Yes, you can get insurance on anything and can insure anyone or anything. Now that said, most homeowners policies will cover theft of personal property while on your property, and some policies will provide coverage of personal property while off your property. Your tractor should be automatically covered on your homeowners policy unless there are specific limitations or exclusions that include tractors. You should inquire with your carrier in any event. If your tractor is used for income production you should get coverage for that purpose. Business use has a higher level of risk to the carrier.
Also as someone else stated above, your tractor would not likely be covered if you took it off property and either had it stolen or damaged; these are normal exclusions. Now having said that and going back to the beginning you can insure absolutely anything. Therefore if you regularly use your tractor off premise, you should get coverage to include off premise use.