To me, it looks more like the toe nail broke and there is still the nail bed in place. If that's actually the case, the nail will grow out again. Otherwise, it looks like dirt. She has a touch of dark on all the visible toes.
I'm not certain it's necrotic. It just looks like she was digging in very black soil to me. Nails can get caught and pop off. I don't think that even slows down a chicken.
Thank you both. I know relative to all the trauma on the site right now it is a minor issue, but I did feel bad when I saw it!I agree with you. That's what I see.
I feel like her other nails look like an OK length. I didn't get to the others or to beaks today.
There was a lot of lounging around in the sun while I was fixing the electric fence.