.
Honestly the closest thing to a reasonable side to your argument would be to point out some few livestock could be fed by the waste of the plant production. Like say wheat stocks or leaves off tomatoes and such. And that's the only argument you haven't actually made either because you didn't think of it or because you know it would produce limited yields of high cost luxury meat and little more.
It's implicit to what I'm saying, that there are things we grow that humans can't realistically eat, but livestock feed is plentiful, grows quickly and doesn't require a lot of nutrients or good soil, thus making it easier to grow in a confined space like a city. You can grow larger volumes of livestock feed in terms of area than you can grow tomatoes, or corn kernels, or other forms of food humans like to eat, and thus this can be fed to cows and converted to something we can actually eat. You can grow things without sunlight at all, like mushrooms, which while not sustainable for human consumption as it doesn't have all the nutrients we need, be fed to cows instead. It would be more expensive, but it would be theoretically feasible if your goal was just mass amounts of food production. With something like fusion energy or cheap electricity, these things become more practical. Because mushrooms for example can be grown underground, underneath a building or in a cold dark building, you could grow enormous amounts, and then turn it in to livestock feed essentially. A large pipe underground could be used to grow tons of mushrooms and various other light-free livestock feed, and then this could be fed to animals, who convert it in to protein and calories humans can easily digest. You then can also grow a small amount of regular aquaponics on top of this where there is sunlight and produce more food.
So basically, my point was grow animal feed. And yes I know there is waste we produce that we feed to livestock, such as corn feed which is the wasted part of corn stalks, wasted mushroom parts and lots of other things. This is what I was saying, which is that you can produce livestock feed for much higher efficiency than human feed, and even when that energy is wasted by feeding it to a cow, you still end up with a net positive. It is so less efficient to grow human food, that growing livestock feed and feeding it to an animal to eat or produce milk and eggs will produce higher yields for human consumption than just growing vegetables for humans to eat. Cows can produce milk daily, and when they die you can eat the meat, chickens can produce eggs. So, by using them to convert the livestock feed which is easy to grow in to something nutritious for humans, you end up with a net positive than if you tried to live solely on vegetables.