Agrogray Soils Research Articles

Assessment of spatial variability of agrochemical properties of agro-gray soil when planning a feld experiment with mineral fertilizers

The purpose of the work is to investigate the statistical parameters and patterns of variability of agrochemical indicators of agro–gray soil, elements of the structure of the spring wheat crop within the plots of the experimental field. Experimental data were obtained on the basis of observations conducted on agricultural landscapes Sukhobuzimskoye land areas in the Krasnoyarsk forest-steppe of the Krasnoyarsk geomorphological district, located borders the Chulym-Yenisei denudation plateau in the southwestern outskirts of Central Siberia. The results of the intra-field heterogeneity of the agrochemical properties of the agro-gray soil and the elements of the structure of the spring wheat crop on the site intended for field experiment are presented. The key statistical and geostatistical values of the intrafield heterogeneity are determined. The statistics of agrochemical indicators and the results of crop data from the plots intended for the placement of repetitions are analyzed. The materials of the agrochemical survey of the agro-gray soil revealed a low humus content. The level of spatial variation of the indicator corresponded to the average. The scope of variation is represented by values covering only one gradation of the evaluation scale. The entire studied area was characterized by a slightly acidic reaction of the medium according to the average pH values. Its variation in the 0-20 cm soil layer indicated uniformity of distribution in space. The level of variability of agrochemical indicators decreased in the following series: yield (40 %) > humus (19 %) > P2O5 (13 %) > K2O (10 %) > pH2O (4 %). According to the generalization of geostatistical information, the analyzed site is classified as unaligned in terms of soil fertility. In general, the soil fertility of the studied area had a significant variation, which determined the choice of elements of the field experience methodology. When laying out field experience, it is necessary to choose the appropriate elements of the methodology: a randomized method of placing repetitions, rectangular or elongated forms of plots.

Aggregate structure of agro-gray soils of Vladimir Opolye: composition and strength of aggregates

A complex of soils characteristic of the Vladimir Opole region was studied: agro-gray typical deep-arable soil, tongue-shaped agrozem and agro-gray gleyic soil. The high contrast of soil properties, which is due to the genesis of field landscapes, can be traced in the differences in the arable and subarable horizons of agro-gray soils at the aggregate and microaggregate levels. The soils have an excellent structural condition, high water resistance and mechanical strength of aggregates. In the aggregate structure of arable horizons, dependences on the position in the relief were found: down the slope the content of agronomically valuable aggregates decreases, the weighted average diameter of aggregates increases, the water resistance of aggregates and the mechanical strength of aggregates at capillary saturation decreases. However, the distribution and size of microaggregates, as well as the strength of aggregates in an air-dry state, reflects the complex genesis of the landscape and retains the influence of paleorelief with depressions and elevations. The weighted average diameter of microaggregates of arable horizons of the soils of the Vladimir Opole region is close to the chernozems of the Kursk region. The granulometric composition of the studied soils is typical of Vladimir Opolye soils and close to each other. In accordance with the classification of N.A. Kachinsky arable horizons are medium loamy, coarse silt, BT horizons are heavy loamy, coarse silt. The most structural is the arable horizon of agro-gray typical deep-arable soil, it has large microaggregates, it also has high water resistance and the highest content of agronomically valuable aggregates. The most homogeneous in terms of aggregate composition is tongue-shaped agrozem; the average diameter of aggregates and microaggregates in the arable and subarable horizons are equal and similar in the content of microaggregates and agronomically valuable aggregates. This soil is also highly water resistant. Agro-gray gleyic soil contains fewer agronomically valuable aggregates and its water stability is unsatisfactory.

