The main pattern of changes in soil fertility. Successes of modern natural science. Dynamics of soil fertility in Chuvashia

(Soils vol. 3 and 4) The degree and nature of the formation and accumulation of humus in soils depends mainly on the radiation balance and moisture regime. The thickness of the humus horizon, the content and reserves of humus regularly change in the soils of the zonal series. The highest value of these indicators is typical for typical chernozems of the forest-steppe zone. The thickness of the humus horizon in them can reach 1.5 m, the humus content is up to 15% (Table 3). To the north and south of the distribution zone of typical chernozems, the thickness of the humus horizon, the content and reserves of humus gradually decrease to the minimum values. In parallel with the total content of humus, the relative content of humic acids also changes. Most of them are in the black soil. To the north and south of the chernozems, their content gradually decreases. The change in the content of fulvic acids is less regular, but generally opposite to the content of humic acids. The content of insoluble residue is 30-40% of the total humus content and varies slightly by soil types. Characteristic for each type of soil is the ratio of humic acid carbon to fulvic acid carbon, which is also the highest in chernozems (about 2 or more), gradually decreasing towards podzolic, brown desert-steppe soils. According to this ratio, the following types of humus are distinguished: humate > 2, fulvate-humate 1-2, humate-fulvate - 0.5-1, fulvate -<0.5.

In the composition of humic acids, the proportion of free and associated with mobile forms of sesquioxides from podzolic soils to soils of arid regions decreases from 90-100% to 10% or less, and with calcium, on the contrary, increases in the same range. In the soils of humid and variable-humid tropical and subtropical regions, the humus content increases by 3-4% with the predominance of fulvic acids in its composition, as a rule.

Table 3 - Geographic patterns of humus distribution in soils

Soils	Humus,%	HA, % of humus	FA, % of humus	Sgk-Sfk	Morphology of humus
Podzolic	2,5–4,0	12-30	25-30	0,6–0,8	Mor
gray forest	4,0– 6,0	25 - 30	25 - 27		Moder, Mull
Chernozems	7,0 – 10,0	35 - 40	15 - 20	1,5- 2,5	Mull
chestnut	1,5 – 4,0	25 - 35	20- 25	1,2 – 1,5	Mull
Brown dry steppe	1,0 – 1,2	15-18	20 - 23	0,7	Mull, Moder
Serosma light	0,8- 1,0	17-23	25-33	0,7	Mull, Moder
Krasnozems	4,0-6,0	15-20	22-28	0,6-0,8	Mor, Moder Mull

The role of organic substances in soil formation, soil fertility and plant nutrition. The role of organic substances in soil formation, soil fertility and plant nutrition is very diverse. A significant part of elementary soil processes (EPS) occurs with the participation of humic substances. These include biogenic-accumulative, eluvial, eluvial-accumulative, metamorphic and others. The processes of interaction of organic substances with the mineral part of soils underlie soil formation.

Organic matter is a source of nitrogen and ash elements of plant nutrition. It contains 98% of gross nitrogen, 40-60% of phosphorus, 80-90% of sulfur, significant amounts of calcium, magnesium, potassium and other macro- and microelements are associated with it. Some of these elements are in an absorbed state and are absorbed by plants as a result of ion-exchange reactions. The other part is released and becomes available to the plant after the mineralization of organic matter. It has been established that about 50% of the nitrogen requirement of cultivated plants is obtained from soil organic matter, primarily easily decomposable, the remaining 50% from mineral fertilizers.

Organic matter optimizes the physicochemical properties of soils. The absorption capacity of organic colloids is much higher than that of mineral colloids, and reaches 1000 or more meq/100 g of the preparation of humic substances. More humus soils have a higher buffering capacity in relation to acid-base influences, oxidation-reduction and the action of toxicants. The cations absorbed by organic and organo-mineral colloids are available for plants and actively participate in their nutrition.

