Soil Composition of the Temperate Grasslands

Precipitation

• Because rainfall in temperate grasslands occurs during the hottest time of the year in late spring and summer, the soils are very well developed. The average rainfall for these areas in a year is between 20 and 35 inches. Having lots of water allows chemical degradation to occur in environments where temperate grasslands occur. This means that rocks, sand and living materials break down faster and are incorporated into the soil, making it highly fertile. However, because rainfall is not consistent throughout the year, dry periods allow nutrients to accumulate and stabilize in the soil.

Temperature

• High summer temperatures of temperate grasslands influence the type of grasses that grow; how fast materials break down, since temperature influences the speed of chemical reactions; and how much water evaporates from the soil. Temperate grasslands usually have ample rainfall, but the high temperatures also cause most of this water to evaporate. Keeping the soil moist but not too wet is what makes the composition of these soils so rich. Evaporation due to high temperatures draws water up from deep in the soil. When water levels rise, they bring nutrients and clay particles towards the surface of the soil. Thus, the evaporation of water from temperate grasslands changes the composition of the soil by mixing nutrients throughout the soil.

Organisms

• The predominant organism of temperate grasslands is grass. However, the amount of water the area receives and the variation in temperature determine what types of grasses will grow. The massive amounts of roots that grass plants grow every year help to add organic matter to the soil. Organic matter is a key component in soil fertility. The small grass roots also bind tiny pieces of soil together into small clods, which helps water penetrate into the soil and make its composition become richer. Other living organisms influence the composition of the soil. Large mammals, insects and worms help add nitrogen and phosphorus to the soil.

Parent Material

• Depending on the locations of the world's temperate grasslands, they will be found on different types of rocky parent material. The parent material may be an old ocean floor, solid bedrock or rubble. However, because of the ample water and temperature fluctuations, the soil of temperate grasslands is quite thick. This is because the chemical reactions that break down rock and sand into small particles of silt and clay are aided by the environmental conditions found in temperate grasslands. Thus, even the though the parent material may be from very different types of rocks or sands, the soil that is formed on it has a similar composition. It is very thick (more than 6 feet), high in organic matter and very good for plant growth.