Эколого-агрохимическая оценка устойчивости серой лесной почвы к воздействию загрязнения и урожайность картофеля при применении удобрений

The article presents studies in potato agrocenoses and an assessment of the gray forest soil of the Ryazan region using various levels of mineral and organomineral nutrition. It was found that to achieve an average level of stability, the buffering value of agro-gray soil should not be lower, according to the adsorption isotherm at a concentration point of 10 mM/l, 2 l/kg for zinc, copper, cadmium and lead. Exceeding the PBSgm value of 2-4 l/kg means a transition to a high level of stability. In the experiment on potato yield, the maximum yield was obtained on the variant with the action of an organomineral fertilizer system – 283.7 c/ha, which is 114.5 c/ha more than on the control variant (without fertilizers). We note the high yield obtained according to the variant with the action of the organomineral fertilizer system (248.2 c/ha, + 79.0 c/ha), which indicates the high efficiency of nutrition in the potato agrocenosis. Keywords: SOIL, POTATOES, NON-CHERNOZEM ZONE, POTATOES, YIELD, FERTILIZER

Влияние новых видов обогащенных удобрений на продуктивность культур и агрохимические свойства почв

The effect and aftereffect of new types of enriched sulfur-containing fertilizers on the productivity of spring wheat of the Novosibirskaya 31 variety and peas of the Radomir variety, as well as the agrochemical properties of leached chernozem and agro-gray soil of the Krasnoyarsk forest-steppe, characterized by an acute deficiency of mobile sulfur, were studied. It was found that the application of fertilizers containing sulfur statistically significantly increased the increase in productivity of pea biomass in the year of application. With the aftereffect of spring wheat, an increase in productivity was noted on leached chernozem; the aftereffect of fertilizers for wheat on agro-gray soil was not effective. The application of enriched fertilizers did not affect the acid-base balance of soils. In chernozem leached in all fertilized variants, the supply of mineral forms of nitrogen is high, while the content of mobile sulfur increases. The supply of nitrate and ammonium forms of nitrogen in agro-gray soil is low, and the amount of mobile sulfur does not increase. Keywords: SULFUR, ENRICHED FERTILIZERS, SPRING WHEAT, PEAS, AGROCHEMICAL INDICATORS, PRODUCTIVITY, AGROGY SOIL, LEACHED CHERNOZEM

Fractional composition of nickel compounds in soil and its accumulation in plants in application of growth promoting rhizosphere bacteriaon heavy metal-contaminated soil

Impact of genus Pseudomonas bacteria on fractional composition of nickel compounds in artificially contaminated agro-gray soil and yield of spring wheat was studied in pot experiment. Plants were grown up to booting stage with NiCl2·6H2O contamination at a rate of 300 Ni/kg of soil against background of NPK fertilization. Distribution of nickel in soil fractions isolated by the method of successive selective extractions has been established. Nickel content in plants after combustion in mixture of HNO3:HClO4 (2:1)and in soil fractions was determined by inductively coupled plasma emission-optical spectrometry. Application of bacteria increased plant resistance to elevated nickel concentration and increased yield, significantly reducing heavy metal phytotoxicity. Bacteria increased nickel content in exchangeable and specifically sorbed fractions and, to a lesser extent, in fractions associated with organic matter and ferruginous minerals, and reduced metal content in residual fraction. Bacteria increased nickel uptake from soil by plant shoots due to increase in yield, without changes or increase in plant metal content. Thus, bacteria increased phytoextraction - cleaning soil from heavy metal. Nickel uptake by plants was increased due to increase in its bioavailability, mainly in exchangeable and specifically sorbed fractions.

Spring wheat yield under application of growth promoting rhizobacterium in soil contaminated with nickel