Organic matter has a significant effect on the structural state, physical, water-physical and physical-mechanical properties of soils. With an increase in humus content, the density decreases, the total porosity increases, the soil structure improves, and the water resistance of structural aggregates increases; moisture capacity and water-holding capacity, water permeability, range of active moisture, hygroscopic humidity increase; the physical and mechanical properties of the soil become optimal: stickiness, plasticity, hardness, resistivity. Humus gives the soil a dark color, which helps to absorb heat.

Organic matter plays a leading role in the biological regime of soils. Humus sources maintain a certain level of biological activity in soils; actually humic substances contribute to the preservation of microorganisms in soils and create comfortable conditions for their functioning. The increased biological activity of soils contributes to a decrease in the number of pathogenic microorganisms, and accelerates the microbiological degradation of pesticides.

The composition of organic substances contains physiologically active substances that accelerate the growth and development of plants.

>>Patterns of soil distribution

§ 27. Patterns of soil distribution

The main types of soils in Russia. Modern soil cover of Russia- the result of a long and complex development of nature as a whole. Depending on the conditions of soil formation in our country, there are the following types soils: arctic, tundra-gley, podzolic, sod-podzolic, gray forest, chernozem, chestnut, etc.

Analyze the soil map, catch it. What soils are in our country.

Compare fig. 48 with a venerable map of the atlas and determine which soils prevail in the forest zone, which ones in the steppe.

In the European part of Russia, various podzolic soils predominate, while in Siberia, taiga and mountain-taiga soils prevail. Large areas in the north of the country are occupied by tundra the soil mi. In the south, there are chernozem and chestnut soils.

The phenomenon of latitudinal zoning in our country, especially in the European part of Russia, is more pronounced than in other countries of the world. This is due not only to its significant length from north to south, but also to the predominance of the flat relief and in a temperate continental climate.

If we make an imaginary journey along the Russian Plain from north to south on the map, we will see how soils of different types replace each other, differing in structure, color, composition, and fertility. Arctic soils are thin (1-5 cm) and form only separate patches. Tundra-gley and marsh soils are formed in the tundra. Podzolic soils are formed in intensively washed soils of northern forests. To the south - with a decrease in the amount of precipitation and an increase in the thickness of the humus horizon - soddy-podzolic soils. In broad-leaved forests and under forest areas of the forest-steppe - gray forest soils. The most fertile soils are formed in the steppes - chernozems. Abundant herbaceous vegetation in this zone contributes to an increase in the amount of humus. Here is the most powerful humus layer. When moving south and east climate it becomes drier and warmer, the grass cover is sparse: the soils brighten and turn into chestnut under dry steppes, brown in semi-deserts, gray-brown and gray (serozems) in deserts. With the clarification of soils, their salinity increases. Salt marshes are widespread in the southern regions of the country (on the Caspian lowland).

Rice. 49. The relationship of soil types with climate and vegetation

In mountainous areas, soils, following vertical zonality, also change following climate and vegetation changes. A common property of these soils is rubbish, roughness of the mechanical composition.

Questions and tasks

1. Name the main types of soils in Russia.
2. Based on the soil map, determine what types of soils prevail in our country. Explain why.
3. What kind of soils do you have in your area?

Geography of Russia: Nature. Population. Economy. 8 cells : studies. for 8 cells. general education institutions / V. P. Dronov, I. I. Barinova, V. Ya. Rom, A. A. Lobzhanidze; ed. V. P. Dronova. - 10th ed., stereotype. - M. : Bustard, 2009. - 271 p. : ill., maps.

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Fertilizers that enter the soil undergo various transformations. They do not remain unchanged, but come into close contact with the soil and change. Fertilizers applied should equally affect crop yields and soil fertility. The influence of the systematic use of fertilizers on the agrochemical properties of the soil depends on the characteristics of the soils themselves, the crops grown, the amount and forms of fertilizers used.

A special role in the formation of soil fertility belongs to humus - the regulator of the most important physico-chemical, physical, physicomechanical, biological properties of the soil, which determine the water-air, thermal and nutrient regimes of soils.

The peculiarity of the natural and climatic conditions of soil formation in Transbaikalia affects the nature of the transformation of plant residues and the nature of humus.

