Soil Zone Research Articles

GRAIN YIELD AND SIDERAL MASS OF FIELD CROPS IN CROP ROTATIONS OF THE LOWER VOLGA REGION

Background. For the first time in the abiotic conditions of the Lower Volga region on light chestnut soils, new methods of biologization of soil fertility preservation and specialized field crop rotations based on the replacement of pure steam with sideral steam with little–studied crops for green fertilizer – biennial yellow clover, oats and phacelia were developed and studied; the structure of sown areas includes cultures of various biological groups, including cereals, legumes, oilseeds, rowed and perennial legumes; in addition to siderates, organic fertilizers are used in the form of straw and crop –root residues of cultivated crops. The purpose of the work is the influence of pure and sideral steam on the yield of field crops Materials and methods. The study of the influence of sideral masses on the yield of grain crops in field crop rotations in the conditions of the Lower Volga region. Results. According to the conducted research, it has been established that biologized crop rotations are the first major stage in the transition to organic farming in the Volgograd region. The best option for the soils of the dry-steppe zone of chestnut subzones of light chestnut soils of the Lower Volga region is a four-field biologized field crop rotation and a five-field crop rotation with sideral steam (donnik). Conclusion. Data analysis showed that the best indicators of winter wheat yield were obtained for pure and sideral (sweet clover) pairs - 1.8 t/ha, chickpeas for the predecessor winter wheat in the five–field crop rotation - 0.87 t/ha and spring barley for the predecessor chickpeas – 1.48 t/ha.

Эколого-биологические методы формирования устойчивых лесомелиоративных комплексов в степных и полупустынных ландшафтах европейской территории России

The arid region of the European territory of Russia includes a zone of dry steppe (dark chestnut soils) and a semi-desert zone (light chestnut and brown soils). There is practically no woody natural vegetation in the region on elevations and plains, and on the prevailing complexes of zonal soils, forest plantations are characterized by low durability. Materials and methods. The work used the results of field (expedition) and laboratory studies of the growth, condition, durability, productivity of protective forest plantations of tree and shrub species in various soil and hydrological conditions of the dry-steppe and semi desert zones. Results and discussion. The author’s developments made it possible to recommend a reliable range of trees and shrubs for the creation of forest-reclamation plantations in each agroforestry area and soil ecological niche. It was revealed that when selecting the assortment, a significant role should be given to selection and genetic methods of using seed and planting material well adapted to local conditions (drought-, salt- and frost-resistant and healthy genotypes). The main reason for the early drying of protective plantations on complex light chestnut soils of the dry-steppe and semi-desert zones has been established. Taking into account the extremely arid conditions and the main causes of their drying, the concept of increasing their stability and effectiveness in adverse growing conditions is given. Agroforestry zoning and groups of soil forest suitability by type and classification, as well as groups of longevity of the main tree species are given. Conclusion. The large diversity of soils contributes to the formation of a stepped profile in adult cereals. Woody species shrink when their root system comes into contact with salt horizons. Ecological techniques are reduced to the correct selection of tree species that correspond to a specific ecological background. The technological use of differentiated agricultural cultivation techniques involves the use of moisture-saving technologies. Biological measures include biological reclamation of unsuitable soils and methods of breeding and genetic improvement of the qualitative composition of forest reclamation plantations. Suggestions for practical applications and directions for future research. The results of the work can be used by managers and specialists of forestry enterprises, researchers, graduate students, students of educational institutions. The assortment of trees and shrubs can be used in the design of plantings of various types on different soils.

