1. Soil & Acid Precipitation

2. What is Soil?

3. Soil is …
a mixture of minerals (rocks), organic matter, gases, liquids, and countless organisms
what supports life on Earth!

4. What defines “healthy soil” ?
To evaluate soil quality, we must consider:
Soil Profile
Soil Type
Acidity

5. Soil Profile
There are 3 distinct layers to the make-up of soil: 1. Topsoil – O and A layers. - made mostly of humus, which is decaying organic matter - has rocks, organisms like bacteria, fungi, insects, worms 2. Subsoil – B layer - very compact - has little/no organic matter except bacteria and roots of large trees 3. Regolith and bedrock – C and R layers - made of of large chunks of rock - bedrock is solid rock - water cannot pass through so it accumulates here  this is where aquifers (groundwater) are located

6. What is the healthiest soils made of?
50% pore space
48% solid material
25% air
25% water
45 to 48% mineral matter
2 to 5% organic matter
What is the healthiest soils made of?
Not all healthy soil has this balance – only the most desirable soils.

7. Soil Particles
All soil originated from bedrock, therefore all soil is made up chipped rock pieces called minerals or soil particles
4 types of soil particles (largest to smallest)
sand, silt, and clay
loam (various sizes)

8. 4 Types of Soil Particles (largest to smallest)
sand
silt
clay
loam

9. Sand: 4 Types of Soil larger, feels coarse and gritty
creates large spaces that allows root growth and air pockets for plants
water drains too easily which takes nutrients away from roots of plants

10. Silt: 4 Types of Soil fine particles, muddy texture
easily transported by water, found in or along rivers and wetlands
soil drains slowly which helps plant grow, but soil also erodes away easily
human activities (ie: logging) results in silt being washed into rivers, acts as a pollutant

11. Clay : 4 Types of Soil very fine particles
dense; particles are packed tight together, so there are no air pockets
traps water = often very wet and sticky
plant growth in clay is difficult

12. 4 Types of Soil
Loam:
contains sand, silt and clay of different sizes which creates pockets that hold air or water
has lots of humus (decaying organic matter)
drains well without drying out
plants grow easily in loam
dark brown or black

13. Which soil type is best for farming?
sand
silt
clay
loam

14. Negative Human Impacts on Soil

15. Negative Human Impacts on Soil
Soil Erosion
soil is washed away by wind or water
occurs when soil is ploughed or overgrazed by livestock
if the top soil is gone, nutrients are gone too!

16. Fertilizers Negative Human Impacts on Soil
farmers add manure, nitrogen and/or phosphorus to soil to make plants grow bigger and faster
these fertilizers are washed away from the soil by water and pollute local water bodies resulting in in excessive algae growth called eutrophication

18. Algae Bloom in Lake Erie

19. China’s Yellow Sea Turns Green!

20. Leaching Negative Human Impacts on Soil
occurs when soil is over-water and nutrients in the topsoil wash downward, making them unavailable to plants

21. Crop Rotation
planting a different kinds of crops every other season allows soil nutrients to be replenished
if crops are not rotated, the certain soil nutrients will get used up and crops will no longer grow well
planting legumes helps to put nitrogen back into the soil since they have nitrogen-fixing bacteria

22. Acids in Soils

23. Acidity is another factor in soil quality and it is measured using the pH scale

24. pH Scale

25. soil pH for humid environments soil pH for drier environments
pH Scale for Soils
soil pH for humid environments
soil pH for drier environments

26. Acidity of Soil
Most plants prefer a somewhat neutral environment (around pH 7)
If soil is too acidic or basic (alkaline) it can harm plants:
damages roots  can’t absorb soil nutrients
damages waxy coating on leaves  infection
worm skin is burned  no recycling of nutrients

27. What is Acid Precipitation?
any form of rain or snow with high levels of nitric acids and sulfuric acids (from pollution)
up to 40X more acidic than normal precipitation
causes soils to become acidic too

29. SO2 NO2 When humans burn fossil fuels,
sulfur dioxide and nitrogen dioxide are released into the atmosphere,
which react with water, oxygen, and other substances
to form sulfuric acid and nitric acid.
SO2
NO2

30. Sources of Sulfuric Acid and Nitric Acid
NO2
coal burning factories
metal extraction factories called smelters
oil refining factories to make gasoline
burning fuels by cars (biggest cause!)

31. A forest affected by acid precipitation

32. Impacts to Lakes, Streams, Rivers & Wetlands
acidic water tends to absorb aluminum from soil which will then spread to other lakes and streams
acidic aluminum-contaminated water is toxic to crayfish, clams, and other aquatic animals – it weakens their hard shells.

33. What can we do to fight acid rain?
laws that limits of factory emissions
“scrubbers” placed in factory smoke stacks to filter out most chemicals before gases are released into the air

34. Is acid precipitation a local or global problem?
Pollution is carried by wind, acidic waters continuously move so problems associated with acid rain is global problem!

35. Read pages 70-75 Soil pg. 75 Q’s #1-5 pg 85 Q’s #3, 13, 14 Acid Rain