The first rotations only alternated grassland and crops, but the big breakthrough in the 18th century was because of the “Norfolk four course”. This was a crop rotation system that was invented by Turnip Townsend. He suggested using a sequence of cop rotation that included wheat, root crop, fallow and beans. In addition, after the introduction of crop rotation many aggressive weeds spread into the farm and grassland. Some weeds were brought along with the wanted seeds, while other were brought by animals, either in the fur or by earlier indigestion. Other weed seeds were probably brought by accident in the folds of clothes and fabrics. It became very important to the settlers to deal with weeds and invent new ways to get rid of them so that their crops would not be ruined. Until now, Americans spend millions of dollars trying to prevent the growth of