Virgin Soil Research Articles

Utilization of Coffee Husk Ash on the Geotechnical Properties of Gypsum-Stabilized Expansive Clayey Soil

Expansive clayey soils (CSs) expand and become softer as moisture content increases, but they get harder and stronger as they dry out. The earth’s swelling and shrinkage characteristics under varying moisture conditions make roads built on expansive CS, in particular, vulnerable to early degradation. In this investigation, coffee husk ash (CHA), gypsum, and a blend of the two additives (G-CHA) were used in experimental tests to treat expansive CS. This study aims to evaluate experimentally the potential of expansive soil stabilization using different additives: CHA, gypsum, and a combination of gypsum and CHA. Five different percentages of CHA (5%, 10%, 15%, 20%, and 25%), three percentages of gypsum (3%, 6%, and 9%), and variable percentages of their combinations were used to stabilize the soil for pavement subgrade application. Atterberg limits, compaction, linear shrinkage (LS), swelling, unconfined compressive strength (UCS), and California bearing ratio (CBR) tests were performed on treated and virgin soil specimens at 3, 7, 14, 28, and 56-day curing times. Results showed that CHA additives effectively reduced the plasticity, LS, and swell potential in addition to increasing the maximum dry unit weight, UCS, and CBR. It was determined that the UCS and CBR values for the 6% stabilized gypsum soil increased by 28.95% and 19.54%, respectively, and reduced by 41% of the plastic index parameter after the addition of 15% CHA. Based on the evaluation of the results, an optimum mixture of 6% gypsum and 15% CHA (SG6C15) stabilized soil can be used in pavement subgrade applications as it achieved the minimum strength target. The performance of CHA-treated samples as subgrade material is superior to that of untreated virgin soil. Because of the stronger subgrade, smaller pavement layers result in a thinner pavement structure.

Kant and “tabula Russia”

The article offers an attempt to understand the present state of Kant’s legacy in Russia on the threshold of the Tercentenary. An explanans is found in the metaphors of “tabula rasa” and “unplowed virgin soil,” first used by Leibniz in relation to Russia in his letters and memoranda addressed to tsar Peter I and other members of the Russian elite, which became the country’s “absolute metaphors to live by” up to present time. Several known and unknown episodes from the history of the reception of Kantian ideas, his followers in Russia, and the transformation of the urban environment of Kant’s life in Königsberg, as it was becoming Kaliningrad, are presented through the prism of this metaphor. Without hoping to make specific recommendations of any use from such metaphorical grounds, this study aims to emphasize the depth, interconnectedness, and basic, metaphysical tension of the relationship between Europe and Russia, which cannot be terminated at will by either side, or by a third party. In a situation where the sides are doomed to dialog, Kant, appropriated by Russia as its “subject,” occupies the unique position of mediator of philosophical understanding and peaceful action.

Performance evaluation of Alccofine stabilised Marine clay as subgrade

Soil stabilization is a remedial measure that reduces permeability and compressibility, increases bearing capacity and shear strength of soil mass, which helps in reducing the settlement of structures. Marine clay is one of the major regional soil deposits in India, widely found in offshore and coastal areas. This is a type of low strength soft clay which majorly causes failure in pavements and foundation structures due to high settlements and low strength characteristics. The scope of this project is to improve the strength of marine clay by stabilizing it with alccofine. The work includes determination of index properties of marine clay by Hydrometer method, Atterberg’s test, Specific Gravity test, Free Swell test. The engineering properties of both virgin soil and soil stabilized with 3%, 6%, and 9% of alccofine are determined by various tests such as Standard Proctor test, California Bearing Ratio test. On the basis of CBR test, the optimum percentage of alccofine in marine clay is found out to be 6%.

Effect of Active Si on Phosphate State in Sod-Podzolic Soils

Samples of the upper horizon of sod-podzolic virgin and arable soil were incubated with lime or superphosphate, then amorphous silicon dioxide was introduced in doses from 50 to 5000 kg/ha and incubated again for 2 weeks. The content of water-soluble and acid-soluble forms of silicon in soils was determined and the fractional composition of phosphorus compounds was analyzed. It is shown that an increase in the concentration of monosilicon acid in the soil solution of sod-podzolic soil initiated the processes of transformation of phosphorus compounds, leading to a decrease in the proportion of insoluble forms of phosphorus and an increase in the phosphorus content available to plants. The introduction of lime or phosphorus fertilizer contributed to the strengthening of these transformational processes, which is important for the development of recommendations for the practical application of silicon fertilizers and the reduction of doses of phosphorus fertilizers.

