1. Soils: A brief introduction

2. How Much Soil Is There?

4. Structure & Texture
Soil structure and texture are often discussed together and often confused. Structure refers to how these particles may be stuck together to form crumbs or larger structures.

5. Structure is very important
Structure is very important. If the soil simply consisted of a mass of individual particles, the spaces in-between would be very small and would seriously restrict the movement of air and water

6. Type of Particle Size Range Sand 2. 0 - 0. 06 millimeters Silt 0
Type of Particle Size Range Sand millimeters Silt millimeters Clay less than millimeters
The texture of a soil refers to the size distribution of the mineral particles found in a representative sample of soil.

7. Granular: Resembles cookie crumbs and
is usually less than 0.5 cm in diameter.
Commonly found in surface horizons where
roots have been growing.

8. Blocky: Irregular blocks that are usually 1.5 - 5.0 cm in diameter.

9. Prismatic: Vertical columns of soil that might be a number of cm long
Prismatic: Vertical columns of soil that might be a number of cm long. Usually found in lower horizons.

10. Columnar: Vertical columns of soil that have a salt "cap" at the top
Columnar: Vertical columns of soil that have a salt "cap" at the top. Found in soils of arid climates.

11. Platy: Thin, flat plates of soil that lie horizontally
Platy: Thin, flat plates of soil that lie horizontally. Usually found in compacted soil.

12. Single Grained: Soil is broken into individual particles that do not stick together. Always accompanies a loose consistence. Commonly found in sandy soils.

13. Massive: Soil has no visible structure, is hard to break apart and appears in very large clods.

14. If you look in a soil pit or on a roadside cut, you will see various layers in the soil. These layers are called soil horizons. The arrangement of these horizons in a soil is known as a soil profile

15. Soil scientists use the capital letters O, A, B, C, and E to identify the master horizons, and lowercase letters for distinctions of these horizons.
Most soils have three major horizons -- the surface horizon (A), the subsoil (B), and the substratum (C). Some soils have an organic horizon (O) on the surface.
The master horizon, E, is used for subsurface horizons that have a significant loss of minerals (eluviation). Hard bedrock, which is not soil, uses the letter R.

16. Humus is the biochemical substance that makes the upper layers of the soil become dark. It is colored dark brown to black.
It enhances a soil's ability to hold and store moisture.
It reduces the eluviation of soluble nutrients from the soil profile.
It is the primary source of carbon and nitrogen required by plants for their nutrition.
It improves soil structure which is necessary for plant growth.

17. ARIZONA DESERT
Paint Branch Creek in Maryland,
A Michigan Soil

18. Synthesis of proteins, chlorophyll Plant residues Phosphorus P
Major nutrients
Nutrient
Chemical Symbol
Importance to Plants
Natural Source
Nitrogen N
Synthesis of proteins, chlorophyll
Plant residues
Phosphorus P
Synthesis of enzymes and the storage of energy.
Little natural reserves in the UK.
Potassium K
Control of water by osmosis.
Much of UK soil, particularly where derived from igneous rocks, have a good reserve.
Calcium Ca
Cell wall synthess, enzyme activity.
Vast reserves in calcareous (chalk) soil.
Magnesium Mg
Chlorophyll synthesis
Reserves in magnesium limestone.
Sulphur S
Synthesis of some amino acids (the building blocks for proteins).
Rocks and organic material.

19. 3 other macronutrients used for strengthening and storage
Carbon - from Carbon Dioxide in the air
Hydrogen – from water
Oxygen – from the air

20. Micronutrients Nutrient Symbol Importance to Plants Boron Bo
Cell division
Manganese Mn
Activation of enzymes
Cooper Cu
Synthesis of enzymes - photosynthesis
Iron Fe
Synthesis of chlorophyll
Molybdenum Mo
Nitrate Fixation
Zinc Zn
Some enzymes
Cobalt Co
Chlorine Cl
Photosynthesis
Silicon Si