Impact of growth promoting rhizobacterium Pseudomonas fluorescens 20 on the yield of spring wheat was studied in pot experiment. Plants were grown up to maturity when agrogray soil was contaminated with Ni as NiCl2·6H2O at a rate of 200 mg Ni/kg of soil against background of applying NPK fertilizers. After harvesting, content of nutrients N, P, K, Ca, Mg, Fe, Mn, Zn and Cu in grain, straw and roots was determined. N was determined by phenol technique. Resistance of plants to Ni toxicity was found under bacterial inoculation. Application of bacterium eliminated phytotoxicity of heavy metal and provided the same biomass production including grain as in control - in non-inoculated plants non-exposed Ni stress. Resistance of plants inoculated with bacterium to Ni toxicity was due to enhanced growth of root system and increase in content and accumulation of Ni in roots and, as a result this was not accompanied by increase in metal incorporation into aboveground organs. Resistance of plants inoculated with bacterium to Ni toxicity was due to enhanced growth of root system and increase in content and accumulation of Ni in roots. Application of bacterium also improved mineral nutrition of plants - increased nutrient uptake from contaminated soil. Increase in nutrient uptake by yield from contaminated soil as influenced by inoculation with bacterium was due to growth promotion and increase of plant weight in general without significant changes in content of most elements in aboveground organs and roots. Bacterium enhanced phytoextraction of heavy metal (soil cleaning) - increased Ni uptake by aboveground organs without significant changes in its content in grain and straw. Increase in Ni uptake by bacterially inoculated plants occurred without changes of soil medium reaction and was probably due to production of bacterial siderophores.

Assessing fertility complexity of Agro-gray soil on the East European Plain using correlation-regression analysis

According to classical concepts, soil fertility is an integrating indicator of soil properties. Correlation-regression analysis allows for the evaluation of the complexity of Agro-gray soil fertility in the East European Plain of Russia. The participation of all recorded soil properties and their equal contribution is the criteria for optimal assessment. The initial data array on soil properties divided into two clusters using the cluster analysis method. The absence of significant differences between clusters and some parameters in the model determined the need for correction. An acceptable level of fertility of Agro-gray soil established. The minimum requirements for the soil include 3.2% humus, 181 mg/kg of mobile phosphorus, and 144 mg/kg of exchangeable potassium pH and 1.5 mg-eq/100 g, respectively, the ratio of saturation of the soil with bases is not lower than 92%. With such a numerical combination of soil properties, the complexity of fertility ensured.

Content and Behavior of Heavy Natural Radionuclides in Tula Zaseki Gray and Agro-Gray Soils

Content and Behavior of Heavy Natural Radionuclides in Tula Zaseki Gray and Agro-Gray Soils

Application of Callopian clay to improve the productivity of zinc-contaminated soils in lawn ecosystems

Pollution of lawn soils with heavy metals leads to the suppression of life and activity of living organisms inhabiting these ecosystems. The use of various means of soil detoxification will make it possible to neutralize the effect of technogenic pressure on the functional properties of urban ecosystems. The article presents data on the sorption-fertilizing properties of Callovian clay when used in zinc-contaminated soils of lawn ecosystems. The study used a small-plot field experiment, which simulated artificial contamination of agro-gray soil with zinc. The article discusses 2 methods of tillage and 4 doses of fertilizer-sorbent. It was found that the use of Callovian clay led to an increase in the production of raw and dry phytomass of lawn grasses by 3.7 - 33.2%, microbiological activity of soils by 0.9 - 132.5 times, as well as a decrease in zinc toxicity by 10 - 25%. The sorption-fertilizing effect and the optimal doses of the applied Callovian clay were determined by the time when the Callovian clay was introduced into the soil (autumn or spring).

Features of the granulometric composition and properties of weakly and low-humus agro-gray soils in the Vyatka strip of the forest-steppe zone

Statistical parameters of agro-gray soil varieties obtained on the basis of generalization of information are the zero-monitoring cycle in the studied region and serve as reliable criteria for the diagnosis of these soils. Numerical indicators reflect the results of past and current soil processes. In agricultural production, the role of the arable layer with all the properties that determine the level of grain yield is especially important. Thus, in the studied varieties, there is a stable relationship between the amount of silt fraction, food elements, and humus. Thus, the clay variety is characterized by the highest fertility of the arable layer - an average content of mobile potassium (10.5 mg/100 g), an increased content of phosphorus (12.4 mg/100 g), low-concentration of humus (2.9%), close to neutral reaction of the medium (5.8 pH). Comparative analysis of soil formation products in the analyzed soil varieties shows their regular change in morphometric characteristics and properties of soils, reflects the result of soil formation processes, partly-economic activity.