Characterization of black cotton soil by using granulated blast furnace slags

Soil stabilization is the best way to enhance the characteristics of low-quality soil. The properties may include, permeability, compressibility, strength, durability, etc. It is required when there is a need for construction on the poor sub-soils that are not suitable for that particular construction. Black cotton soil (BC) has a high clay content and is also considered as compressible soil with shrinkage and swelling characteristics and a constrained bearing capacity. It expands during the rainy season due to water absorption and contracts during the summer, which gives rise to serious structural deterioration. This study targets to stabilize this black cotton soil using ground granulated blast furnace slags (GGBS). It is a by-product of iron found in the blast furnace. It is extremely cementitious and contains a large amount of calcium silicate hydrates that increase its durability, strength, and appearance. In this study, GGBS is used at different percentages such as 5 %, 10 %, 15 %, 20 % and 25 %. Sodium hydroxide is also added in various dosages from 0.5 M, 1 M, 2 M, 4 M and 6 M. The major goal of this study is to investigate how GGBS affects the engineering parameters such as Atterberg’s limit, differential free swell (DFS), Compaction characteristics (i.e., maximum dry density (MDD) and optimum moisture content (OMC)) and unconfined compressive strength (UCS). The durability characteristics of soil-GGBS mixtures are also studied. Results show that as compared to virgin soil, adding 25 % of GGBS to BC soil resulted in an increase in MDD of around 16.5 % and a decrease in OMC of about 29 %. Further, it is also found that compared to (Soil + 20 % GGBS), the UCS value of the (Soil + 20 % GGBS + 4 M NaOH) mixture increased by roughly 36.5 %. Finally, the optimum concentration of GGBS content is found as 20 % while treated with 4 M NaOH solution.

Физико-химическая оценка почвы в технологии выращивания озимого тритикале

In the experiment, it was found that the productivity indicators of the aboveground mass of winter triticale of the Tribune variety and the content of nitrogen, phosphorus and potassium in their plant tissues are generally consistent with water-physical, physico-chemical parameters and with soil bonification data. It was found that there were no differences in the mass of green leaves and the dry mass of the aboveground part of triticale on chernozem typical of agrocenosis and virgin soil. Of the forest soils, the smallest mass of triticale leaves was obtained on gray forest and turf alluvial, and the largest on sod–podzolic light loamy soil. Plants with massive leaves were also obtained on alluvial meadow soil of the same light loamy granulometric composition. The water content of triticale leaves, as a rule, does not depend on soil fertility. Only on the chernozem-meadow soil of the trunk strips of the apple orchard, in contrast to the row-to-row soil, the hydration of the leaves turned out to be significantly higher. This can be explained by a less acidic reaction, greater hygroscopicity and nitrogen content in the soil of the trunk strip. In summary, winter triticale plants are recommended to be used as a test crop when assessing the degree of soil cultivation. Keywords: WINTER TRITICALE, DEGREE OF CULTIVATION, BIOINDICATION, APPLE ORCHARD, NATURAL LANDS

Permeability and Cracking of Compacted Clay Liner Improved by Nano-SiO2 and Sisal Fiber

