SOIL AND ITS FORMATION

Components of Soil Viewed in layers Each layer has different texture and color Deeper into the soil there is less organic matter

Litter Upper layer in forests and grasslands Made up of decomposed legumes and grasses Like a blanket

Topsoil Made up of small particles of rock mixed with decaying plant and animal material (called humus) Rich supply of minerals and nutrients Air and water This is topsoil

Subsoil Contains more stones Small amounts of organic matter Lighter in color because of lack of humus This is subsoil

Bedrock Layer of rock beneath the soil Marks the end of soil This is bedrock

Formation of Soil Begins as bedrock Broken down into smaller particles by rain, wind, frost, snow, living things (called weathering) Small plants start growing Plants speed up weathering, decompose and add to topsoil Larger plants can grow

Soil pH Soil can be acidic, neutral or basic Determined by the type of rock and plants from which it formed Decomposition of organic matter from dead plants or leaves cause acid accumulation Rain and snow, ground water, humans burning fossil fuels SO2 and nitrogen oxides form acidic compounds in in the atmosphere as acid rain or snow

How can the pH of acidic soil be raised? Acidic Water in Soil Causes extreme leaching Leaching: when nutrients and minerals in the soil are dissolved in percolating water and carried into lower layers of soil or bedrock Fertility of soil is reduced Plants grow slower and are vulnerable to diseases pH of the soil determines switch plants grow best Examples: Conifers do bad in acidic soil(needles turn yellow and brown) Mosses love acidic soil due to little competition How can the pH of acidic soil be raised?

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