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Field studies have explored the potential effects of different land use types on the vertical characteristics of dissolved organic matter (DOM) content and quality. However, owing to spatial and temporal variations, potential effects of different vegetation types on the vertical distribution of DOM content and quality remains unclear. Our study investigated the vertical characteristics of DOM in soil profiles of Cambisols across land-use types (grassland and woodland) in Longmenshan fault zone. Chemical characterization of soil DOM and its source identification across land use types inferred by fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC) and principal component analysis (PCA). The results indicated that soil organic carbon (SOC), readily oxidizable carbon (ROC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) content in the different landscape decreased with soil depth. Also, DOC content in soils of woodland was higher than in grassland. Three fluorescence components were identified in all soil samples by EEMs-PARAFAC analysis, including two humic acid-like substances (C1 and C2) and a tryptophan-like substance (C3). Overall, the relative distribution of the three DOM components mainly showed that the proportion of C1 and C2 increased with soil depth, but neither increased significantly; and the proportion of C1 was greater than that of C2 in all samples. The variability in optical indices also indicated that soil DOM was dominated by both microbial and terrestrial sources. PCA further analyze the differences in DOM in soils of different land use types in the region. The first two principal components (PC1 and PC2) across soil layers explained more than 80% of the total data variance. From the scoring plots, the variation in DOM scores across vegetation types and soil layers indicated that DOM components were not only affected by vegetation depended on soil layers, but also by other factors. These findings provided insights into the characteristics of DOC changes in soil profiles of different land use types. [ABSTRACT FROM AUTHOR]

Background and Aims: Organic farmers are showing increasing interest in using conservation tillage to improve the biological activities of soils. Here, we assessed whether conservation tillage in organic farming improves earthworm populations, root growth and soil physical quality in a sandy loam after 16 years of experiment. Methods: We compared the effect of a tillage gradient, with of two non-ploughed treatments (superficial tillage [ST] at 15 cm; very superficial tillage [VST] at 5–7 cm) and two ploughed treatments (moldboard ploughing [MP] at 30 cm; shallow moldboard ploughing [SMP] at 20 cm). Soil clod types, penetration resistance, abundance and activity of earthworms, root traits and biomass were assessed. Results: VST decreased soil compaction in topsoil (0 to 10 cm) compared to ploughed treatments (MP and SMP), but led to more compacted soil at 15 to 30 cm. Earthworm biomass (especially anecic) was higher under VST compared to MP and SMP and their galleries were better connected to the soil surface. However, there was no significant difference in the total volume of pores or diameter of galleries between 0 and 30 cm. Soil compaction in the non-ploughed treatments affected root traits, especially under VST, with lower specific root length, higher root diameter, and lower root tip elongation compared to MP and SMP. Conclusion: Biological activity did not compensate for the compaction of a sandy soil after 16 years without ploughing in organic farming. A more integrated approach (i.e. considering all 5 soil health principles) is needed to sustain soil health and functions, and meet current expectations about "ecological intensification". [ABSTRACT FROM AUTHOR]

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Understanding the stability of soil organic matter (SOM) is essential for making accurate predictions regarding carbon release rates. However, there is limited information on the role of chemical composition of dissolved organic matter (DOM) in SOM stability. To address this gap, the peatland soil profile in the discontinuous frozen soil region of Northeast China was selected as the focus of this research, and a comprehensive analysis was conducted on the differences between the molecular composition of DOM and the stability of SOM. The results indicate a significant carbon accumulation phenomenon near the permafrost table. Through analyses using TG-50, δ13C, and δ15N, it was determined that SOM near the permafrost table exhibits high stability, whereas SOM within the permafrost layer demonstrates poor stability. Investigations utilizing UV-vis, 3D-EEM, FT-IR, and 1H-NMR technologies revealed that DOM near the permafrost table is of high quality and highly aromatic. Furthermore, compared to near the permafrost table, humic acid materials in the permafrost layer decreased by 17%, while protein materials increased by 17%. These findings offer a novel perspective on the understanding of SOM stability in peatland soil profiles within discontinuous permafrost regions. [ABSTRACT FROM AUTHOR]

Abstract Potentially toxic metal(loid) assessment of tea and tea garden soil is a vital guarantee of tea safety and is very necessary. This study analyzed the distribution of seven potentially toxic metal(loid)s in different organs of the tea plants and soil at various depths in the Yangai tea farm of Guiyang City, Guizhou Province, China. Although soil potentially toxic metal(loid) in the study area is safe, there should be attention to the health risks of Cu, Ni, As, and Pb in the later stages of tea garden management. Soil As and Pb are primarily from anthropogenic sources, soil Zn is mainly affected by natural sources and human activities, and soil with other potentially toxic metal(loid) is predominantly from natural sources. Tea plants might be the enrichment of Zn and the exclusion or tolerance of As, Cu, Ni, and Pb. The tea plant has a strong ability for absorbing Cd and preferentially storing it in its roots, stems, and mature leaves. Although the Cd and other potentially toxic metal(loid)s content of tea in Guizhou Province is generally within the range of edible safety, with the increase of tea planting years, it is essential to take corresponding measures to prevent the potential health risks of Cd and other potentially toxic metal(loid)s in tea.

The soil nematode communities in typical tundra soils of southern Chukotka have been analyzed. Five types of shrub and grass-shrub biotopes on Cryosols, Fluvisols, Histosols, Gleysols, and Cambisols were examined. The animals were extracted from the soil by the Baermann technique with subsequent determination of taxonomic diversity, total and relative abundance, and trophic groups. The highest number (7044 individuals/100 g of soil) and biomass (12.15 mg) of nematodes were found in the Histosol, and the minimum one (1000 individuals/100 g of soil; 1.96 mg) of nematodes in the Cryosol. Bacterivorous nematodes dominated in all soil types. The maximum percentage of bacterivorous nematodes (94%) were found in the Cambisol. The percentages of fungivorous nematodes in the studied soils ranged from 1 to 42%. Predatory and omnivorous nematodes were present in all soils except for the litter of the Cambisol. Their percentage ranged from 2 to 32%. Phytonematodes were few, their highest number was found in the Gleysol (18%). The nematode fauna of the soils under analysis differed significantly. The greatest diversity of nematodes was found in the peat horizon of the Fluvisol, and the smallest diversity of nematodes was recorded in the litter of the Cambisol. The values of Sigma Maturity Index ranged between 2 and 3. The Enrichment Index had low and moderate (1.40–41.02) values, and the Structure Index had high values (59.51–84.07). The Eudorylaimus and Plectus genera were eudominants in all soil types. The soil food webs formed in the biocenoses under consideration can be characterized as stable and structured except for the alder biocenosis. [ABSTRACT FROM AUTHOR]

