Soil biota is the biological world of the soil. The importance of soil biota and its composition The role of green plants in soil formation

In addition to minerals and organic remains of plants and animals, there are many small (micro-), medium (meso-) and large (macro-) organisms in the soil, which greatly affect the vital activity of plants.

An outstanding scientist of the past, Vladimir Dokuchaev, wrote: “Try to cut a cube of soil from the virgin ancient steppe. You will see in it more roots, grasses, bugs, larvae than earth. All this drills, grinds, digs the soil, and a sponge is formed, which cannot be compared with anything. This "sponge" absorbs moisture from rains and showers, revitalizes the earth. And the soil treated with a shovel or plow turns into a dense, structureless mass: biota (worms, larvae, algae, crustaceans, fungi) die or go deeper into the ground.

Groups of soil organisms:

• microbiota (bacteria, fungi, soil algae and protozoa);
• mesobiota (nematodes, small insect larvae, mites, springtails);
• macrobiota (insects, earthworms, etc.).

In healthy soil, the mass of living beings is huge, some bacteria - up to 20 tons / ha. And all of them, even those who are called pests, are programmed to increase soil fertility, but they die due to chemical plant protection products, mineral fertilizers, deep plowing with a bed overturn, and stubble burning. Let's take a closer look at the representatives of this "fertility army".

bacteria decompose nitrogen-free organic compounds; decompose protein and urea with the release of ammonia; carry out nitrification, denitrification and nitrogen fixation; oxidize sulfur, iron; convert sparingly soluble compounds of phosphorus and potassium into easily accessible forms for plants.

actinomycetes decompose hemicellulose, water-soluble sugars; form humic substances; together with bacteria complete the decomposition of plant residues.

lower mushrooms process cellulose, lignin; form humic substances; can oxidize sulfur, are often in symbiosis with higher plants, forming mycorrhiza, which accumulates nutrients and moisture, protects the host plant (wheat, oats, millet, rye, barley, cotton, corn, peas, beans) from root rot.

soil algae enrich the soil with organic matter.

Lichens they initiate soil formation by releasing organic acids that accelerate the chemical weathering of the mineral substrate. The products of weathering, together with the dead remains of lichens, form primitive soil.

The roots of higher plants- the system-organizing factor of the soil, they form the rhizosphere (the root-inhabited soil layer) - a biologically active zone of the soil profile, a shelter for a diverse soil biota.

Protozoa(amoebae, radiolarians, ciliates, etc.) actively transform organic matter, including humus.

Springtails, mites, nematodes crush plant residues; regulate the number of certain microorganisms (feed on bacteria).

Slugs penetrate deep into the soil, enriching the soil profile with organic matter and improving its structure.

beetles regularly migrate (daily and seasonal migrations), contributing to the loosening and aeration of the soil; predatory insects regulate the population of other insect species. May beetles crush and move organic matter deep into the soil. Fly larvae crush plant residues, and their waste is a substrate for microorganisms.

earthworms increase the permeability of the soil; disinfect manure; enrich the soil with physiologically active substances.

Vertebrates(ground squirrels, moles and others) crush the soil material, mix it. Through the passages of these animals, natural soil drainage is carried out.

To restore the natural fertility of the soil, organic matter should be returned to it.

To improve soil fertility, it is necessary to look for the most accessible reserves of organic fertilizers. It can be a non-commercial part of the crop (straw, the remains of stem crops), vermicompost. This also includes specially sown green manure. Approximately 5 tons of the non-marketable part of the crop in terms of efficiency correspond to 1 ton of manure. In addition, it is necessary to increase the coefficient of humification of organic residues. The process of humification depends on the presence of soil biota and on the reaction of the soil environment. Studies show that the highest humification coefficients were observed when organic fertilizers were applied to the top layer of soil (to a depth of 10 cm) and the reaction of the soil solution was near neutral.

The amount of organic fertilizer should correspond to the amount of soil biota (effective microorganisms, earthworms, etc.), which should have time to process organic matter. In inactive soil, humification processes do not occur. The consequence of chemicalization is an inactive soil with a small amount of biota. During deep plowing with overturning of the layer, the soil biota of the upper layers of the soil, which actively breathes oxygen (aerobes), finds itself in a depth where there is little oxygen, and as a result dies. Anaerobic creatures, on the contrary, get to the surface, where they also cannot live. Some ecologically valuable microorganisms do not withstand sunlight, such as nodule nitrogen fixers (symbionts of legumes).

Minimal surface cultivation of the soil provides optimal conditions for the activity of soil biota.

If you find an error, please highlight a piece of text and click Ctrl+Enter.

People ask me why, after so many years, I decided to resort to growing beneficial microflora. This doesn't mean that I woke up one morning and thought, "For the past thirty-five years, I've been on the wrong track, and growing beneficial soil biology microflora is the answer to all my troubles!"

It all started with the realization that the very tight operating budget I had at my disposal meant it was impossible to make any improvements on a yearly basis without having to reduce maintenance costs through other items.

I am no different from any other manager. I have always been driven by future results and have a need to see improvements regularly. In the absence of positive results, I lose even the appearance of motivation. And without motivation, you know, it's hard to get out of bed in the morning. Before I did not face a similar problem.

So, faced with the dilemma of a lack of funds, I began to review my annual maintenance costs, and my attention lingered on one of the expenses - the use of pesticides. I averaged eight applications of fungicides per year and was overwhelmed by how much money went into buying pesticides. Then I realized that it would be possible to save a lot if we could reduce the incidence rate.

Before I continue in this vein, I should give you an overview of my course management style, as well as the history of Staverton Park, a 35-year-old woodland golf course with USGA greens.

I took over the field in 2005 and found greens affected by several types of diseases, including Fusarium, Anthracnose and Rhizoctonia, while the typical signs of a niello layer were showing on the surface. The need and attempts to deal with the existing situation were paramount. Obviously, this was the reason that a large amount of money was spent on pesticides.

For the first three years, I ran intensive furrowing programs with rather primitive equipment, which was either a cutting tool or a toothed drum aerator. That first fall, I rented a Sisis Javelin Aer-Aid, which proved to be a worthy tool and an effective tool for dealing with a layer of niello. Every subsequent year I rented Verti-Drain both in spring and summer. Later, in 2010, I was able to purchase a Toro Pro-core 648, which in my opinion is the best aerator on the market.

Right now my greens are mostly aerated with Pro-core, both 9mm and 15mm. A rented Verti-Drain is also used from time to time. Hollow coring is not necessary as I have never had a problem with felt build up.

In those days, the root zone in my field was inert, predominantly anaerobic, with a weak root system, and a push was needed to breathe life into the growing medium. The lack of resources made me look back to my earlier years as a field manager in the heather countryside of East Sussex. Then I followed the advice of the famous Jim Arthur and implemented a program of regular aeration of push-up greens with well-thought-out feeding and irrigation systems.

Four years later, annual bluegrass stopped dominating my greens, and bentgrass appeared naturally. Natural, because the issue of overseeding has never been raised. During that period, I applied my own mixture of mainly organic fertilizers - in spring and autumn. Using such a mixture, the fungicide for preventive purposes needed to be applied only once - in the fall. Everything was much easier back then!

Even after thirty-five years of working with lawns, I will be honest and admit that it never occurred to me how important soil biology is and how close its relationship with plants is. Yes, I read about this when I was educating myself as an adult, and then it seemed to me that this topic was covered less than it should have been.

It was also fashionable to follow USGA green building specifications, the opposite of what I was taught in college. We are surrounded by a myriad of propositions from various literature and commercial appeals talking about inorganic fertilizers and other magic potions, the types and promised effects of which are endless. Perhaps if we paid more attention to how small the effect that some of these products have on plant health (in some cases it is less than 2%), we would realize that most of them are not worth the money spent on them.

Inorganic and organic fertilizers

In most cases, inorganic fertilizers are produced for the purpose of providing nutrition to the plant, often with a quick but not long-term effect. Its actual action corresponds to the description on the package, that is, it nourishes the grass cover, but that's all! Organic fertilizers go beyond just feeding the turf as they also feed the biology.

Soil biology (microorganisms) is incredibly important for the decomposition of organic matter, which is critical in controlling the formation of felt. If this issue is left unresolved, it can lead to moss and/or dry spots. Microorganisms also assist in the suppression of pests and diseases, as well as in the breakdown of chemicals and other toxic substances.

Such symbiotic relationships have been formed over millions of years. If you look at how ecosystems are created, you'll see this: it all starts with annual weeds and grasses that require minimal support from soil biology. They essentially grow in a microbial-free environment, and in general their life support is limited to bacterial support. This means that all the energy of such an annual plant is directed only to survival by reproducing seeds.

