Search

Plant litter is a well-defined pool of organic matter (OM) in which the influence of manganese (Mn) on decomposition (both decomposition rate and the mix of compounds ultimately transferred to soil OM) has been clearly demonstrated in temperate forests. However, no similar study exists on grasslands and the effect of foliar Mn versus soil-derived Mn on litter decomposition is poorly known. We used a 5-month and 12-month field, and 10-month laboratory experiments to evaluate litter decomposition on the Kohala rainfall gradient (Island of Hawai‘i) in areas with different foliar and soil Mn abundances, and on which a single plant species (Pennisetum clandestinum) dominates primary production and the litter pool. The chemical imaging analyses of decomposed litter revealed that Mn2+ oxidized to Mn3+ and Mn4+ on grass litter during decompositions—hallmarks of Mn-driven litter oxidation. However, these transformations and Mn abundance did not predict greater litter mass loss through decomposition. These observations demonstrate that the importance of Mn to an ecosystem’s C cycle does not rely solely on the metal’s abundance and availability. [ABSTRACT FROM AUTHOR]

Minute particles within the soil can normally possess charges and predominantly concentrate on the soil colloids. These charges on the soil surface can contribute to a variety of physical, chemical, and physiochemical characteristics of the soil. Key property parameters of soil colloidal particles can include the surface potential, surface charge density, surface electric field intensity, specific surface area, and surface charge number. The objective of this study was to investigate the impacts of prolonged utilization of organic fertilizer and straw on these electrochemical characteristics of the soil surface. Furthermore, the primary influencing factors were determined to enhance the fertility of arable land. A long-term experiment was conducted at the Shuitou experimental base in Yuncheng City, Shanxi Province since in 2007. Four treatments were set as the exclusive application of chemical fertilizer (F), a combination of organic and chemical fertilizer (MF), the integration of straw returning with chemical fertilizer (SF), and a comprehensive application of organic fertilizer, straw returning, and chemical fertilizer (MSF). The electrochemical properties of the soil surface were examined, including surface potential, surface charge density, surface electric field intensity, specific surface area, and surface charge number. Additionally, organic carbon fractions were also analyzed, such as soluble organic carbon, particulate organic carbon, mineral-associated humus, fulvic acid, and humic acid. Furthermore, the investigation was conducted on the structural characteristics of mineral-associated humus. The results indicated that the application of organic fertilizer and straw returning treatments (MF, SF, and MSF) was substantially enhanced the electrochemical characteristics of the soil surface, compared with the F treatment (P<0.05). Among them, the MSF treatment exhibited the highest values, with the respective measurements of 17.07 cmol/kg, 67.02 m² /g, 0.25 c/m², 5.12×108 V/m, and -91.14 mV, respectively. Compared with the F treatment, the MF, SF, and MSF treatments were significantly enhanced the quantities of total soil organic carbon and organic carbon fractions, including the soluble organic carbon, particulate organic carbon, mineral-associated humus, fulvic acid, and humic acid. Additionally, there was also an increase in the ratio of humic acid to fulvic acid (P<0.05). Specifically, the MSF treatment exhibited the highest contents and ratio, with the values of 21.5, 0.1, 12.1, 5.5, 3.3, 2.2 g/kg and 1.5. Meanwhile, the organic fertilizer and straw returning treatments were resulted in the a significant reduction in the E4/E6 and △lgK values of mineral-associated humus (P<0.05). There was the an increase in the relative abundance of C=O/C(O)N group within the mineral-associated humus. The comprehensive analysis revealed that there was the a significant positive correlation between soil surface electrochemical characteristics and various factors, including the total soil organic carbon, organic carbon fractions, clay content, and the ratio of humic acid to fulvic acid. Notably, there were the most substantial influences on the soil surface electrochemical characteristics by the mineral-associated humus, clay content, and the ratio of humic acid to fulvic acid, with the interpretation rates of 67.0%, 5.9%, and 4.8% respectively. And the E4/E6, △lgK, and C=O/C(O)N groups of humus were strongly associated with the soil surface electrochemical characteristics. In summary, the prolonged use of organic fertilizer and straw were substantially enhanced the electrochemical properties of the soil surface, in terms of the soil organic carbon fraction and the structural characteristics of humus. Consequently, these findings can also provide the theoretical foundation for the microscopic and macroscopic processes in soil. [ABSTRACT FROM AUTHOR]

