5 Different compositions of soils: Soil CompositionDifferent compositions of soils:HIGH % Organic MatterLOW % Organic Matter
6 Different compositions of soils: Soil CompositionDifferent compositions of soils:HIGH % Air & WaterLOW % Air & Water
7 Soil Texture = proportions of different particle sizes U.S. Dept of Agriculture – categories based on amounts of clay, silt and sand.Soil-Texture Diagram (pg 134 Figure 11)Loam has equal parts clay, silt and sand.Loam is best for plant growth.
10 Soil Formation Parent Material = source of minerals in soil. Time = how long it took to form the soil.Climate = did it form in dry or wet areas, under hot or cold temperatures, etc.Organisms = what types of organisms are living or dead in the soil.Slope = the angle of the land on which the soil forms.
11 Parent Material Who’s the mama? Pg. 135 Figure 12 Residual soil = forms on bedrockformed on top of the parent materialTransported soil = forms unconsolidated soilmoved from parent material to another location.
12 Parent Material How did mama affect it? Affects rate of weathering and rate of soil formationUnconsolidated deposits are already weathered some, so they provide more surface area for chemical weathering.Affects the soil’s fertilityMore plant material can grow – more organic matter – better fertility.
13 How long did it take to form? TimeHow long did it take to form?The longer it takes to form, the thicker it becomes.As time passes, weathering can reduce the influence of the parent material.
14 How did and does “neighborhood” affect soils? ClimateHow did and does “neighborhood” affect soils?Has greatest affect on soil formation.Temperature changes affect rate, depth, and type of weathering.Example: hot, wet climate produces a thick layer of chemically weathered soil.Example: cold, dry climate produces a thin layer of chemical weathered soil.
15 How did and does “neighborhood” affect soils? ClimateHow did and does “neighborhood” affect soils?Precipitation influences soil fertility.Climate affects what types and how many animals and plants can live on the soil.Climate can cause similar soils to be produced from different parent materials .
16 How does the “family” affect soil? OrganismsHow does the “family” affect soil?Some soils named based on plants living in them.Prairie soil, tundra soil, forest soil, etc.Plants are main source of organic matter.Protozoans decompose organic matter in soil.Burrowing animals stir, pack and move soil.
17 SlopeSoils on the edge?Slope varies greatly from location to location.The steeper the slope, the faster the erosion and the less water can soak in.Steep slopes have thin layers of soils or none at all.Flat slopes have thick layers of soils.
18 Slope Soils on the edge? The direction a slope faces can affect soils. South-facing slopes receive more sunlight so are warmer and dryer.North-facing slopes receive less sunlight so are colder and wetter.All of these factors work together to affect the formation of soils.
20 SOIL PROFILES = shows soil layers and composition of a section of earth. A Horizon“topsoil”loose, partly decayed organic mattermineral matter mixed with organic matterinsects, fungi, worms, microorganisms
21 SOIL PROFILES = shows soil layers and composition of a section of earth. B Horizon“subsoil”fine clay washed out of Horizon Asometimes packed into “hardpan” soillower limit of plant roots and burrowing animals.
22 SOIL PROFILES = shows soil layers and composition of a section of earth. C Horizonpartially weathered parent materialstill resembles the parent material
23 SOIL PROFILES = shows soil layers and composition of a section of earth. Rockparent materialunweathered
24 SOIL TYPESThree common types of soil:PEDOCALPEDALFERLATERITE
25 SOIL TYPES: Pedalfer Temperate areas receiving > 63 cm/yr Rutherford County, NCB Horizon has lots of iron oxide and aluminum clay.Red or brown color
26 SOIL TYPES: Pedocal Areas with grasses and brush vegetation. Western USAB Horizon has lots of iron oxide and aluminum clay.Red or brown color
27 SOIL TYPES: Laterite Hot, wet tropical areas. Deeper than other soils. When dry, becomes very hard and almost waterproof.Used in brick-making. Pg 139 Fig 15Red or orange color
28 SOIL TYPES: Laterite (cont.) Makes up much of the soil in rainforests.Plants decompose so rapidly in the rainforest there is no organic matter in laterite.Not fertile.
30 SOIL EROSION How WATER erodes soil… IMPACT erosion is a physical effect of water on soil.When falling water hits soil it creates a tiny explosion that tosses soil into the air and displaces it.
31 SOIL EROSION How WATER erodes soil… This is an erosion bed. It is used to test the affects of running water on different types of soil.Here is the bed BEFORE the water is released.FLOWING water picks up particles of soil and carries them with it.This results in a deposition of soil from its original location to another location downstream.Here is the bed AFTER the water is released.
32 SOIL EROSION Rates of erosion… In the past soil erodes more slowly than it does today because more land was covered by plants.
33 SOIL EROSION Rates of erosion… Human activities that remove natural vegetation have greatly accelerated erosion.
34 SOIL EROSION Rates of erosion… Before humans, rivers carried 9 trillion kg of sediment to the oceans each year.
35 SOIL EROSION Rates of erosion… Today rivers carry about 24 trillion kg of sediment to the oceans each year!
36 SOIL EROSION Rates of erosion… Excessive erosion causes excessive sediment deposition in rivers.
37 SOIL EROSION Rates of erosion… Wind can also carry displace large amounts of soil if the land becomes dry from a severe drought.1930’s Dust Bowl