Topdressing: What's to gain?

When a turf manager applies "topdressing" to a field of play, they're applying a layer of sand or soil over the turf to smooth unevenness.  Benefits of topdressing are crown insulation, thatch dilution, and increased drainage and firmness.  From baseball fields to grass tennis courts, where smoothness or surface repair is desired, you're sure to see topdressing employed as a standard practice. 
For golf greens, firm and smooth surfaces equal increased ball roll, or 'fast greens'.  This is good.

Topdressing is done by hand on our tee boxes due to the damage being so concentrated.  Seed is applied first followed with straight sand directly laid onto the divoted areas. This is quickly worked into the turf with a special tool called a 'Levelawn' (pictured below).  This procedure not only reseeds the tee, but helps slow down the unevenness older tees can suffer due to excessive traffic and unfilled divots.

Greens are topdressed with straight sand every Monday, weather permitting.  The primary reason we topdress greens at Tuscarora is to increase ball roll and dilute thatch.  Over time, sand fills the voids between leaf blades and old ball marks, and, in turn, lends a truer putting surface.  This contributes to the ball seeing less 'interference' as it goes to the hole.  With regular topdressing, putts stay on line more often, friction is reduced, and the ball maintains it's velocity (or speed) for a longer period - all positive things. 

This also gives some insight to why greens are noticeably slower after a rain or irrigation -- the same goes for freshly fertilized greens. Anything that makes the plant more lush, or the surface less firm, decreases ball roll.  This is why green speed can vary from spring to summer, week to week, and from morning to afternoon.  The plant responds to environmental changes as well as chemical ones that are, sometimes, beyond our control.
Topdressing can smooth much of that uncertainty out...  

At the end of 2010 we found a great deal on a low hour demo topdressing machine. It's computer controlled and allows us to topdress all 18 greens in under two hours, opposed to 5 hours with our old unit. It also let's us apply at such light rates that the sand rarely needs to be brushed in.  We've kept the older unit to fill practice tee divots and apply stone to cart paths.