Global warming leads to the melting of permafrost, affects changes in soil microbial community structures and related functions, and contributes to the soil carbon cycle in permafrost areas. Located at the southern edge of Eurasia's permafrost region, the Greater Khingan Mountains are very sensitive to climate change. Therefore, by analyzing the bacterial community structure, diversity characteristics, and driving factors of soil profiles (active surface layer, active deep layer, transition layer, and permafrost layer) in this discontinuous permafrost region, this research provides support for the study of the carbon cycling process in permafrost regions. The results show that the microbial diversity (Shannon index (4.81)) was the highest at 0–20 cm, and the Shannon index of the surface soil of the active layer was significantly higher than that of the other soil layers. Acidobacteria and Proteobacteria were the dominant bacteria in the active layer soil of the permafrost area, and Chloroflexi, Actinobacteria, and Firmicutes were the dominant bacteria in the permafrost layer. Chloroflexi made the greatest contribution to the bacterial community in the permafrost soil, and Bacteroidota made the greatest contribution to the bacterial community in the active surface soil. The structure, richness, and diversity of the soil bacterial community significantly differed between the active layer and the permafrost layer. The number of bacterial species was the highest in the active layer surface soil and the active layer bottom soil. The difference in the structure of the bacterial community in the permafrost soil was mainly caused by changes in electrical conductivity and soil–water content, while that in the active layer soil was mainly affected by pH and soil nutrient indices. Soil temperature, NO3−-N, and pH had significant effects on the structure of the bacterial community. The active layer and permafrost soils were susceptible to environmental information processing and genetic information processing. Infectious disease: the number of bacterial species was significantly higher in the surface and permafrost layers than in the other layers of the soil. In conclusion, changes in the microbial community structure in soil profiles in discontinuous permafrost areas sensitive to climate change are the key to soil carbon cycle research. [ABSTRACT FROM AUTHOR]

Forest fires are one of the most significant environmental problems that have a major impact on biodiversity and climate conditions. The purpose of the study was to investigate the impact of military operations on the ground cover in the area of the Bekhy forestry, which was disturbed by fire. It was revealed that for the period 2022-2023, 15 forest fires were recorded on the territory of the Korosten forest hunting enterprise of the state enterprise "Forests of Ukraine", while the total area covered by fires was 15.13 ha. Overall, the number of fires increased from 5 to 10, but the total area covered by fires decreased from 12.1 to 3.03 ha. At the site of fires in 2022, the pH level increased to lower horizons, with the highest values at microhills (7.55) and microdepressions (7.35). There was a slight increase in the organic carbon content in the upper humus horizon of soils (0.42% on microhills and 0.46% on microdepressions). Bekhy forestry suffered a large forest fire in May 2023, which covered an area of 1.2 ha. The fire hazard assessment of each quarter was carried out separately. In the 50th and 51st compartments, Scots pine was the most fire-prone type of plantings. The 2023 fire site also showed an increase in pH in the lower horizons, with the highest values in microhills (7.35) and microdepressions (7.55). The 2023 fire site showed a decrease in organic carbon content compared to the background sites, with minimal values in the lower parts of the soil profile (0.33% on microdepressions and 0.38% on microhills). The results of the study can be used to develop and implement environmental measures and programmes aimed at restoring forests damaged by fire. [ABSTRACT FROM AUTHOR]

The dissemination of antibiotic resistance genes (ARGs) in soil has become a global environmental issue. Vermicomposting is gaining prominence in agricultural practices as a soil amendment to improve soil quality. However, its impact on soil ARGs remains unclear when it occurs in farmland. We comprehensively explored the evolution and fate of ARGs and their hosts in the field soil profiles under vermicompost application for more than 3 years. Vermicompost application increased several ARG loads in soil environment but decreased the high-risk bla -ARGs (bla ampC , bla NDM , and bla GES-1) by log(0.04 – 0.43). ARGs in soil amended with vermicompost primarily occurred in topsoil (approximately 1.04-fold of unfertilized soil), but it is worth noting that their levels in the 40–60 cm soil layer were the same or even less than in the unfertilized soil. The microbial community structure changed in soil profiles after vermicompost application. Vermicompost application altered the microbial community structure in soil profiles, showing that the dominant bacteria (i.e., Proteobacteria, Actinobacteriota, Firmicutes) were decreased 2.62%–5.48% with the increase of soil depth. A network analysis further revealed that most of ARG dominant host bacteria did not migrate from surface soil to deep soil. In particular, those host bacteria harboring high-risk bla -ARGs were primarily concentrated in the surface soil. This study highlights a lower risk of the propagation of ARGs caused by vermicompost application and provides a novel approach to reduce and relieve the dissemination of ARGs derived from animals in agricultural production. [Display omitted] [ABSTRACT FROM AUTHOR]

Introduction: Permafrost and seasonally frozen soil are widely distributed on the Qinghai--Tibetan Plateau, and the freezing--thawing cycle can lead to frequent phase changes in soil water, which can have important impacts on ecosystems. Methods: To understand the process of soil freezing-thawing and to lay the foundation for grassland ecosystems to cope with complex climate change, this study analyzed and investigated the hydrothermal data of Xainza Station on the Northern Tibet from November 2019 to October 2021. Results and Discussion: The results showed that the fluctuation of soil temperature showed a cyclical variation similar to a sine (cosine) curve; the deep soil temperature change was not as drastic as that of the shallow soil, and the shallow soil had the largest monthly mean temperature in September and the smallest monthly mean temperature in January. The soil water content curve was U-shaped; with increased soil depth, the maximum and minimum values of soil water content had a certain lag compared to that of the shallow soil. The daily freezing-thawing of the soil lasted 179 and 198 days and the freezing-thawing process can be roughly divided into the initial freezing period (November), the stable freezing period (December--early February), the early ablation period (mid- February to March), and the later ablation period (March--end of April), except for the latter period when the average temperature of the soil increased with the increase in depth. The trend of water content change with depth at all stages of freezing-thawing was consistent, and negative soil temperature was one of the key factors affecting soil moisture. This study is important for further understanding of hydrothermal coupling and the mechanism of the soil freezing-thawing process. [ABSTRACT FROM AUTHOR]

The differences in soil water content across the soil profiles produce changes in soil microbial and enzymatic properties, which play a major role in the transformation of soil organic matter. Permanent water saturation contributes to the formation of gleyic/stagnic horizons which have reducing conditions, this leads to a depletion in soil oxygen and changes in soil properties. To assess the effect of water content, we compared soil properties in the gleyic/stagnic horizons to the oxidative layers, which occurred at the same/similar depth in other profiles. The enzymatic activity and the number of microbial groups were assessed in eight soil profiles located in central Poland. The studied properties responded differently to the water content. As expected, nitrate-reductase activity and the nitrate content were significantly higher in gleyic/stagnic than in oxidative conditions, while the opposite trend was found for phenol oxidase, urease, N -acetyl-glucosaminidase activity and the fungi number. No clear response in the total bacteria and facultative anaerobic bacteria (Bfa) count toward oxidation-reduction conditions was found. The dehydrogenases did not have a higher activity in the gleyic/stagnic as compared to the oxidative horizons and did not correlate significantly with the Bfa count. Differences in enzyme activities may be caused by the fact that the variation in frequency and duration of the reducing conditions in the soils may be insufficient to affect the short-term dynamics of these enzymes. The higher activity of some hydrolases in the reducing horizons may also be associated with the greater carbon and nitrogen content in these horizons. [ABSTRACT FROM AUTHOR]