The landfill liner is the last line of defense to protect the soil from damage, but it is difficult to satisfy both impermeability and crack resistance requirements with conventionally compacted clay. This paper proposes a new composite material to enhance the anti-seepage and anti-cracking properties of clay as a solution to this problem. In this Study, the effects of two single amendment materials, Nano-SiO2 (6 dopings) and sisal fiber (SF) (4 dopings), and a composite amendment material (Nano-SiO2+SF), on the permeability and cracking resistance of the improved clay were investigated by infiltration tests and dry-wet cycle tests, respectively. The nuclear magnetic resonance test (NMR) test reveals the microscopic pore changes of soil and explore the reinforcement mechanism. The findings of penetration experiments demonstrate that Nano-SiO2 and SF, both single and composite components, can increase the modified clay's impermeability. The optimum content of Nano-SiO2 is 3%, and its permeability coefficient is 5.09 × 10−8 cm·s−1, which is two orders of magnitude lesser than that of virgin soil. The results of three dry and wet cycle tests showed that the overall trend of fracture length and cracking factor (CIF) increased with the increase of the number of de-wetting. After the third de-wetting of the modified clay, 0.75% Nano-SiO2 + 0.3% SF is the optimal dose, which reduces the fissure length by 19.94 times and CIF by 27.25 times compared with the three de-wetting of the plain clay. As a whole, the data demonstrates that the composite Nano-SiO2 and SF are able to make up for the shortcomings of each component. It can simultaneously improve the anti-seepage and anti-cracking properties of the enhanced clay. The test results provide a certain benchmark for the impermeability and anti-cracking of landfill liners.

The image of a "new woman" in the novel "Virgin Soil" by I. S. Turgenev and in the short story "Mourning the Dead" by Lu Xun

The object of this article is the image of "new woman" in Russian and Chinese literature. The subject of the study is the correlation between the characters of two heroines, Zijun and Marianna, who are the bearers of a new female identity, in the story "Mourning the Dead" by Lu Xun and the novel "Virgin Soil" by I. S. Turgenev. The aim of the study is to identify the main factors that determined different outcomes of the storyline of these characters, despite the similarity of their fates. In order to achieve the set goal, it is necessary to solve the following tasks: 1) to reveal the personality of the two characters by analyzing their life path, as well as the beginning and end of their respective love; 2) to analyze the author's intention based on the socio-historical context of the period of creation of these two works. The following methods were used during the study: comparative method, method of holistic analysis of a literary work, as well as cultural-historical method. The scientific novelty of the work lies in the fact that the article is the first attempt to compare Lu Xun's short story "Mourning the Dead" with I. S. Turgenev's novel " Virgin Soil ", with special attention paid to the opposite denouement of the stories of Zijun and Marianna. Based on the analysis, it is concluded that the outcome of the fates of these heroines is directly related to their perceptions of their own lives and love, which are conditioned, in turn, by the different intentions of the authors regarding the logic of the development of their characters. The scientific significance of the study lies in the fact that the data obtained not only reveal the ideas about the image of the "new woman" in general, but also contribute to a deep comparative understanding of the analyzed books, which can contribute to the field of comparative literary studies between Russia and China.

Experimental Investigation on the Post-liquefaction Behavior of Sands in Simple Shear Conditions

Abstract Experimental evidence shows that earthquake induced liquefaction can occur more than once in sandy soils. Moreover, despite an increase in soil density caused by the dissipation of the excess pore pressure induced by earthquakes, the liquefaction resistance of soils that have experienced liquefaction may be lower than that of virgin soils. This paper offers insight into this topic starting from the analysis of the undrained monotonic behavior of post-liquefied sands by means of tests performed with a simple shear cell equipped with flexible boundaries, which maintains a constant diameter to guarantee the “K0-condition.” The control system of cyclic, reconsolidation, and monotonic phases is described in detail. The experimental results show that neither the relative density, effective confining stress, cyclic stress ratio, nor the direction of shear strain play important roles in the monotonic behavior of post-liquefied soils. Moreover, the comparison between the monotonic response of virgin and post-liquefied soils (prepared by moist tamping technique) shows that it is not affected by the stress–strain history experienced by soils. It can be explained through a microstructural interpretation. According to which, the initial soil fabric generated with the moist tamping method and that formed during liquefaction remain almost unchanged because of the rotation of principal stress directions occurring during simple shear tests. A further confirmation is given by the results of tests performed on specimens prepared by air pluviation method.

