One more point about earth ground: The earth isn't always a great conductor, so two stakes hammered into the ground at different places, even relatively close together, aren't always at the same potential. This can be especially true if lighting is in the process of striking the ground close by.
Electrical codes may vary from one region to another, but the ones I'm familiar with require an earth ground at the point where utility service enters a building. Some radio antennas also require an earth ground, and if you have antennas on towers, it's common to require that the tower have an earth ground for lightning protection. These ground points may or may not be right near the utility service entrance. For safety's sake in case of lightning strike, if you have more than one stake pounded into the earth, it's important that all such stakes be bonded together with a conductor with very high current capacity. If there's going to be a potential difference between different earth ground stakes, don't force the potential difference to go through any radios or other delicate equipment. It's not a good idea to have the shield of a radio's antenna connector going to one earth ground by the antenna tower, while its chassis is connected to a different earth ground next to the utility service entrance.