Soil environmental quality related to the residents' life, health, and safety, has been the hotspot issues in science of ecological environment protection. Evaluating the distribution characteristics, ecological risk, and source of heavy metals in farmland is important for protecting soil resources. The agricultural area of Lianhua town, Gongcheng County, Guilin is a typical karst landform. In response to the problem of heavy metal pollution and complex sources in the soil of this area, the characteristics and sources of heavy metal pollution in the soil profiles from farmland, abandoned land, and forest were studied using the single-factor index method, the geoaccumulation index (Igeo) principal component analysis (PCA) and positive matrix factorization (PMF) model. The results showed that: (1) that the contents of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in the soil profile of the study area were higher than that of the soil elements background values in Guangxi. The total and available forms contents of all heavy metal elements exhibited the characteristics of accumulation in the surface profile; (2) among the six heavy elements, the contents of Cd were in a moderately to heavily polluted state. The contents of Cd in some soil profiles exceeded the control standard for agricultural land soil pollution. The contents of Zn and Ni were from slightly to moderately polluted in areas with frequent agricultural activities; (3) according to the PCA and PMF model, there were three main sources of heavy metals in the study area. Among them, Cd, Cu, Ni, and Zn are related to agricultural activities; the elements As, Cd, Cr, and Hg are closely related to geological background; Pb and Zn are mainly affected by atmospheric sedimentation of transportation. Agricultural activities and natural geological background are the main contribution sources of heavy metals in soil. Human activities are the main factors that cause the accumulation of heavy metals in soil. This research has theoretical guidance and practical significance for the prevention and control of soil heavy metal pollution and the protection of farmland environmental quality in the region. [ABSTRACT FROM AUTHOR]

Natural soil and vegetation recovery following human disturbance is the primary means of restoring degraded ecosystems globally. However, it remains unclear how vegetation recovery in the tropical karst areas of China affects the soil physicochemical properties. Here, we investigated the impacts of natural vegetation recovery on soil physicochemical properties at different soil depths in tropical karst areas in southwestern China, using a space–time substitution method. We found that with the natural vegetation recovery, soil bulk density (SBD) decreased. Soil pH initially decreased and then increased, reaching its lowest value during the shrubland stage. There was a significant increase in other soil physicochemical factors. In the soil profiles, SBD tended to increase with depth. The pH, total potassium (TK), total phosphorus (TP), and exchangeable calcium remained relatively stable across the different soil layers. TK, TP, available phosphorus, SBD, total nitrogen, pH, exchangeable magnesium, and available potassium significantly contributed to the soil physicochemical properties. Soil physicochemical properties were predominantly directly affected by litter and biological factors, albeit indirectly influenced by topographic factors. Our study provides crucial insights into karst soils and their relationship with vegetation recovery, which are pivotal for steering vegetation restoration and soil amelioration in karst areas. [ABSTRACT FROM AUTHOR]

Potentially toxic metal(loid) assessment of tea and tea garden soil is a vital guarantee of tea safety and is very necessary. This study analyzed the distribution of seven potentially toxic metal(loid)s in different organs of the tea plants and soil at various depths in the Yangai tea farm of Guiyang City, Guizhou Province, China. Although soil potentially toxic metal(loid) in the study area is safe, there should be attention to the health risks of Cu, Ni, As, and Pb in the later stages of tea garden management. Soil As and Pb are primarily from anthropogenic sources, soil Zn is mainly affected by natural sources and human activities, and soil with other potentially toxic metal(loid) is predominantly from natural sources. Tea plants might be the enrichment of Zn and the exclusion or tolerance of As, Cu, Ni, and Pb. The tea plant has a strong ability for absorbing Cd and preferentially storing it in its roots, stems, and mature leaves. Although the Cd and other potentially toxic metal(loid)s content of tea in Guizhou Province is generally within the range of edible safety, with the increase of tea planting years, it is essential to take corresponding measures to prevent the potential health risks of Cd and other potentially toxic metal(loid)s in tea. [ABSTRACT FROM AUTHOR]

(1) Background: The spontaneous combustion of coal (SCC) not only consumes huge amounts of coal resources but also causes environmental degradation. Rare earth elements (REE) can be taken as an effective indicator to evaluate the environmental effects of SCC. Coal in the Rujigou Mine has been spontaneously combusting for hundreds of years. (2) Methods: The geochemical properties of REE and major elements in the soil of the Rujigou coal mine are methodically examined to reveal the environmental effects of SCC. (3) Results: Soil REE concentration in the Rujigou mine is 216.09 mg/kg, and there is an enrichment of light rare earth elements (LREE) and a depletion of heavy rare earth elements (HREE), LREE/HREE in Rujigou mine was 5.52. The spontaneous combustion of coal could change the vertical distribution of REE, which is conducive to the enrichment of LREE. According to the Eu anomaly and δCe/δEu, the source of material in this mine may be derived from the terrigenous clastic rock controlled by weak reduction. Aluminum and titanium have similar geochemical behavior to REE, especially LREE. The concentration of sulfur is negatively correlated with REE, especially HREE. Calcium, sodium, and magnesium all had a negative correlation with LREE. (4) Conclusions: The spontaneous combustion of coal can lead to the fractionation of light and heavy rare earth elements, resulting in the enrichment of LREE and depletion of HREE. [ABSTRACT FROM AUTHOR]

We studied the morphological properties, pH, organic carbon content, and specific activity of 137Cs and natural radionuclides (40K, 226Ra, 232Th) in the upper horizons of soils in deactivated and slightly damaged areas of the city. The studies were carried out in the urban ecosystems of the city of Elektrostal (Moscow oblast) in 2019, i.e., 6 years after local precipitation of 137Cs due to a radiation incident. The morphological features of the upper horizons of urban soils were the following: brownish-gray color, light-loamy composition, and small-lumpy and lumpy structure, with inclusions of construction and household waste. In the upper horizons of urban quasizems and urban soils, a low carbon content (less than 1%) with high coefficients of variation were detected. In the studied urban soils, a wide range of water pH values was noted: from an acidic (4.6–5.5) to highly alkaline (>8.0) reaction. Correlation analysis showed that, in the upper horizons of UR, the content of organic carbon was reduced and alkalinization of the soil environment was observed. The accumulative type of distribution of 137Cs was recorded for soil profiles of polluted urban ecosystems in which decontamination measures were not carried out. The profiles of urban soils that were subjected to decontamination revealed low values of the specific activity of 137Cs in surface bulk layers and maxima in buried contaminated horizons. In the bulk horizons of UR, which include a large amount of crushed stone, there was an increase in the specific activity of 226Ra. Some technogenic horizons of UR and TCH, consisting mainly of quartz sand, are characterized by very low values of specific activities 226Ra and 40K. Correlations of chemical and radiation indicators in the profiles of urban soils reflect the different compositions and properties of upper horizons formed as a result of excavation and decontamination work. [ABSTRACT FROM AUTHOR]

Long-term excessive fertilization and irrigation under greenhouse cultivation systems cause nitrogen leaching, while the residual content varies at different soil depths with cultivation durations. However, it remains unclear whether it changes the composition and assemblage of the soil bacterial community, especially at deeper layers (as deep as 4 m), after long-term intensified cultivation. This study selected soils from three sites in Shouguang (a typical representative intensive planting area), i.e., greenhouse monoculturing for 20 years (G20), greenhouse monoculturing for 10 years (G10), and an adjacent rotation field (F) for physicochemical property determination and high-throughput pyrosequencing. The results showed that, contrary to the vertical characterization of soil bacterial community composition, the 2-m soil was dominated by Methylomirabilota, a nitrate/nitrite-dependent anaerobic methane oxidizer, uncovered for the first time in the soil habitat. This was attributed to the high levels of dissolved organic carbon (DOC, 201.2–255.7 mg kg−1), proving that applying C-rich organic fertilizers, e.g. plant residues, is effective in preventing accumulated nitrate from moving downward and threatening groundwater in greenhouse soils. Besides, greenhouse cultivation increased the inter-layer composition differences of the bacterial community, and compared with the abundant, the rare subcommunity showed higher sensitivity to environmental changes. The total nitrogen most significantly affected the bacterial community composition and assemblage. Therefore, 20 years of consecutive monocropping significantly decreased the microbial co-occurrence network complexity and species dispersal rate, yielding a low-fitted neutral community model (NCM) and more specialized ecological niches, especially for the rare subcommunity. As far as is known, this is the first study that explores the likely changes in the bacterial community composition and quantifies the responses of the rare subcommunity to long-term greenhouse cultivation at this soil depth. Discovery of Methylomirabilota broadens our understanding of micro-biodiversity in deep-soil ecosystem, and hints its application potential in soil remediation.