However, perennial plants bloom year after year and do not depend on the mere need to leave behind a seed for reproduction. That is why about 50% of the energy produced by perennial grasses is used to feed soil biology, which includes bacteria, fungi, protozoa, nematodes, and higher soil life forms: arthropods and worms. The formation of a diverse ecosystem took millions of years, and then a person comes and counteracts these processes, not thinking about the consequences!

I am absolutely confident in my words when I state that most people do not realize the importance of a healthy state of soil biology, also known as the soil food web.

Like most, my knowledge is superficial, but one thing is clear - soil biology is an integral part of providing plants with nutrients in various ways: preventing groundwater from washing out nutrients, stabilizing atmospheric nitrogen levels, producing ammonium, which is converted into saltpeter. Other roles include enhanced infiltration by improving soil structuring and permeability. The connection between soil biology and plant life has now become all too obvious.

Shortly after the introduction of inorganic fertilizers, we began to observe an increase in the hydrophobic state and, as a result, an increased use of wetting agents. The latter are designed to rehydrate hydrophobic soil.

Soil hydrophobicity is thought to be due to the superimposition of long-chain hydrophobic organic molecules on individual soil particles. These substances can come from decaying organic matter, soil fauna and microorganisms. We should be asking ourselves: have these foods not led to a decline in biodiversity that otherwise would have easily endured such conditions? Do wetting agents dilute the beneficial secretion of soil biota?

All questions are hypothetical, but why are such products now used with enviable regularity as our annual field maintenance programs? I can say with full confidence that I myself did not use them thirty years ago and did not feel the need for it!

The successes that were achieved in Sussex many years ago made me think and look for ways to create a healthy environment for the growth and life of herbs.

I came across a research paper by Dr Elaine Ingham, who has studied the soil food web for many years. It wasn't long before I started reading about the use of compost tea, soil biology, soil diversity, and the important role it plays in plant health. The more I delved into this issue, the more I realized that this could be the solution that I have been looking for!

The basic principle of maintaining soil biology in a healthy state is quite simple, although many of us ignore this fact and resort to the use of inorganic fertilizers to feed plants or to the application of wetting agents or pesticides at the first sign of dry spots and any diseases, while each of listed means either does not affect at all, or harms the biology of the soil. The use of such remedies leads to a decline in the health of the plant and its vitality.

Soil biology and its significance

Like all living organisms, soil biology needs basic things: air, water, temperature, and a source of nutrition. The micro-organisms that we commonly associate with herbs are: bacteria, protozoa, nematodes, and beneficial fungi. Each of these micro-organisms number in the thousands, all occupying a niche in this extraordinary world beneath our feet.

The size and structure of these microbial populations is determined by the field maintenance practices that affect the soil environment. For example, soil loosening or aeration practices that create aerobic conditions; or an insufficient number of such operations or the use of means that lead to soil compaction, which results in the creation of anaerobic conditions.

However, knowing this, and having certain knowledge gained in recent years, I can say that the main reason for the prevalence of annual bluegrass on our lawns is the increased movement. I mean not only the movement associated with movements during the game, but also that which is associated with service operations. Unfortunately, in many cases, the extra traffic is created by random golfers, attracted to the course by reduced green fees, who can easily strut around the course unnecessarily, and who are alien to the basic concepts of golf etiquette!

At this stage of the population, the bluegrass in my field is in decline, while the growth of perennial grasses, fescue and bentgrass, has increased. How could this happen? I always aerate regularly, my maintenance programs have changed very little, and yet the increase in the perennial grass population is noticeable.

I mentioned earlier that annual grasses have little bearing on soil biology and are usually associated with soils with predominant bacterial populations. If we provide the bluegrass with food and water, it will thrive. It is also recognized that bacterial populations, despite their low numbers, will survive/recover in a relatively toxic environment. By toxic, I mean the use of pesticides and, to a certain extent, inorganic fertilizers.

Artificial fertilizers with a high rate of salt burn to plants have a detrimental effect on the entire biology of the soil. Although the bacteria can recover after such introductions, the negative impact still has an effect in the form of a few populations. That's why managers who implement high-nutrition programs that don't involve biology will get more felt in their fields. Since we have, by our actions, weakened the process of microbial decay and thus reduced the effectiveness of Mother Nature's means of decomposition, this has led to an excessive accumulation of felt. And this, in turn, created another chain of work to be done, such as the removal of felt by hollow coring and / or additional sanding sessions to thin it out. Both are poorly displayed in the game.

So we find ourselves doing more of the same bluegrass, using more nutrients, more pesticides, producing shallow root systems, and adding more wetting agents to control the hydrophobicity of the felt.

For years, I have been reluctant to overseed greens because I felt the competition from mature grasses was too high. But now I realize that perennial grass seedlings could not survive in a bacterial-dominated environment more favorable to annual grasses.

It is important to remember that perennial grasses cannot survive without a diverse biology that contains beneficial fungi. An equal ratio of bacteria to fungi will help perennial grasses compete with annuals. And with regular aeration of the root zone and the right food sources, the right biology will thrive.

In healthy soil, about 95% of plant species are in a symbiotic relationship with soil fungi. Some fungi sprout hyphae (roots) for many meters, while other beneficial fungi live in close proximity to the roots. Their functioning is closely connected with plants, from which they receive moisture and nutrients, digest organic matter, and even protect plants from diseases by producing antibiotics in exchange for sugar and carbohydrates.

Unfortunately, beneficial fungi are more sensitive and easily harmed by pesticides. That is why we are seeing an increase in the number of soils with a predominance of bacteria and, as a result, a predominance of bluegrass. I recently seeded the greens and see how the seedlings are maturing, and perennials are gradually starting to dominate the grass cover.

Some managers must find it too costly to grow beneficial microflora. I do not deny that there is some truth in this. But I find that in many cases the price is being driven up by some vendors offering unnecessary additives. Some people think that this process is too time-consuming and complicated. Again, this may be partly true. But it's also true that there are many variations to this method, some of which I use and some I would never use.

Methods for growing beneficial microflora

The standard description of the process of growing the beneficial microflora of compost tea sounds like the extraction of microbiology and nutrients from the compost, which are aerated in a proper container using a special aerator and purified water (no bleach) for a certain period of time. The result may differ depending on the fermentation time, the compost used, the degree of acidity of the medium, the source of food, water and temperature, since all these indicators affect the final result of the biota.

I am constantly asked why there is so little written about compost teas. I believe this is partly because each microorganism must be separated and identified when examined, then scientifically examined for effectiveness as an invader and competitor, since each group will be different and contain a variety of microorganisms at different concentrations.

Then it is necessary to determine how these microorganisms interact with each other. Whether different combinations have the same, better or worse effect compared to single microorganisms. The possible results obtained will be extensive. And a large number of possible variations, of course, will lead to an unproven conclusion.

Some suppliers produce their product under strict control of all processes and ensure that the content meets the buyer's expectations. Some use what is called low-grade compost in production, that is, what can be collected on your own site. Each type of such product should be tested before use, as there are no guarantees regarding its contents.

Homemade compost can be used, but in this case, care must be taken to ensure that neither food nor animal excrement is used, which can cause fermentation pathogens (eg, E. coli). Again, such a product must be tested, and the compost itself must be mainly of woody origin.

Surprisingly, some do not use compost at all. Instead, bacteria and fungi grown under laboratory conditions using similar methods, but without compost.

In the five years that I have been growing beneficial microflora, I have used either homemade or custom-made compost. Now I don't use it at all.

Whatever I do, I always analyze, review the results and simplify the process, while still sticking to my original goal. I applied this approach to work in the case of growing beneficial microflora. My supplier convinced me that I could do this without compost, and the process would be safer, faster, with the nice bonus of easy cleaning of the container at the end of the process. I convinced myself of this by examining all my results of growing beneficial microflora before using it under a microscope.

Pros and cons of using compost

Positive:

Diversity

Contains bacteria, beneficial fungi, protozoa and nematodes

Negative:

Compost should be tested for the presence of pathogens

It must be kept in a large filtered container or in a tea bag.

Composted teas must be settled or filtered in the spray tank

After growing beneficial microflora, washing containers is somewhat difficult.

Recommendations for a suitable type of container are as follows: “Choose a container for growing beneficial microflora without internal tubes, deaf hard-to-reach corners and other parts that can get product particles and complicate the process of cleaning the container.” After all, you can never be sure what is actually inside the compost, whether or not it has been tested!

The entry of pathogens can be limited, although there is no guarantee of their complete absence. To eliminate this possibility, it is necessary that the production takes place in a laboratory, in a sterile room, during which the desired biology will be introduced into the product.

Because I don't use compost to grow beneficial microflora - just pure lab-grown biology - I rule out the possibility of pathogens.

