I would like to know if there are any issues with a full scale airplane or ultralight taking off and landing from a model airplane field.
I have been to fly-ins and have seen this but I would like to know if the AMA has anything problem with this occuring.
I would only like facts, please no opinions.

Not sure exactly what you want to know but AMA clubs have been known to exist at full scale airports.

... and some clubs will get full-scale planes to come in for a fly-in (provided the runway is long enough).

What I am refering to is a full scale aircraft taking off and landing from a model airplane field that is not attached to any airport.

Not sure that is a problem. Certainly not one the AMA worries about. FAA may be a different story, But
There are, all over the West, a number of farmers, ranchers, and others, who keep a Cessna 172, 205, or 150 in their garage, and use their driveway for a runway. Nobody else around. No problem. We flew RC at one such place (OK, he had graded a mile-and-a-half of prairie with a blade). Ultra-lights and powered parachutes can land pretty much anywhere, anyway.
The Roswell Aircraft Fliers often share with hot air balloons, an occasional ultra-lite, and once or twice, a "Kit Fox"

Roger

Thanks all for the replies. I have been to many fly-ins and contests where full scale airplanes have landed and took off but I have never known if the AMA has had any issues or concern with this. I dont see any problem with it at all and I enjoy the difference in scale.
BTW - I am a full scale pilot as well.

The only problem with landing a rider scale at a model field is getting in and out without attracting the attention of the local Flight Safety office. Read AIM again and note that as pilot in command YOU are responsible for selecting the correct runway for the current aircraft. If you bend it, the FSDO will be paying you a visit.

I'm not sure if there would be any problem with General Aviation planes landing at an RC field but Ultralights are considered as "recreational vehicles" by the FAA thus as long as the ultralight pilot has the permission of the owner or leasor of the land and the land is not in a heavily populated ground area, it is not a problem. In the past, I flew my ultralight into a few RC fields (but only with permission.)

In some areas such as Anne Arundel County, Maryland, the problem is that the local zoning prohibits landing or taking off an aircraft at any place other than a "designated" airport or heliport.
If you violate a rule/regulation (it doesn't matter who's), you may be creating an "unsafe operation".
We could lose our field if we (the club) allow an unsafe or "illegal" activity.

Same is true with GA planes, the only problem is if you choose an improper field (too short, obstructions, rough ground) and crash. You would be held at fault for choosing an improper field. Bush pilots do this all the time.