Global warming can accelerate soil organic matter (SOM) decomposition resulting in faster carbon (C) loss and positive climate-C feedback. Previous studies on response of SOM decomposition to climate change mainly focus on plow soil layer. However, the effects of elevated CO2 and soil warming on soil organic carbon (SOC) and total nitrogen (TN) contents and mineralization are rarely studied in subsoil layer. In this study, soil samples were collected from the 0–50-cm paddy soil layer of the Tsukuba free-air CO2 enrichment experimental site with elevated CO2 (+200 ppm) and soil warming (+2 °C), Japan, after 5-year rice growth season. The amounts of SOC, TN, δ13C, and δ15N were analyzed. A 4-week anaerobic incubation experiment was conducted to measure C decomposition and N mineralization potentials. Due to the intrinsic variation in SOC and TN contents in soil layers and fields, the effects of elevated CO2 and soil warming on C decomposition and N mineralization potentials could not be determined here. However, the effect of elevated CO2 on δ13C was only found in 0‒10-cm soil layer. In the 0–50-cm soil profiles, significant correlations were observed among SOC and TN, δ13C and δ15N, decomposed C and mineralized N, and δ13C of decomposed C. The variables associated with soil C and N pools, and dynamics showed large spatial heterogeneity within paddy field, due to variation in the original land use history. Therefore, great caution should be exercised when evaluating the effects of elevated CO2 and temperature on SOM decomposition and sequestration in paddy soil profiles.

Improvement of cultivated cotton adaptability to extreme climate events under climate change promotes sustainable cotton production. Extreme rainfall leads to a significant decrease in cotton yield, which may be related to changes in soil water consumption (SWC) and the vertical distribution of yield, but relevant research is still scarce. Here, a two-year cotton sowing date experiment was conducted in which geostatistics, sensor technology, the spatial grid method, and principal component analysis were combined to analyze cotton utilization of soil water during extreme rainfall (2021) and normal (2022) years. The reasons for cotton yield reduction under extreme rainfall and strategies to improve cotton production adaptability to extreme rainfall were discussed. Under extreme rainfall, the morphogenesis and reproductive organ development of cotton were inhibited. The accumulation of SWC and its relationship with the biomass accumulation of cotton on different sowing dates under extreme rainfall exhibited nearly opposite characteristics to those in a normal year. Simultaneously, the two-year yield showed the opposite trend with the change in sowing date. There existed a trade-off strategy for the vertical distribution (i.e., on the upper, middle and lower fruiting branches) of cotton yield. Extreme rainfall reduced the yield at lower fruiting branches and increased the boll-forming rate of the upper fruiting branches, which was closely related to seed cotton yield, lint yield and water productivity (WP). Optimizing the cotton sowing date (early sowing should be appropriate in this study) may improve the adaptability of cotton production under extreme rainfall, but further long-term studies are needed. This study highlights the critical practice of climate-smart agriculture and has reference value for the sustainable development of cotton production.

ABSTRACTUnderstanding soil types in a specific region is crucial for developing effective approaches to control irrigation water usage and promote sustainable agriculture. This research aimed to characterize and classify the soils of Ajacho Lintala irrigation scheme located in Soro woreda of Southern Ethiopia. Through the analysis of 25 auger observations, 4 pedons, a comprehensive reconnaissance survey, and laboratory analysis, this study examined the morphological, and physicochemical characteristics of the soils in the irrigation. The study identified 16 soil samples from four pedons, consisting of both undisturbed and disturbed soil profiles, which were collected for laboratory analysis. The soils in the research irrigation scheme were classified using the FAO/WRB 2015 classification system. The findings revealed that the texture classes of the study irrigation scheme’s soils varied from loam to clay loam for Nitisols, silt loam to clay loam for Luvisols, and clay for Vertisols. Moreover, the available phosphorus, total nitrogen, and organic carbon in the soils were categorized as very low to low range, while cation exchange capacity and basic cations (Ca2+, Mg2+, K+, and Na+) were in the medium to high range. Based on morphological and physicochemical investigations, the soils were classified as Humic Nitisols, Rhodic Luvisols, Haplic Luvisols, and Pellic Vertisols. These classifications align with the equivalent USDA classification of Ultisols (Typic Haplustults), Alfisols (Typic Haplustalfs), and Vertisols (Typic Haplusterts), respectively. To maintain and enhance soil fertility a sustainable soil management system is recommended, which includes practices such as continuous crop cover, mulching, and organic manuring with suitable inorganic fertilizers. Additionally, implementing physical land management measures to control soil erosion in slope areas is crucial.

Metal(loid)s pose a significant hazard due to inherent toxicity. Individuals are particularly exposed to metal(loid)s in soil through direct or indirect contact. Identifying metal(loid) sources in soil is required for exposure mitigation to anthropogenic metal(loid)s, while metal(loid)s are natural constitutes of soil. Metal(loid) concentrations and Pb isotopes were determined in residential soil profiles impacted by a Zn smelter to distinguish the anthropogenic effect from natural levels. One hundred sixty-nine core soil samples were collected from depths down to 5.5 m below ground level at 19 sites and were divided into Zn-Cd-As- and As-contaminated groups based on the worrisome level (WL) of soil contamination. The Zn-Cd-As-contaminated group (n = 62) was observed at depths < 1 m, showed high Zn levels (mean of 1168 mg/kg) and Cd and As frequently exceeding WLs, and had low 206Pb/207Pb ratios close to the Zn smelter. In contrast, the As-contaminated group (n = 96) was observed at depths > 1 m, did not have other metals exceeding WLs, and showed a wide range of 206Pb/207Pb ratios far away from the Zn smelter. The results indicated that the pollution sources of Zn-Cd-As- and As-contaminated soils were fugitive dust emissions from smelter stacks and geology, respectively. The metal(loid)s in host rock set geochemical baselines in soil profiles, while smelting activities affected the upper layers over 50 years. This study demonstrated the effectiveness of utilizing the vertical distribution of metal(loid) concentrations and Pb isotopes in soil profiles for distinguishing between anthropogenic and geogenic origins, in combination with baseline assessment. [ABSTRACT FROM AUTHOR]