Analysis of Tomographic Images of the Soil Pore Space Structure by Integral Geometry Methods

The technique of numerical analysis of three-dimensional tomographic images of the pore space of soil objects has been used in this paper. It applies methods of integral geometry, topology and morphological analysis. To characterize quantitatively the transformation of the pore space structure, tomographic images of four undisturbed soils were analyzed, i.e., heavy loamy agro-gray soil (Retic Phaeozem), agromineral (Sapric Rheic Mineralic Histosols), and hypnum (brown moss Sapric Rheic Histosols) peat soils in dry and wet conditions. For samples of the subplow horizon in agro-gray soil, a decrease in both Betty numbers was observed on wetting, where the zero number (b0) stands for the amount of topologically simple closed pores, and the first number (b1) indicates a decrease in pore connectivity, which varies in a narrower range of pore sizes as compared to b0. When a sample of agromineral peat soil is moistened, the Euler–Poincaré characteristic is negative ​in the pore range of 0.1–0.16 mm, which points to the predominating complicated branched structure of the pore space and high pore connectivity. When hypnum moss is saturated, a lot of tunnel pores get narrower (“collapse”), and the connectivity decreases due to the structural specifics of long-stemmed plant residues. The number of pores and connections between them in peat soils is an order of magnitude higher than those in the subplow horizon A of the agro-gray soil. The provided quantitative changes in the considered parameters of tomographic images of the soil pore space confirm the possibility of applying them for estimating the transformation of the pore space in soils.

The Influence of Mineral Nutrition on the Productivity of Spring Rape

This article presents data on the influence of mineral nutrition on the productivity of spring bird rape varieties in the conditions of the non-chernozem zone of Russia. The experiments were carried out on agro-gray loamy soils of the experimental agrotechnological station of the Federal State Budgetary Educational Institution of Higher Education “Ryazan State Agrotechnological University” (FSBEI HE RSATU) in the Ryazan Region in 2016-2018. A level of mineral nutrition for spring bird rape was calculated asN180P100K100. Based on this, the options for mineral nutrition in research were established. According to the results of the experiments, the duration of the growing season of spring bird rape varieties was established: 73-91 days.An increase in nitrogen to 150 kg of the active substance turned out to be less effective, as the yield increased slightly or remained at the level of N90P50K50. The use of phosphoruspotassium fertilizers did not contribute to the creation of such a nutritional regime that would increase seed productivity. An increase in the nitrogen nutrition of the plants led to increased protein content anddecreased oil content in seeds. This trend was observed in all varieties of spring bird rape. The average oil content was 38.5-45.5% and the average protein contentwas 18.0-24.7%, depending on the variety and the level of mineral nutrition. On average, the highest oil content was shown by varieties Lipchanka (44.1%) and Kulta (42.6%).
 Keywords: agro-gray soil, level of mineral nutrition, oil content, productivity, spring bird rape, variety

Miscanthus sacchariflorus В СИБИРИ: ПАРАМЕТРЫ ПРОДУКЦИОННОГО ПРОЦЕССА, ДИНАМИКА БИОФИЛЬНЫХ ЭЛЕМЕНТОВ

