5.1 Introduction to soil systems

4 parts of soil

• Minerals

• Organic Matter

• Water

• Air

Functions of soil

1. Medium for plant growth

2. Water storage and purification

3. Serves as a habitat

4. Modifies the atmosphere

Soil storages

• Organic matter

• Organisms

• Nutrients

• Minerals

• Air

• Water

Transfers within soil

• Biological mixing - redistribution of soil materials.

• Translocation - soil forming materials move in the profile

• Leaching - water moving nutrients thru the soil profile

• Salinization - salt content moving into the soil profile

Translocation

Movement of soil particles in suspension

Leaching

Minerals dissolving in water moved in soil

Evaporation

Drawing soil out of water

Decomposition

Breaking down organic matter into the soil

Weathering

Breakdown of parent/rock material

Salinization

Water evaporates and salt content is left behind

What are the layers of the Soil Profile

Made up of 5 vertical layers

• O

• A

• B

• C

• R

O layer

• Organic layer with dead organic matter (DOM)

A layer

• Top soil/mineral layer

• High organic matter with high biological activity

• Zone of leaching

B layer

• Subsoil layer

• Plant roots are most often found here

C layer

• Decomposed parent material and weathered rock

R layer

• Parent material layer (can be bedrock or other forms)

Soil texture

• Based on the ratio of clay sand and soil

• Figured out via the soil triangle

Sandy soil properties

• Large particles

• Good drainage but poor water retention

• Limited biota

• Poor GPP/NPP

• Poor organic matter retention

Clay soil properties

• Small particles (low porosity)

• Good water retention but poor drainage

• Limited biota

• Poor GPP/NPP

• Poor organic matter retention for plants

Loam soil properties

• Medium particles

• Good water retention and drainage

• Good GPP/NPP

• Good organic matter retention

• Good biota

• Best for plant growth

What is the soil structure

• Good soil is crumbly

• Poor soil is coarse with no structure

Porosity

Measure of Air spaces in the soil

Permiability

The ability for water to flow through the soil

Soil as a dynamic ecosystem

Soil has both abiotic and biotic components that work together