1. Soils Tuesday November 2, 2010 Soils

2. Chapter 5 Section 2: Soil What is soil? Soil is part of the ___________ that supports the ___________ of plants. Regolith is the layer of ______ and mineral ___________ that covers most of Earth’s land surface

3. Soil Components What are the components of soil? – There are 4 major components: 1.___________ (from broken down rock) 2.___________ (decayed remains of organisms) The main source of organic matter is ___________ 3.___________ 4.___________

4. Composition by Volume of Good-Quality Soil Most of good- quality soil is made up of what? _______ Together, water and air make up what percentage of soil? ________

5. Soil Texture What is the difference between these two soils? They have different ___________ !

6. Soil Texture Soil texture is determined by the proportions of different particle ___________ – ___________ (large) – ___________ – ___________ (small) ___________, a mixture of all three sizes, is the ___________ ___________ for plant life.

7. Soil Texture NO MATTER WHAT the percentages of sand, silt, and clay should add up to ___________ % (you cannot have less than 100%)

8. Soil Texture HOW DO I READ THIS THING? Percent _________ is read across here  Percent ________ is read diagonally down here  Percent _______ is read diagonally up here 

9. Soil Structure When particles clump together this gives soil its ___________ – ___________- single-grained (doesn’t really clump), like sand – ___________- clumps together tightly, like ___________ – ___________- clumps together, but ______________________easily – ___________- clumps together in large columns

10. Soil Formation The most important factors in soil formation are: – Parent material – ___________ – Organisms – ___________

11. Soil Formation Parent Material (where the soil ___________) – ___________Soil- the parent material is the ______________________ – ___________Soil- the parent material has been ___________from somewhere else and ___________there. Time – The ___________a soil has been forming the ___________it becomes Climate – ___________________________________________________ _____________________________________ – The best climate = ______________________

12. Soil Formation Organisms – Living and dead organisms influence the physical and chemical ___________of the soil – Provide ___________to the soil Slope – The steeper the slope, the more difficult it will be for material to stay – ___________slope = ______________________

13. Soil Formation BOTTOM LINE: Soil formation is greatest in a ___________and ___________climate in a ___________area.

14. Soil Profile At different depth, soil varies in its composition, texture, and structure. This creates layers called soil ____________ A _______________ is a vertical section through all of the horizons The __ horizon is ____________ The __horizon is subsoil and contains ________ particles washed down from A The ___ horizon is underneath the B and above the unaltered parent material (________)

15. Soil Profile

16. Soils Check-in questions Answer the following IN COMPLETE SENTENCES ON A SEPARATE SHEET OF PAPER 1.What are the four main components of soil? 2.What factor determines a soil’s texture? 3.What is the main source of organic matter in soil? 4.Explain why a flat area in a warm, wet climate would have the greatest rate of soil formation. 5.Draw a soil profile and label a)The A, B, and C horizons b)Which layer is topsoil c)Which layer is subsoil 6.What type of material is found in the C horizon?

17. Soils Types

18. Soil Erosion Erosion = the movement of weathered materials – Wind and water are two major erosional agents – The rate of erosion depends on the climate, the steepness of slopes, and type of vegetation in the area – Humans and animals have a huge effect on rates of erosion.

19. Soil Erosion Do you think the rates of erosion have increased or decreased because of humans? What are some human activities that you think have accelerated the rates of soil erosion? (brainstorm with a partner)

20. Soil Erosion Human activities that accelerate erosion: – Removal of natural vegetation through Farming Logging Construction – Sediment Deposition Reservoirs fill with sediment Since humans have appeared the amount of sediment carried by rivers and streams has increased dramatically

21. Soil Erosion Soil Erosion Control – Continue brainstorming with your partner: What are some ways we can control erosion? 1.Planting rows of trees called windbreaks 2.Terracing hillsides 3.Plowing along the contours of hills 4.Rotating crops

22. Soils Check-in questions Answer the following IN COMPLETE SENTENCES ON A SEPARATE SHEET OF PAPER 1.What are the four main components of soil? 2.What factor determines a soil’s texture? 3.What is the main source of organic matter in soil? 4.Explain why a flat area in a warm, wet climate would have the greatest rate of soil formation. 5.How have human activities affected the rates of soil erosion? What are some activities that have the greatest effect?