Top dressing fairways like #5 can also help cut down on earthworm populations. As you know, we are always battling earthworm castings on the start of this fairway. Earthworms are a sign of a healthy soil but can be a nuisance. If the soil was toxic, they wouldn't live there. There are also no chemical means for their control; killing them is illegal. Sandy soils however, irritate their skin and often times will lead them to a new home.