My backyard faces south and has many mature oak, pine and cherry trees. When I first established the yard 30 years ago, I added black dirt (I believe it came from a boggy area) to the yard and mixed / tilled it with the sandy soil to a depth of from 6 - 12". The yard was established via seed. For the first several years, the grass was healthy and full but then the yard got a mold and it has never been healthy since. Moss became established and I have tried to rake it out, add lime and fertilizer to no avail.. I have had a service try to re-establish the lawn but that failed. Last year, I had several soil samples done at the U of M but the results did not indicate a need for additional nutrients and the pH was near normal (I do not have the results handy - not sure where I put then). I have cleared some of the trees and raised the canopy and I am getting more sun. This year I'm thinking or re-establishing the lawn and adding / mixing Cowsmo compost to the soil. I am hoping that you may have a suggestion on how this should be done. My thought was to kill the grass and moss with roundup, wait a while, till in the Cowsmo, re-seed and hope for the best but I need some direction - maybe I'm being too drastic. Any help will be appreciated.
Added 5/6 - I have tried residential moss killers - I believe one of them was a Bayer product. It was a liquid product spayed on with a hose. I've also tried a granular product which was even less effective. In both cases, they had a minor impact (more impact with Bayer) but the moss never disappeared and came back ever worse.