Among the priority areas for the use of plant resources is the problem of introducing new species and ecotypes of plants into culture. And although the processes of natural and artificial selection are interconnected, the latter has a number of features. It is known, for example, that in natural flora the yield index does not play a leading role in selection. Meanwhile, in natural populations there is genotypic variability for this trait, the significance of which for cultivated plants is obvious. Thus, according to Primack, when studying populations of 15 annual and perennial Plantago species, annual species showed higher rates of “reproductive effort” (number of capsules and seeds, seed mass per unit of leaf area) compared to perennial ones. Moreover, in spring annual species they turned out to be greater than in summer ones. There is reason to believe that many of the species and ecotypes selected by humans had high rates of “reproductive effort,” and the level of genotypic variability for this trait had a decisive influence on the effectiveness of targeted selection.
In most cases, the extremely high ecological plasticity of plant species is combined with their very low productivity. Thus, many wild species have a strategy for adapting to unfavorable conditions external environment is based on the low speed of growth processes. It is no coincidence, notes Stuart, that even when wild plant species consume excess nutrients, their growth rate remains unchanged. Among the huge variety of plant species, there are also those whose growth rate is almost unaffected by certain environmental factors. Examples include some types of tundra vegetation, the growth rate of which does not depend on temperature; Plantago coronopus responds only slightly to soil nutrient content; the growth rate of Carex limosa is not affected by changes in K+ concentration in a 100-fold range, etc. Obviously, people preferred those plant species that had a positive growth response to optimization of environmental conditions (plowing, high soil fertility, irrigation, etc.). d.). The leading role was played not only by the features of ontogenetic adaptation of wild species, but also by the potential of their genotypic variability.
The above-mentioned nature of the relationship between the high ecological plasticity of plants and their low productivity deserves special attention. It is possible that it was precisely this feature of the adaptive capabilities of plants that served as the basis for posing the question: “adaptation or maximum yield?”, which is legitimate, however, only for ontogenetic adaptation, since without realizing the potential of phylogenetic adaptation, i.e. spectrum of genotypic variability, an increase in plant productivity is unthinkable. Moreover, this opposition makes sense only in relation to the general and broad adaptation of plants, while specific and narrow adaptations are an indispensable condition for increasing productivity for most cultivated plant species.
The high degree of genetic and morphophysiological integration of the general ecological stability of each plant species in most cases negates the attempts of breeders through hybridization (including interspecific) to achieve the ecological stability of varieties characteristic of other species. The task of combining high potential productivity and environmental sustainability in one variety (and even a hybrid) is no less difficult. Varieties with high potential productivity and low environmental sustainability provide high yields only under favorable environmental conditions, while they sharply reduce them under stressful conditions. Therefore, in breeding practice, especially when using wild species as donors, methods of induced recombinogenesis, reducing the eliminating effect of “breeding sieves” due to gametic and zygotic selection, and using the capabilities of the ecological-geographical breeding and variety testing network are of paramount importance. An important role is given to methods for creating F1 hybrids, mixed, synthetic and multiline varieties.
In general, there are very different points of view regarding the possibilities of combining high potential productivity and environmental sustainability in one genotype. Thus, according to Adamer, increasing the value of some components of yield through selection usually reduces the value of others. And yet, the difficulties of breeding a combination of potential productivity and environmental sustainability, even at the interspecific level, should not be exaggerated, much less absolutized. As is known, the possibility of solving this problem was demonstrated in the works of I.V. Michurina, L. Burbank, N.V. Tsitsin and other researchers. Data on the independent segregation of traits that determine the potential productivity and environmental stability of plants, known since the 1930s, are currently supported by a sufficient number of data on a certain physiological, biochemical and genetic independence of the main components of the ontogenetic adaptation potential of plants. Many traits characterizing plant resistance to water stress (strong root system, waxy coating, spatial orientation of leaves, their pubescence, etc.), as a rule, are not negatively correlated with potential and biological productivity or their components. Moreover, for example, the large branching of the root system and the depth of its penetration provide not only high (and active) resistance of plants to drought, but also the possibility of better use of mineral nutrition elements, thus determining the greater potential and biological productivity of the cultivated species. A typical example in this regard is alfalfa.
The fact that potential productivity and environmental sustainability are controlled by different sets of genes indicates the real possibility of combining them in one variety or hybrid. Coyne provides information on the components of bean yield (number of beans per plant, number of seeds per bean and average seed weight), which have almost the same effect on overall seed yield and are controlled by different genetic systems. Therefore, the most effective for this crop was not individual, but mass selection for yield in later splitting generations.
The combination of high potential productivity and environmental sustainability in one F1 variety or hybrid requires the use of not only special selection methods (interspecific hybridization, induction of recombination, etc.), but also the selection of special backgrounds for assessing the productive yield of initial forms and promising lines. According to Johnson and Frey, Vela-Cardenas and Frey, Allen et al., environmental and genetic variations in plant productivity are higher in environmental conditions favorable for their growth. Moreover, if in an optimal environment the heritability of yield and its components (and the advantage of corresponding selections) is high, then in unfavorable conditions it is extremely low, and the effectiveness of selection sharply decreases. Therefore, selection for high productive yields, provided incl. and due to greater environmental sustainability, it is better to conduct it in a supportive rather than a stressful environment. In practical terms, this means that it is advisable to evaluate the environmental stability of varieties and hybrids under appropriate stress conditions only after their high potential yield under favorable environmental conditions has already been proven.
An effective approach in breeding, for example, for plant resistance to drought is the combined use of optimal and water-stressed environments. This approach is based on the assumption that potential productivity and drought tolerance are controlled by different genetic systems and can therefore be selected independently by breeding. In this regard, the author considers it advisable to carry out selection for drought resistance in an appropriate stress environment, and selection for high potential productivity - in conditions of optimal water availability. An example of independent inheritance of resistance to water stress is the cuticular layer, the greater thickness of which provides better drought resistance of plants and is not negatively correlated with yield or its components. By alternating selection under conditions of water stress (for better manifestation of a particular resistance trait) and optimal water availability (for maximum manifestation of potential yield or its components), it is possible to combine high potential productivity and resistance in one variety. A similar possibility is confirmed by our earlier information that differences between species and varieties in their ability to absorb, accumulate and use elements of mineral nutrition, as well as edaphic resistance, are determined by different gene complexes. For example, significant differences between varieties of tomato, beans, corn and other crops in terms of the efficiency of using N, P and K have been shown; high-yielding varieties of wheat, sorghum and rice have been created that are resistant to acidic and low-productive soils.
