I have a small lawn that is shaded on one end. Since I have owned the house
the shaded part was mostly dirt.

I dug up and turned the soil over and layed sod in this area. I also turned
over the soil and planted shady grass seed in the area between the existing
grass and the new sod. I also patched up areas one the grassy side to fill
it in. Within a week or so the grass and sod looked beautiful almost golf
course like.

But now 3 weeks-4 weeks later all the new areas have thinned quite a bit
(sod, patches, seeded areas). The original grassy area looks the same.

I tried fertilizing the lawn 4-5 days ago and so far no difference, everyday
the lawn looks worse. More dirt less grass.

I have watered it quite a bit and it has rained quite a bit too.

Does anyone have any sugestions why this might be happening and how to fix
it?

Also no one has been on the grass as its a fairly unused lawn.