Universities all over the world are asking that question - and have been for centuries. They have come up with some great answers over time. It takes years for farmers to learn - agriculture (like science) advances on the death of old people who continue their unsustainable practices to the grave - but things are overall much better than the past and getting better.

Yeah there's a lot of that even in the first Dune book. The Fremen's leader is an ecologist and they're explicitly collecting water and preparing to change the entire world to be greener and more livable.

The linked channel has a lot of good videos it, and Mossy Earth is another. They aren't going to make you an expert by any means, but they provide good introductions to various projects that are underway doing ecological restoration. They're nice introductions to the topic.