Chapter 2 - Soil

Physical Properties - Chemical Properties - Biological Properties

=Soil Health

1. Bulk density

2. Soil structure

3. Soil texture

4. Soil colour

Soil Physical Properties

Bulk density

Availability of soil pore space and therefore influences soil hydrology and plant root growth

Soil structure

Erodibility, permeability and runoff and rooting depth

Soil texture

Capacity to hold water in soil and erodibility

Soil Colour

Indicator for organic matter content and translocation processes

1. Soil pH

2. Soil Salinity

3. Cation echange capacity

Soil Chemical Properties:

Soil pH

Availability of plant nutrients and toxics, activity of microorganisms

Soil salinity

Affects plant growth

Cation exchange capacity

Adsorbtion of contaminants and plant nutricient supply

1. Soil texture

2. Soil structure

3. Soil color

4. Soil porosity

5. Soil moisture

6. Soil consistency

What are the Soil Physical Properties

Soil texture

Is the relative proportions of sand, silt, and clay. Texture is used in reference to the size of soil particles.

Soil Structure (peds, aggregates)

Is used in reference to the arrangement of the soil particles. Sand, silt, and clay particles are typically arranged into secondary particles called ________, or __________

1. Spheroid

2. Platelike

3. Blocklike

4. Prismlike

Basic structural types:

Granular

Resembles cookie crumbs and is usually less than 0.5cm in diameter.

Blocky

Irregular blocks that are usually 1.5-5.0 cm in diameter

Prismatic

Vertical columns of soil that might be a number of cm long

Columnar

Vertical columns of soil that have a solt "cap" at the top.

Platy

Thin, flat plates of soil that lie horizontally.

Single Grained

Soil is broken into individual particles that do not stick together.

1. Solids

2. Liquid

3. Gases

Soil is composed of:

Voids

Spaces between solids are called ________ where water is the predominant liquid and air is the predominant gas.

Saturated

If all voids are filled by water, the soil is ____________

Dry

If all voids are filled with air, soil is said to be _________

Sand

Drains quickly - Low water retention

Silt

Holds more water - Moderate retention

Clay

High water-holding - Releases water slowly

Bulk density

Is the ratio of the mass of dry soil to the total volume occupied in the soil.

1. Macro and micro nutrient availability

2. pH

3. Cation exchange capacity (CEC)

4. Heavy metal content

5. Salinity

What are the Soil Chemical Properties?

Soil pH

Is the measure of the acidity or alkalinity of a soil.

Soil pH (Soil reaction)

Is the most responsible for determining the availability of nutrients and minerals.

Cation Exchange Capacity (CEC)

It influences the soil's ability to hold onto essential nutrients and provides a buffer against soil acidification.

1. Microorganisms

2. Earthworms

3. Plant roots

4. Soil insects

5. Organic matter content

6. Active carbon content

7. Disease suppression

What are the Soil Biological Properties?