Rainfall-Groundwater Table Fluctuations Impact on Root Zone Soil Water Simulated in Upflow for Crop Production Planning in Obio Akpa Watershed, Nigeria

The non-predictability of rainfall-groundwater table relationships in the ungauged Obio Akpa watershed has rubbished remedial measures against seasonal crop losses. This study utilizes ten years (2011-2020) climate data obtained from the study area to predict the seasonal rainfall-groundwater table variations and simulate the effects on crop root zone using Upflow model. Twelve wells monitored monthly, characterized the seasonal behaviour of the Groundwater Table (GT). Gravimetric direct measurements of soil water contents were the inputs to UPFLOW model used to simulate the seasonal responses of GT to rainfall. Correlation-regression analysis was used to obtain a prediction equation of GT responses to rainfall. Results showed that in the month of April, the mean rainfall of 230mm induced GT rise of 1.35m (35%) from 3.85m in March to 2.50m in April. The effect on the soil water properties included a corresponding increase of 1.8 vol.% (10.7%) in field capacity at equilibrium with the water table in the preceding month. Mean soil water condition remained optimal at 15.9 vol.% with the GT at 1.5m below the root zone. In September and October when 1859mm and 2129mm of the mean annual rainfall was received, the water table increased by 72% and 74% respectively, and field capacity in equilibrium with the GT increased to 34.9 vol.%. causing GT inundation of the root zone (RZ) and deficit aeration in 74% of the RZ respectively. In November, with reduced rainfall amount and decreased input to groundwater, only 16% of the RZ was in deficit aeration. UPFLOW simulations of the annual soil water regime showed the months of September, October and November as high GT months suitable for planting and harvesting of only shallow rooted, short maturity crops. This knowledge will guide effective water resources and crop management in the watershed.

Assessment of Soil Enzyme Activities in Plant Root Zone of Saline Soil Reclaimed by Drip Irrigation with Saline Groundwater

Drip irrigation with saline water is frequently adopted to realize the sustainable utilization of saline–sodic soil with high water tables, and soil enzyme activities can be used to indicate changes in soil quality. In the current study, spatiotemporal changes in soil urease enzyme (URE), alkaline phosphatase (ALP) and invertase (INV) activities were investigated during consecutive growing seasons. Soil in beds was sampled before planting (0 y) and one, two, three and four years after the growing season (1 y, 2 y, 3 y, 4 y), and these samples were distributed at four horizontal distances from the drip line (0, 10, 20 and 30 cm) and four vertical soil depths (0–10, 10–20, 20–30 and 30–40 cm). The results showed that a distribution pattern of URE and ALP activities formed during the first growing season, while the distribution of INV activity formed until the third growing season. All three soil enzyme activities in the upper soil layers and positions close to the drip line were more greatly affected by planting year. The average URE activity of the soil profile decreased slightly during the first year and increased by about 220% and decreased by 20% after reclamation for two and three years, and finally, it increased to 4.9 μg NH4+·g−1·h−1 at the end of the fourth growing season. ALP activity remained stable during the first two years and rapidly increased in the following years; in particular, in the fourth year, it reached 32.7 μg ph(OH)·g−1·h−1. INV activity increased continually with the number of years after planting and reached 1009.0 μg glu·g−1·h−1 at the fourth season’s end. An analysis of variance indicated that URE, ALP and INV activities varied insignificantly among the time points of 0 y, 1 y, 2 y and 3 y (p < 0.05), while they were significantly higher for 4 y than for 0 y and 1 y. In addition, all three enzyme activities of the soil profile had an exponentially increasing trend with the number of years after planting. These results indicated the soil quality in saline–sodic soils could be improved with time under drip irrigation with local saline groundwater, especially around the drip line.