I use a specially designed aerator that can be placed either in a large volume container or, in my case, directly in a 750 liter atomizer. In this way, I can add a source of nutrition and grow beneficial microflora for a certain time. In order for the fermentation process to start quickly, it is recommended to add organic food sources / biostimulants to the container.

The product is then applied with minimal effort. If I don't have time to cook it, this can be done directly in the atomizer tank by adding the required power supplies. The only downside to this "light" way to grow healthy microflora is that you won't get the most for your money! Naturally, the issue of hygiene is an important part of my program, and therefore, after use, all equipment is thoroughly washed.

Why do I prefer to prepare the basis for growing beneficial microflora not on the basis of compost?

It is safer for biology and easier to use.

This product is cheaper than other similar products.

Targeted sprayer application eliminates spray head blockage

Why is tea an integral part of my field maintenance programs?

Using this product reduced my pesticide budget by 80%.

It also cut the fertilizer budget by 50%.

Applications of wetting agents reduced by 70%

Decreased predominant bluegrass growth

Increased growth of fescue and bent grass.

The key products used, each with its own specific scope:

Combination of more than twenty types of beneficial bacteria and fungi

Combination of nitrogen-fixing bacteria and associated bacteria capable of fixing atmospheric nitrogen

A combination of mushrooms, the action of which is aimed at splitting shrubs that are difficult to do this business

Each product is aimed at solving certain problems, or is part of a broader strategy.

Note: Each product requires a small amount of food to be added to the container initially, approximately 200 mls per 200 liters of water.

In addition, to enhance the effect of these products, the following apply:

Liquid oxygen (addition to the aeration program, does not replace cultural practices)

Fulvic Acid (quality fulvic acid should look like weakly brewed tea and is derived from humic acid)

Organic seaweed (some seaweed extracts can be quite aggressive, depending on the extraction method).

"Whichever method you choose, there is strong evidence that growing favorable biology in a controlled environment will positively impact the health and vitality of your lawn."

Desirable perennial grasses will get a chance to grow on your lawn and gain resistance to the stresses that, after all, come with any field maintenance.

Gradually, the availability and choice of pesticides will be limited by law. It's unavoidable. An increasing number of organic pesticides are being produced, which are less harmful to the environment but are costly alternatives. The benefits of growing beneficial microflora are evident in European countries such as Sweden where pesticides are banned. So why not start the path to change now, before it's too late?

Seek advice or advice on growing beneficial microflora,

soil biota- a complex of diverse soil organisms that differ in ecological functions and taxonomic position (various groups of microorganisms and soil zoofauna).

It takes part in the processes of formation of soil fertility: in the mineralization of organic matter, the involvement of chemical elements of lithosphere minerals in the cycle, and biological nitrogen fixation.

Soil organisms destroy the dead remains of plants and animals entering the soil. One part of the organic matter is completely mineralized, while the other part passes into the form of humic substances and living bodies of soil organisms.

In cultivated soil, the functions of soil organisms are reduced to maintaining an optimal nutritional regime, which is expressed in the partial fixation of mineral fertilizers with subsequent release as plants grow and develop, soil structuring, and the elimination of unfavorable environmental conditions in the soil.

Maintenance of ecologically favorable conditions in the soil is carried out due to the presence of close relationships between soil organisms, which are in a state of continuously changing equilibrium. Some groups of microorganisms have simple requirements for food, while others have complex ones. Between some groups there are symbiotic (mutually beneficial) links, between others - antibiotic. In the latter case, microorganisms secrete substances into the soil that inhibit the development of other microorganisms. This is of direct importance in the purification of the soil from phytopathogenic microflora.

To assess the activity of soil biota, the biological activity of the soil is used. On the one hand, this indicator is characterized by the abundance of soil biota components, and on the other hand, by quantitative criteria for the results of the vital activity of soil organisms.

Determining the abundance of soil biota is carried out, as a rule, by counting the total number of soil organisms. Due to the imperfection of the methods and the small multiplicity of determinations over time, the results of the analysis give an approximate description of the biological activity of the soil. Along with the total count of soil organisms, the number of microorganisms of different physiological groups (nitrifying, cellulose-decomposing, etc.) is sometimes determined.

The assessment of the biological activity of the soil based on the results of the activity of soil organisms is carried out by determining the amount of absorbed oxygen and produced carbon dioxide, cellulose decomposition, the activity of soil enzymes, the amount of nitrate and ammonia nitrogen, as well as phytotoxic compounds. The high biological activity of the soil contributes to the growth of crop yields, all other things being equal. For the normal functioning of soil organisms, first of all, energy and nutrients are necessary. For the vast majority of microorganisms, such an energy source is the organic matter of the soil. Sources of organic matter in the soil are manure, peat, straw, green manure, sapropel, sowing of perennial grasses, intermediate crops. The green mass of stubble green manure increases the biological activity of the soil by 1.3-1.5 times, and in some years even twice. At the same time, the species composition of the soil microflora changes - the content of bacteria of the genus Clostridium increases and the nitrogen-fixing capacity of the soil increases 6-10 times. At the same time, green manure activates the enzymatic activity of the soil: the activity of urease increased by 52%, protease - by 45%, invertase - by 10%, catalase - by 17% (Loshakov V. G., 1986).

Accelerating the decomposition of plant residues - carriers of soil phytopathogens, green fertilizer several times increases the biological activity of saprophytic microflora, which is an antagonist of soil fungi - the causative agents of many diseases of cultivated plants. It has been established that post-harvest sideration reduces damage to potatoes by common scab by 2-2.4 times, rhizoctoniosis by 1.7-5.3 times, barley by root rot by 1.5-2 times. A negative average relationship was established between the degree of development of root rot disease and grain yield, which is expressed by the correlation coefficients r = -0.61 + 0.22 and regression byx = -0.70 + 0.26.

A clear indicator of the activation of soil biota when using stubble green manure is the results of accounting for the number of earthworms. It has been established that the long-term use of stubble green manure in grain crop rotations against the background of mineral fertilizers contributes to an increase in the number of earthworms in the arable layer of soddy-podzolic soil by 1.5-2 times.

If you find an error, please highlight a piece of text and click Ctrl+Enter.

Soil is a complex system, one of the main functional components of which are the living organisms inhabiting it. The nature and intensity of the biological cycle of substances, the scale and intensity of fixation of the main biogenic element - atmospheric nitrogen, the ability of the soil to self-purify, etc., depend on the activity of these organisms.

Recently, the importance of soil biota has increased significantly, not only due to its irreplaceable role in the formation of soil fertility. With technogenic pollution of the components of the biosphere, including soils, soil biota performs another important function - detoxification of various compounds present in the soil and affecting the state of the environment and the quality of agricultural products.

The soil cover is an independent earth shell - the pedosphere. Soil is a product of the joint action of climate, vegetation, animals and microorganisms on the surface layers of rocks. In this complex system, the synthesis and destruction of organic matter, the cycle of elements of ash and nitrogen nutrition of plants, the detoxification of various pollutants entering the soil, etc., are continuously taking place.

These processes are carried out due to the unique structure of the soil, which is a system of interrelated solid, liquid, gaseous and living components. For example, the air regime of the soil is closely related to its moisture content. The optimal combination of these factors contributes to better development of higher plants. The latter, producing a large biomass, supply more food and energy material for the living organisms inhabiting the soil, which improves their vital activity and contributes to the enrichment of the soil with nutrients and biologically active compounds.

The solid phase of the soil, in which sources of nutrients and energy are mainly concentrated - humus, organo-mineral colloids, Ca 2+, Mg 2+ cations on the surface of soil particles, is interconnected with the soil-biotic complex (SBC).

Soil particles, especially colloidal and silty fractions, have absorptive capacity due to their extensive total surface. This ability is of great ecological importance, since it allows the soil to absorb various compounds, including toxic ones, and thereby prevent the entry of toxicants into food chains. In the process of transformation of substances and the formation of energy flows, a huge role is played by the living organisms inhabiting the soil, which make up the PBK, without which there is no and cannot be soil. PBC is represented by a significant (by weight) and diverse group of organisms.

1 g of soil contains 3-90 million bacteria, 0.1-35 million actinomycetes, 8-10 thousand microscopic fungi, 100 thousand algae, 1.5-6 million protozoa.

It is generally accepted that the topsoil as a whole consists of mineral substance (93%) and organic matter (7%). In turn, organic matter includes dead organic matter (85%), plant roots (10%), and edaphon (5%). The structure of edaphon includes bacteria and actinomycetes (40%), fungi and algae (40%), earthworms (12%), other microfauna (5%) and mesofauna (3%).

