Earth is the we alth of all mankind. And we are talking not only about the planet, but also about the reserves of soils on its surface. Without them, there would not have been such a diverse flora, and heterotrophs (which include any animal and person) in principle could not have appeared. How did soil form on the surface of the planet? The factor of soil formation is “guilty” of this. More precisely, a whole group of them.
Main classification
B. V. Dokuchaev believed that five soil-forming factors should be distinguished:
- Maternal breed.
- Climatic parameters. In general, climate as a factor in soil formation is considered by many scientists from a key position, since its role is really impressive.
- Flora.
- Fauna.
- Terrain and past tense.
But these are not all the main factors of soil formation. Today, scientists believe that this list should includeadd two more positions: the action of water (precipitation) and human activity. And now we will deal with all the factors in more detail, discussing their characteristics. So, the most important factor in soil formation is the substance that gave rise to the soil.
Maternal Breeds
As you can understand, these are the minerals from which fertile (or not so) soil was once formed and continues to form. The mechanical, physical, chemical and other properties of the soil depend on the primary rock. Thus, soils originally formed, for example, from granite and similar rocks, may not be equivalent to those that came from tuffs and pumice.
What are the mother breeds? They are igneous, sedimentary and metamorphic. By the way, both granite and pumice with tuff are igneous rocks, but the soils from them are different. What does it depend on, because the soil formation factor is the same?
How do soil properties depend on origin?
The chemical and mineralogical composition, which depends not only on the rock, but also on the specific area of its origin, plays a huge role in the properties of the soil layer. So, if the mineral is carbonate, has an alkaline reaction (or is close to neutral), then the soil formed on its basis quickly begins to accumulate humus and acquires high fertility. Thus, the main factors of soil formation are extremely important, since the size of potential crops in the future directly depends on them.
If the rock is sour, thenAll these processes are several times slower. In the case when the mineral contains a large amount of water-soluble s alts, the soil "turns out" excessively saline. In addition, the mechanical composition is of great importance, since the heat capacity, moisture capacity and other important indicators that directly affect the fertility of the soil in a particular area depend on it.
Relief
This factor of soil formation is rarely remembered, but in vain. After all, it is the relief that influences the distribution of solar radiation, precipitation and other factors over the surface of the rocks, which means that the characteristics of the soil, which ultimately turns out to be “output”, depend on it.
Most of all, this is manifested in mountainous areas with existing pressure drops, illumination and dramatically different temperature conditions. Here, air masses and their convection are of great importance, as a result of which huge volumes of air with different temperatures constantly blow over the mountainous slopes. In many ways, the relief, as a factor in soil formation, also depends on the climatic features of the area, since without a combination of these two conditions, soil cannot be formed.
Air humidity is also different, and after the "transshipment" through the mountain ranges, it decreases sharply. As a result, the rock is weathered to varying degrees, s alted, destroyed with the formation of fractions of various sizes.
Perhaps the most important thing is the effect of lighting and solar radiation,which differs by an order of magnitude in different climatic zones. So, in the zone of the Far North, there are few soils, and they are extremely scarce, and the rocks have been preserved in perfect condition. Compare this with the desert regions, in which the rocks have long been crushed to the state of homogeneous quartz sand. If you look at the main factors of soil formation in the Orenburg region, the importance of the relief will be even more obvious.
In that area, the so-called syrts, that is, relatively low ridges, play a huge role. In combination with flat terrain, such a relief predetermines high speeds of air mass movement over the surface of parent rocks, which leads to their relatively rapid weathering and subsequent destruction.
Under these conditions, the rate of accumulation of humus (and the very presence of organic matter) varies dramatically, as does the fraction and chemical composition of the resulting soil. Accordingly, it will have varying degrees of fertility.
Types of soils depending on differences in relief
Currently, it is generally accepted that as a result of natural processes, three types of soils can form, which are also called "moisture horizons":
- Automorphic varieties. Their formation occurs under conditions of free runoff of surface waters and deep occurrence of soil moisture. At the same time, the biological factor of soil formation begins to play a predominant role.
- Semihydromorphic. The formation of such soils occurs when surface moisture can stagnate for some time on the surface of parent soils.rocks, and soil sources lie at a depth of no more than six meters.
- Hydromorphic soils. Accordingly, such a soil is formed in cases where surface water can stagnate on the surface of the rock for a long time, and soil moisture lies at a depth of no more than three meters.
In all these cases, the anthropogenic factor of soil formation can also be of considerable importance. Man in the course of his economic activities often drains or floods large areas of the earth's surface, which greatly affects the characteristics of soil formation.
Erosive processes
If the slope of the surface is 30 degrees or more, then the relief becomes especially important. Thus, under these conditions, water erosion is widespread. It acts much stronger than the wind variety, which is common in areas with a flat terrain or where the slope of the surface is very slight. If you look at the main factors of soil formation in the Orenburg region, this is easy to see. In those parts, the main role in the “abrasion” of the surface layer of mineral rocks is played by the wind, which can reach extremely high speeds.
Relief plays an important role even in the evolutionary process of flora development in a particular area. This is most clearly manifested when the riverbed changes or the seas leave (or vice versa, when areas are flooded). This leads to an increase or decrease in the level of soil water, a change in the soil development cycle (the automorphic type changes tohydromorphic, or vice versa).
Influence of the biosphere
The biological factor in the formation of each soil is the leading one. Only after the first living microorganisms appeared on land, it was able to develop in principle. In principle, the very process of soil formation can be viewed as a deep interaction between living (microorganisms) and inanimate (destroyed rock) nature. The parent rock itself undergoes considerable transformation during this process. The main condition that ensures the continuity of soil formation is the influx of radiant solar energy to the surface of the planet.