IMPROVEMENT OF ELEMENTARY COMPONENT OF DAMAGED SUBSTRATES BY SAPONITE CLAY INCLUSION

In this proposed article, the impact on the elemental composition of sand substrates is determined using the example of the Andriykovetskyi quarry-dump complex and the Barsukivskyi sand pit, which are located in the Central Podillya region in the conditions of the Right-Bank Forest-Steppe. It was determined, that saponite clay contains a significant amount of macro- and micro- elements, and the directions of this use depend on the composition and origin of saponite: in agriculture, in industry, in construction, an application as a sorbent or as meliorant, etc. It is noted that the use of saponite as an ameliorant is an economical and cost-effective method of reclamation, which allows to reduce the burden on the environment caused by the extraction of minerals, pollution of the territory by heavy metals, the conduct of hostilities, etc. General scientific (analysis), statistical (statistical analysis) and laboratory methods (Fourier-transform spectroscopy) were used to assess the qualitative composition of inorganic and organic components of sand-saponite mixtures and to determine saponite clay as a potentially fertile material. To conduct the research, an averaged sample of sand was taken from the Andriykovetskyi quarry and dump complex and from the Barsukivskyi sand pit. For comparison with reference values, a zonal soil sample was taken from undisturbed areas. Saponite from the Tashkiv deposit with a fraction of 0.1 mm was used for sand-saponite mixtures, the ratio of sand substrate to saponite is 70% to 30%. According to the results of the study of the qualitative composition of the inorganic component, it was determined, that saponite has a positive effect on the composition of the sand-saponite mixture in terms of providing plants with nutrients, such as macro- and micro- elements (Mg, K, Na, Cu, Zn, Ca). This confirms the positive effect of saponite on plant growth, which was obtained by us in previous biotesting experiments, and is explained by the fact that the elements of the sand-saponite substrate are available to plants as a result of their transition into the substrate solution. Adding saponite to the substrate of sand pits also increases the content of organic substances, which accelerates the processes of humification and the formation of soil aggregates: humic acid contributes to the bonding of soil particles; carbohydrates sucrose, fructose, glucose and lactose create a nutrient environment for plants; stearates and stearic acid are the main soap components, lauric acid is a foaming catalyst, their presence in sand-saponite mixtures indicates their transition from saponite. When comparing the samples of sand-saponite mixtures of the Andriykovetskyi quarry-dump complex and the Barsukivskyi sand pit, it was concluded that the processes of soil formation began in the substrate of the Andriykovetskyi quarry-dump complex, since the composition of organic matter is greater here.

Seasonal Maize yield forecasting in South and East African Countries using hybrid Earth observation models

Climate change still adversely affects agriculture in the sub-Saharan Africa. There is need to strengthen early action to bolster livelihoods and food security. Most governments use pre- and post-harvest field surveys to capture statistics for National Food Balance Sheets (NFBS) key in food policy and economic planning. These surveys, though accurate, are costly, time consuming, and may not offer rapid yield estimates to support governments, emergency organizations, and related stakeholders to take advanced strategic decisions in the face of climate change. To help governments in Kenya (KEN), Zambia (ZMB), and Malawi (MWI) adopt digitally advanced maize yield forecasts, we developed a hybrid model based on the Regional Hydrologic Extremes Assessment System (RHEAS) and machine learning. The framework is set-up to use weather data (precipitation, temperature, and wind), simulations from RHEAS model (soil total moisture, soil temperature, solar radiation, surface temperature, net transpiration from vegetation, net evapotranspiration, and root zone soil moisture), simulations from DSSAT (leaf area index and water stress), and MODIS vegetation indices. Random Forest (RF) machine learning model emerged as the best hybrid setup for unit maize yield forecasts per administrative boundary scoring the lowest unbiased Root Mean Square Error (RMSE) of 0.16 MT/ha, 0.18 MT/ha, and 0.20 MT/ha in Malawi's Karonga district, Kenya's Homa Bay county, and Zambia's Senanga district respectively. According to relative RMSE, RF outperformed other hybrid models attaining the lowest score in all countries (ZMB: 25.96%, MWI: 28.97%, and KEN: 27.54%) followed by support vector machines (ZMB: 26.92%, MWI: 31.14%, and KEN: 29.50%), and linear regression (ZMB: 29.44%, MWI: 31.76%, and KEN: 47.00%). Lastly, the integration of VI and RHEAS information using hybrid models improved yield prediction. This information is useful for NFBS bulletins forecasts, design and certification of maize insurance contracts, and estimation of loss and damage in the advent of climate justice.

