While there are specific instances where thrusting a knife into hard soil ten times will kasher it, that does not work for other cutlery, and there is no halachic basis for leaving a knife in the soil for a long period of time.
While there are specific instances where thrusting a knife into hard soil ten times will kasher it, that does not work for other cutlery, and there is no halachic basis for leaving a knife in the soil for a long period of time.