The mass of bacteria is approximately 10 t/ha; microscopic fungi have the same mass; the mass of protozoa reaches about 370 kg/ha, etc.

For 1 ha of arable land there are 250 thousand earthworms (50-140 kg/ha), for 1 ha of pasture - 500-1575 thousand (1150-1680 kg/ha), for 1 ha of hay land - 2-5.6 million (more than 2 t/ha).

Among the animal organisms of the biosphere, the inhabitants of the soil are characterized by the largest biomass. Based on the assumption that the average biomass of soil fauna is 300 kg / ha, on an area of ​​80 million km 2 of the soil cover of the Earth (without deserts), the total biomass of soil animals of the entire globe is 2.5 billion tons. The activity of soil fauna, or pedofauna, consists in the decomposition of litter into complex organic derivatives (the original function of earthworms); these compounds then pass to bacteria, ctinomycetes, soil fungi, releasing the original mineral components from organic residues, which are again assimilated by the producers.

All these organisms are in constant interaction; they are very dynamic in space and time; some of them have an unusually powerful enzymatic apparatus and the ability to release various toxins into the environment.

Soil fertility, its “health”, the quality of agricultural products, and the state of the environment depend on the activity of soil biota. Knowledge of the features of the functioning of PBK in various environmental conditions is fundamentally important for creating productive and sustainable agroecosystems, producing environmentally friendly agricultural products and minimizing pollution of the biosphere.

Introduction

Soil is the basis of the nature of land. It serves as a habitat for many microorganisms, animals, and plant roots and fungal hyphae are also fixed in it. The primary factors important for soil inhabitants are its structure, chemical composition, humidity, and the presence of nutrients.

Edaphic factors - a set of physical and chemical properties of soils that can affect living organisms (plants).

It is well known that the nature of plant development and their distribution depend on edaphic (soil) conditions. However, it is far from always easy to decide which properties of the soil in each individual case affect plants. Edaphic factors include soil reaction, soil salt regime, water, air and thermal regimes, soil density and thickness, its granulometric composition, as well as plants and animals inhabiting the soil. In general, all edaphic factors can be divided into two groups: physical and chemical.

The degree and nature of the influence of each of these factors are very different, most of these factors change all the time, so it is important to take into account the manifestation of one or another of them not only at a certain moment, but it is important to know its entire regime, its change over a whole year or even several years. Therefore, for most of these factors it is necessary to speak about their mode.

The study of edaphic factors and the determination of their role in the life of plants and soil biota is a hot topic, since these factors affect the organisms living in the soil, play an important role in the formation of soil fertility and serve as one of the important factors in soil formation.

1. Soil as a habitat and the main edaphic factors

edaphic soil plant

Soil is the surface layer of the lithosphere, the solid shell of the Earth, in contact with the air. Soil is a dense medium consisting of individual solid particles of various sizes. Solid particles are surrounded by a thin film of air and water. Therefore, the soil is considered as a three-phase system.

The surface layer of the soil is quite loose. It is permeated with a system of cavities and passages and contains a large amount of dead organic matter (plant litter, humus). This is horizon A - humus-accumulative. Deeper is a very dense washout horizon (illuvial) - B. Its solid particles are cemented by colloids from horizon A. Below it is horizon C - the parent (soil-forming) rock (Figure 1). The mechanical heterogeneity of soil horizons determines the specifics of abiotic factors. So, with depth in the soil, aeration worsens. The amount of oxygen decreases, the content of carbon dioxide increases, as well as other gases formed during the decomposition of organic substances. In the upper horizons of the soil, substances necessary for plant nutrition are concentrated - phosphorus, nitrogen, calcium, and many others. Light does not penetrate into the soil.

Figure 1 - Soil horizons

Temperature fluctuations (seasonal and daily) are expressed not only in the surface layer of the soil. At a depth of 1-1.5 m, the temperature is practically stable (4-5°C).

The moisture regime in the soil is more favorable for animals than in the ground-air environment, especially for microscopic organisms that live in the air-water film between solid soil particles. Even in dry soil, film water, which is in the soil air, is preserved, and, first of all, water that fills the soil pores (capillary) and voids (gravitational) evaporates.

The soil also has peculiar biological features, since it is closely related to the vital activity of organisms. Its upper layers contain a mass of plant roots. In the process of growth, death and decomposition, they loosen the soil and create a certain structure, and at the same time conditions for the life of other organisms.

Burrowing animals mix the soil mass, and after death become a source of organic matter for microorganisms. Due to its specific properties, the soil performs one of the important functions in the life of various soil organisms and, above all, plants, providing them with water supply and mineral nutrition.

Water is distinguished in the soil:

a) biologically useful;

b) biologically useless.

Biologically useful is water, freely moving through the capillaries of the soil and uninterruptedly supplying plants with moisture. The value of the soil in the water supply of plants is the higher, the easier it gives them water, which depends on the structure of the soil and the degree of swelling of its particles.

Distinguish dry soil:

a) physical;

c) physiological.

With physical dryness, the soil lacks moisture. This occurs during atmospheric drought, which is usually observed in dry climates and in places where the soil is moistened only due to precipitation. The physiological dryness of the soil is a more complex phenomenon. It arises as a result of the physiological inaccessibility of physically accessible water. Plants, even on wet soils, can experience water deficiency when the low temperature of the soil cover, other unfavorable conditions interfere with the normal functioning of the root system. Physiologically dry are also highly saline soils. Due to the high osmotic pressure of the soil solution, the water of saline soils is inaccessible to many plants.

The soil plays an important role in the mineral nutrition of plants. Together with water, a number of minerals that are in the soil in a dissolved state enter the plants through the root system. However, root nutrition of plants is not a simple absorption of substances, but a complex biochemical process in which soil microorganisms play a special role, the secretions of which are absorbed by the root system. Therefore, most higher plants have mycorrhiza, which significantly increases the active surface of the roots.

Soil organic matter plays an important role in the growth and development of plants. Humus, or humus, for soil inhabitants is the main source of mineral compounds and energy necessary for life. It determines the fertility of soils and their structure. The processes of mineralization of organic matter and humus provide a constant supply of such important plant nutrients as nitrogen, phosphorus, sulfur, calcium, potassium, and microelements to the soil solution. Humus serves as a source of physiologically active compounds (vitamins, organic acids, polyphenols) that stimulate plant growth. Humus substances also provide a water-stable soil structure, which creates a favorable water-air regime for plants.

Microorganisms, plants and animals living in the soil are in constant interaction with each other, as well as with the environment. These relationships are very complex and varied. Animals and bacteria consume vegetable carbohydrates, proteins, fats. Fungi destroy cellulose, in particular wood. Predators feed on the tissues of their prey. Thanks to these relationships and as a result of fundamental changes in the physical, chemical and biochemical properties of the rock, soil-forming processes constantly occur in nature.

Edafogenic (the Greek word "edafos" means "earth" or "soil"), or edaphic factors - these are the properties of the soil that have an ecological impact on living organisms. The most important environmental factors characterizing the soil as a habitat can be divided into physical and chemical.

Physical factors include humidity, temperature, structure and porosity.

Humidity , or rather, the available moisture for plants, depends on the sucking power of the root system of plants and on the physical state of the water itself. The part of the film water, which is firmly bound to the surface of the particle, is practically inaccessible. Free water is readily available, but it quickly goes into deep horizons, and first of all from large pores - fast moving water, and then from small pores - slowly moving water, bound and capillary moisture is retained in the soil for a long time.

In other words, the availability of moisture depends on the water-holding capacity of soils. The strength of the holding capacity is the higher, the more clayey the soil and the drier it is. At very low humidity, if it remains, then only firmly bound water that is inaccessible to plants, and the plant dies, and hygrophilous animals (earthworms) move to wetter deep horizons and there fall into “hibernation” until it rains, however, many arthropods are adapted to active life even with extreme dryness of the soil.

Temperature soil depends on the external temperature, but due to the low thermal conductivity of the soil, the temperature regime is quite stable and already at a depth of 0.3 m the temperature fluctuation amplitude is less than 2 ° C, which is important for soil animals - there is no need to move up and down in search of a more comfortable temperature . Daily fluctuations are noticeable to a depth of 1 m. In summer, the temperature of the soil is lower, and in winter it is higher than that of air.

Structure and porosity soil provides good aeration. Worms actively move in the soil, especially in clay, loamy and sandy, increasing porosity. In dense soils, aeration is difficult and oxygen can become a limiting factor, but most soil organisms are able to live in dense clay soils.

The most important environmental factors are also chemical ones, such as the reaction of the environment and salinity.

Environment reaction - a very important factor for many animals and plants. In a dry climate, neutral and alkaline soils predominate, in humid areas - acidic.