Turbidity currents carve the deepest canyons on Earth, deposit its largest sediment accumulations, and break seabed telecommunication cables. Powerful canyon‐flushing turbidity currents break sensors placed in their path, making them notoriously challenging to measure, and thus poorly understood. This study provides the first remote measurements of canyon‐flushing flows, using ocean‐bottom seismographs located outside the flow's destructive path, revolutionizing flow monitoring. We recorded the internal dynamics of the longest sediment flows yet monitored on Earth, which traveled >1,000 km down the Congo Canyon‐Channel at 3.7–7.6 m s−1 and lasted >3 weeks. These observations allow us to test fundamental models for turbidity current behavior and reveal that flows contain dense and fast frontal‐zones up to ∼400 km in length. These frontal‐zones developed near‐uniform durations and speeds for hundreds of kilometres despite substantial seabed erosion, enabling flows to rapidly transport prodigious volumes of organic carbon, sediment, and warm water to the deep‐sea. Plain Language Summary: Seafloor avalanches of sediment, called turbidity currents, transport huge volumes of sediment and organic carbon to the deep‐sea, and they break critical seabed telecommunication cables that underpin global data transfer. However, turbidity currents are very difficult to measure directly as they often damage sensors placed in their flow path, so they are poorly understood. Here we show that turbidity currents generate ground vibrations that can be measured using ocean‐bottom seismographs placed outside the flow's destructive path, revolutionizing flow monitoring. These seismographs recorded the longest sediment flows yet measured in action on Earth, which traveled >1,000 km along the submarine Congo Canyon‐Channel offshore West Africa. We use these observations to test fundamental models of turbidity current flow behavior. Our measurements show that the front of the flows contain a fast frontal‐zone with high sediment concentrations, which can be up to ∼400 km long, whilst the whole duration of the flow can last for more than 3 weeks. These frontal‐zones develop near‐uniform durations and speeds, despite extensive seabed erosion that adds sediment into the flow. New information on flow durations shows how turbidity currents rapidly deliver prodigious volumes of organic carbon, sediment, and warm water to the deep‐ocean floor. Key Points: Remote seismic monitoring reveals the duration, internal structure, and evolution of powerful canyon‐flushing turbidity currentsFlows contain dense and fast frontal‐zones (up to ∼400 km long) that maintain uniform durations and speeds despite huge seabed erosionCanyon‐flushing flow frontal‐zones can bring substantial fluxes of organic carbon, sediment, and warm water to the deep‐sea in <24 hr [ABSTRACT FROM AUTHOR]

Data on the content and composition of hydrocarbons, like aliphatic and polycyclic aromatic hydrocarbons, in Holocene sediments (undisturbed cores 0–30 cm) are presented. The samples were collected in the southwestern region of the Kara Sea during the first part of cruise 89 of the R/V Akademik Mstislav Keldysh in September 2022. It has been established that the distribution of hydrocarbons, unlike organic carbon, does not depend on the lithotype of bottom sediments, because, along with methane, high molecular weight hydrocarbons are formed in the gas-saturated zone. This leads to an increase in the proportions of aliphatic (>1%) and polycyclic aromatic hydrocarbons (>1 × 10–3%) in the organic carbon composition, as well as to the change in their distribution and composition within the sedimentary sequence. In the lower horizons of columns, the HC composition becomes more autochthonous due to the growth of low molecular weight alkanes and naphthalenes. Changes in the redox potential in the sedimentary sequence also affect the concentrations and composition of hydrocarbons. [ABSTRACT FROM AUTHOR]

Organic carbon (OC) and elemental carbon (EC) play a significant role in aerosol mass and atmospheric processes. This study is focused on the eastern part of the Great Northern Plains of India, namely the Brahmaputra Plains, to understand the influence of regional and local contribution on the carbonaceous fraction of PM2.5. Mean annual PM2.5 concentrations exceeded the National Ambient Air Quality Standards (NAAQS), with values of 46.6 ± 30.0 μg/m3 in the rural area and 50.4 ± 34.4 μg/m3 in the semi-urban area. The range in monsoon-winter was found to be 22.7–71.9 μg/m3. OC and EC contribute 44–50% of the PM2.5 mass concentration. The OC/EC ratios ranged from 3.3 to 9.3 in the rural area and from 4.3 to 6.9 in the semi-urban area, indicating significant secondary organic aerosol (SOA) formation, especially during the high photochemical period of the pre-monsoon season. Lower δ13C values were observed during winter (-27.5‰ rural, -27.3‰ semi-urban), pre-monsoon (-28.1‰ rural, -27.6‰ semi-urban), and post-monsoon (-28.2‰ rural, -28.1‰ semi-urban) periods, suggesting influences from biomass burning, fossil fuel combustion, and aged aerosols. The study employs cluster analysis of air mass trajectory, and Moderate Resolution Imaging Spectroradiometer (MODIS) fire data to determine the influence of the hotspot Indo-Gangetic Plain (IGP) and long-range transport on aerosol carbonaceous content during most seasons except the monsoon period June–September in the Brahmaputra Plains. [ABSTRACT FROM AUTHOR]