Lu, Chiu, Tsai et al., Oka, through sequential selection for high productivity in the offspring of soybean hybrids grown at different sowing dates (disruptive seasonal selection), obtained eurypotent varieties, i.e. capable of providing high yields in a wide range of changes in environmental conditions. Thus, the relationship between plant adaptability to seasonal and regional variability in environmental conditions and the effectiveness of the disruptive seasonal selection method in increasing the overall adaptability of soybean varieties were proven. Due to the fact that soybean, compared to other crops, is more sensitive to changes in day length and temperature, when growing different varieties in different environmental zones and/or in different years, it is necessary to take into account significant interactions in the genotype-environment system, masking genotypic variability . In order to increase the environmental sustainability of wheat, Borlaug made extensive use of the opportunities for greater ecological differentiation of the selected material due to different sowing dates and growing it at different altitudes above sea level.
Finlay and Wilkinson discovered barley genotypes that provide high tolerance in a wide range of environmental environments, and intensive rice varieties adapted to high rates of fertilizer and thickening that maintain tolerance to varying weather conditions at the level of landraces. It was shown that some high-yielding varieties selected under optimal environmental conditions retained an advantage in less favorable environmental conditions, and the yield amount was different environments and its stability turn out to be largely independent of each other.
In cross-pollinating forage crops, unlike self-pollinating wheat and rice, Suzuki was unable to find a combination of high potential productivity and resistance to environmental stressors in one variety, and highly productive varieties of forage crops, as a rule, showed a strong response to changing environmental conditions. The author explains this feature by the fact that the adaptability of cross-pollinating crops is determined not only by the fitness of individual plants (homeostasis individual development), but also by the heterogeneity of the genetic composition of the population (genetic or population homeostasis). Moreover, genetic homeostasis apparently has a more significant impact on ontogenetic adaptation, which contributes to better adaptability of cross-pollinating plants to natural environments than self-pollinating ones. In this regard, in our opinion, the possibility of more effective use genetic homeostasis to increase the potential productivity and environmental sustainability of cross- and self-pollinating crops by creating mixed species and varietal crops, as well as synthetic and multiline varieties.
F. hybrids play a particularly important role in increasing the potential productivity and environmental sustainability of cultivated plants. Not only their high potential productivity was noted, but also greater stability, as well as higher ecological homeostasis compared to the parental lines. And although Griffing and Zsiros rightly believe that environmental stress usually minimizes heterotic effects, there are often cases of greater resistance of F hybrids to environmental stress factors. It has been shown, for example, that the homeostasis of individual development of corn hybrids is due to their heterozygosity, and a significant part of the heterotic effect of hybrids of corn, wheat, barley, Phalaris tuberosa x P. arundinacea and other crops is associated with their increased resistance to temperature stress. According to Langridge's assumption, the latter is due to the greater stability of the F hybrid proteins. Let us recall that in general complex ecological stability of higher plants, tolerance to extreme temperatures is the most deficient property. In addition to resistance to temperature factors, F1 hybrids are characterized by higher overall adaptability. According to Quinby, “strong” sorghum hybrids, adapted to conditions of different latitudes and different altitudes above sea level, at the same time exhibit specific adaptation, incl. according to ripening time.
Thus, the basis of the advantages of F1 hybrids is the positive heterotic effect not of individual components, but of the entire system of ontogenetic adaptation. As a result, phenotypic variability in heterozygotes is usually less pronounced than in inbred lines. The latter are more susceptible to changes under the influence of external conditions, physiologically less able to compensate for the influence of unfavorable factors environment, while heterozygotes in this situation have a wider range of protective and compensatory reactions, greater morphogenetic plasticity and more effective developmental homeostasis.
Note that the widespread use of F1 hybrids is due not only to the phenomenon of “true heterosis”, but also to the possibility of quickly combining the most important economically valuable traits, including those between which there are negative genotypic and environmental correlations and which are usually not possible to combine during varietal selection . It is important to combine high potential productivity and environmental sustainability. In addition, by creating F1 hybrids, it is possible to overcome the difficulties associated with the use of valuable dominant genes linked to unfavorable recessive genes (for example, Tm-2 and nv in tomato), and to more short time provide a combination of valuable dominant genes, incl. controlling resistance to new races of pathogens.
Crop heterogeneity plays an important role in determining potential productivity and environmental sustainability. Literature data on this issue are very contradictory. Thus, in the experiments of Schnell and Becker, the heterogeneity of corn crops had the same effect on the stability of yield as heterozygosity, although their combination provided only a slight advantage compared to the effect of heterozygosity. However, along with the superiority of the mixture of genotypes noted by many researchers, incl. heterozygous over homogeneous crops, in a number of studies such advantages were not recorded.
Taking into account the practical difficulties of breeding changes in the idiotype of plants, indicators of evolutionarily determined environmental sustainability of cultivated species should be considered as a fundamental factor in determining the species structure of crop production in unfavorable soil and climatic zones and the priorities of crops in breeding work. In this regard Special attention should be given to increasing the productive yield of such plant species as sorghum, millet, rapeseed, rye, etc., which have high constitutive resistance to lack of moisture and/or heat, which most limit the size and quality of the harvest in many regions of our country. This approach is not only realistic, but also so far the most effective in solving the problem of increasing the resistance of intensive agrocenoses to weather fluctuations (droughts, hot winds, frosts, frosts, short growing seasons, etc.).
In increasing the potential productivity and environmental sustainability of varieties and agrocenoses, both general and specific fitness plays an important role, characterizing their ability to effectively use favorable environmental conditions and/or resist the effects of abiotic and biotic stressors. Moreover, as already noted, the overall potential productivity and environmental sustainability cannot be reduced to the sum of the corresponding specific adaptations, but are integrative properties of the plant and the agrocenosis as a whole. Besides, overall stability can be weakened or, conversely, strengthened due to one or another specific stability, and between different types the latter can have both positive and negative correlations.
This can be supported by data from Briggle and Vogel on high-yielding, widely adapted varieties of dwarf wheat from the Pacific Northwest that were unsuitable for cultivation in the arid conditions of the Great Plains, as well as information from Quisenberry and Roark on cotton varieties that efficiently use water at optimal levels. humid environment, but do not exhibit this ability under water stress. Select lines for wide adaptation, i.e. adaptability to a wide range of environmental environments, Reitz believes, means selecting for mediocre and even low yields. According to Matsuo, varieties with high potential productivity that provide high yields in favorable environmental conditions respond more strongly to changes in environmental conditions, sharply reducing yields in unfavorable conditions. According to Hurd, in varieties that have a well-developed root system in favorable environmental conditions, under conditions of water stress, its power is significantly reduced. Barley genotypes characterized by broad adaptation usually provide intermediate yields, while genotypes adapted to a specific environment are characterized by the highest productivity values. In general, the highest productive yield of an F1 variety or hybrid can be achieved with their specific adaptation to growing conditions. In cases where selection is aimed at maximizing one particular trait and ends after a number of generations have allowed the population to reach its own genetic equilibrium, the intensively selected trait very often loses some, and often a large part, of the phenotypic success (improvement) achieved during the previous period of intense selection. selection.
In the process of natural and artificial selection, which occurs over the entire phenotype of a plant, and not according to individual traits, their associated variability is inevitable. This situation is realized to the greatest extent and primarily for such yield components, which are usually complex and integrated in their genetic and physiological-biochemical nature, as potential productivity and environmental sustainability. That is why the problem of the relationship between potential productivity and environmental sustainability of varieties is gaining increasing theoretical and practical importance.

