Another thing I do is buy a 50 lb (it's smaller than you think) bag of crushed oyster shell grit sold for chickens. I've cleaned out some growing begs but leaving the rest for bird cover until spring. On the beds I cleaned, I shake/spread multiple cups of the grit all around. The stuff too small or too large for birds (they swallow small rocks in order to grind seeds in their crops) basically just adds calcium to the beds. Win/ win. I think the bags of grit are about $17 and change.