Is there a reason why dogs at Glen Ellen dog park are eating mud?

DEAR JOAN: I enjoy reading your column.  I have an odd question.

We frequent a large 1-acre dog park that during the rainy season sometimes has to close for a few days now and then until the rainwater drains. Lately we’ve noticed that when it dries out a bit, dogs of all breeds, sizes, and personalities seem to like eating the mud, just like it was kibble. This stops when the ground dries out more.

We’ve tried to figure out the attraction of the mud. It’s widespread enough that we...