The process of soil formation

Soil is a valuable resource that supports all human and animal life. Let’s read the article below to discover more about how soil is created.

1. What is Soil?

Definition of soil (most widely accepted): Soil is a naturally occurring object that is the result of the interaction of five components over a long period: organisms, parent rock, terrain, climate, and time.
Soil is the mantle that covers the earth’s surface, a heterogeneous system and an ecosystem that includes a full range of biotic and abiotic factors. Soil is always changing under the impact of nature and humans.

2. The process of soil formation

The process of soil formation includes geological macrocycle and biological microcycle.
The weathering of rocks to produce material samples is known as the geological macrocycle. The new material sample contains only the chemical elements in the parent rock, lacking several crucial components such as organic matter, nitrogen, water, etc. Therefore, plants are unable to survive.
The life activities of organisms lead to microcirculation (animals, plants, and microorganisms). Organisms absorb energy, nutrients, and gases from the atmosphere to synthesize organic matter (photosynthesis). These organic substances are unorganized by microorganisms and serve as a food source for organisms in the next generation.

Weathering process

Rocks and minerals in the outer layer of the earth’s crust under the influence of external factors will be destroyed by various agents, in different forms, collectively known as rock weathering.

Physical weathering
Physical weathering is a process that huge rocks are broken up into smaller pieces by physical forces without changing their chemical compositions. Physical weathering is a pioneering process that helps chemical and biological weathering occur. Some physical weathering mechanisms:
• Sudden temperature change: causes rocks’ minerals to expand unevenly; water seeps through cracks in the rock and freezes; Weak bonding results from dehydrated rocks.
• Sudden changes in pressure cause certain rock particles to evaporate
• Wind distributes minerals
• Erode

Chemical weathering
Chemical weathering, which results from chemical reactions caused by the impact of H2O, O2, and CO2 on rocks and minerals, is the crucial process of turning rock into soil. Features of the chemical weathering process:
• Hydrosphere and atmosphere involved
• The thickness of weathering crust depends heavily on topographical and meteorological conditions (T, P, wind)
• The weathering process takes place very quickly in hot and humid conditions. Water accelerates weathering

Biological weathering
The deterioration of rocks caused by living elements such as microorganisms, plants, and animals (including humans) is known as biological weathering. This process combines chemical and physical weathering. The following are some of the mechanisms that occur:
• Physical mechanism: the growth of plant roots destroys and crumbles rocks or burrowing animals in the rock bed.
• Chemical mechanism: As a part of their metabolism, bacteria, and fungi can dissolve and crystallize minerals and rocks.

3. Soil texture

The soil texture is the percentage of mineral particles (clay, loam, and sand) in the soil. The soil structure greatly affects other properties of the soil. In the classification of soil texture, only particles with a diameter of less than 2mm are considered.
Sand grain
• Size from 0.06mm to 2mm, can be round or angular.
• The main composition is quartz SiO2 or other primary silicate minerals.
• The stomata between sand grains are often large, and water and air can easily move in sand, well-drained soils.
• Because sand has a low specific surface area per unit volume, it has a low capacity to hold water. Sandy soils are often non-sticky and flexible when wet.
Loam grain
• Size from 0.002mm to 0.06mm in diameter.
• Due to the small size, the stomata between the loam particles are much smaller than sand, with high water holding capacity.
• No stickiness, or plasticity when wet (but in fact, the soil can stick due to the mixture of clay particles).
Clay grain
• Size less than 0.002mm in diameter
• It has a very large specific surface area, so it has a high ability to absorb water and nutrients, and retain water well.
• Sticky when wet

A triangulation list is used to determine a potential category of tool that fits within the group of post-structurals.

Credit for the article: Do Thi Hue