Hi,

my point was: 

agricultural = yes means legal access for agricultural motor vehicles = tractors and such. That's almost never correct, at least in Germany. 

The correct tagging is vehicle / motor_vehicle = agricultural which allows any (motor) vehicle with the intend to do agricultural work. Could be (and often is) just a regular car (someone picking apples or cherries).

I was in this area years ago and I vaguely remember that it's one of these situation with inconsistent signages. Depending on your entry point, you might see a restricting sign - or not. I will check next time I am around. 

Best