Biochar plays an important role in agricultural production as it can improve soil fertility, promote nutrient adsorption and enhance plant growth. However, the distribution of biochar in the soil significantly impacts its application effect. In order to investigate the impact of non-uniform biochar distribution on soil nutrient uptake, root shape, peanut development, and the makeup of soil microbial communities, we carried out greenhouse peanut pot studies. This experiment followed a completely randomised design with four treatments, each with three replications. The four treatments were as follows: no biochar application (B0); concentrated biochar application near seeds (B1); relatively concentrated surface application of biochar (B2), and uniformly dispersed application of biochar (B3). The findings demonstrated that, compared to the no-biochar scenario, the aboveground and root nitrogen uptake was significantly (P < 0.05) improved by the B2 treatment, increasing by 42.79% and 51.39%, respectively, compared to the control group. Additionally, it reduced the concentrations of NO3--N and NH4+-N in the soil. The B2 treatment also significantly (P < 0.05) increased the net photosynthetic rate and aboveground dry matter weight, increasing by 196.85% and 53.96%, respectively, compared to the B0 treatment. The B1 and B3 treatments also demonstrated a higher promoting effect. The growth of the root system and the quantity of root nodules were promoted by the addition of biochar. The number of root nodules in the B2 treatment was 72.22% higher than that in the control group. In terms of microbial and bacterial communities, the addition of biochar increased the number of nitrogen--fixing bacteria to a certain extent, while the relative abundance of soil bacterial communities showed no significant differences. In general, the non-uniform distribution of biochar in the soil significantly affected peanuts' vegetative growth and developmental effects. The relatively concentrated surface application of biochar treatments contributes to improving plant nutrient uptake and root system development. This provides a more effective application method for agricultural personnel to apply biochar fertiliser in the future. [ABSTRACT FROM AUTHOR]

To examine the mechanisms of organic carbon transformation and sequestration by biochar in citrus orchard soil, a 100-day organic carbon mineralization test was conducted using citrus orchard soil from a 5-year-old forest. Calcium-modified citrus peel biochar (OBC-Ca) was applied at rates of 0%, 1%, 2%, and 4%. The results indicated that different percentages of OBC-Ca significantly influenced the mineralization processes in citrus orchards. Specifically, the cumulative mineralization of soil organic carbon was notably reduced by 8.68% and 17.00% with the application of 2% and 4% OBC-Ca, respectively, compared to the control group. Random forest analysis revealed that microbial biomass carbon (MBC), readily oxidizable carbon (ROC), and dissolved organic carbon (DOC) were critical indicators for predicting the cumulative mineralization of soil organic carbon. MBC and ROC were found to inhibit the cumulative mineralization, while DOC promoted it. As the proportion of OBC-Ca applications increased, MBC rose by 2.63% to 10.46%, ROC increased by 16.41% to 108.59%, and DOC increased by 0.48% to 11.67%. Correlation analysis demonstrated a significant negative correlation between the cumulative mineralization rate of soil organic carbon and soil enzyme activity, with soil sucrase content increasing significantly by 216.42% to 393.44% compared to the control. The application of calcium-modified biochar effectively reduces carbon dioxide emissions from citrus orchard soils, with a 4% application yielding the most favorable outcomes for enhancing soil carbon sinks, thereby positively impacting the carbon sequestration potential of citrus orchard soil. [ABSTRACT FROM AUTHOR]

The research was carried out to determine the potential effect of microbiota, organic carbon, percentage of moisture content, and microbial biomass concentration as an evaluator of variation in basal soil respiration rate. Relative distribution and composition of the microbial population were estimated from six different chronosequence manganese mine spoil (MBO0, MBO2, MBO4, MBO6, MBO8, MBO10) and forest soil (FS). The variation was seen in moisture content (6.494±0.210-11.535±0.072)%, organic carbon (0.126±0.001-3.469± 0.099)%, MB-C (5.519±1.371-646.969± 11.428) µg.g-1 of soil. A positive correlation was shown between OC with MB-C (r = 0.938; p< 0.01) and moisture content (MC) (r = 0.962; p< 0.01). Variation in the basal soil respiration (BSR) and microbial metabolic quotients (MMQ) was shown to range between 0.352 ± 0.007-0.958 ±0.014µg CO2-C.g-1 and 6.5× 10-3 - 1.481×10-3 µg CO2-C.g-1 microbial-C.h-1 with BSR: OC from (2.793-0.276)% respectively. This result shows that there is a gradual increase in OC, MC, MB-C, and BSR across seven different sites due to progressive enhancement in soil fertility that leads to the initialization of succession. Stepwise multiple regression analysis further confirms the degree of variability added by microbial biomass C, moisture content, organic carbon, and microbial population on basal soil respiration in microbes. Principal component analysis enables the differentiation of seven different soil profiles into independent clusters based on cumulative variance given by physico-chemical and microbial attributes that indicate the level of degradation of land and act as an index to restore soil fertility. [ABSTRACT FROM AUTHOR]

We investigated the total sediment O2 uptake (TOU), sulfate reduction rate (SRR), and benthic nutrient flux (BNF) at the Yellow Sea cold water mass (YSCWM) sediments (N3509 and N3507) and the coastal sediment (N3503) in the southern Yellow Sea. The organic carbon (OC) content increased from coarse- to fine-grained sediment, which was by far the highest at N3503 (0.89% and 6.1 Ø), followed by N3509 (0.72% and 4.5 Ø) and N3507 (0.15% and 3.0 Ø). The bottom water temperature at N3503 (16.0°C) was 6‒7°C higher than N3509 (10.2°C) and N3507 (9.0°C). The TOU and SRR at N3503 were 24.5 ± 5.0 mmol O2 m–2 d–1 and 6.5 mmol S m–2 d–1, 3‒6 times higher than the values measured at N3509 and N3507 (5.5 ± 0.2 and 4.2 ± 0.3 O2 mmol m–2 d–1 and 0.9 and 0.7 mmol S m–2 d–1, respectively). TOU showed a positive correlation with both the OC content and the bottom water temperature (R = 0.71, p < 0.001). The BNF at N3503 (3.4 mmol N m–2 d–1, 0.5 mmol P m–2 d–1, 3.8 mmol Si m–2 d–1) was 3‒37 times higher than the values measured at N3509. The BNF contributed 72–179% of the nutrients required for primary production at N3503, whereas the contribution was less than 30% at N3509. [ABSTRACT FROM AUTHOR]

