Classification of the soil | Types of soil | Soil texture

Classification of soil | Classification of the soil | Classification of soil class 10th | Classification of soil texture | Types of soil.

Classification of the soil | Types of soil | Soil texture
Classification of the soil | Types of soil | Soil texture

What is the soil?

Soil is a very complex natural resource that can be categorised into different soil classification with distinct characteristics that contain all naturally occurring chemical elements and combined continuosly solid, liquid and gaseous states, three different stages physical, chemical and biological characteristics and their combination are endless which is provide growing benefits and limitation for different purposes.

What is classification of the soil?

Regarding this, “classification of the soil”, systems deals with the systematic classification of soils based on distinct characteristics as well as criteria which is used to group soils according to their order of performance under given set of physical condition and its intended purpose of the system.

This is concern the various types of soils into groups with a similar ranges of properties ( biological, chemical and physical) according to their engineering or agricultural properties and various other characteristics, soil possessing similar characteristics can be placed in the same group.

Classification of the soil is carried out by several department , however, from agricultural point of view agricultural departments undertake soil investigations for suitability of the soil, crops and it’s fertility.

According to engineering point of view, the classification of soil use for finding the suitability of the soil for construction of foundation, dams, highways pavement and designed to allow an easy transition from field observation to basic predictions of soil engineering properties and behaviours.

Classification of the soil

Regarding this, classification of the soil systems is done based on grain size, broadly classified as follows:

1. Particle size classification of soil

2.Textural classification

3. AASHTO classification system of soil

4. Unified soil classification system

IS Particle Size Classification System for Soils

Regarding this, particle size classification of soils are arranged according to the grain sizes that concerns with terms such as clay, silt, sand and gravel which are used to indicate grain size, in this system, these terms are used only partical of size and not to occure naturally soil.

This classification of the soil are use in various partical size classifications, but commonly used system are international classification of the soil, M.I.T classification, U.S Bureau of soils and PRA classification and I.S classification.

According to I.S classification

● Clay size- 0.002 mm

● Silt size- 0.002 -0.075 mm

● Sand size- fine sand- 0.075 – 0.425 mm
● Medium sand- 0.425- 2 mm
● Coarse sand- 2- 4.75 mm
● Gravel size- a) Fine gravel- 4.75-20 mm, b) coarse gravel- 20-80 mm and c) cobble size- 80-300 mm

● Boulder size- above 300 mm

Textural Classification of the soil

Textural classification of the soil occuring in nature which is based on the percentages of sand, silt and clay size particle and their percentage distribution is known as textural classification of the soil system. This classification is more suitable for describing coarse grained soil, in this system equilateral triangle chart are used for the percentage of silt, sand and clay sizes forming a soil.

AASHTO classification system of soil

Regarding this, AASHTO Classification of the soil system is also known as Public Road Administration PRA or HRB Highways Research Board classification of the soil which is mostly used for highway pavement design.

This system is based on two characteristics having grain size distribution curve or data and consistency limits of soil (Plasticity characteristics).

Soils are given group numbers A1, A2, A3, A4, A5, A6, A7 and also some of major groups further divided into subgroups. A soil is classified with left to right on the chart from available test data and correct group will found by process of elimination and find the first group which the test data will fit. Black cotton soil falls under A7 group.

Group index

Regarding this, group Index is used to give rating to the quality of soil within same group for highway pavement design, this value is found by an empirical equation which is depend upon three parameters- liquid limit, plasticity index and percentage of soil passing 75 micron sieve.

1.Group index values from 0 to 20
2. If the equation of the group index gives negative value, it should be reported as zero.

3. The value of group index smaller ,the better is the soil

Unified soil classification System

Unified soil classification system is based on air field classification system which is originally adopted by Casegrande (1940) and modified slightly by the Bureau of Reclamation, Corps of engineers of USA, purpose of to make suitable for other construction like foundation, earth dams, earth slopes, earth canals etc.

This system is based on three criteria grain size distribution, plasticity characteristics and compressibility which is commonly used in European countries,the same system with minor modification was adopted by IS 1498 which is widly used in india for other engineering construction purpose (IS 1498 – 1970) .

According to IS soil classification are divided into three parameters- coarse grained, fine grained and highly organic soil .

