No amount of tweaking or work makes a grass texture look good in an environment. People always use polygon grass.
Why is it that environments with grass textures instead of polygon grass look like shit?
Pic related, a grass picture I took
because grass textures lack depth, obviously.
Same reason everyone thinks low polygon hair looks like shit.
Because you're expecting it to have some sort of depth but really it is just a 2D image end you end up disappointed.
use earth texture and redo the parts where green areas should be
used bushes and grass ontop but not too much
Your eye is trained to pick up subtle details which would be too costly to replicate in real time 3d. It's not impossible to make a satisfyingly convincing grassy dirt but it's just no worth the resources
It comes down to style as well. Graphically trying to represent hair in low-poly will look shit unless you are working on something that will only be seen from one perspective.
With stylised representations you can get away with a lot more. Look at LoZ windwaker.Grass looks fine in most circumstances even without normal mapping.