Application of different organic amendments influences the different forms of sulphur in the soil of pea – onion – cauliflower cropping system

A study was conducted in sandy clay loam soils in a subtropical zone of Bihar to evaluate the effect of frequent application of organic amendments on sulphur fractions. Different organic amendments, including farmyard manure (FYM), vermicompost, azotobacter, phosphate solubilizing bacteria (PSB), panchagawya, and neem cake, were applied through nine treatments that resulted in a significant increase of water-soluble S, available S, heat-soluble S, adsorbed S, and organic S in organic treatment compared to the recommended dose of fertilizer (RDF) and control treatment. The maximum increment was observed in the treatment where the recommended dose of nitrogen was replaced by 75% recommended dose of nitrogen substituted farmyard manure + 25% recommended dose of nitrogen (vermicompost) along with azotobacter + PSB + one foliar spray of panchagawya. The total S content varied widely from 382 to 736 mg kg-1. Increment in all the forms of sulphur is observed as a result of the application of different organic nutrient sources. All the forms of sulphur share a mutual positive and significant correlation with each other. Regression analysis suggested that the availability of sulphur was dominated by organic sulphur, which alone can explain 97.8% of the variation in availability of available sulphur in soil.

Carbon leaching from peat soils of the north of Western Siberia under different hydrological conditions

Frozen peat soils in the north of Western Siberia are vulnerable to the on-going climate changes. The increase in temperature which affects the permafrost thaw returns the huge carbon stocks to the global element cycle. Its export in the form of dissolved organic matter from peatlands is determined by a number of factors, among which hydrological conditions are the least studied. The influence of hydrological regimes on carbon export from oligotrophic peat soils in discontinuous permafrost zone was investigated in laboratory conditions. The model column experiment allowed estimating the carbon yield from undisturbed (monolithic) peat samples of different degrees of decomposition. Three types of mesocosms were considered: undisturbed samples of the TO horizon, as well as the TO horizon with underlying material of different texture (sand and loam). The concentration of dissolved organic carbon in the lysimetric waters of a fibric peat does not differ for the “precipitation” and “snowmelt” simulating modes, and in the “stagnation” mode it is 1.4 times less. Sapric peat lysimetric waters show no differences under simulating hydrological regimes. The total export of organic carbon for three successive extractions for fibric peat is 32% higher than for sapric peat. An increase in carbon in the sandy material after three cycles of the experiment was revealed, the loamy material did not show significant differences. The carbon adsorption by mineral soil layers of the study area can be a protective mechanism that prevents increased runoff from the soils.

Flash droughts and their impacts—using newspaper articles to assess the perceived consequences of rapidly emerging droughts

Flash droughts (FDs) have attracted increasing attention in the past decade. They are characterised by a rapid depletion of soil moisture resulting from interactions between the soil and atmospheric conditions. To date, there is a lack of consistent FD definitions and an understanding of their socio-economic impacts. Here, we explore the relationship between biophysical FD conditions and the perceived impacts of FDs in Germany between 2000 and 2022. We measured perceived impacts by analysing consequences reported in newspaper articles (2000–2022) and online search behaviour using Google trends data (2004–2022). To characterise the physical process, we considered root zone soil moisture data. Our results show that FDs are becoming increasingly frequent in Germany, occurring once every two years on average. Despite the lack of knowledge from the general public regarding the phenomenon of FDs, the peaks of interest in drought impacts correspond to the physical occurrence of FDs across the country. We identified an average time gap of four weeks between FD onset and the reporting of perceived impacts. This gap is longer than the average duration of FDs’ onset. Consequently, our findings highlight that consistent monitoring of FD conditions and drivers is necessary to guarantee effective preparedness. As impact perception is too slow to allow the adoption of mitigation measures, FDs require new schemes for response measures compared with slowly emerging (conventional) drought events. The novel method also allows the consistent and impact-based validation of FD identification methods.

Newly plant-derived carbon in the deeper vadose zone of a sandy agricultural soil does not stimulate denitrification

