After looking closely at the image, did you use Corona Scatter or Forest Pack for the grass in the median? If Forest Pack, use the optimize material button in the material rollout, and use "Apply ForestEdge". Then inside the Areas rollout, under Boundary Checking, use Edge. Or if Corona scatter, follow this tutorial:
By using this sort of technique, you can limit where your grass scatters to just the soil and not spill out as you have it now. Additionally you can change the transformation limits in either Corona Scatter or ForestPack to instantly get a more convincing grass.
Also for your background, simple throwing in a photo that matches your perspective and setting will go a long way.