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Soil Use and Abuse

Soil Use and Abuse. Chapter 11 APES January 2007. Objectives. Define the roles of living organisms, physical forces, and other factors on creating and maintaining fertile soil.

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Soil Use and Abuse

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  1. Soil Use and Abuse Chapter 11 APES January 2007

  2. Objectives • Define the roles of living organisms, physical forces, and other factors on creating and maintaining fertile soil. • Differentiate between the sources and effects of land degradation including erosion, nutrient depletion, waterlogging, and salinization.

  3. SO what does that really mean? • How is soil made? • How is it destroyed? • What role are we playing as humans?

  4. What is soil? Soil is made of three things: • Water • Eroded rock material • Dead stuff • Live stuff

  5. The water component The moisture content of the soil will depend upon several factors: • How well drained the soil is • The rock composition/particle size • How much it rains

  6. The rock component • Bigger rock particles such as gravel and sand (see chart page 237) provide good drainage and aeration. It’s easier for roots to push through this type of soil. • Smaller rock particles such as clay and silt tend to pack and offer less air spaces, but are better at holding the minerals.

  7. Humus (dead stuff) in the soil • The dead animal and plant parts in soil act like a sticky glue holding the tiny rock particles together, making the spongy conditions needed for roots to grow. • It also holds the water and minerals needed by plants.

  8. Soil Organisms in the soil • Soil aeration by worms and bugs • Decomposing humus by fungi and bacteria • Algae makes new organic compounds • Burrowing mammals help aerate as well • Plant roots penetrate the soil and secrete acids, breaking down rock further

  9. The Soil Profile/Soil Horizons Field trip flashback: Remember all The differences? The E layer is also Called the Zone of Leaching

  10. Types of Soils • Your text discusses the types of soils, please study them pg. 238-239. 12 soil orders, I will discuss three common to WI. You should be aware of and be able to discuss the rest.

  11. Mollisols: under grasslands

  12. Spodosols: under pine forests

  13. Alfisols: deciduous forests

  14. How do we use our soil? • 11% of our land areas is under agriculture. • 4 times that could be crops but it would affect the wildlife populations. • Many areas cannot support agriculture due to soil chemistry, topography, and rainfall.

  15. How are we using our land? • Land use comparison • Wisconsin land use • Satellite land use • Study chart Page 240 Of your text.

  16. Land use correlations • Developed countries through technology are tilling less land. • Developing countries are destroying forests to create agricultural areas that are not sustainable. • 2/3 crop gains have come from better genetics and methods.

  17. Ecological Trade offs Be sure to read about the challenges facing developing countries. How do you decide between saving the rainforest and feeding your people? Just because you CAN cultivate land SHOULD you?

  18. The Sad Truth about some areas: When you clear the trees from the land And there isn’t very deep soil And there’s lots of rain You have about 5 years Until the soil is ALL gone Washed away It will take 100s of years to rebuild.

  19. If we acted as a team…. There’s plenty of land that COULD be farmed safely and we could feed the world. I have often thought….what if we tried to feed the world as hard as we are trying to liberate Iraq? What would happen?

  20. Degradation of the Land What does that really mean? It means the land gets ruined. Hmmm…..how? Fertilizers , overgrazing, and erosion. Why does that happen?

  21. Every year our land takes a hit: • 3 million hectares are ruined by erosion • 4 million hectares are turned into desert • 8 million hectares are turned into something other than crop land such as malls, homes, highways and parking lots

  22. World Statistics on Land Degradation: • 3oo million hectares: strongly degraded • 910 million hectares: moderatelydegraded • 9 million hectares: not usable anymore Causes: Water, wind, salts

  23. Signs of Degradation: Soil is impoverished or eroded

  24. Signs of Degradation: Water runs off the land or is contaminated

  25. Signs of Degradation: Vegetation is diminished

  26. Signs of Degradation: Biomass production is decreased

  27. Signs of Degradation: Wildlife diversity diminishes

  28. Impacts: Ranches: fewer livestock Farms: poor crop yields Nature: less species Page 241 of the text shows the percentages of degradation by country and region.

  29. Major Issues to Tackle: Water 55% Wind 29% these happen naturally but can be exacerbated Chemical 12% Nutrient depletion, Salinization, acidification, pollution Physical 4% Heavy machinery, cattle, waterlogging, solidification

  30. What exactly is erosion? It’s the transport of soil from one place to another. How does it happen? Wind and Water carrier soil parts from high places to low places. It has shaped the surface of our planet. Is it really bad?

  31. Wind Erosion

  32. Wind Erosion

  33. Wind

  34. Wind

  35. Water Erosion

  36. Water Erosion across the World

  37. Types of Erosion • Rill Erosion Tiny rivers of running water make small channels in the soil • Gully Erosion Rills enlarge to form big channels in the soil

  38. Where is it happening? • Agricultural Fields/runoff The fields loose soil twice as fast as it is being replaced. • Dust Storms Wind carries the soil away and dumps it elsewhere. This can be worse than water in some ways.

  39. US and Canada are big culprits • Intensive cropping/row crops • Deep plowing • Heavy herbicide applications • Machines create gullies • Abandonment of crop rotations/$$ issues • Monoculture cropping check out these stats in your text pg. 242

  40. What are we to do? You tell me gang. What can we do as individuals to help stop the washing away of our future?

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