Soil
Soil – a loose mixture of small mineral fragments and organic material Bedrock to Soil Soil – a loose mixture of small mineral fragments and organic material Bedrock – layer of rock beneath the soil; this layer has never been weathered
Sources of Soil Parent rock is the rock that is the source of the soil. The soil made from granite ( ) will look differently than the soil made from limestone. ( ) Parent Rock Parent Rock
Sources of Soil Residual soil- soil that remains above the bedrock from which it is formed Transported soil – soil that is blown or washed away( ) from its parent rock Erosion
Sources of Soil Humus – very small particles of decayed plants and animal material; also known as the organic part of the soil
Soil Layers Soil layers are also known as horizons.
Horizon ‘0’ Contains fresh or decaying organic material (leaves, plants, animals) known as Forest soil = Desert soil = Humus. Thick Thin
Soil Layers Leaching – Rainwater from the surface travels down through the horizons; it dissolves minerals and nutrients, and other substances from the soil above.
Soil and Climate TROPICAL CLIMATES CLIMATE - Air is humid and the land receives a lot of water Leaching occurs quickly and constantly, producing a thin topsoil layer.
Soil and Climate DESERT CLIMATES CLIMATE - Very dry and very little rain Water evaporates quickly, causing the soil to have large concentrations of salts, which can produce toxic soil (even to desert plants) EX: Death Valley
Soil and Climate TEMPERATE CLIMATES CLIMATE - Enough rain and varying temperatures Thick and fertile soil develops due to the abundance of chemical and mechanical weathering. EX: United States
Soil and climate ARCTIC CLIMATES CLIMATE - Little precipitation and extremely cold temperatures Soil formation occurs slowly due to cold temperatures; the topsoil is extremely thin and unable to support most plants.
What do you remember? The source of mineral fragments in soil is called the ______________. The organic part of soil is called ___________. The soil horizon that contains only humus is called _______________. Soil that remains above the bedrock from which it is formed is called _____________.
What do you remember? (cont.) Describe the topsoil in the desert climates and in temperate climate. What climate in the United States is called the “breadbasket” for the many crops the region’s soil supports? What do you find at the different horizons or what is another name? Horizon A Horizon B Horizon C Horizon R
Answers The source of mineral fragments in soil is called the ______________. Parent rocks The organic part of soil is called ___________. Humus The soil horizon that contains only humus is called _______________. Horizon O Soil that remains above the bedrock from which it is formed is called _____________. Residual Soil
Answers Describe the topsoil in the desert climates and in temperate climate. Desert – thin and salty Temperate – thick and fertile What climate in the United States is called the “breadbasket” for the many crops the region’s soil supports? Temperate Climate
Answers What do you find at the different Horizons? Topsoil Subsoil Horizon A Horizon B Horizon C Horizon R Topsoil Subsoil Partially weathered Rock Bedrock
Soil and Soil Conservation
Soil Conservation Consists of the various methods by which humans take care of soil http://www.youtube.com/watch?v=nPocNfxvKaY&safety_mode=true&persist_safety_mode=1
Review! Humus Soil takes a long time to grow! Is the part of soil made up of decayed parts of once-living things It is dark and soft Soil takes a long time to grow! It takes 500-1,000 years to grow 1 inch of soil Deep soil takes thousands of years to form
Layers of Soil Topsoil Subsoil Bedrock The top layer Made of the smallest grains Richest layer of soil due to the having the most humus Subsoil Layer under topsoil Larger grains Less humus Bedrock Solid rock under soil Weathering breaks down rock into soil Made of different minerals
Importance of Soil Soil contains the minerals that all living things need!
What Did We Learn? There are many types of soil Soils are made from different minerals Soils have different colors and different sized grains Soils can hold different amounts of water Soils that are best for plants have the right mixture of minerals and humus http://www.harcourtschool.com/activity/dirt/formation.html
Soil That is Good for Plants
Soil Facts Soil is an important resource just like water, air, trees, and minerals. If the same type of crop is grown in soil for many years on the same land it could harm the soil. Plants use up the nutrients in the soil, then the soil is too poor for growing more crops.
Why is Soil so Important? Minerals and nutrients for plants Housing for many organisms (earthworms, spiders, moles, prairie dogs) Storage- Soil stores water
Saving Soil Resource: a material found in nature that living things use Conservation: saving resources by using them carefully
How Can Soils Be Harmed? Examples of how soil can be harmed: 1. Cutting down trees 2. Over-farming 3. Erosion- wind and water transport soil and sediment
Ways to Save the Soil 1. Strip cropping 2. Contour plowing 3. Crop rotation 4. Cover crop
Ways to Save the Soil 1. Strip cropping: planting strips of thick grass or clover between strips of crops 2. Contour plowing: planting rows of crops around the sides of hills (across the slope of a hill) instead of up and down
Ways to Save the Soil 3. Crop rotation- In order to prevent nutrient depletion, crops planted in certain areas are changed year to year 4. Cover crop- a crop that is planted between harvests to reduce soil erosion and to replace certain nutrients in soil Ex: Clover and soybeans
What Did We Learn? Growing the same type of crop on the same land for many years removes minerals. When people remove plants and trees, soil may be washed away. Farmers conserve soil
The Dustbowl of the 1930s http://www.youtube.com/watch?v=vNKBEbOFrfk&safety_mode=true&persist_safety_mode=1