Soil layers and soil horizons

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Soil layers and soil horizons

Сообщение Глея » Пн янв 20, 2020 9:47 pm

Have you ever thought that the soil is actually not what we see under our feet. The soil is not just dirt and dust underfoot, the soil goes deep. By analogy with earth rocks or puff cake, the soil consists of several layers. You can imagine the soil as a world ocean, on the surface of which we walk. Have you ever dreamed of being able to walk on water?

Soil is not what it seems.

When I came to field practice in the first year of the Faculty of Soil Science and went into the field, I was surprised to learn that the soil was studied from the inside. To see the soil, you need to dig a soil pit - this is the so-called soil cross-section. The pit must be quite deep to see the soil in full height. All soils are different - there are "short", and there are "long". If the soil is "long", you will have to dig a deep soil cross-section of 2 meters.

When soil scientists dig a soil cross-section, one wall of the section must be straight, and steps are made on the opposite side so that the soil scientist can go down into the soil cross-section, see soil layers and conduct scientific research. Depending on the number of soil layers, their type and characteristics, the soil scientist can attribute the soil to one or another type. So, the soil will have a name, which is assigned in accordance with special books - soil classifications.

Where do the soil layers come from?

Each soil is the result of many years of pedogenesis. Soil is formed From the parent rock under the influence of such factors of soil formation as relief (gravity), solar energy, rain, wind, living organisms, etc. Multi-directional processes occur In the soil such as evaporation, leaching, transformation of matter. A soil substance being under the influence of natural forces is mixed and redistributed in space.

Initially, at the earliest point in time, when the soil is just emerging, it does not yet have layers. There are only the initial loose material on the surface of the parent rock, where a bug or a seed can fall, where the life of plants and soil organisms can begin to develop. Gradually, a new material from parent rock comes or litter falls on top of the soil embryo. The parent rock also begins to loosen more and more from above, giving rise to new horizons.

How to define soil layers - soil horizons?

If we go out into the field and dig a meter-long soil cross-section, we will see developed soil, for example, chernozem. Multi-colored horizons will be visible in the soil. By the way, soil scientists call soil layers as soil horizons. And horizons are indicated by letters and sometimes by numbers, for example, you can meet horizon O, A, B, C or horizon A0, A1, A2, etc. The designation will depend on the scientific tradition and soil classification adopted in your country.

Usually, the upper horizons of the soil are designated as O or A0 - this may be a litter of leaves or other organic matter. In fact, this is not even soil, but rather its cap. If you walk in the forest, then the forest litter on which you walk is a hat for the soil, which is located below. The lower we go deeper into the soil, the higher the number of the horizon or its letter increases. That is, the soil horizon A2 is deeper than A1. A horizon "B" is deeper than horizon "A".

What is the difference between soil horizons?

As we mentioned at the beginning, soil horizons can be of different colors. There are even red, yellow or blue horizons, and not just black or brown. Horizons can vary in density, chemical content, acidity, humidity, and so on. Usually the topsoil layers are the most fertile, as they contain more humus, plants like to "eat" it very much.

Now you understand how deep the soil really is. To learn more about soils, subscribe to our YouTube channel! Have questions? Feel free to write a comment under the video on YouTube. See you!