Salted called soils with an excess content of water-soluble salts (chlorides, sulfates, carbonates). They arise as a result of secondary salinization of soils during the evaporation of groundwater, the level of which has risen to the soil horizons. Among saline soils, solonchaks and solonetzes are distinguished.

2. The role of soil in the life of living organisms

Due to the above properties, the soil provides the organisms living in it with water supply and mineral nutrition. The lack of water in the soil inhibits soil organisms. Soil dryness is usually divided into physical and physiological. Physical - during atmospheric drought; physiological occurs as a result of physiologically inaccessible physically available water. So, the water of some swamps, despite its large amount, is inaccessible to plants due to high acidity and other factors. Physiologically dry are also highly saline soils.

Together with water, the root system of plants supplies them with minerals, which, together with the participation of soil microorganisms, is a complex biochemical process.

An important role in the growth and development of plants is played by soil organic matter, consisting of humification products (aerobic decomposition of plant and animal remains). The resulting humus (humus) is the main source of mineral compounds and energy and determines the fertility and structure of the soil. Humus also serves as a source of active physiological compounds (vitamins, organic acids). The main energy material of the soil is the organic matter of the roots, the amount of which determines the abundance and species diversity of soil inhabitants.

A great contribution to ensuring the circulation of substances in the soil is made by soil animals, which mix and structure it.

The soil cover forms one of the geophysical shells of the Earth - pedosphere. It is in the soil that terrestrial plants take root, small animals, a huge mass of microorganisms live in it. As a result of soil formation, it is in the soil that water and mineral nutrition elements that are vital for organisms are concentrated in the forms of chemical compounds available to them. Thus, it is possible to single out the important functions of the soil, which are important in the life of living organisms:

The soil is the most important condition for the photosynthetic activity of plants. In this way, an enormous amount of energy is accumulated on Earth. And at present, and probably for a long time to come, it is the system soil - plants - animals that will be the main supplier of the transformed energy of the Sun to mankind;

ensuring the constant interaction of large geological and small biological cycles of substances, since the biogeochemical cycles of elements, including such important biophiles as carbon, nitrogen, oxygen, are carried out through the soil. These elements in different forms and in different proportions are involved in the synthesis of organic matter by plants;

regulation of biospheric processes, in particular the density and productivity of living organisms on the earth's surface. The soil has not only fertility, it also has properties that limit the vital activity of certain organisms;

in the soil, the processes of synthesis, biosynthesis are carried out, various chemical reactions of transformation of substances occur, associated with the vital activity of living organisms.

Thus, soil is a condition for the existence of life, but at the same time soil is a consequence of life on Earth (Figure 2).

Figure 2 - Soil

3. Relationship of organisms to soil

3.1 Distribution of animals in soil

Despite the heterogeneity of environmental conditions in the soil, it acts as a fairly stable environment, especially for mobile organisms. A steep temperature and humidity gradient in the soil profile allows soil animals to provide themselves with a suitable ecological environment through minor movements.

The heterogeneity of the soil leads to the fact that for organisms of different sizes it acts as a different environment. For microorganisms, the huge total surface of soil particles is of particular importance, because the vast majority of microorganisms are adsorbed on them. The complexity of the soil environment creates a wide variety of conditions for a variety of functional groups: aerobes, anaerobes, consumers of organic and mineral compounds. The distribution of microorganisms in the soil is characterized by small foci, since different ecological zones can be replaced over several millimeters.

According to the degree of connection with the soil as a habitat, animals are combined into three ecological groups:

geobionts are animals that live permanently in the soil. The entire cycle of their development takes place in the soil environment. Geobionts are earthworms (Figure 3), many primary wingless insects;

Figure 3 - Earthworm

geophiles - animals, part of the development cycle of which (more often one of the phases) necessarily takes place in the soil. Most insects belong to this group: locusts, a number of beetles, centipede mosquitoes (Figure 4). Their larvae develop in the soil. In adulthood, these are typical terrestrial inhabitants;

Figure 4 - Mosquito centipede

3 geoxenes - animals that occasionally visit the soil for temporary shelter or shelter. Insect geoxenes include cockroaches, many hemipterans, and some beetles that develop outside the soil. This also includes rodents and other mammals living in burrows (Figure 5).

Figure 5 - Mole

Soil inhabitants, depending on their size and degree of mobility, can be divided into several groups:

A) microbiotype, microbiota - these are soil microorganisms that make up the main link in the detrital food chain, they are, as it were, an intermediate link between plant residues and soil animals. These include, first of all, green ( Chlorophyta) and blue-green ( Cyanophyta) algae, bacteria ( bacteria), mushrooms ( Fungi) and the simplest ( Protozoa). In essence, we can say that these are aquatic organisms, and the soil for them is a system of micro-reservoirs. They live in soil pores filled with gravitational or capillary water, like microorganisms, part of their life can be in an adsorbed state on the surface of particles in thin layers of film moisture. Many of these species live in ordinary water bodies. At the same time, soil forms are usually smaller than freshwater ones and, in addition, they are distinguished by the ability to remain in an encysted state for a considerable time, waiting out unfavorable periods. So, freshwater amoeba have a size of 50-100 microns, soil - 10-15 microns. Flagella do not exceed 2-5 microns. Soil ciliates are also small in size and can largely change the shape of the body.

For this group of animals, the soil is presented as a system of small caves. They do not have special tools for digging. They crawl along the walls of soil cavities with the help of limbs or wriggling like a worm. Soil air saturated with water vapor allows them to breathe through the integument of the body. Many animal species in this group do not have a tracheal system and are very sensitive to desiccation. The means of salvation from fluctuations in air humidity for them is to move deeper. Larger animals have some adaptations that allow them to tolerate a temporary decrease in soil air humidity: protective scales on the body, partial impermeability of the covers, and a solid thick shell. Animals experience periods of soil flooding with water, as a rule, in air bubbles. The air lingers around their body due to the non-wetting of the integuments, which in most of them are equipped with hairs and scales. An air bubble serves as a kind of "physical gill" for a small animal. Breathing is carried out due to oxygen diffusing into the air layer from the environment.

Animals of mesobiotypes and microbiotypes are able to tolerate winter freezing of the soil, which is especially important, since most of them cannot go down from layers exposed to negative temperatures.

C) macrobiotype, macrobiota - these are large soil animals, with body sizes from 2 to 20 mm. This group includes insect larvae, centipedes, enchytreids, earthworms. The soil for them is a dense medium that provides significant mechanical resistance during movement. They move in the soil, expanding natural wells by moving apart soil particles or digging new passages. Both modes of movement leave an imprint on the external structure of animals. Many species have developed adaptations to an ecologically more beneficial type of movement in the soil - digging with clogging the passage behind them.

Gas exchange of most species of this group is carried out with the help of specialized respiratory organs, but along with this, it is supplemented by gas exchange through the integuments. In earthworms and enchitreids, only cutaneous respiration is noted.

Burrowing animals can leave layers where unfavorable conditions arise. By winter and during drought, they are concentrated in deeper layers, mostly a few tens of centimeters from the surface.

D) megabiotype, megabiota - these are large excavations, mainly from among mammals.

Many of them spend their whole lives in the soil (gold moles in Africa, mole voles, zokors, moles of Eurasia, marsupial moles of Australia, mole rats). They make whole systems of passages and holes in the soil. Adaptability to a burrowing underground lifestyle is reflected in the appearance and anatomical features of these animals: they have underdeveloped eyes, a compact valky body with a short neck, short thick fur, strong compact limbs with strong claws.

Depending on the type of substrate (environment), the following groups of animals are distinguished:

psammophiles - animals that inhabit free-flowing mobile sands. Typical psammophiles include marble beetles (Figure 6), larvae of ant lions and horses, a large number of hymenoptera. Soil animals living in moving sands have specific adaptations that provide them with movement in loose soil;

Figure 6 - Marble Khrushch

2 halophiles - animals adapted to life on saline soils. Usually, in saline soils, the fauna is greatly depleted in quantitative and qualitative terms. For example, the larvae of click beetles and beetles disappear, and at the same time specific halophiles appear, which are not found in soils of normal salinity. Among them, one can note the larvae of some desert dark beetles (Figure 7);

Figure 7 - Dark beetle

inhabitants of holes - animals permanent inhabitants of the soil. This group of animals includes badgers, marmots, ground squirrels, jerboas (Figure 8).

Figure 8 - Gopher

They feed on the surface, but they breed, hibernate, rest, and escape from danger in the soil. A number of other animals use their burrows, finding in them a favorable microclimate and shelter from enemies. The inhabitants of holes, or norniki, have structural features characteristic of terrestrial animals, but at the same time they have a number of adaptations associated with a burrowing lifestyle. So, for badgers, characteristic features are long claws and strong muscles on the forelimbs, a narrow head, and small auricles.