Nogina N.A., 1964, when studying the amount of roots and humus in the soil profile, opened interesting fact. It turns out that the chestnut soils of Transbaikalia are almost twice as poor in humus and twice as rich in root stock than the soils of the same name in the European part of the country. This is due to the fact that not all incoming organic matter is converted into humus, and not all newly formed humic substances are stored in the soil. In the soils of the harsh Transbaikalia, the annual litter does not have time to decompose even by one third in one year.

Studies conducted on the chestnut soils of the experimental opl of the Belarusian State Agricultural Academy for the study of the organic matter of chestnut soils showed that virgin areas contain much more roots and dead organic residues of various degrees of decomposition, while their largest mass is concentrated in horizon A to a depth of 15–20 cm, and the number of dead plant remains outnumber living roots.

Under better conditions for biological processes created in arable land, and especially during soil fallowing, there are much fewer living roots and decomposed organic residues of varying degrees. The latter is confirmed by the nitrification capacity of soils (Table 15). In arable soil after composting, the content of nitrates increases from 27.5 to 46.6 mg/kg of soil, and compared to the original virgin soil, the amount of nitrates increased by more than 10 times.

Table 15 Nitrification capacity of chestnut soils (mg/kg soil, layer 0 - 20 cm)

Intensive use of soils in agricultural production leads to increased biological activity, while humus reserves decrease, especially this trend is manifested in the first two to three decades after the plowing of virgin soils (Kononova M.M., 1972; Aleksandrova L.N., 1980; Orlov D.S., 1986 and others), according to the results of their research over the past 70 - 80 years, the loss of humus during plowing and long-term agricultural use has reached 40 - 50%.

Long-term rainfed agriculture in the republic without the use of organic fertilizers has led to significant losses of humus, especially significant during fallowing (here, losses range from 0.5 to 1.5 t/ha (Chimitdorzhieva G.D., 1990)). For the reproduction of soil fertility of arable soils, an annual application of 7 - 10 tons / ha of manure is necessary (Ishigenov I.A., 1972). With a shortage of manure and provision of only 20 - 25% of the need with manure, it is necessary to develop optimal methods and more effective doses of manure and other organic fertilizers.

Numerous works of researchers confirm the position that not only organic, but also mineral fertilizers when used correctly, they improve the agronomically important properties of the soil - they do not reduce, and in some cases, increase the content of organic matter and total nitrogen in the soil, increase the content of mobile and easily accessible forms of nitrogen, phosphorus and, in part, potassium (Gorbunov N.I., 1978 ; Korenkov D.A., 1976; Pannikov, Mineev and others).

Long-term agricultural use of chestnut soils and the use of fertilizers in crop rotation introduces certain changes in their fertility.

For analysis, 4 variants of the experiment are given (Tables 16, 17), the results of analyzes in the initial state of virgin soil and arable land before the laying of a long-term experiment. Studies show that the use of agricultural land without the use of fertilizers leads to a decrease in the humus content (tab. 16). Thus, the loss in the variant without fertilizers during the experiment amounted to 5 t/ha, and the annual loss in the 0-20 cm layer was 147 kg/ha, compared to the virgin soil, the humus content decreased by 13.5t/ha or 397kg/ha, which is about 32% of the initial content of humus in the virgin soil.

Table 16 Changes in the content and reserves of humus with long-term use of fertilizers on chestnut soil (layer 0 - 20 cm)

Initial	After 34 years	Change to original (+;-)
Virgin soil,horiz.A 0-15cm B 15-20cm
Arable land before laying the experiment					----- -8,5	----- 250
The control						-147 -397
Р20+N40Р40К40					-2,1 -10,6	-62 -311
Р20+40t/ha manure					+3,8 -47	+112 -138
Р20+N200Р100К240 (equivalent to 40t manure)					-0,8 -9,3	-23 -247

Reproduction of soil fertility in comparison with the initial state before the laying of the experiment is achieved only with the introduction of organic fertilizer at the rate of 10 t/ha of crop rotation area, while the annual increase in humus reserves is 112 t/ha. The mineral fertilizer system (N200P100K240) equivalent to this rate of manure does not stabilize the humus content in the soil, as does the rate of fertilizer N40P40K40, but the rate of its decrease is much less than in the variant without fertilization. The latter is probably associated with a large intake and involvement in the biological cycle of the mass of root and crop residues.

