Beautiful picture! I love lonely trees in prairies!
As far as composition goes, I would say that maybe a little more grass and a little less sky would be good. The rule of thirds was applied, but the horizon line seem more like a fourth of the picture rather than a third.
Also, remember that picture quality starts to degrade around f/16. Personally, when I used to shot landscapes with a DSLR I tried not to go over f/16. But I encourage you to make your own tests. Each situation is unique, and different lenses behave differently, so it’s hard to give a perfect max f/stop, but try diffrent apertures on a same subject and compare 100% crops to try to find a compromise between picture quality and getting everything in focus.
Plus, it would have given you a faster exposure and/or a lower ISO. It’s hard to judge on sharpness from my computer, but you would have appreciated to have a faster shutter speed if it was windy.