Analysis of stable carbon (C) isotopic signatures (δ13C) in various soil C pools provides useful information on soil C sources, transport, and availability. Understanding the extent of deeper soil (below 40 cm) sequestration and transport of plant derived C is of particular interest as this provides a source for microorganisms to drive biological denitrification (as indicated by denitrification enzyme activity, DEA) and hence mitigate the nitrate leaching to groundwater. Meanwhile, studies on deeper soil C sequestration are rare due to methodological constraints. This study was done in deeper vadose zone (0–160 cm) of a sandy agricultural soil in a humid and temperature zone after a C3-C4 vegetation change taking advantage of the marked isotopic differences between C3 and C4 plants. It took place in a site previously grown with C3 crops (beet, barley, grass), but where C4 crops (maize) were grown continuously for the last 20 years. The other site where C3 crops were continuously grown was used for comparison. Specifically, the δ13C signature in top and deeper soil layers was used to distinguish between old C3– and newly C4-plant derived C in four C pools, i.e., bulk soil C, hot- and cold-water extractable C, and respired CO2-C. The δ13C signature between C3 soils and C3-C4 shifted soils was similar for bulk soil C but significantly different for water extractable and respired C pools. Hence, we estimated that the contribution of newly derived C to bulk soil C was negligible, whereas the contributions to the other C pools amounted up to 28.4 % along the soil profile. This emphasizes the importance of simultaneously analysing δ13C signature in various soil C pools to accurately assess C vertical transport and distribution. The concentrations of cold-DOC and values of specific ultraviolet visible absorbance of the wavelengths 254 and 280 nm decreased from 50 to 130 cm soil depths, while they increased below these depths. However, this suggested rise in C chemical quality at the deepest soil depths did not cause an increase in soil respiration activity or DEA, which was attributed to the protective effects of iron and aluminium oxides on C decomposition. Upon the application of labile C and N substrates, the deepest soil layers displayed a significantly increased DEA, suggesting the presence of a relatively abundant population of active denitrifying organisms. Overall, this study documents the presence of plant-derived C in the deeper vadose zone. Meanwhile, this particular C pool might not be an important substrate to drive deep-soil denitrification due to constraints imposed by the protection by metal oxides.

The Effect of Fertilizers and Growth Regulators on the Productivity of Safflower (Carthamus tinctorius L.) in the Dry Climate of Russia

Background: Safflower is an oilseed crop capable of forming seeds in extreme conditions, so it can be used as an alternative to sunflower, because their growing technologies are similar. Increasing the yield of safflower seeds can be achieved intensively using agrochemicals. The proposed research results provide information on the use of mineral, micro fertilizers and growth regulators. Methods: Research was carried out in the dry steppe zone of chestnut soils. In the spirit-factor experiment, which was located on a field with an area of 300 m2, in triplicate, using two sorts of safflower. Mineral fertilizers were applied to the soil during sowing and by foliar treatment during the “budding” phase. The obtained yield results were processed by analysis of variance. Result: As a result of the research, elite safflower seeds were obtained using one of the experimental options Ultamag Bor 30 g + Biostim Growth 30 g/10 liters of water of the Alexandrite variety with a yield of 1.8 t/ha with the highest profitability of their production of 414.2%. Analysis of variance of the yield data from the experiment showed that 87% of the yield of safflower seeds depended on the use of mineral fertilizers, 0.62% on the plant variety and agro technical measures for growing safflower plants-11.8%.

Indicators of humus state of virgin and irigated gray-brown soils of khorezm vilayat of Uzbekistan

The humus content, elemental composition and optical density of humic acids in virgin and irrigated soils of the Tashsakinsky massif of the Khorezm region of Uzbekistan were estimated. The studied desert virgin and irrigated soils have characterized by light and medium loamy granulometric composition, dusty-granular structure and slightly alkaline reaction. Carbonates present in small quantities - 3.10-10.60%. The total humus content in the upper horizons varies from 0.19% to 0.76%. In virgin grey-brown soils the humus type is humate-fulvate, agriculture soils are humate. The degree of humification of organic matter in newly irrigated gray-brown-meadow and meadow-marsh soils is higher than in virgin gray-brown soils and decreases down the profile. It was revealed that the optical density of humic acids of virgin gray-brown, irrigated meadow and meadow-marsh soils is characterized by high values. The percentage of the sum of humic acid elements differs little from virgin soils to old-irrigated meadow soils. In the lower horizons, oxidation increases by 1.02 times compared to other studied soils. For the first time, the elemental composition of humic acids in virgin and irrigated soils of the desert zone of the Tashsakinsky massif of the Khorezm region was determined. The elemental composition of humic acids showed the oxidizability of humic acids, which decreases from top to bottom along the profile, which is associated with the features of the genesis of the studied soils, the age of irrigation and the degree of cultivation of these soils.