.2 Relationship of plants to soil

Specific plant associations are formed in connection with the diversity of habitat conditions, including soil conditions, as well as in connection with the selectivity of plants in relation to them in a certain landscape-geographical zone. It should be borne in mind that even in one zone, depending on its topography, groundwater level, slope exposure, and a number of other factors, unequal soil conditions are created that affect the type of vegetation.

The most important property of the soil is its fertility, which is determined primarily by the content of humus, macro- and microelements (nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, copper, boron, zinc, molybdenum). Each of these elements plays a role in the structure and metabolism of the plant and cannot be completely replaced by another.

Classification of plants in relation to soil fertility:

eutrophic (eutrophic), distributed mainly on fertile soils;

mesotrophic species, intermediate group;

oligotrophic, content with a small amount of nutrients.

There is another classification of plants in relation to the chemical composition of soils:

nitrophils are plants that are especially demanding on the increased content of nitrogen in the soil. Usually they settle where there are additional sources of organic waste, and, consequently, nitrogen nutrition. These are clearing plants (raspberries, climbing hops) (Figure 9), garbage, or species that are companions of human habitation (nettle, amaranth). Nitrophils include many umbrella plants that settle on the edges of the forest. In the mass, nitrophils settle where the soil is constantly enriched with nitrogen, for example, through animal excrement. On pastures, in places where manure accumulates, nitrophilous grasses (nettle, amaranth) grow in spots;

Figure 9 - Curly Hops

2calciumphiles -plants of carbonate soils containing more than 3% carbonates. Calcium is the most important element, not only one of the plants necessary for mineral nutrition, but also an important constituent of the soil. Of the trees, Siberian larch, beech, ash are calciphilous (Figure 10);

Figure 10 - Ash

calcium phobes - plants that avoid soils with a high content of lime. These are sphagnum mosses, marsh heather. Among tree species - warty birch, chestnut (Figure 11);

Figure 11 - Chestnut

Plants react differently to soil acidity. The following types of plants are distinguished in relation to soil acidity:

acidophiles - plants that prefer acidic soils with a low pH value = 3.5-4.5 (heather, white-bearded, small sorrel) (Figure 12);

Figure 12 - Heather

basiphylls - plants of alkaline soils with pH = 7.0-7.5 (coltsfoot, field mustard) (Figure 13);

Figure 13 - Mother and stepmother

neutrophils - soil plants with a neutral reaction (meadow foxtail, meadow fescue) (Figure 14).

Figure 14 - Meadow fescue

Classification of plants depending on the type of environment:

halophytes - Plants that have adapted to growing on soils with a high salt content are called . Halophytes have a high osmotic pressure, which allows them to use soil solutions, since the sucking power of the roots exceeds the sucking power of the soil solution. Some halophytes excrete excess salts through their leaves or accumulate them in their bodies. Therefore, sometimes they are used to produce soda and potash. Typical halophytes are European soleros, knobby sarsazan (Figure 15);

Figure 15 - European soleros

2 glycophytes - plants that do not tolerate soil salinity;

psammophytes - plants adapted to loose moving sands. Loose sand plants in all climatic zones have common features of morphology and biology; they have historically developed peculiar adaptations. Thus, tree and shrub psammophytes, when covered with sand, form adventitious roots. Adventitious buds and shoots develop on the roots if the plants are exposed when blowing sand (white saxaul, kandym, sand locust and other typical desert plants) (Figure 16). Some psammophytes are saved from sand drift by the rapid growth of shoots, the reduction of leaves, the volatility and springiness of fruits are often increased. The fruits move along with the moving sand and are not covered by it. Psammophytes easily tolerate drought due to various adaptations: root covers, root corking, strong development of lateral roots. Most psammophytes are leafless or have distinct xeromorphic foliage. This significantly reduces the transpiration surface;

Figure 16 - Kandym

oxylophytes - plants growing in peat bogs (ledum, sundew) (Figure 17). Peat is a special kind of soil substrate formed as a result of incomplete decay of plant residues in conditions of high humidity and difficult air access;

Figure 17 - Ledum

lithophytes - plants that live on stones, rocks, scree, in the life of which the physical properties of the substrate play a predominant role. This group includes, first of all, the first settlers after microorganisms on rocky surfaces and collapsing rocks: autotrophic algae, leaf lichens, which secrete metabolic products that contribute to the destruction of rocks and thus play a significant role in the long process of soil formation (Figure 18);

Figure 18 - Leaf lichen

chasmophytes - slit plants. Chasmophytes are species of the genus saxifrage, shrubs and tree species (juniper, pine) (Figure 19). They have a peculiar form of growth (curved, creeping, dwarf).

Figure 19 - Juniper

4. The role of microorganisms, higher plants and animals in soil-forming processes

4.1 The role of green plants in soil formation

The main importance in soil formation belongs to green plants, especially higher ones. First of all, their role is that the formation of organic matter is associated with photosynthesis, which is carried out only in the green leaf of the plant. Absorbing air carbon dioxide, water, nitrogen and ash substances from the rock (subsequently turning into soil), green plants, using the radiant energy of the sun, synthesize a variety of organic compounds.

After the plants die, the organic matter created by them enters the soil and thereby annually supplies it with elements of ash and nitrogen food and energy. The amount of accumulated solar energy in the synthesized organic matter is very large and is approximately 9.33 kcal per 1 g of carbon. With an annual fall of plant residues from 1 to 21 tons per 1 ha (corresponding to 0.5-10.5 tons of carbon), about 4.7-106 - 9.8-107 kcal of solar energy is concentrated in them. This is truly a huge amount of energy that is used in the course of soil formation.

Different types of green plants - woody and herbaceous - differ in the quantity and quality of the biomass they create and the amount of its entry into the soil.

In woody plants, only a part of the organic mass formed during the summer (needles, foliage, branches, fruits) dies off annually, and the soil is enriched with organic matter mainly from the surface. The other part, often more significant, remains in a living plant, being the material for thickening the stem, branches and roots.

In herbaceous annual plants, the vegetative organs exist for one year and the plant dies off annually, with the exception of ripened seeds; perennial herbaceous plants have underground shoots with tillering nodes, rhizomes, etc., from which a new above-ground part of the plant with a new root system develops the next year. Therefore, herbaceous vegetation brings organic matter into the soil in the form of annually dying aerial parts and roots. Mosses, which do not have a root system, enrich the soil with organic matter from the surface.

The nature of the input of plant residues into the soil determines the further course of the transformation of organic compounds, their interaction with the mineral part of the soil, which affects the formation of the soil profile, the composition and properties of the soil.

The greatest accumulation of organic matter occurs in forest communities. So, in the spruce forests of the northern and southern taiga, the total biomass is 100-330 tons per 1 ha, in pine forests - 280, in oak forests - 400 tons per 1 ha. An even greater mass of organic matter is formed in subtropical and humid evergreen tropical forests - more than 400 tons per 1 ha.

Herbaceous vegetation is characterized by significantly lower productivity. Northern meadow steppes increase biomass up to 25 tons per 1 ha, in dry steppes it is 10 tons, and in semi-shrub desert steppes this value decreases to 4.3 tons.

In the arctic tundra, the biomass is at the level of desert communities, while in the shrub tundra it reaches the level of meadow steppes.

The size of the organic mass entering the soil is determined by the type of vegetation and the annual amount of litter, which depends on the growth and ratio of the above-ground mass and roots. So, in a spruce forest, the average annual plant litter is 3.5-5.5 tons per 1 ha, in a pine forest - 4.7, in a birch forest - 7.0, in an oak forest - 6.5 tons per 1 ha.

In subtropical and tropical forests, the annual litter is very large - 21-25 tons per 1 ha.

In meadow steppes, the annual litter is 13.7 tons per 1 ha, in dry steppes - 4.2 tons, in desert, semi-shrub steppes - 1.2 tons. on the root systems of grasses. This, to a certain extent, explains the large supply of humus in the soil under grassy vegetation.

The great role of green plants in soil formation lies in the fact that their vital activity determines one of the most important processes - biological migration and the concentration of ash elements and nitrogen in the soil, and together with microorganisms - the biological cycle of substances in nature.

Under the forests of the temperate zone, the consumption and annual return with litter of the sum of ash elements and nitrogen are 118-380 and 100-350 kg per 1 ha, respectively. At the same time, birch and oak forests create a more intensive circulation of substances than pine and spruce forests. Therefore, the soils formed under them will be more fertile.

Under meadow herbaceous associations, the amount of ash elements and nitrogen involved in the biological cycle is much greater than in various types of temperate forests, and the consumption and return of substances with litter to the soil are balanced and amount to about 682 kg per 1 ha. Naturally, the soils under the meadow steppes are more fertile than those under the forests.

