Ag science chp 4-soil formation and classification

Name the three different rock types

1)igneous

2)sedimentary

3)metamorphic

Telll me about igneous rock

•basalt-lava,black

•granite-black,White,glittery,mica,quartz,feldspar

Tell me about sedimentary rock

~ layed down in Strata (layers)dead sea plants and animals compacted and cemented together

Tell me about metamorphic rock

~ Changes due to heat or pressure or both and it used to be igneous or sedimentary

~turns to:

Granite—> gneiss

Limestone—> marble

Sandstone—> quartzite

Quartz-large minerals Clay-small minerals(shale)

Types of Physical/mechanical weathering

1) freezing water fills cracks in the rocks. It freezes and turns to ice then expands causing the rock to shatter.

2) activity of animals, animals digging and burrowing contribute to rocket breakdown

3) heating and cooling when rocks heat off minerals inside expand different minerals expand a different rate causing stress when the rock cools down the mineral shrink this constant expanding and shrinking can cause rock to crack and break overtime

4) activity of roots root of trees, penetrate cracks in rocks as the root grow they put pressure on rock and cause it to break

5) grinding action glacier, levelled heels and moved boulders and rock over long distances by grinding action rocks and rock. Particles are also moved by water (rainfall and rivers) wind (aeration sand) and gravity.

Types of chemical weathering

1)hydrolysis found in water react with rock minerals and rock

2) oxidation/ reduction the loss of electrons eg iron is oxidised to rust gain of electrons. OIL RIG oxidation is lost. Reduction is gained.

3) hydration add water to the minerals of the rock

4) solutions minerals dissolve

5) carbonation water dissolves carbon dioxide > carbonic acid ( acidic rain) carbonic acid reacts with limestone > calcium bicarbonate it’s softer and easier to break down

Biological weathering

Bacteria, fungi and lichens take over bare rocks. These micro organisations are able utilise nitrogen and carbon dioxide from the atmosphere. The microorganism secrete acids that dissolve rock minerals.

What is organic parent material?

Dead or decomposing plant and animal remains ( humus)

Table summary basin, peat raised and blanket bogs characteristics

Describe the A2 and the B2 layer of soil profiles

-A2 is the zone of maximum leaching of clay iron and aluminium, light bleach colour

-B2 zone of accumulation of clays iron and aluminium, dark in colour

Name five factors of soil formation(CROPT)

1 climate

2 relief / topography

3 organisms

4) parent material

5) time

Describe three factors of soil formation

1 climate: what are contributes to weathering of rocks? True frost action solution hydrolysis and hydration temperature plays a role in the heating and cooling of rocks

2 parent material: refer to type of rock in which soils are formed from . has an impact on acidity in texture of soil forms e.g. limestone is alkaline and forms alkaline basic soils sandstone is acidic and forms acidic soils.

3 time: the length of time the other four factors have had to influence the soil formation is important. in young soils (like in Ireland). There’s a high-level of parent rock material available for weathering and soil formation. This contributes to the overall fertility of the soil. in older soils, fertility often comes from organic materials.

Soil profiles~draw brown earth and characteristics

>found in low land

>limestone or lime rich parent material

>high pH (more basic calcium in limestone)

>very little leeching

>high levels of organic matter

>uniform brown colour

>very fertile soils darker soil is more fertile so more humus

>good for cereal production, arable, crop production, tillage growing crops

Soil profiles~ Luvisols and characteristics

> High levels of clay but still fertile

>illuviat deposits (move from a horizon to be horizon)

>high ph as well

>County Kildare

Soil profiles~ draw podzol and characteristics

>find in mountains and Hillside areas

>prone to leading

>leeching causes the bleaching of the A horizon (iron and aluminium from A horizon)

>iron pan is in permeable to water which can cause water logging

>can be broken up with a subsoiler

>low pH

Brown podzol is not as leeched. better crops grazing can be grown

Soil profiles~ draw gley soils and characteristics

>Monaghan (West Midlands)

>Poorly drain soils

>lack of oxygen (anaerobic)

>areas of high rainfall

>reduction of minerals ( iron)results in a motheled effect

>Light grazing

Groundwater gleys: formed in valleys (high rainfall)

Surface water gleys: formed in areas where water does not drain freely through soil (low permeability)

Soil profiles~alluvial solis and charachteristics

> Formed by the deposition of materials (alluvium) by rivers and lakes

>rich in minerals due to clay

> Very fertile

Soil profiles~ Draw rendizina and charachteristics

> Chalky shallow soils

> limestone rock

> common areas where exposed limestone is present

>use in agriculture is generally limited to grassland production

>there’s no B horizon

>found in county Clare

Soil profiles~ lithosol charachteristics

>shallow

>strong soils

>rough grazing (limited agricultural use)

Determined the difference between ombotrophic peat and minerotrphic peat

Ombrotrophic peat-receives its water and nutrients from precipitation.

Minerotrophic peat-receives its water and nutrients from ground water.