I realize I am jumping in late here, but I do have something to add. If you use a home equity loan, obviously, you get the interest write off in most cases. You need to think though, would you rather pay for a tractor for 30 years (or whatever the length of you loan is), when you might sell it and trade up in 5, or 10 years? You will still be paying on it, albeit, maybe not a whole heck of a lot when compared to the mortgage on the house itself. I think it would be wiser to add extras to your house that will save you money in the long run - i.e. a better HVAC, one that is more cost effiecient - thus saving you money in the long term.
When I finance a tractor, I have used zero percent interest credit cards. I figure out the term I want to pay for (5 years), and make the payment based on that amoritized schedule. When the zero percent is 2 months away from being over, I then apply for another, transfer the balance, and CLOSE the previous card. The cycle has been going on for almost 3 years now, and I still have not payed any interest on this loan. Also, be leary of zero cards with a balance transfer fee, That fee will add up to signicant 'interest' if you will.
Another option is to look for a loan at a 'farm' friendly bank. Usually, you can get a loan for agricultural equipment for prime + 2 to 4 percent. That is not too bad.
Obviously, it depends on ones financial circumstances, how much you earn each year, and how much debt you feel comfortable carrying. I don't like the idea of putting my house up for collateral against anything but house items (i.e. new HVAC, roof, addition, etc). Just makes ME a bit uneasy.
I have almost 10 years in the mortgage industry, and I have seen way too many people get over thier head in mortgage equity loans, mostly to pay off other debt, and then getting in deeper again, using the credit they paid off with their equity loan. I don't mean to get up on the podium here, I have just seen too many people make some really bad mistakes when it comes to their house.
Good luck on this one,
Ira