This study investigated carbon sequestration potential in reforesting agricultural lands with prevalence of Scots pine (Pinus sylvestris L.) in the "Nasibash" site of the Eurasian Carbon Polygon, located in the Republic of Bashkortostan, Russia. The research focused on analyzing carbon stocks in different ecosystem components (tree stand, herbaceous layer, litter, and soil) across various stages of succession, including fallow land, hayfield, and four stages of Scots pine reforestation. We found that needles during the first stage of succession were characterized by the highest carbon sequestration, while the lowest was in underground phytomass (roots). The tree stand exhibited a higher potential for carbon sequestration in stem wood, branches, and needles compared to other components. The highest carbon accumulation in the tree layer was observed in the stem phytomass at the fourth stage of reforestation, while the highest phytomass accumulation in the herbaceous layer was in the root mass at the fourth stage of succession. The study revealed that the highest organic carbon content in the topsoil layer was observed in areas dominated by herbaceous vegetation, with a decrease in carbon content as the stage of succession increased. The highest carbon content was found in tree pines at the first stage of succession. The research highlighted the importance of considering conversion factors for different stages of reforestation, as the average carbon content in vegetation was 20% higher than the approved conversion factors for young tree stands. Overall, the study demonstrates the significant potential of Scots pine reforestation on former agricultural lands for carbon. The findings suggest that these territories play a decisive role in future environmental and climate projects, contributing to the decarbonization efforts. [ABSTRACT FROM AUTHOR]

Introduction: Seagrass sediments are important 'blue carbon' reservoirs which store climatically significant quantities of organic carbon (Corg) at the global scale. Seagrass meadows that overly these sediments also provide a range of critical ecosystem services including shoreline stabilization, storm surge protection, and fisheries nursery grounds. However, the controls over accumulation and the sources of organic C to these sediments beds are highly variable and poorly understood with the relative importance of hydrodynamic setting, species composition and canopy density being unclear. Methods: Here we address these questions using the first observation-based estimates of Corg stocks and provenance on Turneffe Atoll, Belize, made via remotely-sensed habitat extent, local Corg data and isotopic data. Sedimentary Corg was highest in sediments underlying the most sheltered meadows and decreased with increasing exposure to wind and wave energy with the seagrass meadows in the central lagoon containing an extensive deposit of mangrove derived organic carbon, stabilized and protected by the overlying seagrass meadow. Results: The influence of species composition appeared weak with the ubiquitous species T. testudinum occurring across a wide range of hydrodynamic regimes ranging from the most sheltered to the most energetic and being associated with a wide range of sedimentary organic C concentrations. Importantly from the perspective of remote sensing, org C concentrations were unrelated to canopy density. We hypothesize that this decoupling of organic C concentration from seagrass canopy cover reflects a much longer timescale for carbon storage in the sediments than the lifespan of the seagrass plants themselves and/or a substantial non seagrass derived organic C burden in seagrass sediments. Overall, we conservatively estimate that the top 30cm of sediments underlying the seagrass meadows overlying carbonate sediments on the atoll exterior store 0.58 x 106 Mg Corg, most of which is seagrass-derived, whilst the sediments underlying the meadows within the central lagoon store an additional 1.28 x 106 Mg Corg. When the maximum possible extent of seagrass is considered, this estimate increases to 3.54 x 106 Mg Corg. Substantial Corg stocks extending >1m depth were observed across all sites, and so these inventories are considered conservative. Discussion: A preliminary 'cost of loss' for sedimentary Corg in the top 30 cm of Turneffe Atoll's seagrass meadows, based on a carbon trading value of €60 tCO2 (eq), is estimated at €42 million for the outer atoll, increasing to €136 million when the mangrove-derived sediments of the central atoll are considered and €260 million when turbid areas are assumed to contain seagrass. [ABSTRACT FROM AUTHOR]

