Its Δ value comes entirely from water-saving, but water-saving on traditional horizontal farming is likely to yield larger food benefits than vertical farming.

Its Δ value comes entirely from water-saving, but water-saving on traditional horizontal farming is likely to yield larger food benefits than vertical farming. See, e.g. http://waterbit.com http://waterbit.com. (Disclosure: I am an investor.) The big thing is that most farms could both use less water and concomitantly yield more crop. It's good to make plants work for it. And IME yields better tasting food, too.