Exists three main components agricultural systems: climate, soil, microclimate.

Climate ( from Greek Yipa- tilt) - long-term weather regime, determined by the inclination of the earth's surface to the sun's rays. The nature of the kilimat in any area is influenced by the latitude and altitude of the area,

its proximity to a body of water (sea, river, lake, swamp, reservoir), relief, vegetation cover, presence of snow, ice, air pollution.

The soil is the surface layer of the earth formed as a result of destruction rocks and vital activity of living organisms (bacteria, fungi, worms, etc.).

Fertile soils provide plants with nutrients, water, and the root system with sufficient air and heat.

Soil fertility can be natural And acquired. Natural soil fertility depends on the content in it humus And

composition soil solutions.

Humus(from Latin. nitiz- earth, soil) is humus formed due to the decomposition of plant and animal residues by microorganisms. Humus has a dark color. The largest amount of it is in chernozem.

Soil solution is the moisture contained in the soil. Nutrients are dissolved in it. The richer the soil solution, the more fertile the soil.

Soil acidity is important for fertility. It can be determined using chemical analysis, special devices and vegetation cover.

By chemical composition soils are:

Strongly acidic Medium acidic Weakly acidic Close to neutral Neutral Slightly alkaline Alkaline

pH less than 4.5 pH 4.6 - 5.0 pH 5.1 - 5.5 pH 5.6 - 6.0 pH 6.1 - 7.0 pH 7.1 - 8.0 pH 8.1-9 .0

Agricultural plants prefer a soil solution environment that is close to neutral in acidity (acidic soils are neutralized by adding calcium and magnesium).

Soil acidity is determined by the composition of the vegetation cover:

Acidic soils - Whitebeard sticking out, small sorrel, Ivan da Marya, horsetail, common plantain, speedwell, speedwell, longleaf speedwell, red rosemary, field buttercup, pungent buttercup, mint on the left, popovnik, creeping buttercup. Slightly acidic - fragrant chamomile, creeping wheatgrass, clover meadow, and neutral soils - creeping clover, common thistle, field bindweed

Acquired soil fertility is achieved by processing it, applying fertilizers, irrigation, drainage, which is used in the formation of an agroecosystem, i.e. agricultural land.

Without proper care, the soil becomes depleted and gradually loses nutrients. It is destroyed by water and wind, and the number of soil-forming microorganisms and worms in it decreases. It becomes compacted, salinized, dried out, or, conversely, becomes waterlogged (swamped).

With proper use of the soil, its fertility is maintained and further increased.

Microclimate. The choice of agricultural use of land in a given area largely depends on the microclimate.

The microclimate is formed by: terrain;

Height of vegetation cover; proximity to bodies of water;

Thermal radiation from heating mains; location of factories and houses;

Smoke and gas pollution in the atmosphere, etc.

Terrain the different heating of the slopes, the characteristics and flows of thermal and cold air along the slopes and the distribution of speeds and winds are determined.

In early spring, rapid warming and drying of the soil begins on the southern slopes, while snow may still lie on the northern slopes.

Cold air accumulates in depressions of the relief - more frequent and significant frosts are observed there, dew, frost and fog settle abundantly.

The terrain has a great influence on the evaporation and humidity of soil and air. At higher elevations, evaporation is more intense, so the upper parts of the slopes are drier. The amount of soil moisture gradually increases towards the foot of the slopes.

On the peaks and on the windward slopes, the snow cover is much less than on the leeward side and in the depressions of the relief. The shape of the relief has a significant influence on the intensity

destruction of soil cover. Elevated areas, windward and southern slopes are most susceptible to destruction.

Vegetation height And proximity to bodies of water determine the humidity regime of the area.

Thermal radiation from highways And close proximity to factories and houses have a significant impact on the thermal regime of the ground layer of air and soils and adjacent areas.

Smoke And atmospheric pollution contribute to its warming.

Tasks:

1. Get acquainted with the concept of agrocenosis.
2. Reveal the ecological features of agrocenoses;
3. Ways to increase their productivity;
4. Ecological ways to increase their sustainability and biodiversity;
5. Foster a correct, caring attitude towards nature.

Equipment: support diagram; instructional cards, pictures of various agrocenoses, video film “Hurry to save the planet” textbook “Fundamentals of Ecology” Chernova N.M.

During the classes

I. Repetition of what has been covered:

II. Go to topic:

As a result of human activity, artificial biogeocenoses arose.

Russia is a country with developed agriculture. Agricultural lands (arable land, hayfields, pastures, gardens) occupy more than 40% of its territory; all of these are agrocenoses.

Agrocenoses are biocenoses that have arisen on agricultural lands. Give examples of agrocenoses.

III. Topic message:

Today in class we will learn: (referring to the plan written on the board).

On the desk:

Plan.

1. Basic ecological signs of agrocenosis.
2. Ways to increase the productivity of agrocenosis.

IV. Learning new things:

Independent work in groups.

I suggest you find out the main ecological signs of agrocenosis.

We work in groups.

To answer, use the text §18 p. 117 and the instruction card. Each group is offered an illustration (1 gr. - potato field; 2 gr. - apple orchard; 3 gr. - beet field;)

Questions from the instruction card:

1. What agrocenosis is depicted?
2. Name the species included in the agrocenosis?
3. Draw up 2 power supply circuit diagrams (not forgetting that a person can also be an obligatory link).
4. Draw a conclusion about the stability of the agrocenosis.?

V. Conclusion:

Based on what has been said, we will draw a conclusion.

I hang the support diagram on the board:

Agrocenoses arose as a result economic activity person.

1. They contain few species.
2. They are distinguished by short power circuits.
3. These are unstable systems. They consist of a small number of species. The instability of agrocenosis is caused by the fact that the protective mechanisms of cultivated plants are weaker than those of wild species.

