How much potentially arable land is there that goes unused due to lack of any economically viable method of getting the produce to market? I would say just “arable” land, but apparently to be arable it has to actually be in use. Most urbanized areas are probably usable if the urbanization was removed, but what about places that just aren’t productive enough and are too far away from the rest of civilization for it to be economically viable to grow crops on? Do vast expanses of such land exist in various wilderness areas, potentially covered by forests, that if food prices rose enough, people would start putting under cultivation? How much more food could we theoretically produce if we didn’t have to worry about the costs of producing it and bringing it to market?
Huge areas of the western US could be farmed: if there was water.
My relatives have/had farms that had been sagebrush before. Add water, and soon you have quite fertile, valuable farmland. In some cases, just across the fence there’s still sagebrush.
Similar situation in many other arid areas of the world.
So, theoretically, that’s a lot of untapped farmland. Very theoretically. The costs to create/find fresh water and bring it to those regions is often mind boggling.
It really does no good to calculate potential when the issue of costs limits a lot.
Even with existing farmland in the US, some is going fallow simply because it’s not economical to farm it. (E.g., places in Montana are being hit by their inability to compete against foreign farmers that can grow crops cheaper now that shipping costs are so low.)
Thank you, that last bit was what I was most interested in. People talk about how a growing Earth population is going to be a burden to feed, but I was pretty sure that if food prices rose enough there was plenty of land available to use. In the case of places that need a lot of transported water there certainly is an issue of the cost of water and its transportation increasing in line with food prices as populations grow, but I was unsure is that last case you mentioned actually occurred anywhere. From the definition I read of “arable” it made it sound like absolutely all land possibly suited to agriculture was being used, given a conflicting version of what “arable” meant.
There’s also a bunch of land that’s been taken out of production because of environmental concerns. The land may be too prone to erosion, wetland, habitat for endangered flora or fauna, a toxic waste site, etc. Much of this land may have been farmed at one time or another, but is not considered viable anymore.
It is rather amusing that proponents of population growth, bellowing against arguments of too many humans, often pull out the card — used not only for this subject, but against other changes in use, and against revolutionary change — that there is already enough food to support this and growing population; it just isn’t distributed to starving people, never:
I/ Suggest how this additional transport need can be provided and paid for.
II/ Make the slightest move to changing the present distribution.
I know you mentioned it in the OP, but it always makes me think that the fertile river valleys and associated floodplains, geologically most likely to have great growing conditions for plant agriculture, are often taken up by urban and suburban areas. We should build new cities on mountaintops and deserts so those valleys can be farmed again. When you think about the history of human settlement, it makes perfect sense - we live by our farms, then gradually all the farms are taken up with living space, pushing the farmers ever outward.
Asking what we could do with more land ignoring all other costs is kinda silly. At a very simplified high level it takes land, labor, capital equipment, water, sunlight, and transport to produce useful food, where useful means “delivered to where the consumers are.”
Speculating about unused land is pretty pointless unless we also talk about the available unused labor, capital equipment, water, sunlight, and transport. e.g. We could have another entire Earth’s worth of unused arable land, but if we’re already employing all the available water, we’re not going to get more food from employing that unused land.
IANA expert on this stuff, but it seems pretty clear that land itself, simple reasonably flat acreage, is not the limiting factor to total planetary food production.
Here in Minnesota, the Governor just got the Legislature to pass a bill requiring that a buffer strip of land averaging 30 feet wide be left alongside each lake or river. That got a lot of opposition, because it will take some land out of cultivation. But it eventually passed, because here in Minnesota we like our lakes.