Effect of calcined clay on the improvement of compaction, swell and microstructural characteristics of expansive soil

Expansive soil is problematic soil because its alternate swell shrink behaviour depends on the presence of water. Soil stabilization technique was widely adopted to alter the characteristics of the expansive soil which is suitable for construction. Among the various soil stabilization techniques, chemical stabilization was found to be more suitable method of sustainable stabilizing the soil due to its effective and timely reaction with the chemical compound. Calcined form of clay material is used as an admixture to study the effects on the improvement of soil properties. Calcined Clay (CC) is added into the virgin soil with different percentages of 2%,4%,6%,8% and 10% under varying 1,3,7,14,28 and 60 days of curing by conducting experiments such as standard proctor test, Free Swell test to analyse the compaction characteristics and swelling behaviour of the soil. In addition to that the X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) on virgin and treated soil were studied by varying 2% incremental of CC up to 10% at 28 days of curing. From the test results it shows the variation in the compaction characteristics by rising in Maximum Dry Density (MDD) and reduction in Optimum Moisture Content (OMC) that merges at 8% as an optimum to develop the soil behaviour and from the free swell test, it was found that the Free Swell Index (FSI) of the soil decrease from 210 to 80 at 10% calcined clay added soil and the Mineralogical studies also show the variation in the compounds. Thus, this naturally available calcined clay was used to improve the soil Compaction and swell characteristics that influences the reduction in deformation and increase in shear strength of soil which helped to minimize the environmental problem as well as one of the effective admixtures to improve the expansive soil characteristics.

Nitrogen regime of soddy-podzolic soil with long-term use of different types and combinations of mineral fertilizers

The purpose of the work is to study the effect of various types and combinations of mineral fertilizers on the fractional composition of nitrogen in soddy-podzolic soil in a long-term stationary experiment and compare it with a virgin analogue. The studies were carried out in 2016 and 2018 on the experimental field of the Perm Research Institute of Agriculture after harvesting barley in an eight-field crop rotation deployed on soddy-podzolic heavy loamy soil. The experiment scheme: without fertilizers: N90; Р90; К90; N90P90; N90K90; P90K90; N90Р90К90. To assess the effect of nitrogen, phosphorus, potash fertilizers and their combinations on the nitrogen regime of soddy-podzolic soil, the arable soil was compared with the virgin analogue. The nitrogen fund of soddy-podzolic soil of a long-term stationary experiment is represented by 64…71 % non-hydrolyzable and 17…22 % hardly hydrolyzable forms of nitrogen. Long-term use of various types and combinations of mineral fertilizers did not significantly change the ratio of nitrogen fractions characteristic of virgin soils of this type. Nitrogen fertilizers, both with one-sided application and in combination with potassium chloride (N90К90) and superphosphate (N90P90), contributed to an increase in the total nitrogen content in the arable soil layer by 10…20 % relative to the control, mineral nitrogen compounds - by 2…3 times. Unilateral application of potash fertilizer provided an increase in the content of total nitrogen in the soil by 12 %, the introduction of superphosphate did not have a signi cant effect on the nitrogen regime of the soil. Long-term use of complete mineral fertilizer (N90P90K90) only in this way: (N90P90К90) contributed to maintaining total nitrogen at the level of virgin soil - 1490 mg/kg. Long-term unilateral application of nitrogen fertilizers increased the content of nitrate nitrogen in the soil over the entire meter layer by 1.5-2.5 times, ammonium - by 1.5-14.6 times. The reserves of mineral nitrogen in the variants N90P90, N90K90, and N90P90K90 in the 0-20 cm layer increased 2-3 times, in the 0-100 cm layer - 2 times relative to the control variant.

Assessment of natural radioactivity levels in soil samples from Dejen district, Ethiopia.

Gamma ray spectrometry was used to determine the activity concentrations of naturally occurring radionuclides in 12 soil samples collected at random from Dejen district, Ethiopia. In agricultural soils, the calculated mean activity concentrations of 226Ra, 232Th and 40K were 33.44 ± 2.01, 66.02 ± 4.54 and 214.16 ± 8.90 Bq kg-1, respectively, and in virgin soils, they were 38.05 ± 2.48, 61.78 ± 4.76 and 240.32 ± 10.79 Bq kg-1, respectively. The findings were discussed and compared to other studies' findings. The mean values of absorbed dose rate, annual effective dose rate and radium equivalent activity in agricultural land soils are 67.24 nGyh-1, 0.083 mSvy-1 and 144.57 Bq kg-1, and in virgin land soils are 67.53 nGyh-1, 0.082 mSvy-1 and 144.90 Bq kg-1, respectively. These findings were discussed and compared to the internationally recommended value. As a result, it is possible to conclude that the soil samples are safe for residents and those involved in agricultural activities.