VI. Ways to increase the productivity of agrocenosis.

Man constantly strives to increase the stability of the agrocenosis, increase productivity, i.e. reap a larger harvest of produce.

Think about how this is achieved? What does a person do to increase the yield?

(Students' answers).

So, a person spends additional energy: he applies fertilizers, cultivates the soil, waters, fights pests, rotates crops, i.e. applies crop rotations. Today in the lesson we will get acquainted with certain agricultural techniques for increasing the productivity of agrocenosis. Each group received homework. It was proposed to find out (tasks for groups):

1. Pesticides. Pros and cons of using pesticides. Biological method of control.
2. What does the use of mineral fertilizers lead to? Is there a way out?
3. Monocultures. Crop rotations.

Each group reports on the work done. A conclusion is drawn for each message.

VII. Conclusions:

1) One of the most modern trends V agriculture.: preservation species diversity. A person should strive to maintain diversity soil organisms responsible for soil-forming processes, maintain the cycle of substances through proper crop rotations and the introduction of organic fertilizers into the soil.

Question: Which agricultural methods are anti-ecological, i.e. harmful?

2) Many modern methods industrial agricultural production is anti-ecological, i.e. harmful.

These are: a) Monocultures.

b) Application of pesticides.

c) Large doses of mineral fertilizers.

This list goes on: overgrazing of livestock, improper plowing of fields, use of heavy equipment.

Why are they harmful? They contribute to the accumulation of toxic substances in soil, water, and the accumulation of poisons in plants and animals. Currently, people are increasingly aware of the harm of these methods and abandon them, moving to environmentally friendly agricultural practices and methods of increasing fertility.

VIII. I suggest watching the film and answering the question: what ecological agricultural methods are used to increase the productivity of agrocenoses?

Film screening. "Hurry up to save the planet."

Work in notebooks. Filling out the table.

IX. Lesson summary.

Questions for students:

1. What results from using these ecological or organic methods.
2. What is the result?

(The result of these methods: pure products, no chemical impurities. Clean land, natural resources preserved, stable harvest for several years.)

Conclusion:

Rational use of natural resources in agriculture includes:

• obtaining a high yield while maintaining soil fertility;
• production of environmentally friendly products;
• no pollution of soil, water, atmosphere, animals, plants;

Let the motto in a person’s life be: “Working with nature and for nature is a passport to the future.”

“If we are destined to breathe the same air
Let us all unite forever,
Let's save our souls
Then we ourselves will survive on Earth.”
(N. Starshinov)

X. Homework: Questions - discussions.

INTRODUCTION

Types of agroecosystems

Relationship of organisms in agricultural systems

Cultivated plants as a component of the agricultural system

Features of the cycle of substances in agroecosystems

Ways to increase the productivity of agroecosystems

Bibliography

INTRODUCTION

Agriculture significantly transforms natural systems. As a result, various anthropogenic agricultural formations (arable lands, gardens, meadows, pastures, etc.) were formed, occupying about a third of the land, including almost 1.5 billion hectares of arable land.

In the light of modern concepts of the agroecosystem (agrobiogeocenoses) - secondary, human-modified biogeocenoses that have become significant elementary units of the biosphere; they are based on artificially created biotic communities, usually depleted in species of living organisms. These communities are formed and regulated by people to obtain agricultural products. Agroecosystems are characterized by high biological productivity and the dominance of one or several selected species (varieties, breeds) of plants or animals. Cultivated crops and bred animals are subjected to artificial, and not natural selection. As ecological systems, agroecosystems are unstable: they have a weak ability for self-regulation, without human support they quickly disintegrate or run wild and transform into natural biogeocenoses (for example, reclaimed lands into swamps, forest plantations into forests).

Agroecosystems with a predominance of grain crops exist for no more than one year, perennial grasses - 3...4 years, fruit crops - 20...30 years, and then they disintegrate and die. Shelter forest belts, which are elements of agroecosystems, have existed in the steppe zone for at least 30 years. However, without human support (thinning, additions), they gradually “go wild”, turning into natural ecosystems, or die. The predominant type of agroecosystems are artificial phytocenoses: cultivated (systematically exploited meadows and pastures); semi-cultivated (non-permanently regulated artificial plantings - seeded, perennial meadows); cultural (permanently regulated perennial plantings, field and garden crops); intensively cultivated (greenhouse and greenhouse crops, hydroponics, aeroponics and others that require the creation and maintenance of special soil, water and air conditions). Management of the agroecosystem is carried out from the outside and is subordinated to external goals.

1.
Types of agroecosystems

Agroecosystems, like natural ecosystems, are composed of many interrelated biological, physical and chemical components.

The lack of a generally accepted classification of agroecosystems is compensated to a certain extent by the typification of agricultural structures used by the FAO. According to this typification, five types of land use are identified, for each of which agroecosystems are classified:

1. Agricultural, or field, land use - rainfed, irrigated agroecosystems (rotation of grains, legumes, fodder, vegetables, melons, industrial and medicinal crops).

2. Plantation and garden land use - plantation agroecosystems (tea bush, cocoa tree, coffee tree, sugar cane), garden agroecosystems (orchards, berry fields, vineyards).

3. Pasture land use - pasture agroecosystems (distant pastures: tundra, desert, mountain; forest pastures; improved pastures; hayfields; cultivated meadows).

4. Mixed land use - mixed agroecosystems, characterized by an equal ratio and combination of several types of land use, as well as processes for obtaining both primary and secondary biological products.

5. Land use for the production of secondary biological products - agro-industrial ecosystems (territories of intensive “industrialized” production of milk, meat, eggs and other products based on the prevailing processes of supplying the system with matter and energy from the outside).

Modern agroecosystems include complex, materially, energetically, economically and environmentally interconnected processes for the production of biological products. At the same time, reproduction of natural resource potential and efficient use of anthropogenic energy subsidies are ensured.

The scientifically based organization of agroecosystems involves the creation of rational natural and natural-economic infrastructure (roads, canals, forest plantations, agricultural land, etc.), adequate to the characteristics of the local landscape and economic use of the territory as a whole.

2. Relationship of organisms in agricultural systems

agroecosystem organism agrarian

The components of the agroecosystem are agricultural lands on which grains, row crops, forage and industrial crops are grown, as well as meadows and pastures.

