Soil categories: types and characteristics

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Soil is a complex system of organic and inorganic matter that directly and indirectly supports plant and animal life. Composed of minerals, nutrients, water, microorganisms and decaying living matter that provide the necessary elements to support growth. Soils of different geographical areas differ in chemical composition, structure, pH value, texture and color. The soil is the basis of the ecosystem and performs the functions necessary for the survival of living matter.

Development soil category

A number of systems have been developed to classify different soil types. Some of them were formed specifically in connection with the elucidation of soil suitability for use in specific engineering projects. Others are described more roughly and less precisely, although a certain degree of arbitrariness is inherent in each of the systems.

Overview

The category of soil can be thought of in terms of soil as a material and as a resource. Geotechnical engineers classify soils according to their functional properties. Modern engineering classification systems are designed to provide an easy transition from field observations to basic predictions of soil engineering properties and behavior.

There are three main classification groups:

• coarse-grained (for example, sands and gravel) - soil of the 1st category;
• fine-grained (like silt and clay);
• highly organic (peat).

Other engineering systems classify soils in terms of their suitability for pavement construction.

Full description of Category 4 geotechnical engineering soil will also include other properties (color, moisture, strength).

Basic types

Soil categories are classified into soil, clay, silty, peaty, chalky and loamy soils based on dominant particle sizes.

Sandy soil - light, warm, dry. Sandy soils are also known as light soils due to their high proportion of sand and little clay. This composition has a fast drainage, and it is easy to work with. They warm up faster in spring than clay soils, but dry out just as quickly in summer and suffer from nutrient deficiencies that are washed away by rain.

Clay soil stays wet and cold in winter and dries out in summer. These soils are composed of over 25 percent clay and a largeamount of water.

Silty soil is medium sized, well-drained and water-retaining.

Peat soil contains a lot of organic matter and retains a lot of moisture.

Chalky soil is characterized by an excess of alkali due to calcium carbonate or lime in its structure.

Loam is a mixture of sand, silt and clay. These soils are fertile, easy to work with and provide good drainage. Depending on their predominant composition, they can be either sandy or clayey.

Soil formation

Soil is a part of the earth's surface, consisting of disintegrated rock and humus, which provides a medium for plant growth. Soil development takes time and consists of a variety of materials that are inorganic and organic. Inorganic materials are the non-living aspects of the soil, such as minerals and rocks, while organic materials are the living soil microorganisms.

The process of soil formation is carried out through the mountain cycle along with the integration of microbial and chemical activity originating from living organisms. For example, during the decomposition of dead plants and animals, nutrients are mixed with weathered and destroyed rocks, forming soil. Soil is considered a natural resource because of the agricultural productivity benefits. Different soils have different mineral and organic compositions that set their specific characteristics.

Categoriessoil

The following are common classification systems:

• geological classification;
• classification by structure;
• grading based on grain size;
• unified system;
• preliminary classification by soil type.

Based on constituents, soil can be classified as inorganic and organic.

Organic categories of soil, in turn, are divided into the following types:

• residual;
• sedimentary;
• eolian;
• glacial;
• lake;
• marine.

According to the geological cycle, soils are formed as a result of the disintegration and weathering of rocks. The soil is then subjected to a process of compaction and cementation by heat and pressure.

Depending on the average grain size and the conditions under which soils are formed and deposited in their natural state, they can be classified into the following soil categories based on their structure:

• single grain structure;
• honey comb structures;
• flocculation structure.

In the classification by grain size, they are designated according to the size of the particles. Terms such as gravel, sand, silt, and clay are used to refer to specific ranges of grain sizes.