Originally Posted by Smallaxe
We level out ruts and such with sand or topsoil, when necessary... but we also have sidewalks and roadways, so even 1/4" of new sand every year would mean a full inch every 4 years... not to mention how much will wash down even the slightest slopes over the course of a season...
The idea of sanding bluegrass in Wisco, is not a smart idea at all... I do not know of a lawn that would benefit the KBG by topdressing with sand every Spring... in fact after the Spring rains were finished the lawns would look like sand dunes...
Imitating the greens of Scotland doesn't make for good lawn care here,,, but if that's what the grassy weed called Bermuda needs, then that answers my question...
The topdressing blends into the thatch layer and the soil below that. Putting greens that are topdressed at 1/8" depth twice monthly usually only rise about 1" every 10 years or so. But, if you core aerate regularly, you'll create room for your topdressing material and you don't get much rise at all.
I agree that topdressing lawns isn't needed for the most part (if your lawn is level enough for your taste), since most folks aren't pushing their lawns to the edge of death in an attempt to create a high performing athletic surface. But, using the right amount, you don't get any noticeable sand up on the surface -- its all down in the canopy. After heavy rain (or any kind of rain), you still have a nice lawn.
But, your bluegrass in WI would benefit much more from regular sand topdressing than it would from microbial applications or compost applications. KBG is a good thatch producer and allowing that thatch to accumulate on its own without aeration or topdressing will reduce microbial activity, as opposed to topdressing or aerating, which will improve soil oxygenation, bring C:N ratios in better alignment, and increase microbial activity.
Now, all this won't get you super-noticeable results on your lawn -- you're not adding a fertilizer here. But, research has shown that it will do more good for the "soil food web" than microbial additions or compost applications.