As dead plants, animals, and animal droppings decay into the ground and mix with rocks they make a rich, dark soil called humus. This soil is essential for plants and grasses to grow in grasslands.
Grass roots are also essential to the make up of soil. Roots, that can extend some 6 feet (1.8 meters) into the ground, hold the soil together. The roots prevent the grasslands fine soil from eroding away in the wind and rain. If the grasses and their roots are destroyed, the soil will erode away.