Microbiological parameters as an indicator of acrogenic transformation of medium solonetz by forage crop rotations

Vast territories of Western Siberia (about 40%) are saline. On such lands, perennial grasses - phytomeliorants are mainly grown. The article presents the results of a four-year study of plant-microbial interactions in medium-sodium solonetz under fodder crop rotations with sweet yellow clover and awnless brome. The studies were conducted in the Baraba lowland, where crop rotations using layer-by-layer tillage were cultivated at the SSRIF (Siberian Scientific Research Institute of Feed) station for 33 years. In a six-field crop rotation with sweet clover in the first field, sweet clover of the Alsheevsky variety was sown with a cover crop – Sudan grass of the Novosibirskaya 84 variety; the second field was occupied by sweet clover; the third field was planted with Krasnoobsky oats. After that, everything was repeated all over again. In the crop rotation with rump, millet Kormovoe 45 was buried in the first field; in the second field, an awnless brome cultivar of the Siberian Scientific Research Institute of Agriculture -189 and millet were planted. Then the rump grew for four years. As a result of tillage and long-term exposure to phytomeliorant herbs in the 0–20 cm layer of medium solonetz, the biodiversity of bacteria has changed, the nitrification activity of the soil has increased by 1.9–2.3 times (primarily affecting the productivity of grasses cultivated in crop rotations). Under the sweet clover, the process of microbiological humus accumulation was activated. Using metagenomic analysis of 16S rRNA, four taxonomic groups of bacteria (phyla) were identified, significantly different from the virgin soil. In both crop rotations in the average solonetz, under the influence of agrobiological reclamation, the proportion of bacteria of the phylum firmicutes, mineralises of complex nitrogen-containing substances and producers of plant growth stimulants, as well as beta- and deltaproteobacteria, functionally associated with improving soil fertility, increased. Under the rump, the representation of Chloroflexi, indicators of soil density, significantly decreased.

Роман И. С. Тургенева «Новь» в Китае: переводы и значение

After the publication of I. S. Turgenev’s novel “Virgin Soil” (1877), in which the author touches on the topical social theme of the 1870s (the failure of the mass populist movement “going to the people”), an acute literary controversy arose around the work. In general, criticism in Russia and abroad considered the novel a creative failure of the writer. For this reason, with all the interest in the Russian classic’s creative work, this novel has been relatively little studied in China. The aim of the paper is to identify the reasons for the interest in Turgenev’s most ambitious work in China and to determine the “reception vectors” in their historical and cultural determinacy and chronology based on a comprehensive review of all the existing translations of the novel “Virgin Soil” into Chinese published in China from 1925 to the present. The paper offers the author’s periodisation for the history of the perception of Turgenev’s novel by Chinese readers in the context of socio-cultural and historical processes in the country. The research is original in that it is the first to systematise the history of translations of the novel “Virgin Soil” in China and the reviews of Chinese cultural figures on the novel. The research findings showed that the appearance of translations of Turgenev’s novel “Virgin Soil” is closely related to a number of socio-cultural and historical factors of each studied period.

Soil Enzyme Activity in Natural and Ploughed Catenas as Parameters of Physiological State of Microbial Communities

The study of soil microbial biomass and enzymatic activity of natural and anthropogenically transformed ecosystems was carried out. The catenas of virgin luvisols and chernozems of the Belogorye Natural Reserve and the catenas of arable soils were studied under similar geomorphological and lithological conditions. The activities of enzymes involved in the cycles of carbon (β-glucosidase and xylosidase), nitrogen (chitinase), and phosphorus (acid and alkaline phosphatase) was studied. It has been established that a decrease in soil microbial biomass as a result of ploughing is not accompanied by an equivalent decrease in the enzymatic activity of the soil. Differences in the enzymatic activity of different soils types were revealed, which indicates differences in the structure of the microbial community and the type of phytocenoses. Patterns of changes in the enzymatic activity of soils in watershed areas, in the transit and accumulative parts of catenas have been established. The values of specific enzymes activities (enzymatic activities per unit of microbial biomass) were calculated. The obtained patterns of changes in the specific enzymatic activity of arable soils indicate that, despite the loss of organic matter and a decrease in microbial biomass as a result of plowing, the physiological efficiency of the microbial community of agrochernozem is higher than in virgin soil. High specific enzymatic activity in arable soils is associated with higher rate of enzyme production by soil microorganisms due to land use changes.