With prolonged use of fertilizers, the reaction of the soil solution in all variants of the experiment did not change. The value of the sum of absorbed bases is closely correlated with the humus content, it is higher in the variant with the introduction of manure. On the mineral fertilizer system, the amount of exchange-absorbed calcium and magnesium cations practically did not change, and on the variant without fertilizers, this indicator decreased by 1.3 mg eq per 100 g of soil.

Table 17 Effect of prolonged use of fertilizers on changes in soil fertility (layer 0 - 20 cm)

Soil fertility indicators	Change to original
Movable forms
Sum Ca + Mg, mg equiv. Per 100g
pH water
	The control	Р20+N40Р40К40	Р20+40t manure	Р20+N200Р100К240 (equivalent to 40 tons of manure)	Before bookmarking experience

The amount of mobile phosphorus in the organic fertilizer system remained practically at the same level as before the experiment, and the equivalent dose of manure ensured the replenishment and excess of the reserves of mobile phosphorus compared to the initial content. In other variants of the experiment, the amount of phosphorus available to plants decreased significantly, this was especially evident in the control variant.

The long-term use of fertilizers had a somewhat different effect on the content of exchangeable potassium, its amount increased almost three times over eight rotations of crop rotation with the introduction of 40 t/ha of manure and a mineral system equivalent to this dose. The latter is apparently due to the enrichment of the soil with organic colloids, and in the case of potash fertilizer (dose 240 kg / ha) - a high concentration of potassium in the soil solution and a significantly greater absorption of it in the diffuse layer of colloidal particles and, probably, enhanced chemical weathering of potassium-containing clay minerals. . In the variant without fertilization, there was a decrease in this form of potassium.

From the foregoing, we can say that organic fertilizers have a significantly positive effect on the properties of the soil, the reproduction of its fertility, and mineral fertilizers noticeably slow down the rate of decline in fertility, and in some cases help to maintain it at the same level. The annual alienation with the harvest of nutrients requires the maintenance of optimal fertility parameters of chestnut soils through the systematic use of organic and mineral fertilizers.

The main regularities of soil geography. The formation (genesis) of any soil is the result of a complex interaction of soil formation factors. Since certain patterns are observed in the distribution of factors on the earth's surface, naturally, they are reflected in the distribution of soils. The main regularities in soil geography are expressed by the following laws: the law of horizontal (latitudinal) soil zonality, the law of vertical soil zonality, the law of soil faciality, and the law of analogous topographic series.

Law of horizontal (latitudinal) soil zonality. Formulated by V.V. Dokuchaev. Its essence lies in the fact that since the most important soil-forming agents (climate, flora and fauna) naturally change in the latitudinal direction from north to south, then the main (zonal) soil types should successively replace each other, being located on the earth's surface in latitudinal bands (zones ). This law reflected the main position of Dokuchaev's genetic soil science that the soil as a special natural formation is the result of a certain combination of soil formation factors, and at the same time was the result of a generalization of V.V. Dokuchaev's extensive geographical research on the study of soils of the Russian Plain.

The law of latitudinal soil zonality is reflected in the following two main manifestations . First- in the presence on the territory of the land of the globe successively replacing each other soil-bioclimatic (thermal) belts, characterized by similarity natural conditions and soil cover, due to the commonality of radiation and thermal indicators. When moving from north to south, five belts are distinguished within the Northern Hemisphere: polar, boreal, subboreal, subtropical and tropical. Similar belts can be identified in the Southern Hemisphere.

