What is the greatest wealth of our planet? Of course, this is water and air, but one should not forget about something else. About the soil. It is the fertile substrate that provides millions of diverse species of animals and plants, it is thanks to it that a large part of the biosphere exists. Do you know what the soil is made of? If you are interested, you can read our article!
What is soil?
Many people assume that the ground under their feet is ordinary dirt, and no one will think about its composition at all. Meanwhile, the soil is an extremely complex natural formation. Conventionally, it is divided into solid and liquid parts, a gaseous fraction and a living component. The composition of the solid component includes many minerals, as well as a certain amount of dead organics. The liquid fraction is water and trace elements dissolved in it.
Accordingly, the gaseous part includes air and other gases that are formed in the soil as a result of the occurrence of natural biological processes there. The living phase is millions and billions of fungi, molds, microorganisms, spores and other biomass. That's what the soil is made of.
Solid fraction characterization
Particles of solid mineral elements form the basis of the solid fraction. It is believed that they form sand and clay. Sand refers to elements from 1 to 0.01 mm in diameter, and everything smaller than 0.01 mm forms clay. All particles more than one centimeter across form a rocky skeleton of the soil.
Why do you need to know all this? The fact is that the type of soil depends on the percentage of all these elements. Here is such a definition of soil, which almost all eminent agronomists cite in their writings:
- Loose sand, which contains no more than 5% clay.
- Sand cohesion, in which there are 5-10% clay particles.
- Sandy loam, in which the proportion of clay reaches 20%.
- Light loam. The content of the clay fraction is 20-30%.
- Medium loamy soils. Contain 30-45% clay.
- Heavy loam in which physical clay contains 45-60%.
- Clays
Knowing the name of the soil, you can determine what the soil consists of.
Some characteristics
Of course, the mechanical composition has a predetermining effect on the agrarian qualities of the soil, its fertility and the amount of biomass in it. So, in practice, sandy loams and sands are often called light soils, since it takes a little energy and resources to process them. Accordingly, almost all medium sandy loam and clay itself can be attributed to heavy soil, because for their plowing and cultivation it takes an enormous amount of fuel. Other soil characteristics also largely depend on their mechanical composition.
So, light soils are very loose, and therefore easily pass moisture and air deep into. In the spring, they warm up the fastest. But they practically do not hold water that has got into them, and all organic residues that determine fertility are extremely easily washed out of light soil. Clay soils are poorly heated, disgustingly allow moisture and air to pass through. But their humidity is always about the same. And the nutrient content is much higher when comparing these indicators with sandy soils.
Structural elements
All mineral elements of the soil can aggregate, forming larger structures. If such a phenomenon is not observed, the soil belongs to a variety of structureless. Such a soil may not be a suitable substrate for plant growth, since the root system is not properly fixed in it.
Sandy soil
A perfect example is sandy soil. This is the name of the soil, which contains from 0 to 5% clay particles. Soils of this type are extremely light, they lack any structure. Of these, nutrients are washed out almost instantly, and the water evaporates quickly.
To get at least some kind of crop under such conditions, one often has to lay a large amount of fertilizer, as well as make the soil structural, adding clay, peat and rotted sawdust there. It should be noted that sandy soils in this case are extremely costly, since a lot of time, resources and money have to be spent on their improvement.
Recently, science has been trying not to fight on its own with the lack of sand structure, but to select plants that could create it on their own. In particular, there are varieties of cultivated plants bred specifically for desert conditions.
They develop a fibrous root system, with which several bushes of grass can firmly adhere to each other, forming a strong “canopy”. Under it, an accumulation of useful substances is gradually taking place, since water and air are no longer able to wash away and blow them out. If a semi-desert plot is planted with such crops, then over several years there will be formed quite acceptable soil for growing crops.
What soil is good for agriculture?
Agronomists believe that the most optimal is soil with a particle size of 10 to 0.25 mm. It is porous enough and resists erosion well. In addition, such soil passes water well, but its evaporation occurs relatively slowly.
The main advantage is the fact that on the surface of this kind of soil there is practically no dense caked crust that prevents the growth and development of cultivated agricultural plants. Even with a strong wind, the soil structure remains intact; a fertile layer is not blown out of it. Thus, structural soil, ceteris paribus, will allow you to collect a much richer crop.
Of course, you can get such a result on unstructured soil, but for this you will need to spend a lot of time and money, trying to somehow level out its negative characteristics.
Humus
Along with various mineral particles, the composition of the solid fraction also includes humus particles. Recall that the so-called remains of animals and plants processed by soil microflora. In general, ordinary soil contains a huge amount of nutrients, but most of them are not available for plants.
Only thanks to saprophytic microorganisms that process such organics, plants get nutrients available for absorption. In the upper soil horizon contains up to 15% humus. The larger it is, the better the most important soil properties - its fertility and ease of cultivation.
Water and gas
It is no exaggeration to say that all soil processes can proceed only if moisture is present in the soil. In any case, without it, plants will not grow and develop, and the microflora will die. All ground moisture and salts of trace elements that are dissolved in it together form a soil solution. From it, the vegetation extracts the mineral elements necessary for life and development.
All gaps between particles that are not normally occupied by water are filled with air. However, in some cases, methane, hydrogen sulfide or pure carbon dioxide (forest soils in lowlands) may take its place. By the way, soil air is just the same and has a high content of carbon monoxide. In order for the plants to feel good, and saprophytic microorganisms to actively carry out their activities on processing the substrate, there should be at least 15% of air in the soil.
Living fraction
As we have already said, the composition of the living fraction includes bacteria, algae and fungi. Bacteria are incredibly important for the soil, as it is they that convert minerals into forms that are available to plants. In addition, legumes enter into a symbiotic relationship with microorganisms that have the ability to fix nitrogen in the air and translate it into an easily digestible form.
Important! If the soil has a low pH (acidic soil), then there are very few bacteria in it. The work on the decomposition of organic residues in this case is completely performed by the mushrooms. Of course, a large number of multicellular invertebrates and even vertebrates (moles, mole rats) animals also live in the ground.
Now you know what the soil is made of.
Acidic soil
Since we mentioned one characteristic feature of acidic soils, let's talk about this type of soil in a little more detail. What is this all about?
The most important factor in determining the quality of soils is their acidity. This indicator is neutral if the pH is 7. If it is larger, the soil is alkaline. Less is acidic soil. This factor affects not only the microflora, but also the amount of mineral and nutrients dissolved in the soil. Most cultivated plants are in dire need of neutral or slightly alkaline soil, but there are also species that need an acidic environment. For example, rye, which alone can significantly acidify the soil.
Determine the pH yourself
This will require a flask and a solution of an indicator (phenolphthalein, for example), which can change color depending on the characteristics of the medium. A small amount of soil is added to the vessel with it, and then everything is thoroughly shaken so that everything is mixed properly. After this, you need to wait until the suspension settles and the solution changes color. Using the instructions for the drug, determine the acidity of the soil. This is how soil characterization is determined.
Attention! Contrary to popular belief, the pH is not constant. It can be different even in neighboring areas of the garden, and therefore, studies need to be carried out several times, taking soil samples from at least three or four places. After each fertilizer application (especially mineral fertilizers) it is also necessary to check the acidity level.
What to do to change the indicator?
If the soil is too acidic, then it needs to be deoxidized. For this, limestone, chalk and some buffer mixtures, which are specially manufactured by the agricultural industry, are used. In the case when the acidity just needs to be increased, use peat or ordinary manure. Yes, acidic soils are often obtained precisely from those gardeners who use this natural fertilizer in large quantities.