I cut lawns in southeastern Michigan and all of my customers (residential) have bluegrass which I can mulch very easily. I do have 1 customer whose backyard has a real thick, sponge like lawn that I can't mulch no matter how many times I go over it (clippings will NOT sink into turf) and was wondering if anyone had any ideas as to what it could be. I don't have any pictures unfortunately. There is never any weeds growing in it and I have to cut it around 3 1/2 - 4 " so it doesn't look scalped or to have my mower bottom out! Any ideas? Thanks!