The processes of decomposition of organic residues are greatly influenced by their chemical composition.

Organic residues consist of a variety of ash elements, carbohydrates, proteins, lignin, resins, tannins and other compounds, and their content in the litter of different plants is not the same. All parts of most tree species are rich in tannins and resins, contain a lot of lignin, little ash elements and proteins. Therefore, the remains of woody plants decompose slowly and mainly by fungi. Unlike trees, herbaceous vegetation, with a few exceptions, does not contain tannins, it is richer in protein substances and ash elements, due to which the remains of this vegetation are easily subjected to bacterial decomposition in the soil.

In addition, there are other differences between these groups of plants. So, all woody plants lay dead leaves, needles, branches, shoots during the year, mainly on the soil surface. Trees leave a relatively small part of dead organic matter in the soil layer during the year, since their root system is perennial.

Herbaceous plants, on the other hand, in which all aboveground vegetative organs and partially roots die off annually, deposit dead organic matter both on the soil surface and at various depths.

Herbaceous vegetation is divided into three groups: meadow, steppe and marsh.

In meadow plants - meadow timothy grass, hedgehogs, bluegrass, fescue, foxtail, various clovers and other perennial grasses - the above-ground mass dies off annually at the beginning of winter with the onset of persistent frosts.

The steppe vegetation dies off mostly in summer because of the physical dryness of the soil. By this time, the steppe flora usually completes its development cycle and produces viable seeds. Plant residues fall into conditions of insufficient soil moisture, i.e. into conditions opposite to those in which the organic mass of meadow vegetation finds itself at the time of death. In late autumn, by the beginning of the death of meadow vegetation, all the gaps in the soil, as a rule, are filled with water, and in connection with this, the access of air to the soil is completely stopped. Meadow plants also find themselves in similar conditions in the spring, when the soil thaws, while the amount of water in the soil reaches a maximum, and the amount of air reaches a minimum. The decomposition of plant residues, therefore, goes without access to air, slowly, which leads to the accumulation of organic matter in the soil.

Even more slowly, the remnants of marsh vegetation decompose, experiencing constant excess moisture.

But no matter how individual groups of green plants differ from each other in one way or another, their main significance in soil formation comes down to the synthesis of organic matter from mineral compounds. Organic matter, which plays an important role in soil fertility, can only be created by green plants.

.2 Role of microorganisms in soil formation

Along with green plants, microorganisms play an important role in the soil-forming process. These are predominantly unicellular, chlorophyll-free organisms that are not capable of direct assimilation of solar energy and in the vast majority draw the energy they need by decomposing ready-made organic substances created by higher green plants.

Thus, the activity of microorganisms is opposite to the activity of green plants: while green plants synthesize organic matter from mineral compounds, water and carbon dioxide, lower organisms decompose this organic matter into its constituent parts, using the energy released in the process for their life activity.

Microorganisms are ubiquitous in nature. They are found in soil and air, on high mountains and bare rocks, in the desert and in the depths of the Arctic Ocean.

The development of microorganisms in the soil is closely related to organic matter: the richer the soil in plant residues, the more microorganisms it contains. Cultural, well-cultivated and manure-fertilized soils are especially rich in them.

1 g of soddy-podzolic soils contains 300-400 million bacteria; chestnut soils - 1-1.5 billion; chernozems, very rich in organic matter - 2-3 billion. Despite the negligible size of microorganisms, their total weight in the soil often reaches 1-3 tons per 1 ha.

Microorganisms are unevenly distributed in the soil layer. The upper layers of the soil are the richest in them within the range of approximately 30-40 cm, with depth the number of microorganisms gradually decreases.

The root system of plants has a great influence on the distribution of microflora in the soil. It constantly releases various kinds of organic and mineral compounds into the environment, which serve as a good source of nutrition for microorganisms. In the root zone of plants, the most favorable water and air regimes for microorganisms are usually created. This root zone is called the rhizosphere. In it, the number of microorganisms is hundreds, and sometimes thousands of times greater than outside the root zone. Microorganisms cover the root system of plants in an almost continuous layer. The abundance of microflora in the rhizosphere and in the entire soil layer plays an important role in the development of soil fertility.

Microorganisms include bacteria, which are divided into:

autotrophic bacteria, they absorb carbon from carbon dioxide, using the energy of oxidation of certain mineral compounds (chemoautotrophs);

heterotrophic bacteria, they use the energy of the sun, carrying out photosynthesis (photoautotrophs).

Nitrogen-containing organic compounds as a result of the process ammonificationunder the influence of decomposition by bacteria form ammonia. It can be partially absorbed by the soil, being converted into nitrates or into molecular nitrogen. In progress nitrificationammonia is initially converted to nitrous acid, and later to nitric acid. Nitric acid combines with bases in the soil to form nitrates, which are used by plants as nitrogen food.

Nitrogen-fixing bacteria are of great importance in improving soil fertility. They are divided into:

free-living bacteria that are involved in the decomposition of organic matter to mineral;

nodule bacteria that inhabit the cells on the roots of leguminous plants (clover, beans), as a result of which microbiological accumulation of nitrogen from the atmosphere occurs;

heterotrophic bacteria that absorb carbon from ready-made organic compounds, decomposing complex compounds into simple ones. In connection with their activity, dead organic matter is destroyed with the formation of mineral substances (reducers). As a result of biochemical transformations, nitrogen contained in the proteins of organic substances, under the influence of heterotrophic bacteria, becomes available for absorption by plants.

Microorganisms that decompose organic residues in the soil are divided into three main groups: aerobic bacteria, anaerobic bacteria and fungi.

Aerobic bacteria can live and multiply only with free access to air. Insufficient air supply has a depressing effect on the vital activity of these bacteria, and a complete cessation of air access causes death.

Anaerobic bacteria develop in the absence of free oxygen. Anaerobes are divided into:

a) obligate anaerobes (lat. obligatus - obligatory, indispensable), which can live only in the complete absence of oxygen;

c) facultative anaerobes (pfacultatif - possible, optional), capable of living both in the absence of oxygen and in the presence of it.

For respiration, anaerobic bacteria use oxygen from various oxidized compounds, while performing recovery work. Therefore, recovery processes are very characteristic of anaerobic soil conditions.

In loose, well-ventilated soils, the aerobic process of decomposition of organic matter always predominates. On the contrary, in compacted, heavy or waterlogged soils, with a continuous occurrence of organic matter, anaerobic processes will inevitably dominate. In the upper layers of the soil, where air freely penetrates, mainly aerobic processes take place, in the lower layers with difficult gas exchange - anaerobic ones. Moreover, in each individual, more or less compacted, lump of soil, both processes can occur simultaneously: anaerobic inside the lump, aerobic in the surface parts.

The aerobic process is accompanied by the release of thermal energy, the anaerobic process proceeds without a noticeable increase in temperature.

Favorable conditions for cultivated plants can be created in the soil only with the simultaneous development of aerobic and anaerobic processes, which is possible only in loose soils with good aeration.

4.3 Algae and lichens in the soil-forming process

Among the soil microflora, algae occupy a significant place (Table 1). Most often, flagella, green, blue-green and diatoms are found in the soil. Algae are actively involved in the processes of weathering of rocks and minerals, such as kaolinite, decomposing this mineral into free silicon and aluminum oxides. Being organisms containing chlorophyll, they are capable of photosynthesis and therefore enrich the soil layer with some amount of organic matter.

It should also be noted that lichens, complex symbiotic organisms consisting of fungi and algae, participate in the soil-forming process. Lichens are able to grow directly on rocks and rocks, so they are usually the pioneers of plant life on exposed rock surfaces. Most lichens penetrate into the rock mass with the help of fungal hyphae and cause active destruction of all rocks that come to the surface.

Quantity of algae in some soils (in 1 g of soil)

SoilCyanobacteriaGreenDiatomsTotal Podzolic0-2.03.0-25.02.0-7.55.0-30.0Sod-podzolic2.0-24.010.0-128.010.0-76.012.0-220.0Chernozems5.0-50.010.0- 85.08.0-35.025.0-120.0 Dark chestnut 660.0-2000.06.0-35.086.0-116.0800.0-2160.0 Brown dry steppe 43.037.015.096.0

4.4 Fungal microflora in soils

Along with bacteria, fungi play an important part in soil-forming processes. Fungal microflora in soils is very diverse and is represented by a large number of species.

Many species of fungi are able to form mycorrhiza on the roots of green plants (Greek mykes - mushroom, rhiza - root), causing a special mycotrophic (Greek mykes - mushroom, trophe - food) type of root nutrition of plants. Mycorrhizacalled the cohabitation of many plants with special soil fungi, called mycorrhizal. Mycorrhizal fungi are the most widespread among woody plants. Each type of plant is characterized by a specific type of fungus.

