Funny thing is your talking to a person whos spending the summer building a half acre catchment among other things. Yes i know it can be done larger scale. Its rather expensive though in my case anyway, and not likely to be economically feasible for most, especially when there are other crops....
i certainly never implied dryland farming is new, only that it can be used where it was not before, or atleast not as reliably as we can do today. Of course it can feed the world, because though heavily irrigated areas might produce a bit less, (although alternative cropping systems could still outpace it in different models) many areas not used well or at all can be productive. 50 percent of the worlds beef comes from arid regions, and all of these im aware of can increase yields greatly.
in regards tot he dustbowl they expected to much from the area, and had extremely poor systems. they perpetuated the dryness of the area, when they COULD of had the area a bit wetter then usual, and the drought would of had less impact, and the dustbowl would not of happened.... these practices can REVERSE desertification. Unlike current practices which increase it.....
As far as shipping food, I dont care what you grow. Id be rooting for folks to widen the range and push the envelope, trust me on that. Im working on doing this with the full range of foods myself. you might not believe me if i told you. my point wasnt to imply things can be hard so the shouldnt be tried, or anything similar. Only that some things are much easier to grow in many areas or impossible in others. I highly doubt people will stop transporting food. Id be perfectly fine if thats how things turn out, and have a solid range of foods adpated to my eco system, I just doubt that will be the case. really it doesnt matter though, its not up to us and anything we say at this point is opinion, and guessing. transporting food isnt even remotely un sustainable, especially when in your worldview the economy would be vastly different. there would be much less shipping going on in other areas as well. Much less processed junk being shipped in 20 directions etc. If you take it down to trains shipping staples and the like it would be extremely easy to sustain that, and likely more.
I dont understand what you mean that trying to match industrial ag would be at odds with the stated goals
I always assumed wed want all people to be fed? In which case we have to match or beat it system wide. that is the exact goal actually, doing that in a way that will last through the ages, keeping fertility and water tables intact. Rather then beating eco systems into the ground as we do now. Of course theres also the fact irrigation is not detrimental at all levels in all areas. In my area it is. If we had local ag and it relied on irrigation wed devastate the water tables over time which in turn would slowly make the soil accept less water and it would be perpetually drier. humans did exactly this to the middle east long ago, it used to be wet and fertile.... Its time to rebuild eden. I also think a lot of progress will come when we get animals back to more natural diets. they evolved eating forage not grains. this also includes parts of plants humans do not use. Lots of efficiency to be gained there depending on how you look at it.