Философия или история философии: анализ инверсивных отношений

The article examines the current situation related to the prospects for further development of philosophical knowledge. It is pointed out that in the interpretation of a number of authors, philosophy is now actually reduced to the history of philosophy, turning into a purely historical discipline. Philosophical thought boils down to the analysis and systematization of what was created before, but not to the free search and creation directed to the future. The current situation has been created due to the practice in which every thought does not arise by itself, but is necessarily based on previously expressed thoughts. Philosophy deals mainly not with the actual, but with the previously described and interpreted reality. Therefore, it is almost impossible for modern philosophers to create on virgin soil. In addition, the amount of philosophical knowledge has reached such a volume that it is almost impossible to keep it within individual human memory. A significant part of philosophical research at present is actually aimed at studying the history of philosophy, while such works sometimes do not contain their own thoughts at all. This situation is considered in philosophy as a systemic inversion: the service, subordinate element of the system acquires a dominant meaning in it. Of course, the role of the history of philosophy in this discipline itself cannot be disputed. Philosophy is a kind of cumulative knowledge in which the past is inseparable from the present and the future. However, it is impossible to identify the history of philosophy with philosophy itself, because this approach closes any path leading to the future for philosophical thought. It is implied that philosophers from now on should be engaged exclusively in rethinking what was created earlier. The further development of philosophical thought with this approach is actually denied. However, Aristotle pointed out that even the complete denial of philosophy implies the use of philosophical argumentation, and therefore, willingly or unwittingly forces one to accept the existence of a philosophical discipline. The most important point is that philosophy is a discipline of interest not only for philosophers themselves. Philosophy is not a ‘toy for philosophers’, it is a cognitive tool that is in demand in all other areas of human knowledge. And since science and practice as a whole continue to develop, philosophy will remain in demand precisely as a living, developing discipline, and not as a frozen collection of accumulated thoughts.

Laser induced breakdown spectroscopy for strength assessment in Ca binded soils

In this study, two distinct types of soil having different parent mineral (WS: White Soil and RS: Red Soil) is chosen and efforts are made to identify the presence/influence of Calcium (Ca), on these bulk soil solids following chemical processing. The two doped samples are named as “WS_DOPED” where Ca is doped in White Soil and “RS_DOPED” with Ca doped in Red Soil. Laser Induced Breakdown Spectroscopy (LIBS) is performed on the surface of these soil samples to understand the variation in spatial deposition of Ca with different soil matrices. Also, the influence onto the compressive strength of the soil samples is probed using LIBS. Using LIBS the ratio of ionization to the neutral state of the most predominant element “Silicon (Si)” in these samples are compared to the unconfined compressive strength of the WS_DOPED and RS_DOPED soil samples which is found to be 13.6 kPa and 15.7 kPa respectively wherein the virgin soil samples are non-cohesive in nature. Also, a comparison of LIBS with EDX measurements is carried out wherein LIBS found to be more sensitive towards detecting trace elements.

Feasibility of soil oxidation-reduction potential in judging shear behaviour of hydrocarbon-contaminated soil

This study investigates the indicative role of oxidation-reduction potential (ORP) and pH of hydrocarbon-contaminated soils on their shear characteristics, contributing to safer and more efficient ex-situ remediation and management processes. The presence of hydrocarbons alters the soil's shear strength by affecting the hydration shell thickness, fluid's dielectric properties, and ion/electron exchange, as well as the soil's electrochemical force, which in turn affects the ORP and pH. The relationship between hydrocarbon concentrations in contaminated soils (0.1–15%) and corresponding ORP/pH values could be fitted linearly with a good correlation coefficient r (0.978), highlighting the potential of ORP/pH as an indicator for pollutant occurrence. Furthermore, the relationships between ORP/pH and shear strength, as tested in our study and obtained after processing from relevant literature sources, exhibited a strong fit (r = 0.976–0.995). The Mohr-Coulomb criterion modified using the ORP/pH parameter was established, which could improve the fitting effect of these relationships (r = 0.988–0.996), verifying the reliability of the novel criterion and application feasibility of ORP/pH. In future research, this modified criterion can be employed to conveniently assess the shear strength of contaminated soil by considering the shear behaviour of virgin soil and the ORP/pH values of the contaminated soil.

