So many assumptions about smooth substitution in this stat. * How much of that land is pasture, and cannot be viably used for other purposes? * How much of th

So many assumptions about smooth substitution in this stat. * How much of that land is pasture, and cannot be viably used for other purposes? * How much of the remaining arable land is suitable for growing plants humans will consume directly? * How much of the corn/soy/etc that can be viably grown on the balance would humans choose to eat? We're very, very good at growing bulk crops, but not so excited about eating them. Feeding the excess to animals, and eating the animals makes ~1/3 of that productive capacity available (and appetizing) to humans. Modulo environmental impacts of CAFOs and such (which need to be addressed) that's a pretty efficient use of excess productive capacity for bulk crops beyond demand for human consumption.