Which Olympic circle represents which continent?

Each ring in the 16 prints symbolizes one of the five continents competing at the Olympics: Africa (yellow), the Americas (red), Asia (green), Europe (black), and Oceania (blue

crop rotation kepy different plants in the soil instead of once constintly. when switching out plants you have different nutrients being absorbed at different speeds and different roots growing differently therfore the spoil and water flow have to adapt and carry fresh nutrients to carry the constant changes that were going on in the soil.