In 1866, the first attempt in the united states at a union for workers was called the

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.

these civilizations were located around fertile rivers, where they could produce an abundance of crops