Throughout the world, bioenergy crops are grown to replace fossil resources and reduce greenhouse gas emission. Miscanthus is one of the bioenergetic plants that is widely cultivated in countries with optimal hydrothermal conditions. There is little research on the specifics of Miscanthus spp. cultivation in the continental climate. The aim of the study was a preliminary assessment of the possibility of Miscanthus cultivation in Siberia. The production process of Miscanthus sacchariflorus cv. Soranovsky (The State Register of Breeding Achievements, patent No. 6931 dated 06/06/2013) was assessed under conditions of the Central Forest-Steppe of Novosibirsk Ob (Novosibirsk Province, agro-gray soil, the experimental base of the Siberian Research Institute of Plant Cultivation and Breeding). During the formation of Miscanthus long-term stands (1-4 years), the aboveground biomass averaged 13 t/ha, the belowground biomass 17 t/ha. These figures are close to the average for this species in the world. The total N, P and K removal with biomass of stems and leaves was 51, 6, and 49 kg/ha, and with stems it was only 23, 3, and 26 kg/ha, respectively. Accumulation of N, P and K in the belowground biomass was 130, 10, and 126 kg/ha, respectively. Therefore, our experiment did not show any depletion of biophilic elements in soil during a four-year growth of miscanthus. Rough estimates have shown the presence of objective prerequisites for the atmospheric carbon sequestration in the fractions of the soil organic matter. During the first year of Miscanthus vegetation, at least 300 kg/ha of carbon accumulated in the mobile fractions of the soil organic matter; an increase in the C/N ratio in the belowground biomass of Miscanthus up to 74 vs. 20 in the initial soil was accompanied by a significant decrease in the mineralization rate of newly incoming plant residues. The parameters of the production process of Miscanthus sacchariflorus cv. Soranovsky on agro-gray soil in the Central Forest-Steppe of Novosibirsk Ob region correspond to the growth characteristics of M. sacchariflorus cultivated in other regions of the world on different soil types. We conclude that cultivation of M. sacchariflorus in Siberia is ecologically and commercially reasonable.

Miscanthus sacchariflorus IN SIBERIA — BIOLOGICAL YIELD PARAMETERS AND DYNAMICS OF BIOFILIC ELEMENTS

Throughout the world, bioenergy crops are grown to replace fossil resources and reduce greenhouse gas emission. Miscanthus is one of the bioenergetic plants that is widely cultivated in countries with optimal hydrothermal conditions. There is little research on the specifics of Miscanthus spp. cultivation in the continental climate. The aim of the study was a preliminary assessment of the possibility of Miscanthus cultivation in Siberia. The production process of Miscanthus sacchariflorus cv. Soranovsky (The State Register of Breeding Achievements, patent No. 6931 dated 06/06/2013) was assessed under conditions of the Central Forest-Steppe of Novosibirsk Ob (Novosibirsk Province, agro-gray soil, the experimental base of the Siberian Research Institute of Plant Cultivation and Breeding). During the formation of Miscanthus long-term stands (1-4 years), the aboveground biomass averaged 13 t/ha, the belowground biomass 17 t/ha. These figures are close to the average for this species in the world. The total N, P and K removal with biomass of stems and leaves was 51, 6, and 49 kg/ha, and with stems it was only 23, 3, and 26 kg/ha, respectively. Accumulation of N, P and K in the belowground biomass was 130, 10, and 126 kg/ha, respectively. Therefore, our experiment did not show any depletion of biophilic elements in soil during a four-year growth of miscanthus. Rough estimates have shown the presence of objective prerequisites for the atmospheric carbon sequestration in the fractions of the soil organic matter. During the first year of Miscanthus vegetation, at least 300 kg/ha of carbon accumulated in the mobile fractions of the soil organic matter; an increase in the C/N ratio in the belowground biomass of Miscanthus up to 74 vs. 20 in the initial soil was accompanied by a significant decrease in the mineralization rate of newly incoming plant residues. The parameters of the production process of Miscanthus sacchariflorus cv. Soranovsky on agro-gray soil in the Central Forest-Steppe of Novosibirsk Ob region correspond to the growth characteristics of M. sacchariflorus cultivated in other regions of the world on different soil types. We conclude that cultivation of M. sacchariflorus in Siberia is ecologically and commercially reasonable.

Using the principal component analysis to assess some properties of agro-gray soil and bonitet

To understand all the structural complexity of soil fertility, one can use the principal component analysis of factor analysis. Factor analysis, with all its shortcomings to identify structural relationships between variables, can be used to understand the complexity of soil fertility, by some assumptions. It can be estimated through bonitet. The work was carried out on the basis of materials from an agrochemical survey of agro-gray soils. Exchangeable acidity, mobile forms of phosphorus and potassium, humus, the sum of exchangeable bases and bonitet calculated in accordance with them were analyzed. The sample number was 68. Group 0 included bonitet with values less than 90 units and group 1 had bonitet with values more than 90 units. It was found that the contribution of exchangeable acidity and phosphorus to the first main component, which accounted for about 39% of the total dispersion, was maximum and equal to 0.7 and 0.84 units, respectively. Humus and potassium were positively associated with the second component (29% of dispersion) and their contribution was 0.7 and 0.81 units, respectively.