Regarding this, coarse grained, this soil is percentage of soil retained on 75 micron IS seive is greater than 50 percentage of the soil, it is designated as corse grained soil, if 50 percentage or more of the coarse fraction is retained in 475 micron US sieve, then it is degined for gravel, otherwise it is indicated as sand.

This soil is containing less than 5 percentage fines are indicated by symbols for well graded GW and SW, if the percentage of fines having more than 12 percentage, then it is designated by symbols GM, GC, SM or SC, and lies between 5 to 12 percentage , course grained soils are designed by GW-GM or SP-SM.

Gravel:- 1. Well graded gravel (GW)

2. Poorly graded gravel (GP)

3. Silty gravel (GM)

4. Clayey gravel ( GC)

Sand:- 1. Well graded sand (SW)

2. Poorly graded sand(SP)

3. Silty sand(SM)

4. Clayey sand ( SC)

Regarding this, fine grained soil, this is designed as fine grained if more than 50 percentage of the soil sample passes No. 200 US sieve that is divided in inorganic silt, inorganic clay, organic silt and organic clay.

Inorganic silt (M)

Inorganic clay (C)

Organic silt and clay (O)

The fine grained soils are classified based on plasticity chart developed by casagrande-

Equation of A line

Ip =0.73(Wl -20)

Classification of soil based on compressibility characteristics

● Silt (M):- Low compressible inorganic silt is designed (ML),

● Intermediate compressible inorganic silt is designed (MI)

● High compressible inorganic silt is
designed (MH)

● Clay (C):- Low compressible inorganic clay is designed (CL)

● Intermediate compressible inorganic Clay is designed (CI)

● High compressible inorganic Clay is
designed (CH)

● Organic soils (O):- Low compressible organic silty and clay is designed (OL)

● Intermediate compressible organic Clay and silty is designed (OI)

● High compressible organic Clay and
silty is designed (OH)

Classification of soil is based on a parameter of liquid limit

If liquid limit WL < 35 % is designed for low compressible, WL – 35% – 50% is designed for intermediate compressible and WL- ,> 50% is designed for highly compressible.

Plasticity chart the below A-line, use M for silt or O for organic, above A-line, use C-Clay high plasticity, use H- WL>50% low plasticity, use L- WL-<50 %

Classification of soil class 10th

Regarding this, classification of soil class 10th, soil is the mixtures of small rock particles, organic materials and inorganic materials which is develop on the earth surface, it is give the plant growth and contributed in varied relief featears,landforms, climatic realms and vegetation types and also this type of soil development of various types of soils.

1. Alluvial soil

2. Black soil

3. Red and Yellow soils

4. Laterite soil

5. Arid soil

6. Forest soils

Alluvial soil

Alluvial soil:- Regarding this, alluvial soil is widely spread and very important soil having various proportions of clay, silt and sand that is suitable for agriculture and rich in mineral contents, this type of soil can be also called as Bangar termed as (Old Alluvial) and Khadar termed as (New Alluvial).

Black soil

Black soil:- regarding this, black soils, this type of soils are black in colour and these soils are clayed, impermeable having rich in soil nutrients such as magnesium, potash and lime, due to fact that this type of soil is ideal for growing cotton and is also known as black cotton soil.

This soil is also known as refute soil,  these soils are typical of the Deccan trap region , Malwa, Mp crown region, spread over northwest Deccan plateau.

Red and yellow soil

Red and yellow soil:- this type of soil develops on crystalline igneous rocks and give a reddish colour due to diffusion of iron in crystalline and metamorphic rock in areas of low rainfall in the eastern and southern parts of Deccan plateau.

Yellow and red soils are widly spread in parts of Chhattisgarh, Orissa, southern parts of the middle Ganga plain and along the piedmont zone of the western ghats and cultivated wheat, tobacco, cotton, pulses etc.

Laterite soil

Laterite soil:- this type of soil contant humus is low and develops in areas with high temperature and heavy rainfall that is required high content for fertilizers. It has contained property so soft when wet and so hard when dried, this type of soil crops crown tea, cashew nuts and cofee in Karnataka, Kerala, tamilnadu and mp region.

Arid soil

Arid soil:- this type of soil contains property of lack of water content and humus and soils range from red to brown in colour. These are sandy in texture and saline nature that is insufficient in fertilizer minerals nitrogen and kankar or impure calsium carbonate content is high, crops crown wheat,millets in western rajsthan region.

