Soil is a unique natural formation characterized by fertility. Quite often, "earth" is used as a synonym for this word. How did soil form on our planet and what factors influenced this process?
What is soil?
This is the top layer of land on the globe. Soil was formed under the influence of a number of factors on rocks. It has its own unique composition, structure and properties.
This is one of the most important components of the biosphere and biocenoses on Earth, since it maintains the ecological ties of absolutely all living beings with the solid, liquid and gaseous shells of the planet.
Dokuchaev, who studied the question of how the soil formed in the most detail, called it "a reflection of the landscape", because the main features of a particular area are expressed through it. The soil cover is at the same time determining for plant communities, but at the same time it depends on them.
Soil properties
The most important property of the soil cover is fertility, expressed in its ability to ensure the development and growth of plants.
Physical properties include:
- mechanical composition (density and size of soil particles);
- water capacity (the ability to absorb and retain water);
- microbial composition;
- acidity.
Soil formation factors
The course of the process of soil formation directly depends on the natural conditions or factors in which it occurs. Their combinations must also be taken into account, as they determine the direction of the entire process.
Soil formation conditions are divided into five types:
- soil-forming rock;
- plant communities;
- activities of animals and microorganisms;
- climatic conditions;
- relief;
- age of land cover.
Currently, two more factors are also singled out separately - the impact of water and humans. In the question of how the soil was formed, the leading factor is biological.
Soil-forming rocks
Absolutely the entire soil cover of our planet began to form on the basis of rocks. The determining factor is their chemical composition, since the soil cover absorbs part of the parent rocks. The nature and direction of the process is influenced by the properties of rocks, such as density, porosity, ability to conduct heat, sizemicroparticles.
Climate
The influence of climate on the process of soil formation is very diverse. The main factors of climate impact are precipitation and temperature regime. The conditions for the process are the amount of heat, humidity, as well as their circulation and distribution in space. The climatic factor also manifests itself in the process of weathering. Climate also has an indirect effect, as it determines the existence of certain types of plant communities.
Plants and animals
Plants with their root systems penetrate the parent rock and deliver valuable minerals to the surface, which are subsequently converted into organic compounds.
How is soil humus formed? Dead parts of plants, saturated with ash substances, remain in the upper horizons. Due to the constant synthesis and decay of organic matter on the surface, the soil becomes fertile.
Plant communities change the microclimate of the area. For example, it is quite cool in the forests in summer, the humidity is high, the wind strength is minimal, unlike the meadows.
A large number of living organisms live in the upper fertile layer of the Earth. In the process of their vital activity, plants and their organic remains decompose. Subsequently, animal waste products are reabsorbed by plants.
The totality of plant and animal communities in certain areas influences the formation of soil type. For example, chernozems are formed only under the meadow-steppe type of vegetation.
Relief
This factor has an indirect effect on the process of soil formation. The relief determines the law of redistribution of moisture and heat. The temperature regime changes depending on the altitude. Vertical zonality in the mountainous regions of the planet is associated with height.
The nature of the relief determines the degree of climate impact on soil formation. Redistribution of precipitation occurs due to elevation changes. In low-lying areas, moisture accumulates, and on slopes and hills it does not linger. The southern slopes in the northern hemisphere receive more heat than the northern slopes.
Soil age
Soil is a natural body that is constantly evolving. The way we see the soil cover now is only one of the stages of its continuous development. Even if the soil-forming processes do not change in the future, the top fertile layer may undergo radical transformations.
Age is of two types - relative and absolute. The absolute age is the time that has elapsed from the formation of the soil cover to the present stage of its development. However, not all parts of the land during the entire period of its historical development were it. Relative age - the difference in the development of the upper fertile layer within the same territory.
Age can vary from hundreds to thousands of years.
How did soil form?
This question has been of interest for several generations of scientists and researchers. Considerbelow is the generally accepted version of the history of the soil-forming process.
Earth has a solid hot core, which is surrounded by a hot mantle with a viscous structure. Above is the outer crust, which includes rocks.
Four billion years ago, the Earth began to cool. In some places, magma came to the surface and formed bas alts, and where it remained under it, granites formed. The primary parent rock changed under the influence of external factors, the synthesis of new minerals gradually occurred.
After oxygen appeared in the atmosphere, a sedimentary layer began to form. Gradually, as a result of the weathering process, the parent rock became looser and saturated with oxygen. Thus, clays, sands, gypsum and limestone arose.
The generally accepted point of view is that life on the planet has existed for more than three billion years. According to recent studies, bacteria and protozoa were already living on Earth at that time. The first living organisms easily adapted to new environmental factors and were omnivores. In the process of life, they secreted some enzymes that dissolved rocks and multiplied rather quickly. Gradually formed soil was populated by mosses, lichens, and then by plants and animals. As a result of such settlement, humus was formed.
The soil cover is very important for a person. It must be studied for the development of agriculture and forestry, as well as for engineering and construction surveys. Property Knowledgethe top fertile layer of the earth is used in solving the problems of geological exploration and extraction of mineral resources, he alth care, ecology.
