Most of the barn looks original. However some parts of the floor do look like they've been repoured (including the area that's breaking up). Drainage around the barn is fair. The gutters are in disrepair, but the ground slopes away fairly steeply on all sides. There are no obvious signs of washout anywhere, or "critter holes." As far as I can tell, I've got the only brick barn in the area (which contributed to buying the property). I've made friends with some of the old timers, but since I've got a full time job and it's not in ag, and also due to our 1 month old daughter, I don't have many good opportunities to talk to them. I hadn't had a chance to call the extension office either, but I probably will before I start breaking too much ground. I'll also probably call some of the Ag professors at Iowa State University - it's only an hour away, and they've some professors who study things like this.
Thanks for your help everyone. Maybe some day I'll get my tractor so I can post on the other boards too! This is a great forum.