Rick - thanks for all of the wonderful info. Trying to stay non-chemical here as we've had such good luck with the Chickity Doo Doo - no burning, no explosive growth and the lawn seems to survive weather extremes much better. Clay in the shade is challenging for a lawn but we've been winning the battle. We'll have to go on a quest to see what's available locally but I think we'll have to go beyond the boundaries of the big box stores. Compost would be lovely but I can't make enough and not sure that I want to go the local municipality route as I don't want all of the residual chemicals. We do use a mulching mower and some of the shredded fall leaves remain on the lawn in the fall as well. Will definitely take your calculations along on the hunt!
