Buying from a dealer? Ask them about their financing. Deere does reasonably well on used machines.
Private owner sale? Depending on how much you'll need to finance, a personal loan or home equity might be the way to go.
When I bought my older Deere 670, I tried the bank but they don't consider used tractors a good risk (my bank didn't, anyway). I ended up financing through the dealer.
As far as interest rates...they change pretty frequently so I wouldn't venture a guess.
Personal opinion...the Home Equity loan or line of credit. That's probably going to be the best interest rate and you can deduct the interest or at least part of it.