Sorption and mobility assessment of tembotrione in soils of upper, trans and middle Gangetic plain zones of India.

The presence of undesired agrochemicals residues in soil and water poses risks to both human health and the environment. The behavior of pesticides in soil depends both on the physico-chemical properties of pesticides and soil type. This study examined the adsorption-desorption and leaching behavior of the maize herbicide tembotrione in soils of the upper (UGPZ), trans (TGPZ) and middle Gangetic plain zones of India. Soil samples were extracted using acetone followed by partitioning with dichloromethane, whereas liquid-liquid extraction using dichloromethane was used for aqueous samples. Residues of tembotrione and its metabolite TCMBA, {2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy) methyl] benzoic acid}, were quantified using liquid chromatography-tandem mass spectrometry. The data revealed that tembotrione adsorption decreased with increasing pH and dissolved organic matter but increased with salinity. The maximum adsorption occurred at pH4, 0.01m sodium citrate and 4g/L NaCl, with corresponding Freundlich constants of 1.83, 2.28 and 3.32, respectively. The hysteresis index <1 indicated faster adsorption than desorption. Leaching studies under different flow conditions revealed least mobility in UGPZ soil and high mobility in TGPZ soil, consistent with groundwater ubiquity scores of 4.27 and 4.81, respectively. Soil amendments decreased tembotrione mobility in the order: unamended > wheat straw ash > wheat straw > farm yard manure > compost. The transformation of tembotrione to TCMBA and its mobility in soil columns were also assessed.

Hydraulic Dynamics of the Riparian Soil in the Chapadão do Diamante - Serra da Canastra, Minas Gerais

Serra da Canastra National Park, located in the Cerrado Biome in the State of Minas Gerais, Brazil, consolidates a conservation unit that includes the sources of several important Brazilian hydrographic basins. Given the significance of local and national water supply and regulation, this study aimed to analyze and understand the physical-hydraulic characteristics of the soil in the riparian zone within the park. Field data were collected using a rainfall simulator and a concentric ring infiltrometer. The results demonstrated an elevated infiltration capacity in the study área. Only 23.74% of the 57.4mm of artificially precipitated high-intensity rainfall was runoff. Basic infiltration velocity (BIV) values were considered very high (50.74 mm/h). Overall, these values were associated with the characteristics of the landscape, highlighting the importance of vegetation in the soil cover and the physical attributes of the soil. These factors influenced the modulation of the soil's capacity to retain, infiltrate, and store large volumes of water. In this regard, the importance of these riparian zones for the environment was emphasized as they play a crucial role in protecting watercourses. They act as barriers against erosive flow from upstream areas, incorporating water into the soil profile to store and release over time. These areas thus become important sites for water regulation.

SCIENTIFIC SUBSTANTIATION OF THE MAXIMUM PERMISSIBLE CONCENTRATION OF OIL IN THE SOIL FOR THE TERRITORY OF THE INDUSTRIAL ZONE OF THE UZEN DEPOSIT IN THE MANGYSTAU REGION

The development and operation of an oil field is accompanied by an oil spill and the formation of oil-contaminated soils. The process of natural restoration of oil-contaminated soils is extremely slow. Therefore, among environmental protection measures, the rationing of oil content in soils is extremely important. The purpose of the work is to develop a standard for the maximum permissible concentration of oil in the soil for the industrial zone of the Uzen field.Methods. The basis for the development of the maximum permissible concentration of oil in the soils of the studied field is the "Methodological recommendations for the hygienic justification of the maximum permissible concentration of chemicals in the soil". The determination of the mass fraction of oil in the studied media was performed by gas-liquid chromatography. The chemical composition of the soil was determined by atomic absorption spectrometry. The determination of the specific activity of radionuclides was carried out by gamma-spectrometric method on the «MKS 01A Multirad» spectrometer. Results and discussion. During the work for the field, in accordance with the requirements for substantiating the maximum permissible concentration, an assessment was made on the physico-chemical and biological properties of soils and oils. Based on the experimental data obtained, the maximum permissible concentration of oil in the soil of the industrial zone of the Uzen field at the level of 3 g/kg is justified and reflects the real conditions in which oil intake in the soil will not cause harmful effects on human health and the environment.

