The advantage of rotating crops in Medieval Europe was that it allowed the soil to recover and get the nutrition base required for certain type of plant by planting crops with different needs every year. If the people were planting the same crops every year, very quickly the nutrition base in the soil would have diminished and the crops would have been weaker and weaker every year. But with rotating the crops, and planting crops with different needs every year, the soil was able to recover its nutrition deposits and the crops were of greater quality.