Atmospheric gases, flora and fauna, their metabolic products - all these factors and conditions of soil formation "led" to the fact that today we have fertile land under our feet, on which humanity grows food for itself and food for farm animals.
We repeat once again that a kind of "energy meter" is the amount of incoming solar energy. On the surface of the planet, it helps the transition of minerals (that is, inanimate nature) into living. As you probably guessed, we are talking about the process of photosynthesis. In addition, solar energy helps the transition of dead plant parts back into the composition of inanimate matter. Due to a continuous process that has been going on for thousands and millions of years, our planet has acquired a unique "soil shell", which is the key to fertility and reproduction of plant biomass.
What other factors of soil formation should be mentioned? Essay,written even by a middle school student will inevitably consider flora in the context of its important role in the process of humus accumulation. And that's absolutely right!
The role of plant mass
The main "supplier" of huge amounts of biomass for the entire soil is plants. In addition, they also accumulate solar energy (9.33 kcal / gram). Since, on average, up to ten tons of plant organisms grow on one hectare, about 9.33107 kcal of energy accumulates on this area. Such a gigantic amount of it not only plays an important role in all processes of soil formation, but can also be successfully used by humans. So plants are not only factors of soil formation, but also a valuable energy resource! An ideal example is coal, whose incredible reserves began to be intensively exploited by man in the 19th century.
Autotrophs extract all the minerals they need from the parent rock, and then transfer it to the most complex organic compounds, from which humus is subsequently obtained. Partially, these compounds come back again when they are washed out of dead plant residues by water. These important factors and processes of soil formation contribute, among other things, to the uniform mixing of the remaining parent rock and organic matter.
Places of plant biomass concentration
It is quite natural that forests contain the largest amount of plant biomass. But this is not an entirely accurate impression, since it is really hugegrowth occurs only in the steppe zone, where at least 85% of all accumulated organic matter returns to the soil again. That is why in the steppes the latter is much more fertile than in the forests, where the characteristics of the soil in this regard are not too “outstanding”. That is, the factors of soil formation, in short, differ significantly, even though they are outwardly similar.
Why is this happening? The fact is that in forests from the soil layer with a low humus content, many mineral and organic substances are simply washed out under the action of atmospheric moisture. In herbaceous biocenoses, plant remains are tightly compressed, forming massive soil horizons. The same conditions contribute to the formation of peat, since the lower tiers have a lot of moisture and little oxygen, which could stimulate decomposition processes. What other characteristic of soil formation factors exists?
Soil ash content
In many ways, the process of decomposition of plant residues depends on the chemical composition of the latter. So, the ash content of needles (that is, the amount of the remaining mineral part) is no more than 1-2%, and in deciduous forests this figure increases to 4%. In the steppes, the degree of ash content of plant residues can immediately reach 5-6%, and in saline deserts, this figure generally increases to 14%! True, in the latter case, this does not really matter, since 90% of the mineral part is the same sodium, calcium and potassium chloride, which is found in abundance in the s alt marshes themselves.
Plants are characterized by the fact that fromsoils with different mineral composition, they take exactly the amount of s alts and compounds that they really need for growth and development. For example, in cereals and diatoms, the concentration of those elements that are mainly characteristic only of silicas is very high. In the soil of this particular region, the concentration of these compounds can be negligible. Desert plants are the most striking example of this statement, as they contain a huge amount of mineral s alts.
What do they need these compounds for? It's simple - the sand in which these autotrophs grow is extremely scarce in the content of all the elements necessary for plants that have to be stored inside their own organism.
The role of the animal world
But if in a school or other educational institution you are asked the question: “Name the factors of soil formation”, do not forget to mention the great role of fauna. Animals also play an important role in the formation of fertile soil. And here the fact that the soil itself is home to many thousands of species of a wide variety of animals and microorganisms plays a significant role. They have the "duty" of crushing and processing the plant mass and its subsequent mixing with the underlying soil horizons.
Mammals and all other vertebrates create their burrows and nests in the thickness of the earth. Moles, mole rats, ground squirrels and other burrowing creatures carry the lower parts of the rock up. It is in those areas where there are a lot of these animals (steppes) that there are saturated chernozems. Earthworms and larvae also do a lot of workon the transformation of the organic component of the soil into humus. In addition, invertebrates mix organic and inorganic matter. Like all natural factors of soil formation, they contribute to the acceleration of the accumulation of organic matter.
Of course, the prevalence of the animal world and its diversity are entirely dependent on both geographical and climatic factors. The more diverse the flora and fauna, the better and “higher quality” the soil turns out to be, the more organic matter it contains and the higher its fertility.
Climatic factors
Finally, consider the climate as a factor in soil formation. A lot depends on geographical and climatic conditions: just look at Kazakhstan and the Gobi Desert. The total amount of radiant energy reaching the surface of the earth also depends on the location. Accordingly, it is maximum at the equator, minimum - at the pole. Both circumstances negatively affect the processes of soil formation. How is soil formed? Soil formation factors also strongly depend on the weather.
To a large extent, the weather and climate depend on the height of the area above sea level. It should be understood that there are two forms of climate: macro and micro. The greatest part in soil formation is taken by wind and various types of precipitation. The more diverse the climate, the more “variegated” the soil at the output turns out. One way or another, but the thermal regime plays a significant role in the heat capacity of the soil. This is especially noticeable in mountainous conditions, with different slopes of surfaces.