Bacterial Communities, Network Complexity, and Multifunctionality Affected by Soil Types in Northeastern China

The Northeast China Plain (NCP) is the country’s most important grain-producing area. Unraveling how bacterial communities in this region assemble and distribute according to soil type is essential for sustainable agricultural development and optimizing the precise management of soil resources. In this study, 106 soil samples were collected from three typical zonal soil types (black calcium soil (BCS), black soil (BS), and dark brown soil (DBS)) spanning from west to east in the NCP. By combining soil field surveys and high-throughput microbial sequencing analysis, we found that bacterial diversity and community structure differed significantly by soil type. Proteobacteria, Gemmatimonadetes, and Acidobacteria were enriched in BCS, BS, and DBS, respectively. Compared to BSC and DBS, BS had the highest nutrient concentration and most neutral pH values, which may recruit more diverse bacterial communities and construct a more connected ecological network. Network analysis further identified Burkholderiales, Sphingomonadales, and SC_I_84 as key hubs in BS, BCS, and BCS, respectively. The majority of classified hubs consistent with the results of the linear discriminant analysis effect size belonged to the predominant biomarkers. Redundancy and Mantel test analyses revealed that the bacterial composition in various soil types showed distinctive responses to heterogeneity in soil physicochemical properties. Soil pH and TP were the primary factors shaping the soil bacterial community structure in these three soil types on the NCP. Moreover, bacterial composition and diversity were strongly related to changes in soil multifunctionality in BCS, and the relative abundances of three classes (TM1, Opitutae, and Deinococci) were the most important biotic variables for predicting BCS ecosystem multifunctionality. In summary, our results suggest that soil type variation has a strong influence in terms of shaping bacterial community structure and affecting soil multifunctionality. Correspondingly, diverse co-occurrence patterns were observed in different soil types.

Redistribution of Hydrothermal Resources on Different Elements of the Microrelief of Soils in the Semi-desert Zone and Agrolandscapes under Wheat

In the semi-desert regions of Azerbaijan there are habitats with varying elevations of only a few tens of centimeters. The zonal soils on the territory of the massif are gray-brown soils. Gray-brown soils develop under ephemeral plant cover. The soil is carbonate throughout the entire profile. Below the carbonate horizon lies a layer enriched with sulfates in the form of veins of crystalline gypsum. The content of absorbed sodium in the gray-brown soils of the deluvial plain of the Siyazan-Sumgait massif is 30-50% of the number of absorbed bases in the Solonetz-Columnar soil horizon. The amount of humus in the upper layers of the soil fluctuates between 1-2%, towards the bottom it sharply decreases. In studies carried out on gray-brown soils of the Siyazan-Sumgait massif, hydrothermal potential indicators vary within the range of 426-552 m3/ha. The distribution of temperature and humidity in depth in the soil under wheat differs from the natural habitat. In the arable layer, the temperature is evenly distributed throughout the entire profile, while the humidity gradually increases in the lower layers. The influence of the hydrothermal regime on wheat yield was: 2022 — 24.0-30.0 cwt/ha; 2023 — 16.0-24.5 cwt/ha.

Influence of anti-seasonal inundation on geochemical processes of arsenic speciation in the water-level-fluctuation zone soil of the Three Gorges Reservoir, China