The main elements of agrobiocenosis in agricultural ecosystems are:

1. Cultivated plants sown or planted by man.

2. Weeds that have penetrated into the agrobiocenosis in addition to, and sometimes against, the will of man.

3. Microorganisms of rhizospheres of cultivated and weed plants.

4. Nodule bacteria on the roots of legumes, fixing free nitrogen from the air.

5. Mycorrhiza-forming fungi on the roots of higher plants.

6. Bacteria, fungi, actinomycetes, algae living freely in the soil.

7. Invertebrate animals living in the soil and on plants.

8.Vertebrates (rodents, birds, etc.) living in soil and crops.

Flowchart of agroecosystem productivity

An agroecosystem has biological productivity or biological capacity.

The population size of individual species within them fluctuates due to constant changes in abiotic and biotic factors. Factors influencing the population density of a species include interspecific competition for food and space. Interspecific competition occurs mainly when different species have the same or similar requirements for environmental conditions. With the increasing lack of means of subsistence, competition intensifies. Typically, the population density of various groups of organisms in an agroecosystem is maintained at optimal level. In agrophytocenosis, regulation of population density manifests itself in the form of intraspecific competition of plants, and as a result, their relative optimal density is established in the occupied territory. For example, the number of clover plants per 1 m2 at the time of harvesting the cover crop is 400 pcs./m2. Next year, by the beginning of the growing season, it may drop to 150-200 pcs./m2, which creates the most favorable conditions for crop formation. Regulation of vegetation cover density also occurs under the influence of factors such as leaf surface density, expressed through assimilating surface index. Competition intensifies at high leaf surface densities. Since not all plants receive enough light, weaker ones are suppressed. Consequently, intraspecific competition is observed between individuals of the same species. The population size of a species is limited by the amount of environmental resources necessary for its life.

Interspecific plant competition does not lead to the complete displacement of a less competitive species. As a process of struggle between cultivated plants and weeds, interspecific competition manifests itself in an open agroecosystem. In meadows and pastures this form of competition predominates. Plant communities here are characterized by typical features characteristic of this territory. Crops of cultivated plants in agrophytocenosis are the only source of food for herbivores and phytophagous insects. During periods favorable for plant growth, producer populations can increase sharply and quickly. Mass reproduction of herbivores and phytophagous insects usually causes great damage to agricultural crops. Natural regulation of the number of herbivores and phytophagous insects and bringing their populations to an economically harmless threshold by using their natural predator enemies is difficult and does not always give good results. Hence, in agricultural practice, artificial intervention and regulation of the number of phytophages is carried out through the use of various artificial remedies.

Under the influence of phytophages, the decrease in plant productivity is not always proportional to the amount of food they consume, their dominance or biomass, but is due to the nature of damage to autotrophs, their age and condition. For example, if a phytophage attacks a young plant, then in some cases more damage is caused than when feeding on adult plants (cruciferous flea beetles, etc.). On the contrary, in other cases, young plants are more successful in compensating for damage by producing new shoots or more intensive growth of healthy shoots than plants that suffered at a later date. Often the damage caused by animals is balanced by the benefits they bring. Thus, when feeding their offspring, rooks destroy pests of agricultural crops, and at the same time can cause damage by damaging seedlings of corn and grain crops.

The originality of the ecological pyramid, at the top of which is a person, is a specific feature of any agroecosystem. In agroecosystems, the species composition of plants and animals is depleted. Agricultural ecosystems have few components. Few components are also one of the characteristics of an agroecosystem.

3. Cultivated plants as a component of the agricultural system

A cultivated plant is the main component of not only the ecological, but also the socio-economic system. Sowing agricultural crops, fodder and medicinal herbs is, first of all, a social order in order to satisfy the needs of people for one or another product of plant origin: food, feed, raw materials for industry, etc. Cultivated plants are not only a product of nature, but also an object human labor. Therefore, their growth and development are determined by both natural and anthropogenic factors.

Currently, about 4,000 plant species are cultivated. Most often, cultivated plants are sown; less often, wild plants are sown.

Despite the relatively large variety of cultivated plants, the most widespread among farmers are the following (according to Zlobin):

spring annual plants - cultivated most widely, have a growing season from several weeks to several months;

winter annual plants - sown in autumn, harvested in mid-summer of the following year;

biennials - often grown as annual crops;

perennial herbs;

trees and shrubs, some of their species (for example, cotton) are grown as annuals.

As a rule, high-yielding crops are cultivated. Rice, wheat, corn, potatoes, barley, sweet potatoes, cassava, soybeans, oats, sorghum, millet, sugar cane, sugar beets, rye, and peanuts are widespread around the globe. The cultural flora of the CIS consists of more than fifty species. Seeds of wild plants are used relatively rarely, mainly in the creation of meadows, pastures and plantations of medicinal herbs.

Cultivated plants occupy a central place in agrophytocenosis. They, according to M.V. Markov, are the main component, the core of this biological system. Cultivated plants have the strongest, often dominant, influence on agrophytocenosis. The dominant plant is not only a component of the phytocenosis, but also an important environmental factor that has a multifaceted impact on the environment and the ecological situation in the agrobiogeocenosis. Therefore, the dominant received the title “edificator”. However, some authors object to the introduction of this term, since the edificatory effect of cultivated plants is much less pronounced than wild ones, and sometimes it may not be manifested at all in agrophytocenoses. Perhaps the term “edificator” is not entirely appropriate, but it is quite widespread in agrobiogeocenology.

One type of cultivated plant (for example, wheat, rye or corn) is most often introduced into the agrobiogeocenosis as a dominant edifier. Mixed crops of two or more species (condominants) - vetch with oats, a multicomponent herbal mixture - are relatively rare. Sometimes two or more varieties of the same plant species are sown, i.e., they create single-species differentiated (according to Markov) or joint (according to Yurin) sowing.

The forms of edificatory influence of dominant plants (and condominants) are varied. Edifiers change the microclimate of agrobiogeocenosis and affect the physicochemical properties of soils and soil moisture. By releasing biologically active substances, edificators significantly influence the flora and fauna of agrobiogeocenosis. Sown plants influence the environment by releasing metabolites. Among the metabolites, colins (agents of influence of higher plants on higher ones) and phytoncides (agents of influence of higher plants on lower ones) play an important edificatory role in the phytocenosis. The edificatory role of dominants (and condominants) of agrophytocenosis needs to be comprehensively studied in the future.

The edificatory role of cultivated plants of different species is not the same. According to the degree of decreasing edificatory influence, they, according to N. E. Vorobyov, can be located in the following series: perennial grasses, winter cereal crops, spring cereal crops, grain legumes, spring row crops (sunflower, potatoes, corn), melons, vegetables.

According to edificatory properties, i.e., according to their ability to influence the environment, cultivated plants are divided into three groups by V.V. Tuganaev.

