How can I pump 1000 watts in the ground
The Popular Electronics article I remembered described a short distance communications system made by pumping the AUDIO from an AUDIO PA into the ground through two ground connections about 20 feet apart. To achieve an approximate match into the earth, they used an audio output transformer turned around backwards. 

The amplifier had something like a 3 to 8ohm output impedance meant to drive a speaker system. Feeding the amp's output into the transformer gave something around 3,000 ohms...far from a match of earth resistance between the ground connections, however it DID work.

I was a kid but could NOT resist trying this. I scrapped an AC/DC record player and used its 5 watt (probably 3 watt), amplifier into the added matching transformer. I used one cold water pipe and a ground rod about 20 feet away from the pipe to feed the audio into the ground.

A neighbor kid built up a similar system and we were able to talk about 500 feet using high impedance headphones hooked across two ground connections.

AC hum and many, man other signals such as lightning whilstlers, large motors turning on and off, and who knows what else interfered with communications. We eventually used switches on each end to swap the amplifier's output with the high impedance headphones....sort of like an antenna transfer switch.

We wanted to try filtering out some of the noise but at 12 years old, neither of us had a clue how to accomplish such a thing. After a summer of playing with the system we decided to get into ham radio. I became WA4GZV, and my friend became WA4GWG. Needless to say, we talked anywhere we wanted to after that.  we are still friends today. He is an engineer with a defense contractor and I am retired from Motorola.

Life was fun back then and still is today!