Since the completion of Three Gorges Dam, the water-level-fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) experiences the periodic anti-seasonal inundation. However, knowledge for mechanisms of mobilization and transformation of arsenic (As) in WLFZ soils of the TGR remains scarce. To address this gap, a combination of field observation and simulated flooding experiments attempts to illustrate the As mobilization, the transformation between As(V) and As(III), and the factors driving these processes. The study revealed that anti-seasonal inundation (with a temperature at 13 ℃) mitigated As release from submerged soils. Interestingly, the total As and ratio of As(III) (the more toxic form of As) concentrations in porewater at 13 ℃ was lower, and the prevalence of As(III) occurred later than those at 32 °C (imitate the seasonal inundation condition). The results indicated that the As reduction and the corresponding toxic risks in submerged soils were alleviated under anti-seasonal inundation. The study proposes the reduction of As-bearing manganese (Mn) mineral assemblages and competitive adsorption of dissolved organic carbon (DOC) as primary mechanisms for As mobilization. Furthermore, microorganism-mediated detoxification/reduction processes involving DOC, nitrogen, and Mn (oxyhydr)oxides were identified as central pathways for As(III) enrichment under anti-seasonal inundation. This study enhances understandings of the biogeochemical processes and fate of As in WLFZ soils influenced by artificial regulation of the reservoir.

Soil and unsaturated zone as a long-term source for pesticide metabolites in groundwater

Pesticide metabolites are frequently detected in groundwater, often exceeding the concentrations of their parent pesticides. Ceasing the application of certain pesticides has often not led to the expected decrease in metabolite concentrations in groundwater, which is potentially caused by residues in soil. Whereas pesticide residues in soils are well-documented, there are only few studies about metabolite residues. We investigated if the soil/unsaturated zone can act as a long-term source for metabolites in groundwater by combining soil analysis, groundwater analysis and numerical modelling. The field study focused on the herbicide chloridazon (CLZ) and its frequently detected metabolites desphenyl-chloridazon (DPC) and methyl-desphenyl-chloridazon (MDPC) while in the model additional pesticides and metabolites were considered. In soil samples from an agricultural area, where the last CLZ application was 5 to 10 years ago, we observed 10 times (DPC: 0.22 – 7.4 µg kg−1) and 6 times (MDPC: 0.12 – 3.1 µg kg−1) higher metabolite concentrations compared to CLZ (< 0.050 – 1.0 µg kg−1). Calculations suggested that the majority of the metabolites (DPC: 63 - 96%, MDPC: 74 – 97%) were sorbed despite their lower sorption tendency. The metabolite retention was in particular related to the organic carbon content. The calculated pore water concentrations were highest in the deepest part of the soil profile (75 – 100 cm) with median concentrations of 3.6 and 1.7 µg L−1 for DPC and MDPC, respectively. The groundwater concentrations of DPC and MDPC were 3 to 3.5 times higher in monitoring wells downgradient from the agricultural zone than upgradient of it. This increase highlights the potential of soil and unsaturated zone as a long-term metabolite source after the application stop of pesticides, consistent with the calculated elevated pore water concentrations. Numerical flow and transport model simulations suggested that this input from soil and unsaturated zone can cause elevated metabolite concentrations (> 0.1 µg L−1) in groundwater over more than one decade. The study highlights that soil and unsaturated zone can act as a long-term source of pesticide metabolites even if they have much higher mobility than the parent compound.

Quantitative Evaluation and Evolution Characteristics of Consistency Level of Black Soil Conservation Policy, Taking China’s Black Soil Protection Policy as an Example

Scientifically evaluating China’s black soil protection policy and exploring its evolution characteristics are crucial for promoting high-quality and efficient black soil protection projects worldwide. Utilizing the Policy Modeling Consistency (PMC) index model, the effectiveness of China’s black soil protection policy system is assessed. Building upon this evaluation, the research delves into the evolution process of the black soil protection policy system, examining its dynamic characteristics across different government levels. Through the application of text mining technology and visual analysis techniques, the study explores four dimensions: keyword co-occurrence, vertical synergy calculation, policy theme identification, and policy tool analysis. The results show the following: (1) The PMC index showed a phased growth trend, and various indicators gradually improved and tended to be stable. (2) Government policies at the same level exhibit progressive evolution patterns in terms of policy keywords and themes. (3) Across different levels of government, there are hierarchical lag evolution rules observed in policy keywords and provincial policy tools. Additionally, policy keywords display vertical synergy evolution patterns. In conclusion, future black soil conservation policies need to reduce hierarchical delays, enhance the coverage and comprehensiveness of policy content, and establish a sound policy feedback mechanism. The conclusions of the study are significant for improving management approaches throughout the black soil zones of the world.