The first group includes strongly edificatory plants. These include plants of continuous sowing, forming a grass stand, the projective cover of which is about 100%. This group also includes plants that are tall (up to 3 m) and medium-sized, but quickly developing in the spring (winter rye, rapeseed, vetch, sunflower for silage).

The second group consists medium edificatory plants. These include plants of continuous and row spring sowing, quite tall, with a projective cover of 70-80%, mostly developing rapidly after emergence (spring grains, including rice), row crops (cotton, corn, buckwheat, soybeans).

The third group consists weakly edificatory plants. These include some plants that develop slowly after emergence and with a projective cover of no more than 50%: melons, vegetables, peas, etc.

This classification, reflecting the degree of edificatory influence of agricultural crops, can be used in assessing agrobiogeocenoses.

Acting as dominant edifiers, cultivated plants determine the structure and function of agrobiogeocenoses and their component composition. They significantly affect the condition of companion plants (weeds, etc.).

Multifaceted production activity humans makes noticeable adjustments to the processes of mass and energy exchange, affecting and changing their territorial and temporal characteristics. Agroecosystems, of course, are involved in these changes (and sometimes to a large extent), contributing, in particular, to the openness of substance cycles, etc. Thus, due to the openness of the nitrogen cycle, under the influence of the chemicalization of the planet’s agroecosystems, it accumulates in water and soil and does not return to the atmosphere for approximately 10 million tons of this element. An excess of nutrients is the cause of pollution of natural waters, the development of undesirable processes in soils, etc. Disruption of natural cycles of substances is not the only consequence of human intervention in natural cycles. Agriculture changes the intensity and trajectories of their movement in the cycle of substances and energy flows. Particularly dangerous is the involvement of artificially synthesized substances, including xenobiotics, in the cycle.

Within the territorial areas under the influence of emerging and functioning agroecosystems, there are specific features of the development and movement of migration flows of substances, which differently affect the state of natural complexes and their components and require non-standard solutions when considering specific environmental situations.

All ecosystems function on the basis of the passage of biogeochemical cycles - evolutionarily established universal natural processes. In accordance with the principles of homeostasis, noticeable changes in any of the functional components that form the ecosystem can serve as the root cause of significant changes in other components; in this case, the previous internal structure of the system is disrupted (composition of plant and animal communities, dominance of organic matter, etc.). The stability of the ecosystem is maintained even if it switches to new level homeostasis. If any of the functional components are excluded or become ineffective, the ecosystem may collapse under the influence of abiotic factors, such as erosion.

Achieving stable functioning of agroecosystems and preventing the occurrence and development of degradation processes require constant focused work: scientific understanding of the characteristics of biological production, the formation of appropriate directions for practical activities. A comparative assessment of the properties of natural and cultivated systems is fundamentally important. In the future, the properties of artificial formations should be ensured as close as possible to the properties of natural ones - this, in essence, is what agroecological decisions based on taking into account the characteristics of mass and energy exchange in agroecosystems should be reduced to.

The production process of an agroecosystem depends not on separately acting abiotic (location, solar radiation, thermal and water regimes, mineral nutrition, etc.), biotic and anthropogenic factors, but simultaneously on their entire complex (the resulting vector of complex combinations of interfactor interactions). The productivity of the agroecosystem is ensured by the intensity and direction of metabolic processes and energy transfer between the cultivated crop and the natural environment, which are under human control. The ecosystem level of the biological organization of agroecosystems ultimately depends on the quality of management and the degree of its natural conformity.

5. Ways to increase the productivity of agroecosystems

The earth's surface is represented by a huge variety of natural and transformed (anthropogenic) ecosystems. A common property for each of them is autotrophy as a result of photosynthesis under the influence of a unidirectional flow of solar energy passing through substances and living organisms of both natural and modified ecosystems.

For a plant, the components of the total flow of solar energy are of significant importance: due to spatiotemporal changes, they influence the course of physiological processes, etc.

For all plant objects, the accumulation of energy is accompanied by the formation or accumulation of biomass, which serves as structural material for the formation of plant organs and energy material for biosynthesis, ensuring the existence of not only an individual plant, but also the entire complex biological structure.

The growth and development of plants as an organoformative process and the process of biomass production begin after the formation of the optical-photosynthetic system of the leaf and the further implementation of photosynthesis reactions. This is the only process on Earth during which the accumulation and transformation of the energy of simple inorganic substances into the energy of chemical bonds of organic substances is ensured by the absorption of the energy of a natural source, the radiant energy of the Sun.

The highest productivity of an agroecosystem (as well as an ecosystem), i.e., the maximum accumulation of biomass in the form of various vegetative and reproductive organs of cultivated plant species, is determined by the adaptability of the optical apparatus to solar energy. One of the signs of such adaptation is the maximum accumulation of energy, i.e., biomass, by a plant per unit of time. Provided that other environmental factors that ensure the process of photosynthesis are not limited, 95...97% of organic compounds represented by plant biomass are formed due to the absorbed light energy. In this case, of course, part of the energy is spent on breathing.

To maximize the use of incoming energy, ecosystems have evolved a number of adaptive properties (for example, diversity of species composition). Agroecosystems should be created by analogy, since the latter have the same fundamental basis for the production of biological products. In this regard, it is interesting to remember that Mayan farmers managed to develop high-yielding varieties of corn, legumes, and pumpkins, and the manual technique of cultivating a small forest plot and the combination of several crops (corn and beans) in one field made it possible to maintain its fertility for a long time and did not require frequent changing areas.

Creating highly productive combinations of agricultural crops is one of the real and effective ways to increase productivity and cost efficiency in agroecosystems. Mixed and joint crops can be used in agroecosystems with a high level of mechanization of work. Agricultural crops are sown in alternating strips or rows, and are also sown between grain rows. In areas with a temperate climate, various combinations of crops are used: peas and soybeans with oats and corn, soybeans and beans with corn, soybeans with wheat, peas with sunflowers, rapeseed with corn. With the optimal selection of cereal and legume components, crop productivity and protein yield are significantly increased, not only due to legume grains, but also by increasing the protein content in cereal grains, which use nitrogen fixed by the legume crop.

