Humans have cultivated many crops on grassland soil. The soil is rich and almost anything in it can grow if it is both used and treated right. Poor agriculture practices can ruin soil and turn a grassland into a lifeless, barren land. If crops are not rotated properly, all nutrients in the soil are stripped and poor soil results. The soil then turns to dust and nothing can grow in it for many years.
Cattle and livestock ranchers have also ruined grasslands. Many years ago, North America was covered with 250 million acres (101 million meters) of prairie grasslands. Today, because of over grazed land and over worked soil, only five percent of the original prairie remains. Over grazed grasslands in Australia and South America have caused native animals to compete for food.