I don't think this is entirely true. I know in Canada we grow wheat, soy, rapeseed and rye in the Prairies, which has a harder time with traditional yellow hum

I don't think this is entirely true. I know in Canada we grow wheat, soy, rapeseed and rye in the Prairies, which has a harder time with traditional yellow human corn. And wheat is a very important staple. We feed a lot of the world! So while there is some fallow land, this exists everywhere, and I don't think repurposing will help.