Most good farming land up north is already farmed. Mainly North Queensland along the coast. But it's a tiny fraction of the land. Head inland a bit and the land is some of the most infertile anywhere in the world. It gets a thousand mills of rainfall in the 4 months of the wet season, and then nothing for the rest. Just terrible conditions to grow anything.
The Ord River has been one big disaster. Economically speaking anyway. And it's the best bit of land up there, and it's tiny. Nothing will grow in the wet, as it's too wet and too many insects, disease [caused by waterlogging and constant humidity] and other pests. But great conditions in the dry if irrigated. Problem is it's mostly flat up there, and not many other areas to build dams, to catch water in the wet, to irrigate in the dry. Historically, agriculture developed in temperate fertile areas of the world with 500 to 800 mill rainfall, and continue to supply most of the worlds food.
All this talk of moving farming to the wet north is just rubbish by people who don't have any idea. It takes more than just a thousand mills of rain in 4 months on rubbish dirt to grow food profitably.
See ya's.