Getting to Know Soil Changes Your neighborhood park is an ecosystem There are plants animals and other organisms coexisting in the area There are rocks lakes or ponds and other nonliving features All of these biotic or living and abiotic or nonliving entities interact and keep the ecosystem in balance Soil is an important link between the biotic and abiotic factors in an ecosystem

Soil composition varies by location because the parent materials in each area differ Climate and other factors also affect the composition of soils

What is soil Soil is composed mainly of weathered rock material and organic matter The organic material in soil called humus comes from the remains of organisms Soil also contains air water and a varietyof microorganisms such as bacteria and fungi

Soil formation begins with the process of weathering which creates sediment or fine particles of rock The original soil-forming material in a region known as the parent material determines the types of minerals present in soil Parent material may be deep bedrock sediments deposited from another location or an older soil layer The parent material is broken down by weathering thereby creating a place for organic matter to collect

Misconception 1 Are soils important for an ecosystem

Soils are essential for life on Earth A new ecosystem cannot be established until soil has formed in enough quantity to support plant growth The characteristics of the soil will determine what other organisms will thrive in the area If the soil is contaminated other organisms will likely be damaged and if the soil is carried away by erosion the ecosystem could be destroyed altogether

Are there different types of soil Parent material on Earth is not evenly distributed That means the minerals that make up the soil in a region are unique and closely related to the type of parent material present For instance some soils in the southeastern United States are derived from an iron-rich parent material When exposed to oxygen in the air the particles rust giving the soil a red color

Concept Soil Changes Getting to Know wwwdiscoveryeducationcom

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Climate also factors into the type of soil present in an area The type of climate determines the type of weathering that occurs Cold regions produce different soils than hot regions Wet regions have different soils than dry regions

Plants and animals also affect soil formation Soils need small pockets of air for the exchange of gases with the atmosphere Worms beetles larvae prairie dogs and badgers all contribute to soil formation through digging and burrowing Small organisms within the soil break down decaying matter and release nutrients into the soil The distribution of plants and animals is an important factor in determining soil type Burrowing animals such as this badger

affect the soils in an area

Which minerals are in soil There are three main nonliving components of soilsmdashsand clay and silt which are derived from the parent material Sand is coarse and does not hold water well Clay is made of very small particles of minerals and holds larger amounts of water Silt is made of medium-sized particles The type of parent material determines the percentage of sand clay and silt in soil

Soils are naturally arranged in layers Scientists call the layers a soil horizon and they characterize each by its texture mineral composition color and depth The surface layer the A horizon or topsoil consists of insoluble minerals and humus The B horizon or subsoil contains soluble minerals and clay that have been washed down from the surface along with oxide minerals The deepest layer the C horizon consists of larger rock fragments and rests on a solid rock layer known as bedrock

Misconception 2 It does not take long to replenish soils

That assumption is incorrect Fertile soils full of many nutrients take hundreds or even thousands of years to form That is why soil erosion is a major environmental concern When soil is washed away it takes a long time for the soil to form again

Concept Soil Changes Getting to Know wwwdiscoveryeducationcom

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Discovery Education is a subsidiary of Discovery Communications LLC