The topsoil, densely overgrown with herbaceous plants, is called turf in soil science. The well-being of the country depends on the fertility of this horizon. No wonder Franklin Delano Roosevelt (thirty-second president of the USA) said that a people destroying the soil ultimately destroys itself.
Soil formation process: why is fertility different everywhere?
Several stages are characteristic for the formation of soils on the globe. At first, the destruction of rocks under the influence of temperature, wind, water. Small pieces formed ruhlyak - these are primary minerals (quartz, feldspar , etc.). He gave the opportunity to settle organics.
The first settlers were mosses, lichens, microorganisms. Their life activity changed the layer itself, it became already suitable for the existence of higher plants in it. The next stage already depended on the climate: the more favorable the conditions (higher temperature, less moisture, lack of prolonged frosts), the easier and faster the further process went. That is, in the southern areas of the soil are formed faster than in the northern. The terrain affects the soil-forming process - the slopes cannot completely absorb moisture, the water runs down, it stagnates: there are different soils on the slopes and in the lowlands.
Summing up, we can say that the soil coverings of different places differ in mechanical composition - from sand to clay, in chemical - from sod to podzolic, water regime - from normal to excessive. In their pure form, soils are very rare, forming various subtypes under the influence of various natural factors.
What is the name of the topsoil?
The soil profile (vertical section) has several layers called horizons. The upper fertile soil layer (horizon) is called humus, the next - transitional, the last - soil-forming.
The future of the planet depends on the thickness and composition (fertility) of the humus horizon. Unreasonable human influence adversely affects the state of the soil - improper use of soil cultivation techniques to obtain ultra-high yields destroys the humus layer, its erosion occurs. Deforestation and frequent fires are changing the green face of the planet. Wind and rainfall complete the destruction.
Living soil microorganisms are working on soil fertility . Their livelihoods include: plant debris (grass, hay, fallen leaves, branches, mushrooms), animal debris (worms, insects, bacteria, microorganisms). Organics and chemical compounds called humus make up the humus horizon. Microflora and microfauna, working on the formation and restoration of fertile soils, are called microbiocenosis.
Layers of fertile soil
Mulch is the first layer of fertile soil.
This layer is under our feet - plant-animal remains. Beetles, various worms, flies, and fleas live under their layer. Their number can reach several tons per hectare. All this huge number of small creatures leads a fairly active lifestyle: they move, eat, multiply, fulfill their natural needs, die, in the end. Their remains are decomposed to their original state. The topsoil, densely overgrown with herbaceous plants, develops only under favorable conditions.
Biohumus is the second layer of fertile soil.
It consists of the waste products of microflora and microfauna of the first layer, the remains of themselves, plant remains. In some places, its thickness is significant - up to 20 centimeters. Biohumus serves as an environment due to which plants not only receive good nutrition, but also maintain (develop) their immunity.
An absurd deep plowing (digging) destroys the biohumus layer, and the seeds sown after this process give a frail plant.
Biomineral (third) layer of fertile soil.
The top layer of soil, densely overgrown with herbaceous plants, a layer of mulch protects the soil from drying out on the one hand, and on the other - allows moisture to penetrate deep inside. In this case, decomposed remains of plants along with biohumus are also transported inland. Biochemical reactions taking place in this layer accumulate biomineral fertilizers for plant growth. The roots of plants, penetrating deep into the soil (almost to such a depth as the height of the plants), from this layer receive good nutrition.
The fourth layer of fertile soil is humus.
Microorganisms work in it in conditions of limited access of air and moisture, creating unique hydrocarbon compounds, carbon dioxide, methane and combustible biogas. This process is called biosynthesis; it is it that creates bio-nitrogen accumulations. This layer heats plants on the one hand, and plants, on the other hand, as well as microflora and microfauna, absorb the released carbon dioxide and methane. Thus, soil bio-nitrogen accumulations are formed.
Subsoil, clay - the fifth layer of fertile soil
It regulates moisture exchange and gas exchange at a depth of more than 20 cm.
Classification of Russian soils according to V.V. Dokuchaev
Vasily Vasilievich Dokuchaev (1846-1903), a geologist and soil scientist, created a classification of Russian soils. Among the soils by composition, he distinguished the following: clay, sand, loamy, peat, calcareous, sod, and loamy soils.
Clay
It is fertile, rich in nutrients, but difficult to till. After drying, they become very dense. To improve their structure, it is necessary to annually carry out a set of agrotechnical measures: digging, making deciduous land, manure, ash and peat.
Sand
These are loose, easily water-passing soils. They are depleted in potassium and magnesium, require the addition of litter, mineral fertilizers (in small doses) and turf land. Only in this case can the topsoil overgrown with grass be obtained.
Loamy
These soils are very fertile: they are breathable on the one hand, and on the other hand, retain moisture well. But if they are often dug up from above, a dense crust forms, which prevents the entry of moisture.
Peaty
In these soils, there is a catastrophic lack of calcium and potassium, and little phosphorus. But if you add sand, lime and mineral fertilizers - after a while the soil will become uniform and very fertile.
Calcareous
There are a lot of such soils in Russia. In their composition - half lime, the rest is clay or sand. In this case, the roots of the plants receive little water, it is retained by the crust on the surface.
Soddy
The topsoil, densely overgrown with herbaceous plants, is the definition of turf. Such soils formed in vast open areas from St. Petersburg to Kaliningrad and Kamchatka. Moisture and an abundance of meadow grasses created a special microclimate in the fertile layer, which enriches planted plants with minerals and organic matter as well as chernozem. These soils have long been used as hayfields and pastures.
Sandy loam
These lands easily absorb moisture without forming a crust. They warm up very quickly. Agricultural practices for them - the introduction of peat, compost and manure.
Modern soil classification
Since the 50s of the twentieth century, a new systematization of soils has been established, taking into account diagnostic indicators for taking into account soil formation regimes and modern environmental conditions.
The latest classification published in 2000. It is called profile genetic and takes into account the structure of the soil profile and its properties.