My 80 acres is fenced with 650 + T-posts. Four strands of barbed wire. Each post was manually driven with my home made 45# pipe - T-post pounder. Glad it was all done 42 years ago. Mile and a half of fence. I must have done it right. Still standing - straight, true and tight.
I was thinking ( smell the wood smoke ). If your ground is so very hard that you can not pound in a T-post - what kind of crop will you grow on that land??