We also used to pay around £/acre or £7.50/hectare for spreading fertiliser (ammonium nitrate 34.5%N) in the 80's.
Used it mostly on trial plots to eliminate the tractor wheeling damage to the crop.
The chap used a Pawnee which carried 500kgs payload,and he handled it like a fighter around low level obstacles!
I imagine the current fuel prices would hike the cost up quite a bit nowadays.
We also used a helicopter,again flown incredibly close to power cables and trees but somehow not quite as impressive as the fixed wing stuff.
Lister
