The large scale Ag farms are highly inefficient at calories per M².
If they were actually turned into actively managed farms, the output could be seriously increased.

The water is already there.
But the land is almost completely barren of people.

Oh, we have more than enough land to feed and house everyone, but we don't use it, instead we make these unsustainable cluster of houses that are so close they should have been built together. And all live in a few giant cities.