Understanding Soil Formation

Five different factors that affect soil formation 2. Topography -the slope characteristics of the soil 1.Parent material -type of rock material from which the soil is formed

What are five different factors that affect soil formation? 3. Living organisms 4. Time or weathering 5. Climate - the temperature and moisture characteristics of the area

Types of Parent Material Most soils in Illinois have been formed from material originally moved by glaciers.

Types of Parent Material Loess –About 64% of the soil in Illinois comes from this –occurred from the blowing of the soil after the glaciers melted and dried –most desirable single soil parent material

Types of Parent Material Outwash –About 16% of the soil in Illinois comes from this –occurred when the glaciers melted

Types of Parent Material Glacial till –About 11% of the soil in Illinois –Pebbles and various sizes of boulders

Types of Parent Material Alluvium –sediments deposited by streams Bedrock –shale, sandstone, or limestone –buried by loess, glacial till, outwash, or alluvium.

Topography Slope of the land –More slope = more runoff –More runoff = depletion of nutrients

Living Organisms Organisms that live in soil (i.e., plants, insects, and microbes) actively affect soil formation. More organisms = more aeration and drainage Organisms can break down soil

Living Organisms Organic matter –Left over, decomposed matter from once living organisms –Gives soil its dark black color –Ideal, good soil has about 5%

Time and Weathering There are two types of weathering. 1. Physical weathering is caused by the effects of climatic factors (e.g., temperature, water, and wind). 2. Chemical weathering changes the chemical makeup of rock and breaks it down. More time = more weathering

Climate Ties into each previous area –Dictates temperature and moisture –Effects enhanced by the organisms and topography of the area