In response to the degraded soil health and lack of improvement in the yield of rice–wheat cropping systems in South Asia's Indo-Gangetic Plains, an experiment was formulated in a split-plot design. Four rice residue management practices were the primary factor, alongside two nitrogen levels (150 and 180 kg/ha) and two nitrogen split levels (two and three splits) as sub-treatments. The findings revealed a notable increase in soil organic carbon (SOC), microbial count, and enzymatic activity in plots subjected to conservation tillage and residue treatment compared to those in plots subjected to partial residue (anchored stubbles) and conventional methods (residue incorporated with chopping). The collective analysis demonstrated a significant influence of rice residue management practices and nitrogen application levels on wheat yield attributes and productivity. Specifically, zero tillage with full residue (unchopped) in wheat exhibited a 5.23% increase in grain yield compared to conventional tillage with full residue (chopped), concurrently boosting the soil microbial count by 19.80–25%, the diazotrophic count by 29.43–31.6%, and the actinomycete count by 20.15–32.99% compared with conventional tillage. Moreover, applying nitrogen in three splits (at sowing, before the 1st irrigation, and after the 1st irrigation) led to a 6.25% increase in grain yield than that in two splits (at sowing and after the 1st irrigation), significantly impacting wheat productivity in the soil. Furthermore, the zero tillage-happy seeder with full residue elevated dehydrogenase activity from 77.94 to 88.32 μg TPF/g soil/24 h during the study year, surpassing that in the conventional plot. This increase in enzymatic activity was paralleled by a robust positive correlation between the microbial population and enzymatic activity across various residue retention practices. In conclusion, the results underscore the efficacy of crop residue retention following conservation tillage, in tandem with nitrogen optimization and scheduling, in enhancing wheat yield within the rice–wheat cropping system. [ABSTRACT FROM AUTHOR]

Investigating carbon (C), nitrogen (N) and phosphorus (P) contents and ecological stoichiometric characteristics in leaf litter from tropical rainforests is crucial for elucidating nutrient cycling and energy flow in forest ecosystems. In this study, a 60-ha tropical montane rainforest dynamic monitoring plot in Jianfengling, was selected as the research site and 60 subplots were selected for detailed study. Leaf litter was collected monthly throughout 2016, branches of similar height were placed atthe four corners of each sample square to support a nylon cloth (1 m× 1 m) with 1 mm apertures. The collected plant leaves were sorted,placed into envelopes, labelled, and transported to the laboratory and samples from various plant species were identified, resulting in a total of 107 samples collected and analyzed. For the 31 dominant species, the leaf litter had C, N and P contents of 312.71 ± 28.42, 4.95 ± 0.46 and 0.40 ± 0.03 g/kg, respectively. The C:N, C:P and N:P ratios were 63.61 ± 7.50, 790.91 ± 82.30 and 12.49 ± 1.00, respectively, indicating moderate variability. The C, N and P contents exhibited greater variability among the plant groups, indicating significant heterogeneity among the samples. In contrast, the data from the subplots exhibited less variability, highlighting significant homogeneity. Overall, the mean carbon, nitrogen and phosphorus contents in the leaf litter from tropical montane rainforests were lower than those observed at national and global scales. The N:P ratios in leaf litter below 14 indicated that nitrogen limited litter decomposition in Jianfengling. However, no significant correlations were observed between the C, N and P contents and their stoichiometric ratios in leaf litter and those in soil. The above results provide important reference data and scientific basis for the nutrient cycling and energy flow processes, and in the future, we can explore the limiting role and mechanism of nitrogen in the decomposition process of leaf litter. [ABSTRACT FROM AUTHOR]

Aim: To identify the main factors affecting Al mobilization in soils from different climate zones. Methods: XRD and 27Al NMR were used to analyse clay minerals and the relative contents of four- and six-coordination Al. Soil acidification and Al mobilization were studied by constant pH automatic potentiometric titrator. Results: The relative content of tetrahedral Al (AlIV) in the soils increased gradually from low to high latitude, and an opposite trend was observed for soil octahedral Al (AlVI). The larger organic carbon (OC) content in surface soils (0–20 cm) effectively inhibited both soil acidification and Al mobilization compared with subsurface soils (20–40 cm). The content of mobilized Al followed the order: Inceptisol > Alfisol > Mollisol > Ultisol in both surface and subsurface soils, which determined by soil CEC, the contents of OC and clay and relative contents of AlIV and AlVI. After removal of OC from soil colloids, the amounts of mobilized Al were consistent with the relative contents of AlIV in soil colloids and followed Mollisol > Inceptisol > Alfisol > Ultisol, suggesting that the solid Al in the soils from temperate and north subtropical regions was readily mobilized during soil acidification. Conclusions: Al mobilization in different soils mainly depended on the CEC, the contents of OC and clay, and the coordination nature of Al in the soils. A larger CEC, a lower OC content, a greater clay content, and a higher content of AlIV led to a greater amount of mobilized Al during soil acidification. [ABSTRACT FROM AUTHOR]