Second the manifestation of the law of horizontal soil zonality is expressed in the division of soil-bioclimatic zones according to the totality of soil formation conditions and the general features of the soil cover into soil zones - latitudinal bands in connection with the regular pattern of not only thermal conditions, but also moisture and, as a result, vegetation.

Latitudinal soil zones stand out most distinctly in the vast flat areas within the continents (the Russian Plain, Western Siberia, etc.). Thus, the subboreal belt within Central Eurasia is divided into the following zones: forest-steppe(gray forest soils, podzolized, leached and typical chernozems) - steppe(ordinary and southern chernozems) - dry steppe(chestnut soils) - semi-desert(brown semi-desert soils) - desert(gray-brown desert, takyrs, takyr-like and desert sandy soils). On the territory of the continents adjacent to the oceanic and sea basins, such a sequence in the change of latitudinal soil zones is violated due to the complicating effect of moist air masses flowing from vast water spaces on the change in soil formation conditions (climate, vegetation, and soils).

Law of vertical soil zonality . It says that in the conditions of mountainous relief, natural successive changes in climate, vegetation and soils occur due to changes in the absolute height of the terrain. As you rise from the foot of the mountains to their peaks, the air temperature drops by an average of 0.5 ° C for every 100 m of absolute heights, which entails a change in the amount of precipitation and, as a result, changes in vegetation and soils. These changes are manifested in the formation of vertical vegetation-climatic and soil belts (vertical zones). AT general view sequential change of zones is similar to their change in flat spaces when moving from south to north.

Such a general scheme of successive changes in vertical soil zones can be complicated and disrupted due to the features of the mountainous terrain (a sharp change in absolute heights, steepness and exposure of slopes, types of macrorelief - plateaus, intermountain depressions, a variety of slopes, etc.) and frequent changes in soil-forming rocks .

The specific composition of soil vertical zones is determined by the position of a mountainous country in the system of latitudinal zones and the absolute heights of its relief.

Soil facies law . It lies in the fact that the soil cover in certain meridional parts of thermal belts and zones can change markedly due to climate change under the influence of thermodynamic atmospheric processes. These changes are due to the proximity or remoteness of specific parts of the belt or zone from sea and ocean basins, as well as the influence of mountain systems, etc. They manifest themselves in the form of an increase or decrease in atmospheric moisture and a continental climate.

Such changes affect the vegetation and the manifestation of soil-forming processes. The facies features of the soil cover are often expressed in the differentiation of soils according to temperature regime(warm, moderate, cold, non-freezing, freezing, long-freezing soils, etc.), in the emerging differences in the structure of the profile (thickness of humus horizons, etc.) and in the properties of the zonal type or subtype of soils, and sometimes in the appearance of new types in this facies.

As an example of the manifestation of the law of faciality, one can cite the territory of the boreal belt on the Eurasian continent. Here, when moving from west to east, more humid and warm climate conditions are gradually replaced by an increase in continentality and coldness in Eastern Europe and further on the Territories of Western and Eastern Siberia. In the Far Eastern Primorye, conditions of a humid oceanic climate again prevail. In connection with such a change in hydrothermal conditions, there is a succession of soddy-podzolic, moderately warm, short-term freezing soils, moderate freezing soils (the center of the European part of the belt) and then moderately cold, long-term freezing soils (southern part of the taiga Siberia), then the appearance of specific types of permafrost-taiga soils (Eastern Siberia) and brown-taiga soils (Primorye).

Patterns in soil geography, manifested in the form of laws of latitudinal and vertical zonality and the law of soil facies, are a consequence of the pattern of changes in bioclimatic conditions over vast territories due to their latitudinal and meridional position on the continents.

Law of analogous topographic series. It reflects a similar regular change of soils according to the elements of meso- and microrelief in all zones. The essence of this law lies in the fact that in any zone the distribution of soils on relief elements has a similar character: on elevated elements, soils occur that are genetically independent (automorphic), which are characterized by the removal of mobile products of soil formation and the accumulation of slow-moving ones; on low relief elements (slope trails, bottoms of lowlands and depressions, lakeside depressions, floodplain terraces, etc.) there are genetically subordinate soils (semihydromorphic and hydromorphic) with the accumulation of mobile products of soil formation brought with surface and subsoil runoff from watersheds and slopes; transitional soils lie on the slope elements of the relief, in which, as one approaches negative relief forms, the accumulation of mobile substances increases.