Влияние агрохимикатов на пространственно-временные изменения агрохимических свойств почвы и урожай брокколи

The aim of the study. The aim of the study was to examine the effect of agrochemicals (mineral and organo-mineral fertilizers, plant growth regulators and ameliorants) on the spatio-temporal changes in the properties of agro-gray soil and broccoli yield using a cartographic approach. Methodology. The field experiment was conducted in 2016 at the site located near the Bykovo village in the south-east of West Siberia (54°58 '02.8" N; 83°5'21.45" E, Novosibirsk region). The objects of the study were the agro-gray soil (Luvic Retic Greyzemic Phaeozem (Siltic, Aric)) and the medium-ripe broccoli cabbage variety "Linda". The experiment scheme included the following treatments: (1) Control (without fertilizers), (2) Background (N100P60K160), (3) Background + succinic acid, (4) Background + dolomite, (5) Background + mulch, (6) Organo- mineral fertilizer "Criall". Soil samples were analyzed for the content of organic carbon, nitrates, total, mineral and organic phosphorus, as well as its mobile form; exchangeable potassium, calcium and magnesium, and pH. The dried samples of broccoli inflorescences were analyzed for the total content of nitrogen, phosphorus, potassium, calcium and magnesium. Main results. After applying agrochemicals and harvesting broccoli, the variation coefficients of рН, mobile phosphorus, potassium and calcium increased by two or more times. The use of agrochemicals increased the yield and improved the nutritional value of broccoli inflorescences. The treatments with mineral fertilization (2, 3, 4 and 5) the treatment 2 (Background N100P60K160) provided the greatest return. The application of the studied agrochemicals resulted in the negative (acidification, binding of phosphorus, calcium and magnesium) and positive (increase in the content of elements) effects. The immobilization of nutrients (phosphorus, calcium, magnesium) in poorly soluble soil compounds and the respective decrease in the content of the elements’ mobile forms did not have a negative effect on the elemental composition of broccoli inflorescences. Thus, chemical immobilization, leading to the fixation of nutrients in the upper soil horizon, prevents their leaching by melt- and rainwater into the lower horizons.

Paleocryogenesis as a Factor of Heterogeneity of Agro-Gray Soil

Delineation of the features of paleocryogenic microtopography by zero-curvature morphoisographs on a test plot in the south of Moscow oblast enabled us to reveal the polygonal-blocky microrelief (microelevations, microdepressions, slopes, and runoff strips), forming eluvial, trans-eluvial, and trans-accumulative agrolandscapes. The soil cover pattern of eluvial agrolandscape includes elementary soil areas of noneroded, slightly eroded, moderately eroded, and aggraded soils. The agrolandscape is dominated by noneroded soils. The soil cover pattern of trans-eluvial agrolandscapes with microdepressions includes elementary soil areas of slightly, moderately, and strongly eroded soils, as well as eroded–aggraded and aggraded soils, with the dominations of slightly eroded soils. The soil cover pattern of trans-accumulative agrolandscapes also includes elementary soil areas of slightly, moderately, and strongly eroded soils; eroded–aggraded soils; and aggraded soils with the domination of strongly eroded soils. The paleocryogenic microrelief became the initial factor of the formation of elementary soil areas with different erosion rates during the long-term (200 years) agricultural use of these lands. Elementary soil areas with different erosion rates of the upper horizons are characterized by outcropping of underlying horizons of different textures. We have identified silt loam, light clay, and clay loam exposed to the surface by erosion on the studied plot. As a result, a complex soil cover pattern with differentiation of soils at the level of varieties (in Russian soil classification system, a taxonomic category based on the topsoil texture) was formed.

