the poppster
Songster
I use sawmill sawdust....it's more like little white cedar wood chips....and before anyone starts on the dangers of cedar...my birds have been walking...digging....scratching and dusting in it for two years....and I haven't lost one...it's about 12 inches deep...and I turn it over with a fork a couple times a week...the girls love it...they pick the sprouts from the oats I give them and the bugs..it's moist but not muddy...and the poop composites the chips/sawdust....works great.As fresh cut grass is 98% water, it won't help with a moisture/mud issue.
Too much will actually clump into a slimy anaerobic odorous mess...unless placed on about 12 inches of wood chips....
Hope this helps.