3.4 The Soil SystemYour tasks

O –A –E –B – C –R -

http://www.enchantedlearning.com/geology/soil/soillayers.GIF

Match these up with the correct letter

Bedrock.

Leaf litter and dead organics.

Layer where soluble minerals and organic matter from above ends up.

Layer with a mix of humus from above and minerals from below with many living organisms eg fungi, bacteria, worms…

Weathered bed rock, breaking into smaller and smaller particles. Region where minerals and organic matter have been leached leaving silica behind.

Structure of a soilWhat are these?Why are they important?

http://www.dse.vic.gov.au/dpi/vro/vroimages.nsf/Images/soilhealth_soil_structure/$File/soilhealth_soil_structure.gif

What is it? HumusWhere does it come from?Why is it important?

What are these? Insoluble rock particlesWhere do they come from?Why are they important?

What is it? WaterHow does it get here?Where does it go from here?Why is it important?

What are these?What job do they do?Why are they important?

True? False? Correct the false ones. Read pages 224-225

1. The soil layer forms at the border between the biosphere and the lithosphere.

2. The pedosphere is influenced by the hydrosphere and the atmosphere.

3. Soil is made up of abiotic components.4. Its main components are: mineral particles from the atmosphere,

organic remains from dead plants and animals, water in the soil particles and air in the spaces between soil particles.

5. It is a habitat for plants and animals. 6. Soil is non-porous.

IB question: Outline how soils integrate aspects of living systems

Soil Processes - Translocation Means: The movement of water within the soil - it can be either ………… or ………………..

Water

http://www.enchantedlearning.com/geology/soil/soillayers.GIF

In (wet / dry) climates, where …………………… is higher than precipitation, water moves ……. the soil taking dissolved minerals with it and depositing them on the surface.

Salinization is (bad / good) for plants.

Soil Processes - Salinization

Water

http://www.enchantedlearning.com/geology/soil/soillayers.GIF

Soil Processes - Leaching • In (dry / wet)regions,

where there more …………………………. than evaporation, the water moves ……………………. towards the bedrock taking dissolved minerals away from the surface. This leaves the soil (less / more) fertile.

Water

http://www.enchantedlearning.com/geology/soil/soillayers.GIF

Soil Processes - Podsolization In very wet regions, where there is lots more……………………………………than …………………………………, and there is extreme leaching of the minerals to make the soil acidic with a nutrient poor bleached ‘A horizon’ and a very red ‘B horizon’ full of Iron oxide

Water

http://www.enchantedlearning.com/geology/soil/soillayers.GIF

Soil Processes - Gleying • When the water cannot …………………………… the soil becomes

waterlogged and the air spaces in the soil fill and so become (rich/poor) in oxygen making a very blue/grey soil– eg a rice paddy. Tends to become nitrate poor due to nitrifying bacteria needing oxygen to create nitrates.

Microsoft Clip art

• ‘Draw’ a systems diagram to show the movement of nutrients coming from water, organic matter and minerals through the soil system. Boxes and arrows

• Show the transfers and transformations and label the processes and stores..

Jill Rutherford - Environmental Systems and Societies Course Companion (Page 230)– Oxford University Press

Different types of soil

• Clay particles <0.002mm diameter

• Silt particles 0.002 – 0.005mm diam.• Sand particles0.005mm + diameter

Think colours!

http://www.atpm.com/9.08/images/design-color_triangle.gif http://www.sciencebuddies.org/mentoring/project_ideas/EnvSci_img014.jpg

What percentage mix of sand and silt and clay does a medium loam

have?

Properties of soil types: complete the table using the phrases from the next slide

Sand Loam ClayMineral content

Drainage

Water holding capacityAir spaces

Biota – Amount of Living stuff!Ability to hold organic matter

Primary productivity

Properties of soil typesYour choice

Mineral content HighHighRelatively low due to higher organic content

Drainage Low – small particles sit close together leaving little space for water to flowIntermediateHigh – big particles give big spaces so water flows easily

Water holding capacity HighIntermediateLow

Air spaces LowHighIntermediate

Biota – Amount of Living stuff! Low – not enough waterHigh – some air and some water availableLow – not enough air

Ability to hold organic matter Poor – particles pass through the big gaps easilyGoodPoor – particles wash of the surface without penetration.

Primary productivity HighSome but LimitedVery Limited

Use the table above to explain why loam is the ideal soil type for high productivity.

Loam…

IB question: Compare AND contrast the structure and properties of sand, clay and loam soils, including their effect on primary productivity.

Soil Degradation - Overgrazing

Causes:Effects:

Microsoft Clip art

Soil Degradation - Deforestation

Causes:Effects:

Microsoft Clip art

Soil Degradation – unsustainable agricultureMonoculture means…Negative effects on soil:

Empty fields:Negative effects:

Up and down ploughing:Negative effects:

Pesticides:Negative effects:

Burning stubble:Negative effects:

Microsoft Clip art

Soil Degradation - Irrigation

Problems for soil:

Microsoft Clip art

Soil Degradation – Toxifi_ _ _ _ _ _

The build up of toxic / poisonous chemicals in the soils can kill beneficial organisms in the soil eg. earthworms, bacteria and fungi.

Microsoft Clip art

Soil degradation at its worst: Desertification

Causes and effects in The SahelMap of Sahel:Causes:Effects:

Solution- Terracing

http://biagkensiak.files.wordpress.com/2009/12/banaue-rice-terraces-715556.jpg

Solutions: Contour ploughinghttp://en.wikipedia.org/wiki/Contour_plowing

http://www.uwsp.edu/geo/faculty/ozsvath/images/contour%20plowing.jpghttp://www.cottoninc.com/Soil-Resources/Controlling-Soil-Erosion/images/ContourPlowing.jpg

Solution: Trees as a windbreak

Image and explanation needed

Solution: Drip irrigation

Image and explanation needed

Solutions : Set-aside

A set aside strip between two fields.Image by - Walter Baxter http://www.yourlocalweb.co.uk/images/pictures/24/48/a-set-aside-strip-between-two-fields-241790.jpg

Solutions: Multi Cropping http://www.strandtea.com/shop/images/uploads/inline-images/sustainable-agriculture.jpg

Also known as poly-cultureImage needed and explanation

What is a soil conditioner?

• A material added to soil to enhance plant growth.

Soil Remediation – Conditioning -

Solution: Soil Conditioning

http://www.blackmaxozone.com.au/img/assets/gary/gel%20hydroponics%20alberton%20qld%203.jpg

Solution – Hydroponics

Solution: Crop Rotation

http://www.betterhensandgardens.com/wp-content/uploads/Crop-Rotation.jpg

Solution - Biological Pest Control

http://www.richard-seaman.com/Wallpaper/Nature/Damselflies/

OrangeDamselflyEatingMosquito.jpg

Solution- Reforestation

http://en.wikipedia.org/wiki/Reforestation

http://www.treehugger.com/peru-national-reforestation-campaign.jpg

Challenge: IB question: without using the previous slides to help, Outline the processes and consequences of soil degradation and possible soil conservation measures.

If extra time: Review questions pg 239-240 textbook

Named commercial farming system: North American prairies cereal farming

Soil management techniques:

Named subsistence farming system: Burkina Faso subsistencefarming

Soil management techniques:

IB question: Evaluate the soil management strategies used in two contrasting farming systems.