Prairies are enormous stretches of flat grassland with moderate temperatures, moderate rainfall, and few trees.
When people talk about the prairie, they are usually referring to the golden, wheat-covered land in the middle of North America. The Great Plains, in the United States and Canada, has some of the world's most valuable prairies, which grow some of the world’s most important crops. The U.S. states of North Dakota, South Dakota, Montana, Nebraska, Kansas, Oklahoma, Texas, Wyoming, Colorado, and New Mexico, and the Canadian provinces of Alberta, Manitoba, and Saskatchewan make up the Great Plains.
The prairies in North America formed as the Rocky Mountains grew taller and taller. They grew taller and taller because of plate tectonics, the process where a small number of plates on the Earth’s crust interact with each other. Once the mountains got tall enough, they blocked significant amounts of rain from falling on the east side of the mountains, creating what is called a rain shadow. This rain shadow prevented trees from growing extensively east of the mountains, and the result was the prairie landscape.
The North American prairie is ideal for agriculture. In fact, of the 2 million acres of North American prairie, less than one percent is not used for agricultural development. The weather is moderate, and there are no trees to move to create large, open fields. The very small hills on the prairie are called pimples, and they usually don’t rise taller than 1.5 meters (4 feet). The prairie grasses hold the soil firmly in place, so soil erosion is minimal. Prairie grass roots are very good at reaching water very far down under the surface, and they can live for a very long time. Grains are a type of grass, so the prairie grassland is perfect for growing grain like wheat, rye, and oats.
North American prairie grass is usually split into three different groups: wet, mesic, and dry. Wet prairie soil is usually very moist, and it doesn't drain water very well. The Woolsey Wet Prairie Sanctuary, in Fayetteville, Arkansas, has revived more than 300 native plant species. All the plants in the Woolsey Wet Prairie Sanctuary, a project that was started in 2001, were grown without planting new seeds—native prairie plant seeds can lie dormant for more than 50 years, until the soil and climate conditions allow the plants to grow.
Mesic prairies have good drainage and good moisture in the soil. This type of prairie is popular for farming and agriculture. The mesic prairie of Saskatchewan is known as the “Breadbasket of Canada.”
Dry prairies are more arid than wet or mesic prairies. They have good drainage and are often found on hills, slopes, or higher elevations. Because dry prairies are not useful for agricultural or business development, they retain much of their natural landscape. Species native to the dry prairie include the timber rattlesnake and the greater prairie-chicken, which is nearly extinct in most other prairie ecosystems.
Some animal species contribute to the prairie ecosystem’s agricultural value. The bison, a relative of cattle, is native to the North American prairie. Bison are the largest land mammals in North America, but they have small, pointed hooves. These hooves turn up the soil, just like a plow does. This aerates the soil and allows it to hold more water.
By the middle of the twentieth century, nearly all of the North American prairie grasslands had been destroyed due to extensive farming. The result was miles and miles of soil with no strong prairie grass to hold it in place, and few trees to block the wind. When drought, a period of little rain, struck the prairie in the 1930s, high winds blew the dry soil into huge, frequent dust storms, devastating the Great Plains. The Great Plains were called the Dust Bowl during the Great Depression period.
Large stretches of grasslands called pampas in Argentina, Uruguay, and Brazil are similar to the North American prairie. The pampas are among the chief agricultural areas of South America. In addition to cattle grazing and wheat farming, Argentina also has vineyards in the pampas.