Background and aims: Dissolved organic matter (DOM) is a vital bioactive component in soil nutrient cycling. However, the dynamics of its characteristics and composition along the soil profile during desertification reversal are poorly understood. Methods: Soil samples were gathered from shrub and arbor forests that have been established for 25, 35, 46, and 56 years on semifixed sand of Mu Us Sandy Land. The evolution of DOM composition and chemical properties were explored by ultraviolet-visible and fluorescence spectrophotometry. Results: After 56 revegetation years, DOM increased significantly. In arbor lands, DOM was impacted mainly by dissolved organic carbon, with mean concentrations increasing from 58.89 mg·kg-1 to 131.95 mg·kg-1 in 0-100 cm soil profile. In the shrubland, changes in dissolved organic nitrogen were more remarkable, with mean concentrations increasing from 3.43 mg·kg−1 to 6.82 mg·kg−1 in 0-100 cm soil profile. Concurrently, as soil depth increased, noticeably decreased in the proportion of humic-like components within DOM, while protein-like components displayed an upward trend. The chemical properties of DOM in arbor lands display a higher proportion of hydrophobic substances along with an elevated aromaticity and humification degree. Conversely, in shrubland, the DOM composition exhibits a higher proportion of tryptophan components that are more available for microbial metabolism. Correlation analysis showed that DOM content and specific environmental factors (including soil depth, vegetation type, and afforestation age) profoundly affected soil DOM properties. Conclusions: The DOM in arbor land and surface soil layer were more humified and relatively stable. Conversely, the DOM in shrubland and deeper soil layers contains more bioactive substances for microbial utilization. [ABSTRACT FROM AUTHOR]

The study of the chemical and mineralogical composition of the agricultural soils is essential to know its process of formation. and the characteristics associated to the fertility and to the retention of nutrients as foundations for conduct its use and management. With this objective are evaluated Brown sialitic and Vertisols soils representative of the eastern region of Cuba. The technique of X-rays diffraction (DRX) was used for determine the mineralogical and chemistry composition of the predominant soils. Were calculated the oxides SiO2, Al2O3, Fe2O3 and the molecular relations SiO2 / Al2O3, SiO2 / Fe2O3 and SiO2 / R2O3 for characterize the soils. The predominant minerals in the Brown soils were in that order: calcite, quartz, montmorillonite and anortite. In the Vertisols were detected quartz, albite and vermiculite that are very resistant to the meteorism. The vertical distribution of the minerals show a degree of evolution uniform of the parent rocks. The sequence of free oxides (SiO2> Al2O3> Fe2O3) corroborated the sialitic origin of the soil profiles, associated with the predominance of minerals in a relation 2:1. The uniform distribution of the total of elements in all the profiles shows a lithogenic origin. [ABSTRACT FROM AUTHOR]

In the modern world, rare earth elements (REE) and yttrium (Y) dominate the development of high-end electronic equipment and green energy technologies. The global economic deposits of REE and Y are primarily associated with alkaline and peralkaline igneous rocks. The REE deposit of the Siwana ring complex, Rajasthan, India, is entirely composed of peralkaline igneous rocks. This complex is made up of REE and Y-enriched (both LREE and HREE) peralkaline granite, rhyolite and its younger felsic intrusives such as rhyolite, microgranite, aplite and felsite dykes. We present a study of the REE and Y potential of granites, volcanic rocks and felsic dykes from 17 quarries in the Siwana area. Monazite, zircon and apatite were the primary (magmatic) REE-bearing phases identified under a microscope. The late/post-magmatic replacement in granite is evident as coarsening of perthite lamellae, pseudomorphic replacement of alkali feldspar grains by aegirine, replacement of aenigmatite by aegirine, etc. The granites, volcanic rocks and dykes show significant enrichment of REE + Y and other trace elements (Sn, Hf and U). A total of 20 rock samples were analysed using inductively coupled plasma mass spectrometry, which indicated significant REE + Y values ranging between 1061.22 and 9088.62 ppm, with an average of 2361.89 ppm. This includes LREE (707.42-5743.83 ppm, avg. 2080.40 ppm) and HREE (135.77-1422.23 ppm, avg. 402.41 ppm) Hf up to 425.55 ppm. Totally five samples from a soil profile were also analysed, yielding REE + Y values between 223.39 and 3175.75 ppm, with an average of 1714.51 ppm. The ion adsorption clay horizon developed within the soil profile showed a maximum REE + Y value of 3175.75 ppm. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the responses of crop production and soil profile nutrient status to biochar (BC) application, we conducted a soil column experiment considering two BC addition rates (0.5 and 1.5 wt% of the weight of 0–20 cm topsoil) combined with two nitrogen (N) input levels (low N: 144 kg ha−1, LN; high N: 240 kg ha−1, HN). The results showed that BC application increased the soil pH. The soil pH of the 0–10 cm profile under LN and the 20–40 cm profile under HN were both significantly increased by 0.1–0.2 units after BC addition. Under LN, BC addition significantly increased NH4+-N (17.8–46.9%), total N (15.4–38.4%), and soil organic carbon (19.9–24.0%) in the 0–10 cm profile, but decreased NH4+-N in the 20–30 cm soil profile and NO3−-N in the 10–30 cm profile by 13.8–28.5% and 13.0–34.9%, respectively. BC had an increasing effect on the available phosphorus, the contents of which in the 10–20 and 30–40 cm soil profiles under LN and 20–30 cm profile under HN were significantly elevated by 14.1%, 24.0%, and 23.27%, respectively. However, BC exerted no effect on the available potassium in the soil profile. BC had a strong improving effect (15.3%) on the wheat yield, especially the N144 + BC0.5% treatment, which could be compared to the HN treatment, but there was no yield-increasing effect when high N fertilizer was supplied. In summary, BC improved the fertility of agriculture soil (0–20 cm) with wheat. In particular, low N inputs together with an appropriate rate of BC (0.5 wt%) could not only achieve the low inputs but also the high outputs in wheat production. In future study, we will compare the effects of multiple doses of N and BC on soil fertility and crop production. [ABSTRACT FROM AUTHOR]

In order to study the impact of human activities on urban soil environment, the soil profile of a plot of dry-land dug at the foot of the Zhuizi Mountain (117.46°E, 32.91°N) in Bengbu City was investigated to examine its property regarding the content of mineral components and heavy metal elements (Zn, Pb, Cr, Ni, Cu); additionally, its magnetic parameters were measured including low-frequency volume magnetic susceptibility (KL), high-frequency volume magnetic susceptibility (KH), anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM, SIRM), temperature-dependent magnetic susceptibilities (k-T curve), and the measured data were calculated and statistically analyzed. The findings of the study reveals that the soil profile mainly consists of minerals such as quartz, albite, potassium feldspar, illite and montmorillonite; owing to the influence of human activities in the City, the content of Zn and Pb in the top soil was significantly increased; magnetic minerals in the soil includes magnetite hematite, goethite and lepidocrocite, but was relatively low, the magnetic properties of the soil profile are mainly dominated by ferrimagnetic minerals. According to the variation of magnetic parameters related with depth of the soil profile, the soil profile can be divided into two layers: 0-20 cm being the first layer, 20-80 cm the second layer. The magnetic property of the second layer of soil is mainly determined by the soil parent material, on the other hand, the first layer of soil has been affected by strong magnetic particles brought about by urban human activities, the average values of x, SIRM and XARM being remarkably higher than those of the second layer, while Xfd and XARM/SIRM average values lower than those of the second layer, reflecting an increase in the content of magnetic mineral and coarsening of particles in the first layer of soil. The facts of magnetic parameter values vary with depth of the soil profile within 0-20 cm reflected the process and degree of influence on the dry-land soil profile, exerted by urban human activities. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nitrous oxide (N2O) emissions from organic waste and animal slurry contribute to climate change and endanger our ecosystems. For the development of efficient mitigation technologies, in-depth knowledge of emission processes is needed. This can be obtained by non-destructive, temporal measurements of in-situ soil profiles and the transformation of ammonium (NH4+) during events of emissions. Planar optode imaging is a non-destructive measuring method that can be used to visualize spatiotemporal changes of ammonia (NH3) and pH in soil systems. In this study, soil amended with dairy processing sludge (DPS) was incubated in static chambers for 23 days, and GHG emissions, NH3 concentrations and pH in the soil were measured simultaneously over time. The aim was to investigate the potential of applying different planar optodes to provide information that gives insight into processes of N2O emissions. The DPS was applied to the soil as a surface layer (SL), with untreated soil as a control (CK). We were able to measure N2O emissions while monitoring spatiotemporal changes of soil pH and NH3 concentrations. The visualized microscale heterogeneity of the soil contributed to a better understanding of N2O emission processes. While technical challenges (e.g., humidity sensitivity of the NH3 optode and airtightness of the chambers) still need to be overcome, the method is a promising non-destructive method to study soil processes after application of different types of soil amendments.

