Which event convince the united states to enter world war 1 on the side of the allies 1. assassination of archduke franz ferdinand 2. overthrow of the russian tsar 3. election of woodrow wilson 4. sinking of lusitania

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.

it was bribing i think i might be wrong though