Characterization of an antimicrobial pentapeptide produced by a drug-sensitive Pseudomonas aeruginosa strain PAST18

The members of the genus Pseudomonas can secrete a wide range of ribosomally encoded antagonistic peptides and proteins, ranging from small microcins to large tailocins. In this study, a drug-sensitive Pseudomonas aeruginosa strain isolated from a high-altitude virgin soil sample showed a broad range of antibacterial activity against Gram-positive and Gram-negative bacteria. The antimicrobial compound, purified by affinity chromatography, ultrafiltration, and high-performance liquid chromatography, showed a molecular weight (M + H)+ of 494.7667 daltons, as revealed by ESI-MS analysis. The MS-MS analysis divulged the compound as an antimicrobial pentapeptide with the sequence NH2-Thr-Leu-Ser-Ala-Cys-COOH (TLSAC) and was further verified by evaluating the antimicrobial activity of the chemically synthesized pentapeptide. The extracellularly released pentapeptide, which is relatively hydrophobic in nature, is encoded in a symporter protein, as appraised from the whole genome sequence analysis of strain PAST18. The influence of different environmental factors was examined to determine the stability of the antimicrobial peptide (AMP), which was also assessed for several other biological functions, including antibiofilm activity. Further, the antibacterial mechanism of the AMP was evaluated by a permeability assay. Overall, the characterised pentapeptide, as revealed in this study, may find use as a potential biocontrol agent in various commercial applications.

An acid-base buffering model to describe pH buffering capacity of an acid albic stagnic luvisol under long-term agricultural land use and management

Aim. To study acid-base buffering capacity depending on the intensity of different fertilization systems, including lim- ing, with different doses of CaCO3 in a long-term (55 years) stationary experiment on Albic Stagnic Luvisol (light grey forest surface-gleyed soil). This study should serve as a basis for the restoration and protection of fertility and yield and preservation of ecological restorative functions of this soil type. Methods. Field stationary experiment, using monitoring, laboratory-analytical and statistical-mathematical methods. Results. It was found that after 35 years of a seven-field crop rotation the exclusion of the intensive crops of sugar beet, potato and one winter wheat, in combina- tion with low (2.5 time less) mineral fertilization levels, contributed to an increase in resistance to acidification over the next 20 years from 5.53 to 7.48 points (using a 100-point scale) with a simultaneous increase in soil рНКСl from 3.77 to 4.12. Organo-mineral fertilization (N65P68K68 + 10 t manure/ha of crop rotation area) and periodic application of CaCO3 by hydrolytic acidity (6.0 t/ha) and an optimal dose of lime (2.5 t/ha CaCO3) increased pH buffering over these 20 years in a four-field rotation. The general evaluation index of buffering was 21.8–21.9 points, exceeding the virgin soil by 1.9 to 2 points. In the control variants without the use of fertilizers the general evaluation index of buffering was 14.3 ± 0.3, and the coefficient of buffer asymmetry was the highest – 0.646 ± 0.013, which under these conditions indicated the danger of soil losing its ability for self-regulation and self-healing. Conclusions. The resis- tance of Albic Stagnic Luvisol to acidification increased most in the combined application of N65P68K68 and 10 t/ha manure, together with an optimum calculated dose of lime in a 4-year crop rotation. An optimal dose of CaCO3 (2.5 t/ha) and organo-mineral fertilizing system in a 4-year crop rotation improved the soil buffering capacity of the acid shoulder by 2.45 points compared to the mineral fertilization system. To support a determination of acid-buffering effects graphic charts representing pH buffering capacity proved to be useful and could be instrumental in diagnostics and optimization of the acid-base regime for acid forest soils in general.