Why did the Maya collapse?

I believe that the leading cause of the Maya collapsing would be not enough rotation of the crops which would have a similar effect to the dustbowl. Many Mayans died of anemia, which comes down to not having enough nutrition in their diet. Another clue that points to my theory would be the erosian of the hillside coming down on houses. Many monuments from the Mayan time just suddenly ended one day, which ties into the land, this would give the land enough time to repair. Although my theory looks pretty good there are a lot of theories out there that are worth looking at also.