All mushroom microflora is very demanding on oxygen, therefore, the surface layers of the soil are the most rich in fungi. The processes of decomposition of cellulose, fats, lignin, proteins and other organic compounds are associated with the vital activity of fungi in the soil.

Actinomycetes also play a significant role in the decomposition of organic matter. Actinomycetes, or radiant fungi, are a transitional form between bacteria and fungi.

Colonies of actinomycetes are often pigmented and colored in pink, red, greenish, brown and black colors. All actinomycetes are typical aerobes and develop best with free access to air. They actively decompose without nitrogenous and nitrogenous organic substances, including the most persistent compounds that make up humus.

4.5 The role of animals in soil formation

soil animalsparticipate in the transformation of organic matter (Figure 20). This process occurs in the system of food relations, in the system of producers - consumers (I-II orders) - decomposers.

From soil animals it is necessary to note earthworms. They are widely distributed in nature and are part of biocenoses of different natural zones. More than 80 species of these animals have been recorded on the territory of Russia and neighboring countries. On non-acidic meadow and forest soils, they contain up to 1 million individuals per 1 ha, and they can make up to 90% or more of the soil zoomass. Sufficiently moist soils are favorable for them, but without stagnant water, salinization and high acidity, therefore there are many earthworms in the soils of broad-leaved forests (up to 500 per 1 m²) and meadow steppes (over 100 per 1 m²). Here, in the period from 30 to 200 years, they completely process a 20-cm layer of soil. One worm per year accounts for up to 400 g of ingested mixture of organic residues and mineral particles. They not only recycle litter, but also have a significant direct and indirect effect on all soil components. Penetrating the soil with passages, improving its aeration, water permeability and moisture capacity, earthworms create favorable conditions for the development of both plants and various soil organisms involved in the decomposition of organic matter. Feeding on dead plant organs and animal excrement, earthworms also ingest many bacteria, fungi, protozoa and nematodes. Participating in the decomposition of livestock excrement on pastures, they partially transfer them to the depth of the soil, enriching these layers. The walls of their passages are impregnated with secretions of worms containing ammonia and urea; so that the total amount of nitrogen introduced into the soil ranges from 18 to 150 kg/ha. And secreted by earthworms caprolitesare quite moisture resistant aggregates that contribute to the creation of a cloddy soil structure. All this improves the living conditions of plants, which has been repeatedly proven by many experiments.

In arid regions, the activity of ants and termites is manifested. Annually, termites bring up to 109 kg/ha of soil mass to the surface. Burrowing animals help to mix the soil and create a favorable water-air regime. Big and different digging (marmots, ground squirrels, moles, voles) have a figurative effect on the soil. They change the microrelief, increase the area of ​​contact of the soil with air, contribute to the penetration of precipitation into it, and improve the conditions for the mineralization of organic matter. All this has a positive effect on plants, breaking through the soil, excavators carry out a substrate that differs in properties from the depth to the surface.

Figure 20 - Soil organisms

5. Significance of edaphic factors in the distribution of animals and plants

Specific plant associations are formed in connection with the diversity of habitat conditions, including soil, as well as in connection with the selectivity of plants in relation to them in a certain landscape-geographical zone. It should be borne in mind that even in one zone, depending on its topography, groundwater level, slope exposure, and a number of other factors, unequal soil conditions are created that affect the type of vegetation. So, in the feather-grass-fescue steppe, you can always find areas where feather grass dominates or, conversely, fescue. That is why soil types are a powerful factor in the distribution of plants.

Terrestrial animals are less affected by edaphic factors. At the same time, animals are closely related to vegetation, and it plays a decisive role in their distribution. However, even among large vertebrates it is easy to find forms that are adapted to specific soils. This is especially characteristic of the fauna of clay soils with a hard surface, free-flowing sands, waterlogged soils and peat bogs. In close connection with soil conditions are burrowing forms of animals. Some of them are adapted to denser soils, others can only tear through light sandy soils. Typical soil animals are also adapted to different types of soils. For example, in Central Europe, up to 20 beetles have been noted, which are distributed only on saline or alkaline soils. And at the same time, soil animals often have very wide ranges and are found in different soils. The earthworm reaches a high abundance in tundra and taiga soils, in the soils of mixed forests and meadows, and even in the mountains. This is due to the fact that in the distribution of soil inhabitants, in addition to the properties of the soil, their evolutionary level and body size are of great importance. Tendencies towards cosmopolitanism are clearly expressed in small forms: bacteria, fungi, protozoa, microartopods (ticks), and soil nematodes.

For a number of ecological features, the soil is an intermediate medium between terrestrial and aquatic. The presence of soil air, the threat of desiccation in the upper horizons, and rather sharp changes in the temperature regime of the surface layers bring the soil closer to the air environment.

The soil is brought closer to the aquatic environment by its temperature regime, the reduced oxygen content in the soil air, its saturation with water vapor and the presence of water in other forms, the presence of salts and organic substances in soil solutions, and the ability to move in three dimensions. As in water, chemical interdependencies and mutual influence of organisms are highly developed in soil.

The intermediate ecological properties of the soil as a habitat for animals make it possible to conclude that the soil played a special role in the evolution of the animal world. For example, for many groups of arthropods, in the process of historical development, the soil was the medium through which typically aquatic organisms could move to a terrestrial lifestyle and populate the land.

Conclusion

Soil is a stable habitat in which temperature and moisture always change smoothly. The soil is saturated with organisms, the number of which is huge, due to the physical and chemical properties, mechanical composition. Plants, animals, microorganisms living in the soil are in constant interaction with each other and with the environment. Therefore, for organisms, a slight movement is enough to find favorable living conditions. The complexity of the soil environment creates a wide variety of conditions for a wide variety of organisms. The soil is saturated with various nutrients that are necessary for the development of plants and animals. It is an indispensable link between the terrestrial and aquatic environment. The biological relationship between soil and man is carried out mainly through metabolism. The soil is, as it were, a supplier of minerals necessary for the metabolic cycle, for the growth of plants consumed by humans and herbivores, eaten in turn by humans and carnivores. Thus, the soil provides food for many representatives of the plant and animal world.

The main function of the soil is to provide life on Earth. This is determined by the fact that it is in the soil that the biogenic elements necessary for organisms are concentrated in the forms of chemical compounds available to them. In addition, the soil has the ability to accumulate the water reserves necessary for the life of the producers of biogeocenoses, also in a form accessible to them, evenly providing them with water throughout the entire growing season. Finally, the soil serves as an optimal environment for the rooting of terrestrial plants, the habitat of terrestrial invertebrates and vertebrates, and various microorganisms.

List of sources used

1 Edaphic factors and their role in the life of plants and soil biota [Electronic resource]. Access mode: http://yandex.by.ru Access date - 08.02.2013

Shamileva, I.A. Ecology / I.A. Shamilev. - M., 2004. - 144 p.

Rassashko, I.F. General ecology: texts of lectures / I.F. Rassashko, O.V. Kovaleva, A.V. Crook. - Gomel, 2010. - 252 p.

Stepanovskikh, A.S. General ecology / A.S. Stepanovsky. - M.: UNITI-DANA, 2002. - 510 p.

Korobkin, V.I. Ecology / V.I. Korobkin, L.V. Peredelsky. - Rostov-n / D .: Phoenix, 2010. - 602 p.

Edaphic factors and their role in the life of plants and soil biota [Electronic resource]. Access mode: http://ychebalegko.ru. Access date - 08.02.2013

Edaphic factors and their role in the life of plants and soil biota [Electronic resource]. Access mode: http://ecology-online.ru. Access date - 08.02.2013

Edaphic factors and their role in the life of plants and soil biota

Stepanovskikh, A.S. Ecology: a textbook for universities / A.S. Stepanovsky. - M.: UNITI-DANA, 2001. - 703 p.

Edaphic factors and their role in the life of plants and soil biota [Electronic resource]. Access mode: http://greenfuture.ru. Access date - 08.02.2013

Edaphic factors and their role in the life of plants and soil biota [Electronic resource]. Access mode: http://botcad.ru. Access date - 08.02.2013

Meshechko, E.N. Physical geography / E.N. Meshechko, V.P. Shpetny; ed. E.N. Pouch. - Minsk, 2012. - 416 p.

Soil science with the basics of geology: textbook / ed. A.I. Gorbylev. - Minsk, 2002. - 106 p.

Tutoring

Need help learning a topic?

Our experts will advise or provide tutoring services on topics of interest to you.
Submit an application indicating the topic right now to find out about the possibility of obtaining a consultation.