Metal stakes versus wooden ones
Metal stakes are are more beneficial to the plants than wooden ones. During thunderstorms, a charge is built up. When it discharges, nacent oxygen (O) is created. When the nacent oxygen (O) combines with the molecular oxygen (O2) in the air, it creates ozone (O3). Ionizers in our homes produce ozone which is invigorating to man and beast, and everyone has breathed the ozone-rich air after a thunderstorm. Well, it perks up plants as well, increasing their ability to absorb nutrients.
Something beneficial also happens underground, but I can't recall what.