SOIL CHEMISTRY

Pedogenesis

process of soil formation as regulated by the effects of place, environment, and history.

Soil Composition

- 45% minerals - 25% water - 25% air - 5% organic matter

Soil

- a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. - formed from the weathering of rocks.

Types of Soil: Loamy

- a mixture of sand, clay, and silt and has the ability to retain water. - high in calcium, aeration, and ideal for crops and vegetables. - soft and easy to cultivate.

Base

- a substance that releases hydroxyl ions.

Acid

- a substance that tends to release hydrogen ions.

Types of Soil: Peaty

- acidic, does not support decomposition very well, - dark in color, rich in organic material, contains less nutrients than loamy soils. - retains water very well.

Factors Affecting Soil Formation: Climate

- affects the rate of weathering and organic decomposition. - rainfall dissolves some soil materials and holds others in suspension.

Types of Soil: Chalky

- alkaline with pH level of 7.5. - not acidic, often stony. - free draining because of its coarse and stony nature. - lacks manganese and iron.

Causes of Acidic Soils: Rainfall and Leaching

- an affective agent for removing basic cations. - sandy soils are often first to become more acidic.

Soil Profile: R Horizon

- bedrock. - a mass of rock such as granite, basalt, quartzite, limestone, or sandstone that forms the parent material for some soils.

Soil Chemistry

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

Soil Formation: Biological Weathering

- breakdown of rocks by living things. - when burrowing animals hep water and air get into rock, plant roots can grow into cracks causing it to split.

Soil Formation: Chemical Weathering

- breakdown of rocks through a change in their chemical makeup. - when minerals react with water, air, or other chemicals.

Causes of Acidic Soils: Crop Production

- crops absorbs lime-like elements, as cations, for their nutrition.

Types Soil Pollution: Widespread Pollution

- difficult to identify. - spreading of pollutants by air-ground water systems, seriously affecting human health and environment.

Causes of Acidic Soils: Acidic Parent Material

- due to differences in chemical composition of parent materials, soils become acidic overtime.

Pedosphere

- earth's body of soil. Has four important functions: - a medium for plant growth. - a means of water storage, supply, and purification. - modifier of earth's atmosphere. - a habitat for organisms. - a protector from water loss problems.

Solutions to Reduce Soil Pollution

- eat sustainable foodstuffs, properly recycle batteries, produce homemade compost and dispose of drugs in authorized places. - encourage more eco-friendly model for industry, faring, and stock breeding. - improve urban planning, transport planning, and wastewater treatment. - improve management of mining waste, restore landscapes and conserve topsoil. - implement and assess sustainable land and soil management.

Soil Profile: E Horizon

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

Causes of Soil Degradation

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

Types of Soil: Silty Soils

- finer, smoother in texture and holds water better than sandy soils. - heavier than sandy soils, midway between properties of sandy and clay soils.

Types of Soil: Clay

- finest and binds very well. - has very little air spaces. - very sticky when wet, can be molded into any shape and form. - rock hard when dry. - do not drain very well.

Types of Soil: Sandy Soils

- free draining, with the largest, but fine and hard particles. - it has a gritty feel. - poor in holding water. - warms up easily in spring season. - has very low nutrients.

Factors Affecting Soil Formation: Topography

- grade of scope affects drainage, erosion, and deposition. Transported Soils: - Alluvial - water transported. - Colluvial - gravity transported. - Aeolian - wind transported.

Soil Profile: O Horizon

- humus or organic matter, such as decomposing leaves. - thin in some soils, thick in other, not present in others.

Causes of Soil Contamination: Human Activities

- industry, mining, military activities, waste (technological waste), wastewater management, farming, stock breeding of urban and transport infrastructures.

Factors Affecting Soil Formation: Living Organisms

- influences soil formation, such as micro-organisms, burrowing insects, animals, and humans.

Factors Affecting Soil Formation: Time

- influences soil properties.

Soil Acidity

- intensity aspect, universally characterized by measurements of pH.

Soil pH

- measure of acidity or alkalinity of a soil. pH Level: - below 7, acidic/sour. - 7, neutral. - above 7, alkaline/sweet. *5-7 pH level, plants.

Factors Affecting Soil Formation: Parent Material

- minerals forming the basis of soil. - produced from rocks through the processes of weathering and natural erosion.

Types Soil Pollution: Specific Pollution

- occurs in small areas. - land pollution found in cities, old factory sites, roadways, illegal dumps, and sewage treatment stations.

Causes of Acidic Soils: Organic Matter Decay

- organic matter decaying process produces H+ which is responsible for acidity.

Soil Profile: C Horizon

- parent material. - deposit at earth's surface from which the soil developed.

Environmental Soil Chemistry

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

Soil Profile: B Horizon

- subsoil. - rich in minerals that leached from A or E horizons then accumulated.

Soil Alkalinity/Alkaline Soil

- sweet soil. - pH level is above 7. - contains sodium, calcium, and magnesium.

Soil Profile: A Horizon

- topsoil. - mostly minerals from parent material with organic matter incorporated.

Causes of Acidic Soils: Nitrification of Ammonium

- usage of fertilizers that has nitrogen causes soils to become acidic.