"Dave" wrote in message
om...
I have a section of lawn in a shady area that seems to have become too
miserable to keep grass growing thickly. The grass is sparse. Applying
fertilizer and grass seed does not seem to have much effect. It is
clay soil and well packed. I don't know if I need to apply something
or simply give up and rototill in a load of horse manure? Any
semi-expert opinions? Thanks.

I think you have the right idea. The best way to improve clay soil is by
adding organic material. The organic material will encourage earth worm and
beneficial microbe activity.