Numerous studies by domestic and foreign scientists have specified the optical properties of almost 1,500 plant species (mesophytes, xerophytes, hygrophytes and succulents of herbaceous, shrub and tree forms) and obtained the average spectral absorption curve of radiant energy. According to the established distribution, the lowest absorption of radiant energy by an “average” sheet (up to 20%) is observed in the wavelength range 0.75... 1.30 microns, and the highest (70% or more) in the ranges 0.30...0 .70; 1.80...2.10 and 2.23...2.50 microns. The energy balance of ecosystems, which varies depending on the climatic zone, objectively determines the formation of ecosystems’ adaptation to the “optimal” absorption of radiant energy, which is possible in specific conditions. The adaptability of the energy balance of the ecosystem, corresponding to the energy consumption for heat exchange and transpiration, everywhere determines the production efficiency of both natural and artificial coenotic formations. The energy characteristics of various natural zones of the planet allow us to distinguish 5 main (global) types of agroecosystems.

The tropical type is characterized by a high supply of heat, which promotes continuous vegetation. Agriculture is based mainly on the functioning of agroecosystems with a predominance of perennial crops (pineapples, bananas, cocoa, coffee, perennial cotton, etc.). Annual crops produce several harvests per year. The features of this type of agricultural system include the need for continuous investment of anthropogenic energy in connection with the constant conduct of field work throughout the year. Agroecosystems of this type are characterized by virtually equivalence of natural and anthropogenic processes of mass and energy exchange.

In subtropical agroecosystems, the intensity of anthropogenic flows of substances and energy is less; discreteness and dispersion of these flows appear. Basically, there are two growing seasons - summer and winter. Perennial plants grow that have a well-defined dormant period (grapes, Walnut, tea, etc.). Summer annual plants are represented by corn, rice, soybeans, cotton, greens, etc.

Temperate agroecosystems are characterized by only one (summer) growing season and a long (“non-working”) period of winter dormancy. A very high need for the investment of anthropogenic energy occurs in spring, summer and the first half of autumn.

Agriculture in polar agroecosystems is of a focal nature. Agroecosystems are significantly limited geographically and by the types of crops cultivated (leafy vegetables, barley, some root crops, early potatoes).

There are no Arctic-type agroecosystems in open ground. The cultivation of cultivated plants is excluded due to the very low temperatures of the warm period: in the summer months there are long cold spells with negative temperatures. It is possible to use closed ground.

On the territory of Russia, temperate agroecosystems are dominant. When organizing agroecosystems, it is important to ensure more efficient use of radiant energy.

Bibliography

1. Agroecology / V. A. Chernikov, R. M. Aleksakhin, A. V. Golubev and others; Ed. V.A. Chernikova, A.I. Chekeres. - M.: Kolos, 2000. - 536 p.: ill.-

Agricultural ecology / N.A. Urazaev, A.A. Vakulin, A.V. Nikitin et al. - M.: Kolos, 2000. - 304 p.: ill.

Stepanovskikh A.S. Ecology. - Kurgan: GIPP "Zauralye". - 2000. - 704 p., ill.

