I am writing a young adult, non-fiction, half of the story takes place in Kentucky, and the other half in rural China.
I have chosen an actual city in Kentucky, and having read about it but not actually having been there, how important is it for my descriptions to match reality? For example, if I am describing the smells and sites of a tobacco field - something I've only seen in pictures and never smelled, but the kind ready made for smoking, is it alright to create and fill in the blanks with my own imagination? I know it is fiction, but want to be factual when I can be.
Just curious on the points of creating a believable surrounding.

In my own novel I'm writing a character with one leg shorter than the other. I don't have this problem personally, but it would affect the character's life significantly, and the plot of the novel, so it was vital to get it right. I started with internet research as a jumping off place. Then, just yesterday actually, I met someone with different length legs and asked him to tell me if I was being accurate in my portrayal of my character.

Taking the example of tobacco fields, if you've never smelled one, then it's very difficult to write a POV character who's grown up with them. If your POV character is someone who--like yourself--has never smelled a tobacco field before, then you can just say that it was full of strange plants, never mind about the smell unless your POV character has a super sense of smell.

Check out some early interviews with Kazuo Ishiguro. He became known from his first couple novels as an author who was very good at portraying Japanese culture. He grew up in England, though (although he is, obviously, of Japanese ethnicity). He talked a lot at the beginning of his career about how he created such a vivid world that so many critics bought into as the real thing, when he had no idea if the stories he wrote were at all close to actual Japanese culture.

I'm hip-deep into writing a novel set ostensibly in 1947. (Science fiction, though.) But I've only done minimal research into the period. I'm still pounding away at it but I'm sure lots of it will have to be rewritten in the face of said research.

Oh. I also concur with CoriSCapnSkip about accuracy in terms of setting. If you're going to set something in a definite place, you definitely have to know what what that place looks like in many details, big and small.

(Jack Finney wrote a time-travel novel (Time and Again) set partly in the now-infamous but then-relatively-unknown Dakota Building in New York City---the story was set in, I think, 1882, but the building wasn't built until 1885. (It's been awhile since I read it and I don't have a copy in front of me.) If you change something, you'll have to make a note of it.)

[edited to close parentheses]