The man most closely associated with the peanut, Dr. George Washington Carver, was not interested in personal rewards. Thus, when offered lucrative business offers and foreign travel, he declined to remain a researcher and educator at Tuskegee Institute. He revolutionized farming by introducing the concept of crop rotation, specifically the planting of peanuts in fields depleted of minerals by years of cotton crops. He recommended the planting of peanuts, sweet potatoes, and soybeans every other year, instead of cotton, to help replace the soil's nutrients. Furthermore, because he was challenged on the usefulness of the peanut and sweet potato, he created 300 useful ways to use peanuts and 100 ways to use sweet potatoes.