This study sheds light on the effect of diversity in the parent rock on some properties and development of soil profiles in the northern part of the coastal region of Syria. To achieve the goal of this study, several different profiles of the parent material were selected: profiles (P1, P2, P3, P4) on sedimentary rocks and profiles (P5, P6, P7. P8, P9) on ophiolites. Profiles were excavated, described morphologically, and samples were taken from each horizon to conduct the necessary analyzes, according to internationally accepted methods. The results showed that most soil properties are affected by changes in the parent material and its composition, such as carbonate content, amount of organic matter, soil texture and color, pH level, chemical composition, and other properties studied, thus affecting the classification of these soils. The Mollisols order dominated the areas where ophiolite rocks spread, while the orders varied between Mollisols, Entisols, and Vertisols in the areas of sedimentary rocks. The presence of forest vegetation, along with the mineral composition of the parent rock, in addition to secondary factors such as fires, played a role in the development of soils and their taxonomic level.

X-ray diffractometry (XRD) and Mössbauer spectroscopy (MS) were used to study the clay fractions of soil profile samples from the quinoa (Chenopodium quinoa Willd.) plantations at the Salcedo Experimental Station of the National Institute of Agrarian Innovation located in the southern Peruvian plateau. The sample extraction was made at 40 cm intervals from 20 cm to 180 cm in depth, and the clay fraction was obtained by the Stokes' law. In addition, the tests of the physical and chemical properties were included, such as pH, organic matter, and humidity, which present values that increase in relation to the depth from 6.75 to 8.09, 4.31% to 6.25%, and 5.38% to 27.08% respectively, and with class texture of sandy loam (first three) and clay loam (remaining two samples). The XRD results showed the presence of phases such as quartz, montmorillonite, andesine and hematite. The room temperature MS spectra were fitted using four paramagnetic sites, doublets, and one magnetic site, sextet. The hyperfine parameters for the sextet are compatible with hematite. Three of the paramagnetic sites were assigned to montmorillonite, two in the octahedral sites, trans and cis configurations, and one at the edge site. The presence of hematite and montmorillonite were confirmed at low temperature; in addition, a second sextet was observed with hyperfine parameters that were compatible with goethite. [ABSTRACT FROM AUTHOR]

Bacterial communities inhabiting the soil of mountain ecosystems perform critical ecological functions. Although several studies have reported the altitudinal distribution patterns of bacterial communities in warm-temperate mountain forests, our understanding of typical zonal vegetation dominated by Larix principis-rupprechtii Mayr (abbreviated as larch hereafter) and the understory elevation distribution patterns of soil bacterial communities is still limited. In this study, the Illumina NovaSeq 6000 sequencing platform was used to investigate the changes of surface and subsurface soil bacterial communities along an altitudinal gradient (from 1720 m to 2250 m) in larch forests in northern China. Altitude significantly affected the relative abundance of Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi (bacterial dominant phylum) and Alphaproteobacteria, Gammaproteobacteria, and Actinobacteria (bacterial dominant classes). The diversity of bacterial communities showed a concomitant increase with altitude. The variations in available nitrogen and soil temperature content at different altitudes were the main factors explaining the bacterial community structures in pure stands and mixed stands, respectively. Altitude and the contents of soil organic carbon and soil organic matter were the main factors explaining the dominant phylum (taxonomy). Our results suggest that stand type has a greater effect on the structure and composition of soil bacterial communities than elevation and soil depth, and bacterial communities show divergent patterns along the altitudes, stand types, and soil profiles. [ABSTRACT FROM AUTHOR]

Determination of the microbial and enzymatic properties in soil is primarily concentrated on the surface layers of the soil profiles; however, it is well known that the transformation of soil organic matter also occurs in the deeper horizons of the soil profile. The aim of this study was to assess any changes in specific sets of enzyme activities and their associated physicochemical properties as affected by two different agricultural land-use systems and soil depth. Changes in the studied properties were determined across four Luvisol profiles in two agricultural land uses (arable land and vineyards). The enzyme activities associated with the transformation of C, N and P were analyzed. Additionally, the activity of some oxidoreductases and the fluorescein diacetate hydrolysis (FDAH) rate were also determined. Moreover, the content of the various forms of soil carbon, nitrogen, phosphorus (including microbial biomass C, N and P) and some other properties (pH, clay and silt content) were assessed. Agricultural land use significantly affected the microbial biomass content and as well as the studied enzyme activities. Most of the studied enzymes exhibited a higher activity in the grapevine (GV) profiles, which was followed by the winter wheat (WW) profiles; however, the largest variability occurred for the urease activity. There was no clear differentiation between the two studied land uses for the activity of nitrate reductase, dehydrogenases, acid phosphatase, or endo- and exo-cellulase. Irrespective of the plant being cultivated, the soil variables decreased significantly with increasing soil depth, wherein the greatest changes were observed between the surface and sub-surface soil horizons (I–II). The activity of some enzymes (e.g., the urease activity in WW profiles) decreased gradually across the soil profiles, while others were located almost solely within the surface layers (e.g., the nitrate reductase activity in the GV profiles as well as invertase in the WW profiles). The α-glucosidase activity did not exhibit any statistically significant changes along the analyzed profiles. The activity of phenol oxidase and peroxidase also revealed different trends along the studied profiles compared to the other enzymes and did not decrease gradually with depth. The microbial biomass of the C, N and P content was generally the highest in the upper horizons and gradually decreased with depth, wherein the largest decrease was observed between the surface and sub-surface horizon. The studied enzyme activities were more dependent on the soil carbon content compared to the other soil properties. And thus, in the C-rich horizons (C > 4 g kg) for the surface and subsurface layers the enzyme activities were highly correlated with TOC, DOC and MBC content as compared to the deeper, C-low horizons (C < 4 g kg). By examining how the microbial and enzymatic properties change across the soil profiles, it is possible to gain valuable insight into the long-term biogeochemical processes that are involved in soil fertility and in the health of agricultural ecosystems. [ABSTRACT FROM AUTHOR]