Remediation of Cadmium-Polluted Soil Using Plant Growth-Promoting Rhizobacteria and Natural Zeolite

The impact of two strains of Pseudomonas bacteria and natural zeolite on the growth and elemental composition of barley plants was studied in an agrogray soil (Luvisol) artificially contaminated with cadmium in pot experiments. Application of P. fluorescens 21, or P. putida 23, or zeolite eliminated the heavy metal toxicity for plants. The cumulative effect of co-application of P. fluorescens 21 and zeolite was insignificant. The bacteria- or zeolite-mediated plant tolerance to cadmium was attributed to the enhanced root system development, decreased cadmium translocation into the roots, and improved mineral nutrition of the plants. Elevated nutrient uptake by the plants under the influence of bacteria and zeolite was the result of plant growth stimulation without significant changes in the concentrations of macronutrients N, P, K, Ca, and Mg, as well as Fe and micronutrients Zn, Mn, and Cu in plant tissues, including grain. Application of P. fluorescens 21 enhanced the Cd fixation in the soil organic matter in the first half of the growing season, which could be due to the metal sequestration by bacterial siderophores. Thus, application of the bacteria and natural zeolite can be recommended in the strategies for Cd-polluted soil remediation based on environment-friendly technologies.

Relationships between the Size of Aggregates, Particulate Organic Matter Content, and Decomposition of Plant Residues in Soil

The distribution of total organic matter (Corg), particulate organic matter (CPOM), and potentially mineralizable organic matter (C0) in mega- (10–5 and 5–2 mm), macro- (2–0.25 mm), and microaggregates (<0.25 mm) isolated by dry sieving from gray and agrogray soils (Luvic Retic Greyzemic Phaeozems) of different land uses was studied. In the soils under forest and meadow, the highest Corg content was detected in the megaaggregates of 5–2 mm in size (43 and 37% of Corg in whole soil sample, respectively), whereas in the arable soil, it was found in macroaggregates (45%). In the uncultivated soil, the CPOM was mainly accumulated in megaaggregates (65–72% of the CPOM in the whole sample); in the arable soil, it was equally distributed between mega- and macroaggregates (46–45%). The fine (0.25–0.05 mm) CPOM subfraction in the uncultivated and arable soils contained 1.3- and 2.3-fold more carbon, respectively, as compared with the coarse (2–0.25 mm) CPOM subfraction. The C0 content in the aggregates correlated with CPOM and Corg. Decomposition of plant residues with a wide C : N ratio in soil increased with a decrease in the aggregate size. However, aggregate size did not influence the decomposition of plant residues with a narrow C : N ratio. The effect of aggregate size on the decomposition rate mainly appeared at the early stages of transformation of plant residues.

Evaluation of anthropogenic sustainability of agro-gray forest soil in intensive agriculture by change of its biological activity indicators

Studies have been carried out with the identification of criteria for the anthropogenic stability of agro-gray forest soils according to the main indicators of biological activity under conditions of intensive farming. Soils of this type are dominant in the soil cover of the Republic of Tatarstan, so the results of the experiment can be widely interpolated to similar conditions of soil formation and serve as quickly defined markers for diagnosing anthropogenic pressure. Studies have been carried out in field crop rotation since 1992, using various doses of potassium at three levels of soil nitrogen supply. As a result of long-term use of fertilizers, changes in microbiological activity have been revealed, in the variant with the use of environmentally balanced doses of mineral nutrition, an increase in microorganisms from 3,400 thousand (control) to 4,000 thousand per 1 g of soil is observed. A subsequent increase in the dose of fertilizers led to a decrease in the number of microorganisms relative to the control. Under the influence of the optimal combination of fertilizers (option 3), conditions for the development of actinomycetes, ammonifiers, nitrifiers, cellulose-decomposing bacteria are improved, while very high doses of mineral fertilizers (N180P60K200) worsen them, indicating a decrease in the activity of beneficial bacterial microflora. This leads to a slowdown in decomposition of fiber, nitrification and other biochemical processes. Indicators of the biological activity of the soil correlate among themselves, as well as with other indicators of its fertility, with the productivity of crop rotation and therefore can serve as an additional diagnostic sign when assessing the anthropogenic stability of the agricultural soil of the agricultural soil in intensive agriculture.