Soil pores are dominated in various soil functions, including water infiltration and retention, soil permeability, nutrient availability, as well as aeration and mechanical impedance to root elongation. The dynamic behavior of soil pores is primarily influenced by tillage practices, the presence of crop roots, and the return of soil organic matter. In this research, a systematic investigation was implemented to explore the impacts of the long-term application of organic fertilizers and straw on the soil pore structure. An analysis was also made to elucidate the relationship between soil organic carbon and soil pore structure. The data was collected from a 16-year long-term field experiment located in Shui Tou agricultural experimental base, Shanxi Agricultural University (Shanxi Academy of Agricultural Sciences), Yuncheng, Shanxi Province. Four treatments were set as sole chemical fertilizer (F), organic fertilizer + chemical fertilizer (MF), straw returning + chemical fertilizer (SF), and organic fertilizer + straw returning + chemical fertilizer (MSF). The soil pore structure was examined using X-ray computed tomography (CT) and advanced image processing. While the soil organic carbon was assessed to determine the physical fraction contents (free particulate organic matter (FPOM), occluded particulate organic matter (OPOM), and mineral-associated organic matter (MOM)). Additionally, the structural properties of the organic carbon were qualitatively and quantitatively analyzed by Fourier transform infrared (FTIR) spectroscopy. The results indicated that all organic amendment treatments significantly enhanced the total porosity and porosity of >0.5 mm aperture, compared with the F treatment (P<0.05). the MSF treatment exhibited the highest values. Additionally, the porosity ranging from 0.5 to 0.2 mm in the MF and MSF treatments was significantly higher than that in the F treatment (P<0.05). However, there was no significant difference in porosity ranging from 0.2 to 0.06 mm among all treatments. Furthermore, MSF treatment significantly enhanced the connectivity and complexity of soil pores, with increases of 33.2% and 17.9%, respectively, compared with the F treatment P<0.05). The organic fertilizer and straw returning treatments (SF, MF, and MSF) achieved a significant increase (P<0.05) in the contents of total soil organic carbon, FPOM, OPOM, and MOM. MSF also exhibited the highest values among these treatments, with concentrations of 21.5, 7.1, 4.2, and 10.2 g/kg, respectively. The long-term straw incorporation and the application of organic fertilizers (MSF) were performed better to accumulate the polysaccharide and lipid organic carbon in the soil, while concurrently reducing the content of aromatic organic carbon. The Pearson correlation analysis revealed that there was a positive and significant relationship between soil total porosity, porosity of >0.5 mm aperture, as well as the connectivity and complexity of soil pores with the contents of total soil organic carbon, FPOM, OPOM, MOM, and polysaccharide and lipid organic carbon (P<0.05). These findings suggested that the application of organic fertilizer and straw incorporation enhanced the content of soil organic carbon to accumulate the polysaccharide and lipid organic carbon, which facilitated the formation and modification of soil pores. Consequently, the enhanced physical properties of the soil were attributed to the regulation of soil structure by the organic amendment. An optimal distribution of soil pores was achieved to increase the soil complexity and pore connectivity. Accordingly, the organic amendment can be an effective strategy to optimize the soil pore structure. Future studies should also examine the response of soil pore structure and pore size distribution to the decomposition of incorporated organic manure. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the structure of microbial communities, the physicochemical characteristics of the burozems' profiles, and the soil material infilling the humus pockets. Burozems (Cambisols) in the south of the Vitim Plateau are characterized by specific morphological features: presence of frost cracks, which form wedge-shaped humus pockets, sharply narrowing down the profile. Humus pockets are filled with dark brown humus-enriched material with black stripes that are sharply contrasting in color and properties with the enclosing soil. Compared to the profile of burozems at corresponding depths, the soil mass from humus pockets is less compacted. An increase in total porosity results in greater water permeability of the soil material in the frost cracks. Specific features of the microbial cenosis structure and of the microbial biomass carbon in the soil profile and in the soil material of pockets were revealed. The organic carbon and the absorbed bases are rather evenly distributed in the soil material of the pockets and their contents sharply decrease down the soil profile. The experimental data obtained during the study will replenish the database of the properties and status of microbial cenosis in burozems and in the soil material of their humus pockets in the south of the Vitim Plateau. [ABSTRACT FROM AUTHOR]

Machine learning approaches are utilized to identify patterns in behavior and generate predictions across various applications. The objective of this work is to create a highly efficient model for accurately measuring and analyzing the levels of soil organic carbon (SOC) in the Chambo river subbasin, which is situated in the province of Chimborazo. The model evaluation entails the application of diverse machine learning algorithms and approaches to determine the most efficient regression model. Regression models are improved using techniques such as Artificial Neural Networks, Support Vector Machines, and Decision Trees. The Resilient Backpropagation method yields the most precise model, as it accounts for a greater proportion of the variability in SOC content for the test data. This aligns with the findings from the training data, demonstrating a relatively low mean absolute error and a processing time that is approximately 400 times faster than that of the Multilayer Perceptron algorithm. The evaluation of estimating models is an objective procedure that considers not only the findings and precise metrics derived from the model's design, but also other relevant elements. The effectiveness of the Random Forest approach, specifically the quantile regression forests technique, has been established for estimating SOC contents in the Chambo river sub-basin data. [ABSTRACT FROM AUTHOR]