Forest soils

Forest soils:- this type of soils is acidic and low water content property ,also contains loamy and silty which is found in the hilly and mountainous areas where sufficient rain forests are available.

Classification of soil texture

Regarding this, classification of soil texture, in this classification of soil texture depends upon the percentage of clay, silt and sand in presence of soil having varies according to the mountain environment where they are formed, property of soil textures are depend upon the response of the soil to environmental having loamy and silly in valley sides and coarse grained in the upper slopes.

Soil texture is classified by both in the field and laboratory to determine physical texture of particles that are less than two millimeters in diameter which include clay, silt and sand, that soil taxures are measurement by using qualitative method, quantitative method and hydrometer for use of agricultural sector to determining crop suitability and environmental.

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What is textural classification of soil?

Regarding this, what is textural classification of soil, this soil textures are also classified by the United States Department of Agriculture, in the United States of twelve major soil texture that are following Soil textural class and Soil textural groups-

1. Sand – Coarse to very course

2. Loamy sand – Coarse to very course

3. Sandy loam – Moderately course

4. Loam – Medium

5. Siltt loam – Medium

6. Silt – Medium

7. Sandy clay loam – Moderately fine

8. Clay loam -Moderately fine

9. Silty clay loam -Moderately fine

10. Sandy clay – Moderately fine

11. Silty clay – Moderately fine

12. Clay – Moderately fine

Which soil has lowest water holding capacity?

Regarding this, “which soil has lowest water holding capacity?”, in this classification of soil textures coarse soils group having particles sand, loamy sand and sandy loam have the property of lowest water holding capacity.

Which soil has highest water holding capacity?

Regarding this,”which soil has highest water holding capacity?”, in this classification of soil textures in Unites States of Agricultural medium textured soils group having class soil textures silt loam, fine Sandy loam and silty clay loam have the highest water holding capacity.

What is the objective of soil classification

Regarding this, what is the objective of soil classification, in this classification of soil system is to group together soils with similar properties which is the classification of soil use for finding the suitability of the soil for construction of foundation,dams, highways pavement and designed to allow an easy transition from field observation to basic predictions of soil engineering properties, behaviours and purpose of point of vie of geotechnical properties which gives idea of compressibility, permeability and shear strength.

What are six main soil types?

Regarding this, what are six main soil types?, soil can be categorised are six main soil types based on the size of the particles within a soil that is clay, silt, chalk, peat, sand and loam.

1. Clay

2. Sandy soils

3. Silt

4. Peat

5. Chalk

6. Loam

What is Clay soil?

Regarding this,”what is Clay soil?”, clay soil is a heavy soil type that composed of the smallest particles of soil having property of hold a high amount of water that is cold in winter and dry out in summer, give benifits from high nutrients.

This type of soil densely closed with very little or no airspace, in fact that this soil is not suitable for growing of plant.

What is Sandy soil?

Regarding this, “what is sandy soil?”, Sandy soil is light, warm ,dry which is formed by the smallest or fine particles of weathering rocks having low nutrients and tend to be acidic properties due to fact that it has not suitable for growing of plant and agricultural sector.

This type of soil can be improve low nutrients and capabilities of use for growing of plant and agricultural by additiona of organic materials.

What is Silt soil?

Regarding this,”what is silt soil?”, silt soil is a light and smaller particles compared to sand having property of water content soil type with a high fertility and that is can be improved more stable clumps by adding organic materials due to fact that it is useful for agricultural sector, this type of soil well drained and holding capacity of moisture content is better than sand.

What is Peat soil?

Regarding this, “what is Peat soil?”, Peat soil is high nutrients in organic matter that is best suitable in garden and improve the garden planting by provide an optimum moisture content soil base.

What is Chalk soil?

Regarding this,”what is Chalk soik?”, chalk soil is the type of soil which is either light or heavy having acidic property and highly alkaline due to presence of calcium carbonate within its soil structure due to fact that this soil is not support the growth of plants. this type of soil is beneficial for plants that prefer an alkaline soil.

What is Loam soil?

Regarding this, “what is Loam soil?”, Loam soil is the type of soil that is combination of sand, clay and silt which is improve perfect balance of soil particles due to having properties of ability to restain moisture content and nutrients.

This type of soil gain all properties of equilibrium of three types of soil Sandy, silt and clay due to fact that loam soil is more suitable for farming and also referred to as agricultural soil ,these soils are fertile and provide good drainage.