Where are you in the books? I found the first book to be pretty slow. They get progressively better.
The sixth chapter of the first book.
But the city in Return of the King...where were the farm fields? What did they eat?
I noticed and wondered about the same thing too.
As others have said, the first book gets started excruciatingly slowly, but things do pick up to an extent later in the series. There are spots later on that are give-me-that-part-of-my-life-back dull, though. I've read the whole series a number of times, and I'd wager that I know it about as well as it's possible to know it while not being a mom's-basement-dwelling Tolkien Dork.
The thing that is different about LOTR is that it's not a book, or even a series of books. It's a
world. Tolkien was, among other things, a linguist. The various languages and mythologies presented in LOTR are actually pretty thoroughly put together, and the races each have a history that Tolkien put together as meticulously as any anthropologist. The fact that he was making stuff up doesn't change the level of detail that he put into it. I'd wager to say that Tolkien, by the time he was done, knew more about the fictional races in his books than we know about some ancient cultures that actually existed.
Middle Earth even has
scripture.
With respect to the way that Minas Tirith fed itself, there's a certain amount of discussion of that in the books, and more in some of the side works. Thing is, the Tower of Guard was just that: a fortress; it was there for one purpose only, to provide a military stronghold against the potential that Mordor might rise and attack Gondor again. So it was built not with economics in mind, but with strategic position and defensibility in mind. Food was carried to the city in wagons from all over the country of Gondor. One might as well look at New York City and ask where they grow
their food; simple...they don't. They haul it from elsewhere.
This fine-grained world-building is both a strength and a weakness for the stories; on the one hand, it means that it's one of the most internally-consistent works of that magnitude ever written. On the other hand, since he put all that effort into it, I get the feeling that Tolkien occasionally got carried away in putting too much detail into things. Later on in the first book, for instance, Frodo will come to a mountain called Caradhras, and Tolkien will carefully point out that that it its name in Elvish (Sindarin specifically), and that in the language of Men it means "Redhorn", and in the tongue of the Dwarves, it is called "Barazinbar". None of which advances the story, but provides insight into the depth of the people and races in it.
That may be your cup of tea. It may not. I find Tolkien's worlds compelling for their completeness and consistency. Even so, I still occasionally get frustrated with how long it takes for him to get to the point in some parts of the story.
-BP