[Objective] It is of great significance for clarifying the influence of different pretreatment methods on the measurement of soil particle composition(PSD), which is the basis of studies on water transport, nutrient transport, soil erosion and sediment transport processes. Soil particle composition(PSD) is the basis of soil physical properties and has important implications for [Methods] Typical purple soil natural woodland profile soil(0-110 cm) was selected, and 9 pretreatment methods were adopted, including physical methods of soaking and shaking, and chemical methods of H2O2 and HCl treatment, and then particle analysis was carried out with a Mastersizer 2000 laser particle size analyzer. [Results](1) The median particle size of each physical pretreatment decreased by 33.79 μm on average compared with the direct measurement without any pretreatment(control). The median particle size under pretreatments of soaking, shaking for 2 h, and shaking for 10 h decreased sequentially, but their release effects on clay were weak. There was no significant difference in clay content between different shaking times(p＞0.05). The median particle size of each chemical treatment could be reduced by 32.72 μm on average compared with control. Among them, the H2O2 treatments had a stronger dispersing effect than the HCl treatments, and the clay contents of H2O2 treatments were the highest among all treatments, which were greater than 4%.(2) Each physical pretreatment method had a uniform dispersion effect among soil layers. Sensitivity to different H2O2 dosage of different layer of soil was middle(30-70 cm)＞lower(70-110 cm)＞upper(0-30 cm). Specifically, sand content in the 20-90 cm soil layer under sufficient H2O2 pretreatment increased by 9.5% and silt content decreased by 9.7% compared with 10 ml H2O2 pretreatment. Sensitivity to different HCl pretreatments of different layer of soil was upper and middle＞lower, specifically the sand content of the upper and middle soil(0-90 cm) increased by 6.2% on average under the treatment of 10 ml HCl plus acid washing compared with the treatment without acid washing. The silt content reduced by an average of 5.4%. There was no significant difference in clay content among soil layers under these treatments.(3) There was a significant linear correlation(r＞0.8) between the content of sand and silt and the content of organic matter in the profile under the treatment of sufficient H2O2, but there was no significant correlation between the content of calcium carbonate and any particles under the treatment of HCl. [Conclusion] There are significant differences in PSD between different pretreatment methods, and the amount of reagent in chemical pretreatments affects the PSD obviously, too. This study can provide a reference for the analysis of purple soil particle composition under different research purposes. [ABSTRACT FROM AUTHOR]

The combination of karst high geological background and mining activities in northwest Guangxi leads to increase soil pollution risk, which poses a potential threat to food and ecological security. Study on the spatial distribution characteristics and bioavailability of cadmium(Cd)in soil profiles in this region can effectively assess the pollution status and ecological risk of Cd in soil. Soil samples were collected from rice field profiles(0-100 cm)at three different positions within Dachang mining area, located in the typical karst region of Nandan county, Hechi city, Guangxi. The distribution characteristics and bioavailability of Cd in soil profiles were analyzed, and the ecological risk and pollution status of Cd in three soil profiles were evaluated by using the enrichment index method and risk assessment index. The results show that the vertical distributions of Cd contents are different among the three soil profiles, and the soil Cd is significantly enriched in the surface(0-20 cm), with 86.7% of samples showing soil enrichment factor values over 2, indicating that there is obvious accumulation of heavy metal Cd from human sources in the soil surface. According to Soil Environmental Quality: Risk Control Standard for Soil Contamination of Agricultural Land(GB 15618—2018), the Cd contents of some samples in the two soil profiles far from the mining area exceed the screening value of soil pollution risk of agricultural land, and in the soil profile adjacent to the mining area, the Cd contents of 90% soil samples surpass the pollution risk control value for agricultural land. The Cd content of soil profiles in the study area is mainly controlled by the superimposed effects of multiple factors such as geological background, agricultural cultivation and mining activities. The difference in the content of soil profiles mainly depends on the distance to the mining area(the closer the distance to the mining area, the higher the Cd content), while the same profile is primarily influenced by pH value and organic matter content. The Cd predominantly exists in the Fe-Mn binding state, ion exchange state, and residue state within the soil matrix. The bioavailability of Cd is primarily influenced by total Cd content, pH value, organic matter content and fixation of Fe-Mn oxides in soil, showing a relatively high availability in soil profile and soil surface far from the mining area. [ABSTRACT FROM AUTHOR]

Microbial necromass, an important and stable source of soil organic carbon (SOC), is an important index to evaluate the contribution of microorganisms to SOC transformation and accumulation. It is not clear about the accumulation of microbial necromass in deep soil layer and its contribution to SOC during the restoration process of Caragana korshinskii forests. Combined with the biomarker method, we investigated the carbon contents of bacterial, fungal, and microbial necromass in the soil profiles (0-100 cm) of C. korshinskii forests in 16, 28, and 38 years of restoration, with natural grassland as control. We further examined the contribution of microbial necromass to soil organic carbon. The results showed that: 1) Along the soil profile (0-100 cm), the contents of fungal neccrease in FNC/SOC, BNC/SOC, and MNC/SOC in the soil of C. korshinskii forests in 38 years of restoration, FNC/SOC and MNC/SOC generally showed an increasing trend followed by a decreasing trend in other plots, while BNC/SOC gradually decreased. 2) With the increases of restoration years, the contents of FNC, BNC, and MNC significantly decreased in C. korshinskii forests. FNC/SOC and MNC/SOC showed an overall increasing trend followed by a decreasing trend, while BNC/SOC gradually decreased. 3) The average contribution of microbial necromass carbon to SOC was highest in C. korshinskii forests in 28 years of restoration (35.0%), followed by C. korshinskii forests in 16 years of restoration (33.5%), natural grassland (31.0%), and C. korshinskii forests in 38 years of restoration (28.6%). In conclusion, when the restoration years of C. korshinskii forests are 16, the contents of microbial necromass carbon and their contributions to SOC are higher compared to natural grassland, which are beneficial for SOC sequestration. [ABSTRACT FROM AUTHOR]

In urban ecosystems to the west of the Elektrostal Heavy Machinery Plant, six years after the radiation incident, local sites with a total area of 0.2 km2 with an increased equivalent dose rate of γ radiation of 0.15–0.40 μSv/h and a high specific activity of 137Cs reaching 8328–8740 Bq/kg in the upper soil horizons were identified. Statistically significant direct correlations were noted between the specific activity of 137Cs in the layer of 0–10 cm of soil and the equivalent dose rate of γ radiation at the surface and height of one meter. The types of vertical distribution of 137Cs in soils of polluted urban ecosystems, including those on which earth decontamination works were carried out, have been determined. The calculated 137Cs transfer coefficients increase in the series of trees Salix alba < Sórbus aucupária < Ácer platanoídes < Malus domestica < Alnus incana < Ácernegúndo; and grassy vegetation Týpha angustifólia < Artemísia vulgáris < Tussilágo fárfara < Cirsium arvense < Urtíca dióica. [ABSTRACT FROM AUTHOR]

Reducing CO2 emissions from agricultural soils is a key component of the overall carbon reduction strategy. The closed chamber method was used to continuously monitor CO2 concentration in soil profiles of winter wheat-summer maize rotation fields in the North China Plain (NCP) during 2015–2017. Additionally, we evaluated the contribution of different tillage methods (Rotary tillage (RT), Subsoiling (SS), No- tillage (ZT), and conventional tillage (CT) in combination with Straw return (s) and straw removal (0)) to reducing soil CO2 emission. The results showed that the concentration of CO2 increased with the soil depth and peaked at the 150 cm layer. The trend of CO2 concentration in soil profiles under different tillage treatments was CTS > RTS > ZTS > SSS, and the average concentration in maize season was higher than that in wheat season. In addition, soil moisture and temperature in the 0–10 cm soil layer were significantly correlated with soil CO2 concentrations. Thus, our results highlight that the SSs plays a critical role in moderating soil CO2 emissions. This process merits further study to effectively regulate soil CO2 release and achieve carbon neutrality with less carbon emissions in farmland ecosystems. [ABSTRACT FROM AUTHOR]

