I've been asked a few times how I did this achievement, so here is the answer.
I used the cultivator on field 32. Use a spiral pattern from the outskirts of the field working your way towards the centre.
Don't take your finger of the throttle (Right Trigger)
Be ready to quickly press the 'a' button when you run out of fuel on the in game tablet to refuel.
Maybe keep time on a watch or stopwatch for the 30min because it feels a lot longer when doing this achievement.
Don't let go of throttle till it pops