I ended up doing this:

1) on two ends of the row, I sledgehammered two pipes into the ground
so that 1 foot sticks out

2) Put larger pipes on top of those. So they are removable.

3) To the top of the pipes, I welded other pipes so that they look
like letters "T"

4) I put a 2x4 by 14 feet boards on both sides.

5) I used little 1x2 boards to lean from the ground to these 2x4

The total cost was $16 for the 2x4s, I had the rest.

I can post pictures if anyone is interested.