Land degradation is accelerating in the Himalayan ecosystem, resulting in the loss of soil nutrients due to severe erosion. Soil erosion presents a significant environmental challenge, resulting in both on-site and off-site consequences, such as reduced soil productivity and siltation in reservoirs. Soil erodibility (K factor), an inherent soil property, determines the susceptibility of soils to erosion. Sampling across hilly and mountainous terrain pose challenges due to its complex landscape. Despite these challenges, it is essential to study K factor variations in different land use/land cover types to comprehend the threat of erosion. Digital soil mapping offers an opportunity to overcome this limitation by providing spatial predictions of soil properties. The objective of our study is to map the spatial distribution of soil erodibility using the Random Forest (RF) model, a machine learning method based on sampled in situ soil data and environmental covariates. We collected 556 surface soil samples from the mountainous catchment (Tehri dam catchment) using the stratified random sampling approach. The model performed satisfactorily in both training (r2 = 0.91; RMSE = 0.00185) and testing (r2 = 0.45; RMSE = 0.00318) phases. Subsequently, we generated a digital map with a resolution of 12.5 m to depict the distribution of the K factor. Our analysis revealed that key environmental variables influencing the prediction of the K factor included geology, mean NDVI, and climatic factors. The average K factor value was estimated at 0.0304 and ranging from 0.0251 to 0.0400 t ha h ha−1 MJ−1 mm−1. A higher K factor was observed in the barren land (0.0344) primarily located in the higher and trans-Himalayan region of seasonally snow-covered areas. These areas typically feature young soils with weak soil formation and unstable soil aggregates. Subsequently cropland/cultivated soils (0.0307) exhibited higher K factor values due to the breakdown of soil aggregates by ploughing activities and exposing carbon to decomposition. The average K factor value of evergreen (0.0294) and deciduous (0.0295) forests were the lowest compared to other land use/land cover types indicating the role of forests in resisting soil erosion. By assessing and predicting soil erodibility, land planners and farmers can implement erosion control measures to protect soil health, prevent sedimentation in water bodies, and sustain agricultural productivity in the Himalayas. [ABSTRACT FROM AUTHOR]

In recent years, mangrove restoration has gained significant attention due to its carbon storage capacity, role as a pollution sink, and ecological and economic benefits. Moreover, the United Nations Sustainable Development Goals' strategies include mangrove restoration. This review investigates the status of mangrove restoration research and the influence of restoration on trace metal accumulation, speciation, and associated risks in mangrove sediments. Our analysis reveals that research on mangrove restoration is increasing globally, with a notable surge in publications after 2017. However, fewer than 25 articles published between 2007 and 2024 address trace metals in restored mangroves, indicating limited focus from researchers on this topic. Research shows that mangrove restoration can quickly alter sediment properties, such as texture, salinity, and pH. As a result, restored sediments tend to accumulate higher organic carbon content than barren areas. Most studies also suggest that trace metal accumulation is higher in restored sites than in non-restored areas. However, metal speciation varies considerably between sites due to local environmental factors. Furthermore, many studies suggest that restoration may increase the risks posed by trace metals to aquatic biota. The challenges of mangrove restoration research include short study timeframes, low success rates, poorly defined targets, small-scale efforts, conflicts with local communities over resources and benefits, insufficient government funding, and a lack of historical data on community health and pollution status. [ABSTRACT FROM AUTHOR]

Carbon burial patterns in lakes and their dynamic changes significantly impact terrestrial carbon sink fluxes and global carbon budgets. In this study, multi-indicator analysis of sediment core samples (P1, P2, and P3) from Pipahai Lake was conducted. Integrating the chronological sequences of 210Pb and 137Cs, we identified the historical changes and spatial characteristics of total organic carbon (TOC) and inorganic carbon (TIC) burial in Pipahai Lake since 1884. The results show that the TOC content was higher than that of the TIC. They exhibited an increasing trend with decreasing depth. Linear regression results indicated that the variation of TOC is less directly affected by precipitation (R = 0.39) and temperature (R = 0.58), while temperature may have a greater impact on TOC. From 1884 to 1995, nutrients were not the primary factor influencing changes in TOC. The synchronous variation in TIC and TOC contents reflects a higher contribution of external inputs to carbon burial in the Pipahai Lake basin. After 1996, nutrients may have begun to affect variations in TOC. The TOC primarily originates from distal aeolian transport or autochthonous sources, though human activity has played a role in its evolution. The TIC content is controlled by the TOC content and autochthonous sources. This study will contribute to the understanding of the carbon cycling dynamics and their influencing mechanisms in a high-altitude lake ecosystem. [ABSTRACT FROM AUTHOR]

The purpose of the study is the determination of heavy metals in soil samples and their circulation in the food chain. In this study, the correlation between the presence of heavy metals in agricultural soils and the quality preservation of wheat, specifically Triticum Aestivum and Triticum Durum, was investigated. The results indicate that over 85% of the samples contain a high presence of metals compared to Kosovar standards. Land surveying was conducted at distances ranging from 20 m to 400 m from the highway. The results for Pb at a distance from 20 m showed a value of 2.11 mg·kg-1, while Zn varied with a value of 5.12 mg·kg-1. However, the amount of heavy metals in agricultural soil is not sufficient to determine their risk in the food chain. The samples studied from the wheat varieties exhibited the accumulation of metals in the wheat cultivated in the studied soils. Some wheat samples showed high levels of heavy metals, with Pb varying significantly with a value of 1.99 mg·kg-1, and Cr with a value of 6.12 mg·kg-1. In this study, the circulation of soil metals such as Pb, Cd, Cr, Fe, Cu, Zn, and Mn was monitored. The study then continued with the monitoring of soil physicochemical parameters as indicators of soil quality, such as organic carbon. The results showed variations depending on the distance and its concentration. The maximum protein value varied at 11.9%, gluten at 22.8%, moisture at 11.4%, etc., especially for Triticum E. and Triticum D. wheat varieties. [ABSTRACT FROM AUTHOR]

