Maya collapse

My collapse theory is that the Maya simply farmed themselves out of power to feed their city-states, war efforts and religion. They were organized into city-states that fought endlessly, and required a lot of food to feed the warriors. These city-states also required vast amounts of food to feed the people living there. Maize (corn) was considered sacred, and every man had to plant a blood crop, maize seeds doused in blood from when his umbilical cord was cut. Crops had a great value to the Maya, so they toiled the soil so much that it lost its fertility, forcing them to abandon their great cities lest they all starve.