Introduction to Soils

1
Introduction to Soils

• The most important natural resource around the
  earth!

2
What is soil?

• Defined as
• Mineral Organic material that supports plant
  growth on the earths surface
• Mixture of particles of rock, organic materials,
  living forms, air, water

3
What soil resources help in supporting life?

• Oxygen needed for adequate root growth
• Temperature soil absorbs heat from the sun
  loses heat to atmosphere (plant growth and seed
  germination)
• Water plant growth
• Carbon organic matter
• Nutrients minerals

4
Briefly explain the process of soil origin.

• All soil originated as rocks.
• Powerful forces act on the rocks to break them
  down into smaller fragments.
• Water penetrates the cracks in the rock and when
  it freezes the water acts as a wedge to split the
  rock.

5
Soil origin cont.

• Rivers, glaciers, landslides and avalanches cause
  rock particles to grind against each other
  wearing them down.
• Chemicals mix with water to further break the
  rocks down.
• Plants began to grow in the weathered rocks and
  as they die, they add organic matter to the soil
  which attracts soil micro-organisms.

6
Soil origin cont.

• When this happens, the soil is capable of
  supporting plant life and can then truly be
  called soil.

7
What does the term weathering mean?

• Weathering is the processes that occur to break
  down rock into soil. This process includes water
  freezing, thawing, landslides, wind and chemical
  action.

8
What is parent material?

• Rock material that has undergone some weathering
  and change, but not enough to be called true
  soil, as it is not capable of sustaining plant
  life.

9
List the 5 factors responsible for soil
development.

1. Parent material
2. Climate
3. Variation in the earths surface (topography)
4. Plant animal life
5. Time

10
Components of Soil

• Mineral Matter about 45 of soil (partially
  decomposed rock material (sand, silt, clay)
• Organic Matter about 5 of soil (partially
  decomposed plant animal matter)
• Air about 25 of soil (constant fluctuation as
  soil is dry and wet)
• Water about 25 of soil

11
Water in the soil

• Infiltration process of water soaking into the
  soil
• Percolation water movement downward
• Permeable quality soil allows for both
  infiltration and percolation then it is said to
  be permeable

12
Living Organisms in the soil

• Forms of life
• Earthworms
• Insects
• Bacteria
• Fungi
• Other organisms

13
Bacteria Fungi Jobs

• Break down organic matter and release nutrients

14
Earthworm other soil organism jobs

• Improve soil tilth
• Ease at which soil can be worked
• Create openings in soil as they tunnel
• Enhances drainage and improves air exchange

15
Plants use soil

• Anchorage roots
• Water absorbed through roots
• Oxygen all living organisms need oxygen
• -plants release oxygen during photosynthesis and
  consume oxygen during respiration
• -good soil aeration needed for below ground plant
  parts to get oxygen

16
Plants use soil cont.

• D. Nutrients of the 16 essential nutrients for
  plant growth 13 are obtained from the soil
• -root hairs absorb the nutrients dissolved in
  soil water

17
Soil uses in agriculture

• Cropland
• Grazing land
• Forest
• Water structures
• Agriculture depends on soil to grow food, fiber,
  and ornamental plants.

18
Nonagricultural uses of soil

• Recreation playgrounds, sports fields, jogging
  paths, golf courses, parks, campgrounds
• Foundations buildings have to have solid base
• Waste Disposal
• Building materials