The state of agriculture in Russia and in the world is characterized by a steady trend towards an exponential increase in the cost of irreplaceable energy for each additional unit of production (including food calories), an ever-increasing danger of global pollution and destruction of the natural environment, as well as a high dependence of the size and quality of the harvest on effects of abiotic and biotic stressors. Meanwhile, the widespread use of technogenic means in the second half of the 20th century created the illusion of a supposedly high degree of protection of agroecosystems from weather fluctuations. At the same time, it was not taken into account that increasing the potential productivity of agrocenoses and their resistance to abiotic and biotic stressors turn out to be qualitatively different and, to a certain extent, independent tasks. It is known that under the influence of abiotic stressors (temperature, water, edaphic, etc.), the greatest damage is caused by varieties and hybrids with high potential productivity, which, compared to extensive ones, are usually more sensitive to unfavorable, and even more so extreme, environmental conditions .
The action of abiotic and biotic stressors is the main reason for 2-3-fold or more differences between the potential and realized yields of agricultural crops. Moreover, the worse the soil-climatic and weather conditions of the region, the lower the level of technological equipment of farms, the higher the indicated difference. Note that the effectiveness of the use of ameliorants, fertilizers, irrigation, pesticides and other technogenic factors ultimately also depends on the environmental sustainability of agroecosystems and agricultural landscapes. Moreover, the ecological stability of plants is also important under controlled environmental conditions (for example, only the “drought resistance” of irrigated crops allows them to withstand dry winds; vegetable crops in greenhouses must be protected from the action of biotic stressors, etc.). Environmental sustainability is also the main condition for the promotion of economically viable cultivation of agricultural crops in agricultural zones unfavorable in terms of soil, climatic and weather conditions. It is known that the high dependence of crop production on the vagaries of the weather leads to negative consequences in the entire chain of intersectoral (feed production, livestock farming, processing industry) and interregional ties in the agro-industrial complex, significantly aggravating the problem of rhythmically providing the population with food, and industry with raw materials.
The state of stability or dynamic equilibrium of an agroecosystem involves maintaining a certain level of its productivity in varying conditions, incl. extreme environmental conditions. At the same time, the indicators of conservation of population dynamics of various species of fauna and flora, as well as biogeochemical cycles, remain fairly constant in time and space. The advantage of sustainable ecosystems in a state of dynamic equilibrium is manifested in their ability to most efficiently utilize environmental resources and accumulate greatest number biomass per unit area during the growing season and per unit time.
The strategy of adaptive intensification of crop production focuses on an environmentally, economically, morally and psychologically acceptable (acceptable) level of risk. The most important stages of its determination are the identification of the mechanisms and nature of the hazard, as well as the assessment of the likelihood of their occurrence, taking into account the adoption of preventive measures. Currently, for this purpose, the basic provisions of the theory of disasters are widely used, according to which protection against them can be active and passive, preventive and restorative. In this regard, a distinction is made between annual, seasonal, and short-term forecasts, as well as operational information about upcoming events. For example, measures to prevent the harmful effects of drought include agroecological macro-, meso- and microzoning of crops and plantings; selection of drought-resistant crops and varieties (hybrids); preservation of moisture reserves through vapor, mulching, use of curtains and forest belts, construction of irrigation structures, etc.
Increasing the environmental sustainability of agroecosystems and agricultural landscapes is the main reserve sustainable growth their productivity, resource and energy efficiency, environmental safety and profitability. Moreover, modern chemical-technogenic methods of intensifying crop production are only to a small extent capable of increasing the resistance of agrocenoses to the “vagaries” of the weather. Moreover, high doses of nitrogen fertilizers, irrigation, species uniformity and crop density usually reduce the ecological sustainability of agroecosystems. With existing technologies, about 50-60% of nitrogen, 70-80% of phosphorus and over 50% of potassium fertilizers, up to 60-90% of irrigation water are lost, polluting the environment, and the rate and scale of water and wind erosion in conditions of technogenic-intensive agriculture in most countries have reached catastrophic levels. As a result, as the potential yield of agroecosystems increases, their resistance to environmental stressors usually decreases, and the variability in the absolute size and quality of the harvest is increasingly determined by weather rather than agrotechnical factors. It is no coincidence that even in countries with the highest level of technogenic intensification of agriculture, the year-to-year variability of absolute yield for many crops depends by 30-80% on the “vags” of the weather. Thus, in the state of Illinois (USA), the average correlation coefficient between corn yield and weather factors is 0.88. It is shown that the climatic component of the variability in winter wheat yields in the CIS countries varies up to 30% in Ukraine and the North Caucasus up to 60%, in the northeastern and eastern regions of Russia the interannual variability in grain crop yields exceeds 25%.
It was previously noted that only 10% of arable land in the world is free from stress factors, about 20% is subject to mineral stress, 26% to drought and 15% to low temperatures. Acidic soils (toxic concentrations of aluminum or manganese ions) account for 40% of the world's arable land. It is the effect of abiotic stressors that is the main reason that only 25-30% of the potential crop yield is realized. Complete elimination of the effects of abiotic stressors through technogenic reclamation of the environment usually turns out to be economically unprofitable or technically infeasible.
The most important factors determining the low ecological sustainability of modern agroecosystems include the depletion of their species composition, the ever-increasing genetic homogeneity of varieties and hybrids, as well as the uniformity of agricultural landscapes. Thus, in semi-arid regions of the world, about 90% of total grain production is provided by only four crops: wheat, barley, sorghum and millet. The trend towards a reduction in species diversity not only does not contribute to an increase in the usefulness of the nutritional structure, but is also non-adaptive from the point of view of the most effective use of soil, climatic and weather conditions unevenly distributed in time and space, as well as increasing the environmental sustainability of agroecosystems and agricultural landscapes. It is known that each species and variety of plants has its own optimum environmental conditions for the normal functioning of the photosynthetic apparatus (temperature, pH of the substrate, content of N, P, K in the soil, etc.). If C4-type plants (corn, sorghum, sugar cane, etc.) are better adapted to areas with high temperatures (higher temperature optimum for photosynthesis), then C3-type plants (beets, sunflowers, carrots, etc.) provide high productivity in regions with lower temperatures and better ventilated crops. Moreover different types cultivated plants in the same soil-climatic zone have significantly different values ​​of the climatic and weather components of yield variability. That is why a greater variety of crops, especially those selected according to the principle of mutual compensatoryness, ensures better pre-adaptation, and, consequently, environmental reliability of crop production systems.
Numerous data confirm that predominantly chemical-technogenic intensification and narrow specialization farms are usually accompanied by the destruction of natural landscape elements, a decrease in the diversity of natural biotopes, and the disappearance of many species of plants and animals. At the same time, the widespread use of pesticides disrupts the ecological balance in agroecosystems and in most cases leads to the emergence of more aggressive and virulent races of pathogens, as well as increased harmfulness individual species insects and weeds. The destruction of insects must be carried out in a timely manner.
All this sharply reduces not only the efficiency of using technogenic factors, but also the reserves of available moisture (the likelihood of droughts increases), the level of soil biogenicity, the rate of microbiological detoxification of pesticides, etc. Due to water, wind and man-made erosion, the diversity of fields in terms of soil fertility increases, its water-physical properties sharply deteriorate, which also significantly increases the dependence of the size and quality of harvests on the “whims” of the weather.
Thus, the currently most widespread, predominantly chemical-technogenic intensification of agriculture is in obvious contradiction with the basic evolutionary laws, as well as the concept of the harmonious development of the biosphere and human society. Even supporters of predominantly chemical-technogenic intensification recognize the crisis of the situation in modern agriculture, although they classify it as a “mild crisis”. A systematic analysis of the contradictions of the existing strategy for intensifying the agro-industrial complex indicates its futility not only in terms of resource-energy saving and environmental protection, but also in sustainable increase in the productive potential of agroecosystems, including their adaptation to possible unfavorable global and local climate changes.
When discussing ways to increase the resilience of domestic agriculture to unfavorable and extreme environmental conditions, a brief historical analysis of this problem also deserves attention. It is known that the average yield of the main grain crops (rye, wheat, oats, barley, etc.) for the period from the 17th to the first half of the 19th centuries. in Russia remained almost unchanged, amounting to at the end of the 16th - beginning of the 17th centuries. - 4.7; in the first and second half of the 18th century. 4.8 and 4.9, respectively; in the first half of the 19th century. - 4.7 c/ha. And only in the period 1860-1914. grain yields in European Russia almost doubled, reaching 9-10 c/ha. It is noteworthy that the coefficient of interannual variability in the yield of the main grain crops in Russia has practically not decreased over the past 100 years. So, in 1883 -1911. The average variability of grain crops across 50 provinces of the European part of Russia was 13.5% for rye, 19.5% for oats, 23.7 and 26.9% for spring and winter wheat, respectively. Moreover, in terms of the variability of gross wheat grain harvests, Russia surpassed all European countries and the United States, second only to Australia (Tables 6.143, 6.144, 6.145). It turned out that for Russia the norm is not average fees, but sharply deviating from the norm. If we take into account the difference in the number of collections above and below the norm, then in Russia it takes 4.5 times longer to eliminate crop shortages than in other countries. The number of outstanding collections per 10 averages for different regions of Russia varied from 3.5 to 16.7, the number of phenomenal ones - from 0 to 50, and on average - 5. The intensity of fluctuations grew from the north and west to the south and east. Unlike other countries, where fluctuations tend from (-) to (+), in Russia there is no clear trend towards increasing fees.
The greatest damage to crops is caused by soil and atmospheric droughts, which are observed almost annually on 70% of the area of ​​grain crops. “In the Non-Black Earth zone of Russia,” wrote A. Levitsky, “there has long been a popular saying that “it is not the earth that gives birth, but the sky...”. The most destructive droughts in Russia are spring droughts, lasting 3-12 days. That is why even the most grain-producing black earth provinces, which made up the “granary” of Russia, V. Wiener noted with regret in 1912, in some years feed on imported bread. It is typical that on nearby farms the amount of precipitation that falls during the year can vary by 2-3 times. Even in an average year in terms of moisture in the southern steppes of the Volga region, due to a lack of moisture both during the spring-summer growing season and in the autumn, a systematic shortfall in winter wheat yield is 5-15 c/ha. Taking into account different coefficients of variation in the yield of different crops under the same environmental conditions, it is possible, through an appropriate combination of crops, to level out the gross grain yield, increasing the sustainability of its production as a whole (with different ratios of crops in the total crop) (Table 6.146).