Full disclosure, I work with a few soil scientists and I now understand how critical it is that we know the potential of the land if we're relying on it to produce ag or to be used as rangeland.
I've never seen this chart. What a story!
There's a lovely quote by Rebecca Solnit, "to hope is to accept despair as an emotion but not as an analysis. To recognize that what is unlikely is possible, just as what likely is not inevitable."