The structure of the soil cover. For the territory of any farm, often a separate field and even a small plot, a combination of several soils is characteristic.

The totality of soils of a particular territory is called its soil cover (SP). We can talk about the soil cover of the Earth, individual continents, countries, farms, their individual land plots, etc.

In his practical work, an agronomist always deals not with some kind of soil, but with all their diversity, which characterizes the soil cover of a particular territory. For rational use of the soil cover of a particular territory, it is important to take into account not only the properties and level of fertility of each soil of the site, but also to know how many contours, what size and shape each soil in this territory is represented, i.e. what PP pattern is formed by all the soils that make it up, how close or different (contrasting) these soils are in relation to each other in terms of their agronomic qualities, which determine the conditions and terms of field work, the set of cultivated crops, the use of fertilizers, etc.

An idea of ​​this is given by knowledge of the structure of the soil cover. (SPP). The theory of the structure of the soil cover is based on the concept of the elementary soil area (EPA). Elementary soil area - a plot of territory occupied by one specific soil of the lowest taxonomic level (category), limited on all sides by others ESA or non-soil formations (quarry, reservoir, etc.). The characteristic of ESA is determined by the name of the soil, the size and shape of the contour, as well as the dissection of its boundaries.<1 га), среднеконтурные (1-20 га), крупноконтурные (>20 ha).

Elementary soil areas, replacing each other, form soil combinations (PC), which characterize the SPP of a particular territory.

The most important characteristics of PCs are their component composition, the size of ESAs included in them, and the degree of agronomic difference (contrast) between them.

There are six (classes) of soil combinations. The larger the ESA area in the soil combination, the more homogeneous they are in terms of agronomic properties, the more favorable the SPP is agronomically. And, vice versa, the more (contrasting) one soil differs from another in the combination, the smaller the ESA area, the more unfavorable the SPP is in agronomic terms. In patchiness, the small size of ESA does not play a noticeable negative role, since the components of soil patchiness are similar (non-contrasting) in their agronomic properties. . There are three groups of SPP according to their agronomic qualities: agronomically homogeneous, agronomically heterogeneous compatible, agronomically heterogeneous incompatible.

Agronomically homogeneous SPP allow on plots (crop rotation fields, etc.) to apply the same set of agrotechnical and reclamation measures, to sow and harvest in the same optimal timing and get similar crop yields. Agronomically homogeneous SPPs can always be included in the same crop rotation field. Agronomically homogeneous soils are represented by patches, variations and tachets. For example, the SPP of a crop rotation field with a combination of spotting (small-contour stands) of medium-thick and thick chernozems or variations of soddy-weakly and medium podzolic loamy soils.

Towards agronomically heterogeneous compatible SPPs include territories that, when using soils of an array, require small differences in the systems of agrotechnical and reclamation measures, with their general uniformity. At the same time, the terms of field work on the contours of the soils of this structure are close, although the yields can differ markedly. Such WBS can be included in a single field. At the same time, it is necessary to carry out methods for leveling the fertility of soils that make up the SPP of the site. An example of agronomically heterogeneous compatible soils can be combinations of non-eroded and weakly eroded soils.

Agronomically incompatible NGNs require qualitatively different measures, do not allow the main field work to be carried out at the same time. They are usually not included in the same field. In some cases, they can be included in the composition of one field of specialized crop rotations (forage, soil protection). In this case, it is necessary to take into account the ratio of agronomically incompatible soils in the soil composition, the areas of their contours, the nature of the boundaries, their relative position, etc. As an example of the agronomic incompatibility of SPP, one can cite a combination of soddy-podzolic soils of upland and gentle slopes with strongly gleyed soils of hollows and hollows, a combination of non-saline and highly saline soils.