where i was born and learned my german, we never say " ... am meisten in china... " it sounds strange, like you made up your mind during your speech. but of course, thats only in austria, no kangaroos... as far as i know in german the ordering is not so important, so basically both versions are correct from the grammatical point of view, but as a native german speaker i would say it as "In China wird am meisten Reis angebaut."