[GilB57]

Just some (late) idea if not already done :
I noticed that in actual landscapes, hills are less cultivated than valleys and river sides.

maybe your "buffer texture" should be placed with some connection with slopes (using map_H data ?).

Explanation:
your buffer tex. appears like some kind of dull open grass field.

RULES :
-Bottom of valleys near rivers : no buffer tex .
-More slope = more buffer tex
-Low areas = less buffer tex
-high areas = more buffer tex