Could be damage from voles, from a weedeater or mower. I'm sure that others will suggest other issues, as well. I SURE have seen vole damage just like that, though.

im gonna have to agree that it looks like mechanical damage from something. you may want to put a trunk protector on it.

It sure does appear to be buried awfully deep. Is that an optical illusion or the fact?

If this were a newly planted tree, I'd tell you that it is damage from being banged around at the nursery or during transport or when planting. Seen that a few gajillion times, too.

many thanks many thanks. (this was the first In Ground Citrus that I planted and I did plant it too flush with ground level, but its not as deep as it appears).

I feel confident now that its mechanical damage. Our soil has a lot of gravel, river rock in it, etc. From time to time the mower shoots out a missle. Or maybe the yard guy hit it with the weed whacker.

Thanks so much!