We used to have fertiliser and some chemicals applied by air to our farm in the UK in the early 80's.
The benefit is that there is no soil compaction or crop damage caused through tractor wheelings.
The company we used had a Pawnee that could lift around 500 kgs if I remember correctly.
We also used helicopters at times.
The pilot of the Pawnee was a middle aged South African,Noel Kimvik, and I got to know him quite well,when we were spreading fertiliser I had to stand in the field to mark for him,so he was flying over my head,with very little clearance,maybe 20 feet?
I also marked a couple of times for a fungicide,a bit stupid looking back!
He certailny pulled the aircraft round in low steep turn but thinking back he did exactly as Guppy said,a climbing turn.
When I asked about fatalities he said ,
"The pilots are either young or old,the others are dead"
I would imagine an ex fighter pilot civil instructor would know how to teach you,I was taught to fly by one and a couple times we would need to get a quick circuit in before the parachutists dropped,he would take control and do a really,really tight low circuit,nothing like a normal one.
Lister