SOIL POLLUTION

Loamy

It is the soil all farmers dream of, as it is full of nutrients from decomposed organic material.

Peaty

It retains water very well.

Nitrification

The use of fertilizers, especially those supplying nitrogen, has often been blamed as a cause of soil acidity.

Silty Soils

This kind is finer, smoother in texture and holds water better than sandy soils. It also holds up nutrients and makes it better for crop cultivation.

Loamy

This soil is a mixture of sand, clay and silt particles and has the ability to retain

Specific Pollution and Widespread Pollution

Two types of Soil Pollution:

Soil

a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere,

Specific Pollution

accounted for by particular causes, occurring in small areas the reasons for which can be easily identified.

Climate

affecting the rate of weathering and organic decomposition

Peaty

are acidic and as a result, do not support decomposition very well.

Chalky

are alkaline with a pH of about 7.5.

Rainfall and Leaching Excessive rainfall

is an effective agent for removing basic cations over a long time period (thousand of years).

The more ammoniacal nitrogen fertilizer

is applied, the more acidic the soil gets.

Clay

is believed to form in places where the rock is in contact with water, air or steam. Example, sediments on sea or lake bottoms may become clay soils with time.

base

is defined as a substance that releases hydroxyl ions (OH-)

acid

is defined as a substance that tends to release hydrogen ions (H+)

silt

is deposited and cemented with time, it forms siltstone.

The pH scale

is divided into 14 divisions or pH units numbered from 1 to 14.

Soil formation

is influenced by organisms (such as plants), micro-organisms (such as bacteria or fungi), burrowing insects, animals and humans.

Rainfalls

is most effective in causing soils to become acidic if a lot of water moves through the soil rapidly.

Acidity

is produced when ammonium-containing materials are transformed to nitrate in the soil.

Soil chemistry

is the branch of soil science that deals with the chemical composition, chemical properties, and chemical reactions of soils.

Soil pH

is the measure of acidity or alkalinity of a soil.

Pedogenesis

is the process of soil formation as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order within soils.

Soil

is the thin layer of material covering the earth's surface and is formed from the weathering of rocks.

Horizon O

is thin in some soils, thick in others, and not present at all in others.

Erosion

loss of organic carbon, increased salt content, compacting, acidification and chemical pollution

Parent Material

minerals forming the basis of soil

oil forms

plants begin to grow in it. The plants mature, die and new ones take their place. Their leaves and roots are added to the soil.

Alkaline or "sweet"

soils with pH values above 7

Environmental soil chemistry

study of chemical reactions between soils and environmentally important plant nutrients, radionuclides, metals, metalloids, and organic chemicals.

Land pollution

such as this is normally found in cities, old factory sites, around roadways, illegal dumps and sewage treatment stations.

biological weathering

the breakdown of rocks by living things. Burrowing animals help water and air get into rock, and plant roots can grow into cracks in the rock, making it split.

Topography

The shape, length and grade of a slope affects drainage.

colluvial

(gravity transported)

Horizon O

(humus or organic) Mostly organic matter such as decomposing leaves.

alluvial

(water transported)

aeolian

(wind transported) soils

Horizon R - (bedrock)

A mass of rock such as granite, basalt, quartzite, limestone or sandstone that forms the parent material for some soils - if the bedrock is close enough to the surface to weather. This is not soil and is located under the C horizon.

Organic Matter Decay

Decaying organic matter produces H+ which is responsible for acidity.

Acidic Parent Material

Due to differences in chemical composition of parent materials, soils will become acidic after different lengths of time.

Crop Production

Harvesting of crops has its effect on soil acidity development because crops absorb the lime- like elements, as cations, for their nutrition.

Soil alkalinity/Alkaline soil

Is referred to by some gardeners as "sweet soil." The pH level of alkaline soil is above 7, and it usually contains a great deal of sodium, calcium and magnesium.

Soil pH

It describes the concentration of hydrogen ions in the soil solution.

Peaty

It is dark in color, rich in organic material, although contains less nutrients than loamy soils.

Chalky

It is free draining because of its coarse and stony nature.

Loamy

It is high in calcium, aeration and ideal for most crops and vegetables.

Chalky

It is not acidic and often stony with chalk or limestone bedrock.

Horizon E - (eluviated)

Leaching of clay, minerals, and organic matter, leaving a concentration of sand and silt particles of quartz or other resistant materials - missing in some soils but often found in older soils and forest soils.

Horizon A - (topsoil)

Mostly minerals from parent material with organic matter incorporated. A good material for plants and other organisms to live.

Chalky

Not the best for crops to grow in as they lack manganese and iron.

The major causes for soils to become acidic are listed below

Rainfall and Leaching

Horizon B - (subsoil)

Rich in minerals that leached (moved down) from the A or E horizons and accumulated here.

Parent Materials

Soil minerals form the basis of soil. They are produced from rocks (parent material) through the processes of weathering and natural erosion. Water, wind, temperature change, gravity, chemical interaction, living organisms and pressure differences all help break down parent material.

Time

Soil properties may vary depending on how long the soil has been weathered.

Neutral

Soils with a pH of 7

Acid or "sour"

Soils with pH values below 7

Climate

Temperature affects the rate of weathering and organic decomposition. With a colder and drier climate, these processes can be slow but, with heat and moisture, they are relatively rapid.

Factors Affecting Soil Formation

The accumulation of material through the action of water, wind and gravity also contributes to soil formation. These processes can be very slow, taking many tens of thousands of years.

Horizon C - (parent material)

The deposit at Earth's surface from which the soil developed.

Clay

The particles that make up clay are the finest and they bind very well.

Sandy Soils

are free draining, with the largest, but fine and hard particles. It has a gritty feel. It does not bind very well. It is poor in holding water and easily warms up in the spring season.

Silty Soils

are heavier than sandy soils, and almost midway between the properties of sandy and clay.

Sandy soils

are often the first to become more acidic because water percolates rapidly, and sandy soils: contain only a small reservoir of bases (buffer capacity) due to low clay and organic matter contents.

Soil materials

are progressively moved within the natural landscape by the action of water, gravity and wind The soils left on steep hills are usually shallower. Transported soils include:

Silt particles

are so small and not easily seen by the eyes. It leaves a bit of residue after you touch them.

Sandy soils

are very low in nutrients, as they are usually washed away. Its degree of aeration depends on the sizes of the particles, which vary a lot in size. It is usually formed from the weathering or disintegration of bedrock such as shale, limestone, granite and quartz.

physical weathering

breakdown of rocks from the result of a mechanical action. Temperature changes, abrasion (when rocks collide with each other) or frost can all cause rocks to break down.

chemical weathering

breakdown of rocks through a change in their chemical makeup. This can happen when the minerals within rocks react with water, air or other chemicals.

Widespread Pollution

covers extensive areas and has several causes, the reasons for which are difficult to identify.

Soil chemistry, as a discipline

embracing all chemical and mineralogical compounds and reactions occurring in soils and soil- forming processes.

Soil

forms continuously, but slowly, from the gradual breakdown of rocks through weathering. Weathering can be a physical, chemical or biological process:

Topography

grade of slope affecting drainage, erosion and deposition

Living Organisms

influencing soil formation

Time

influencing soil properties.

Soil degradation

is a complex problem that requires governments, institutions, communities and individuals to take joint measures.

Queensland (and Australia)

is a very old weathered landscape with many ancient soils.