I was wondering, and have been wondering, as you get your lawns soil, or any soil for that matter, rebuilt with OM and all. How do you know when you need to add more OM to replenish the nutrients needed in the soil. What I am speaking of is something such as N, you can't get a reading on the N in the soil even though it is there locked up in the OM. SO... surely over time, the N will be deminished over time... maybe a LONG time, maybe there is so much there it isn't an issue... BUT... if it were an issue, how do you know when to make an additional treatment? To me I say just throw a light dressing of compost every so often and you don't have to worry about it. One other question... N can be locked up in the soil and not be able to be read... is there P and K also locked up in the soil that can't be read by your basic soil tests?