Soil Classification Systems

Study Notes

Soil Classification

Soil Classification Systems:

USDA Soil Taxonomy: Most widely used system, categorizes soils into 12 orders based on soil properties and characteristics.
FAO Soil Classification: Developed by the Food and Agriculture Organization, categorizes soils into 106 soil groups.
World Soil Classification: Combines elements of USDA and FAO systems, recognizes 32 soil groups.

Soil Classification Criteria:

Texture: Proportion of sand, silt, and clay particles.
Structure: Arrangement of soil particles, including blocky, granular, and prismatic.
Consistency: Soil's ability to be molded and shaped.
Reaction: Soil pH, acidity, or alkalinity.
Mineralogy: Composition of soil minerals.
Moisture: Soil's water-holding capacity and drainage.

Soil Orders (USDA Soil Taxonomy):

Alfisols: High in clay and aluminum, acidic to neutral pH.
Andisols: Formed from volcanic ash, high in amorphous materials.
Aridisols: Dry soils, low in organic matter and high in salt.
Entisols: Young, undeveloped soils, lacking distinctive features.
Gelisols: Permafrost soils, frozen for most of the year.
Histosols: Organic soils, high in peat and humus.
Inceptisols: Soils with weakly developed features, intermediate between Entisols and other orders.
Mollisols: High in calcium and magnesium, alkaline to neutral pH.
Oxisols: Highly weathered, acidic soils with high iron and aluminum content.
Podzols: Acidic soils with high humus and iron content.
Spodosols: Acidic soils with high humus and aluminum content.
Ultisols: Weathered soils with high clay and iron content, acidic to neutral pH.

Soil Classification Importance:

Agricultural Management: Soil classification informs crop selection, fertilizer application, and irrigation management.
Environmental Management: Soil classification helps predict soil behavior, water quality, and ecosystem function.
Urban Planning: Soil classification informs construction, infrastructure development, and land-use planning.

Soil Classification Systems

There are three main soil classification systems: USDA Soil Taxonomy, FAO Soil Classification, and World Soil Classification.
USDA Soil Taxonomy is the most widely used system, categorizing soils into 12 orders based on soil properties and characteristics.

Soil Classification Criteria

Soil texture is determined by the proportion of sand, silt, and clay particles.
Soil structure refers to the arrangement of soil particles, including blocky, granular, and prismatic.
Soil consistency is the ability of the soil to be molded and shaped.
Soil reaction refers to the pH, acidity, or alkalinity of the soil.
Soil mineralogy is the composition of soil minerals.
Soil moisture refers to the soil's water-holding capacity and drainage.

Soil Orders (USDA Soil Taxonomy)

Alfisols are high in clay and aluminum, with acidic to neutral pH.
Andisols are formed from volcanic ash, high in amorphous materials.
Aridisols are dry soils, low in organic matter and high in salt.
Entisols are young, undeveloped soils, lacking distinctive features.
Gelisols are permafrost soils, frozen for most of the year.
Histosols are organic soils, high in peat and humus.
Inceptisols are soils with weakly developed features, intermediate between Entisols and other orders.
Mollisols are high in calcium and magnesium, with alkaline to neutral pH.
Oxisols are highly weathered, acidic soils with high iron and aluminum content.
Podzols are acidic soils with high humus and iron content.
Spodosols are acidic soils with high humus and aluminum content.
Ultisols are weathered soils with high clay and iron content, acidic to neutral pH.

Importance of Soil Classification

Soil classification informs agricultural management, including crop selection, fertilizer application, and irrigation management.
Soil classification helps predict soil behavior, water quality, and ecosystem function in environmental management.
Soil classification informs construction, infrastructure development, and land-use planning in urban planning.

Description

Learn about different soil classification systems, including USDA Soil Taxonomy, FAO Soil Classification, and World Soil Classification. Understand the criteria used to classify soils, such as texture and more.