I can only speak about my experience on the Canadian prairies. It is very difficult to compete against the commercial aerial applicators.
They have their own agronomist on staff. They have direct connection with the chemical companies. If the farmer hires their services they do the prescription for free. On a typical day they will cover 10,000 to 20.000 acres. An agronomist is expected to cover 5,000 to 6,000 acres per day.
Unless you specialize in a high value crop or find a niche I found it very difficult to be competitive when the work is being done for them for free.