Are you saying .1 amps? Another way of expressing this is 100 milliamps. If so, NO, that would be an excessive parasitic load. Lets do the math. If you battery is an 80 amp hour battery which is probably optimistic. We are not talking about Cold Cranking Amps but actual capacity. Typically from 60 to 80 amp hours in a tractor battery. So THEORETICALLY you could pull 80 amps for an hour, 8 amps for 10 hours .8 amps for 100 hours or in your case of .1 amps for 800 hours. Actual capacity us usually less than maximum theoretical capacity. So 800 hours divided by 24 hours per day equals 33 days to total discharge. Likely the tractor would not start in far less than that 33 days.
So, you must find the cause of the parasitic current drain. Did you unhook the alternator connections and measure the current drain again? Remember I mention faulty diodes or regulator in the alternator. You must start unhooking things in the electrical path until the current drain falls to near zero.