How Soils are Formed

Transcript How Soils are Formed

Introduction to Agriculture, Food, and Natural Resources

How Soils are Formed

Unit 3 – Lesson 3.3 Starting from the Ground Up 2

Five Formation Factors

The basis of all soil will be derived by or aided in development by the following factors: Climate Organisms Parent Material Time Topography 3

Climate

Climate includes several forces that act upon soils, which breakdown rock into smaller fragments and eventually down to small particles.

Rainfall Temperature 4

Organisms

If conditions are appropriate to support plants and soil dwelling animals, organisms thrive and assist in creating optimal soils for plant production.

Parent Material

• Parent material is the substance from which soil is created. • In most cases, soil is formed from a type of rock that has been broken down by weathering or chemical processes.

Time

• Soils develop at varying rates depending upon the climate and other formation factors. • The forces that form a given soil indicate how long it took the soil to be formed.

Topography

What would soil be like on top of a hill compared to the bottom of the hill?

Top – larger particles and less organized Bottom – smaller particles and deep Why?

Soil Development Classifications

There are four main ways that the process of soil formation occurs:

Addition –

accumulation or deposition

Reduction –

leaching and erosion

Translocation –

movement within soil profile

Transformation –

soil changes in place by weathering or microorganism conversion 9

Erosion

• The opposite of soil formation is erosion, which has a detrimental effect on soil.

• Erosion comes in two forms: Water Wind 10

Erosion Happens

In what circumstances is soil erosion more likely to happen?

• Steep ground • Too much irrigation • Working soil in a rainy season • Not protecting soil with ground cover • Allowing wind to blow across worked soil 11

What happens when the soil is gone?

• Poor crop production • More inputs are required like water and fertilizers to grow crops • Soil could be unusable in some cases 12

References

Huddleston, J. H., & Kling, G. F. (1996).

Manual for judging Oregon soils

. Corvallis, OR: Oregon State University.

Parker, R. (2010). P

lant and soil science: Fundamentals and applications

. Clifton Park, NY: Delmar.