"Das Kind isst nicht Orangen."
It's nicht because in this case, nicht signifies not eating oranges in general. The child doesn't eat oranges, ever. If it was keine instead, it would imply a specific amount of oranges the kid is refusing to eat. "Das Kind isst keine drei Orangen" is more appropriate for such an instance.
Here's my take.
- Das Kind isst nicht Orangen.
This is grammatical, but it sounds quite odd to me as I'd expect the sentence to continue and tell what the child is in fact eating. For instance: "Das Kind isst nicht Orangen, sondern Birnen."
- Das Kind isst Orangen nicht.
This means that the child never eats oranges. The sentence is grammatical, but personally, I'd use the "kein" negation. This might just be my personal preference, though.
- Das Kind isst keine Orangen.
This negation sounds the most natural to me. It's also the most universal one in terms of context. It means the child isn't eating oranges or the child doesn't (ever) eat oranges.
I have no reason to doubt your explanation, it's just I've never heard that before. Of course that should come as no surprise to me, because my German is not that good. But, assuming that it is okay to use "nicht" here, it still seems awkward to me. Why not "Das Kind isst Orangen nicht."? Or are both okay? Or is my way simply wrong?
For some reason I can't reply to your comment further down the chain...so...My non-native language guess is "Das Kind isst nicht Orangen" means "The kid does NOT eat oranges". "Das Kind isst keine Orangen" means "The kid eats no oranges"....not that he never eats oranges, just that right now, that kid is eating a sum of 0 oranges. I would say that "Das Kind ist Orangen nicht" also works but maybe it sounds bad to a German ear.
I agree with chubbard. I just discussed this with a native and of course he understands (used to my broken German) but basically we considered two options: the child eats no oranges (never ever) and the child does not eat the oranges (at this moment, those particular oranges) and would be, respectively,
( Das Kind isst keine Orangen, Das Kind isst Orangen nicht) , Das kind isst die Orangen nicht.
It is not really possible to do translation word by word on this sentence.