It is not exactly clear as to who invented crop rotation, though early crop rotation methods were mentioned in Roman literature and also during the Middle Ages. There are a number of different crop rotation plans, ranging from three, four or even five years.
The idea behind crop rotation is to ensure the same crops are not grown in the same place for more than two years. Using the three- or four-year method helps to decrease the crops pest population by denying a long-term host to sustain them. Crop rotation also allows new crops to take advantage of the nutrients left by the previous set of crops.