Already exists. Simple Sprinklers: http://community.playstarbound.com/threads/smapi-simple-sprinkler.110326/ All that is missing is an icon.
Umm... I think it only makes scarecrow acts like a sprinkler. Does not affect the "scare" area of the scarecrow.
It's actually a really simple edit to make, at least as far as the functionality goes. You just need to have "arecrow" in the name, and it'll behave like a scarecrow.