Inorganic fertilizers are widely used to provide crops with significant amounts of nitrogen (N) and phosphorus (P), but can exacerbate soil carbon (C) limitation and acidification. Crop residues with distinct ecological stoichiometry from inorganic fertilizers can help balance soil ecological stoichiometry and thus increase soil organic matter accumulation. The combined use of inorganic fertilizers and crop residues is expected to alleviate the metabolic limitations of organisms and enhance soil C, N, and P sequestration, hence increasing grain yields. However, the effects of this practice on soil C, N, and P stocks and grain yield remain unclear. In this study, we conducted a meta-analysis of 806 paired data to investigate the impact of crop residue return combined with inorganic fertilizer on soil and grain yield across different land uses (paddy, upland, paddy-upland rotation) and soil profiles (0–60 cm). Our findings indicate that crop residue return significantly enhances soil C (8–13%) stocks across all soil layers, particularly in the topsoil (0–20 cm). Soil N (9%) and P (5%) stocks also increase significantly in the topsoil. In uplands, crop residue return can mitigate soil acidification and increase grain yield (by 7%). Moreover, the soil C and N stocks increase depending on the initial soil pH, C and N levels, and C:N ratio. In contrast, the soil P stock increase depends on rainfall, while the grain yield increase is closely linked to the soil texture and fertilizer rate. Our study highlights that crop residue return can increase topsoil C, N, and P stocks, which can benefit crop growth and environmental mitigation efforts. Furthermore, this practice can increase C stocks in deeper soil horizons (below 20 cm), providing a long-term solution to mitigate climate change. [ABSTRACT FROM AUTHOR]

Copyright of Anbar Journal of Agricultural Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research work examines the effects of sawdust ash (SDA) and palm kernel shell ash (PKSA) on the geotechnical properties of termite-reworked soil obtained from different rock types and at various depth layers as filler or construction material for pre-engineering construction. The reworked soil samples were collected at the depth layers of 0.5 m (top layer), 1.0 m (middle layer) and 1.5 m (third layer) of a soil profile. Both index and strength tests were carried out on the termite reworked soil samples. The average values of the quartzite-derived, grey gneiss–derived and granite gneiss–derived rock type soil profiles are 24.1%, 53.3% and 40.7% (percentage of fines); 36.9%, 51.3% and 45.8% (liquid limit); 18%, 23.6% and 19.3% (plasticity index); 7.1%, 8.4% and 10.7% (linear shrinkage); 1974 kg/m3, 1534 kg/m3 and 1755 kg/m3 (maximum dry density); 14.1%, 22.2% and 17.1% (optimum moisture content); and 36%, 22% and 30% (California bearing ratio) respectively. The soil samples have fair to good ratings with favourable strength according to the American Association of State Highway and Transportation Officials classification and Nigeria specification. Quartzite-derived termite reworked soil gave the better performance and offered the higher strength ratings while grey gneiss–derived termite reworked soil gave the least performance. The soil properties improved down the three soil profiles. SDA and PKSA additives were added to the termite reworked soil samples at 6% of the weight of the reworked soil. For most of the tests carried out, SDA additive produced the better result when compared to PKSA additive. The results also revealed that the two additives on termite reworked soils are independent of the different horizons (top, middle and third layers). Analysis of variance shows that there are significant statistical differences between the termite reworked soils derived from the three parent rock types before and after the addition of the additives basically because of their clay content. [ABSTRACT FROM AUTHOR]

The dissolved organic matter (DOM) in forest ecosystems significantly impacts soil carbon cycling due to its active turnover characteristics. However, whether different plantation forest soil profiles exhibit distinct DOM characteristics remains unclear. Hence, utilizing fluorescence spectroscopy and the parallel factor analysis (PARAFAC) method, a 1-meter soil profile analysis was carried out on three distinct artificial forests (Pinus tabuliformis (PT), Quercus crispula (QC), and a mixed forest of PT and QC (MF)), concurrently assessing the impact of soil chemical properties and enzyme activity on dissolved organic matter (DOM). The findings indicated that the mean concentration of dissolved organic carbon (DOC) was greatest in the MF and lowest in PT, exhibiting considerable variation with soil depth, suggesting that mixed tree species may promote the discharge of organic matter. The fluorescence spectra revealed two distinct peaks: humic-like fluorescence peaks (Peaks A and C) and a protein-like fluorescence peak (Peak T), with the most intense fluorescence observed in MF soil. As the soil depth increased, the fluorescence intensity of Peaks A and C steadily declined, while the intensity of Peak T rose. Four DOM components were identified in three types of plantations forests: surface soil was dominated by humic acid-like fluorescent components (C1 and C2), while the deep soil was primarily characterized by protein-like fluorescence components (C3 and C4). Different soil profile fluorescence parameter indices indicated that the source of DOM in the surface soil (i.e., 0–20 cm) was mainly allochthonous inputs, whereas, in the deep soil (i.e., 60–100 cm), it was mainly autochthonous, such as microbial activity. The findings from the partial least squares path modeling (PLS-PM) revealed that TP, aP, NH4+-N, and the combined impact of soil enzymes were influential in shaping the diversity of DOM attributes. Put differently, alterations in DOM concentration were concomitantly influenced by forest classification, soil characteristics, and depth. It has been demonstrated that, in contrast to monoculture forests, the establishment of mixed forest models has been more advantageous in enhancing the soil dissolved organic matter (DOM). These discoveries offer innovative perspectives on the dynamic characteristics of DOM in soil profiles and its influencing factors under different plantations forest planting patterns.

More than half of the carbon pools in peatlands are stored in the soil layers below 30 cm, yet little is known about the carbon stabilizing factors at these depths. Although iron oxide minerals are considered to be important for stabilizing organic carbon (OC), their role in the preservation of OC in peatlands, especially in the deep layers, is poorly understood. Here, we collected 1 m soil profiles from six peatlands in Central and West China to quantitatively study the vertical distribution characteristics of iron-bound OC (Fe-bound OC), and the influencing physicochemical properties of the soil. The results showed that the content of reactive iron (FeR) was enriched in the top layer and decreased gradually with depth. While Fe-bound OC was positively correlated with FeR, its concentration did not decrease with depth in the peat profile. There were no obvious trends in the distributions of FeR and Fe-bound OC with water level fluctuations in the peat profile. In addition, the proportion of Fe-bound OC to soil organic carbon in the deep peat (31 to 100 cm) was equivalent to that in the surface peat (0 to 30 cm), indicating that iron oxide mineral provides comparable protection of OC in both layers. According to upper estimates of global peatland carbon storage (612 Pg), it could be predicted that 23.81 ± 11.75 Pg of OC is protected by association with FeR. These results indicated that iron oxide minerals are the effective ''rusty sink'' of OC sequestration in peatland, and a key factor for its long-term preservation. The results from this study make a valuable contribution to the carbon dynamics knowledgebase for peatlands, and provide a basis for improved predictive simulations.