Purpose: Microbial community composition in soil is shaped by land uses. In this study, we aimed to investigate the influences of land uses on functional gene profiles. Methods: The soil was sampled from three different types of land use. The metagenomic DNA was sequenced by Illumina shotgun sequencing. The functional gene profiles were annotated by NR, KEGG, CAZyme, CARD, VFDB and PHI databases. Results: The results showed that agriculture soil showed significantly higher ACE and Chao1 indexes in terms of taxonomic and functional genes composition than that in forest soil and park soil. PCoA and multivariate analysis indicated the influence of land use on taxonomic composition, KEGG ortholog, carbohydrate-active enzymes, antibiotic resistance genes, virulence factors and pathogen-host interaction genes. Mantel test results demonstrated that organic carbon and phosphorus are critical drivers that shape taxonomic and functional gene compositions across different land uses. Human- and phyto-pathogens were indigenously present in soils and their compositions were influenced by land use. Conclusion: Collectively, our data demonstrate that land use impacts soil microbial taxonomic and functional composition via organic carbon and phosphorus, and imply the importance of land use management in soil function and soil health. [ABSTRACT FROM AUTHOR]

Purpose: to develop scientific approaches and an algorithm for optimizing organic carbon and nitrogen flows on reclaimed lands. Materials and methods. The working hypothesis of the research is that any level of agrocenosis bioproductivity requires a proportional amount of decomposable organic matter, which should not exceed a certain share of labile organic matter contained in the soil. Results. An algorithm that operates with two main regulators: the application mass of mineral nitrogen and organic matter, and determines the optimal balance for them, ensuring at least a non-negative trend in stable humus reproduction while achieving target indicators for the level of agrocenosis bioproductivity, has been developed. The algorithm is based on forecasting the dynamics of organic matter decomposition under given conditions. The dynamics of decomposition determines the amount of nitrogen released in the soil and the bioproductivity of crops correlated with it, on the one hand, and the direction of the transformation processes of pools of stable and labile organic matter, on the other hand. To solve the optimization problem on the part of the “carbon” branch of the algorithm, a limitation of the permissible decomposition of labile forms of organic matter is established. On the part of the “nitrogen” branch of the algorithm, the target function of achieving the planned agrocenosis bioproductivity is used. As a result of the solution, the main parameters of the application of mineral forms of nitrogen and organic matter are derived, including crop-root residues, straw biomass, green manure, livestock waste and products of their processing. Conclusion: an algorithm for optimizing the management of organic carbon and nitrogen flows is proposed, which allows solving problems of intensifying production, preserving and expanding the soil fertility reproduction on reclaimed lands.

Extended Abstract Background: Forest fire is very common in all ecosystems of the world that affects both vegetation and soil and is also helpful in maintaining the diversity and stability of ecosystems. The effect of forest fires and prescribed fires on forest soil is very complex. It affects the organic matter, macro and micronutrients, and physical properties of soil, such as texture, color, pH, and bulk density, as well as soil biota. Fire is a natural factor in the forest that temporarily reduces the vegetation on the soil surface. After a fire, the soil can experience long-term, medium-term, and short-term changes, which are different depending on the type of soil characteristics, weather conditions, duration, intensity, and frequency of the fire. The Zagros forest ecosystem is generally in the coppice form, and these forests are not safe from fire, which constantly affects them. Considering that the long-term stability of these forests depends on maintaining the soil quality, it is essential to investigate the effects of fire on soil properties. This study aimed to investigate the effect of fire on Zagros forests in Kermanshah province, Gahvareh city in the Lerini region. Methods: The studied area is a part of Zagros forests in Kermanshah province, Gahvareh city, the Lerini region located at 34° 10' 35″ E and 46° 34' 28″ N, with an average height of 1468 m above sea level. In this research, the points were determined by measuring with a meter on transects, and they were sampled regularly in specific time intervals (October, November, February, April, and June). The distance between the samples in each row was 20 m and the distance between the rows was 50 m, and three rows were determined in each of the burnt and control areas. Some soil characteristics, such as pH, electrical conductivity (EC), organic carbon, absorbable phosphorus, soil respiration, microbial biomass carbon, substrate-induced respiration, and metabolic quotient, were measured in soil samples. The effect of the treatments on all measured variables was investigated by the two-way ANOVA. Means were compared by Duncan’s Multiple Range Test (DMRT). Data were analyzed using the Windows version of SAS (version 9.4, SAS Institute Inc., Cary, NC). Results: The soil pH decreased with the passage of time and a decrease in air temperature under the crown (unburnt and burned) and outside the unburnt crown. An upward trend in the pH of the soil in these three places occurred after the cold season. The soil pH ranged from 7.31 to 7.66 in all treatments from October to June. The results of the two-way ANOVA showed that the fire and sampling location did not affect the soil EC in different months of sampling. The amount of absorbable phosphorus increased with the occurrence of fire. The highest and lowest amounts of absorbable phosphorus occurred under and outside the burnt and the control crowns, respectively. The range of organic carbon changes indicates that soil organic carbon has increased over time in all treatments. The highest and the lowest increases were observed under the burnt (1.51%) and the control (unburned) crowns, respectively. Examining the changes indicates that the basic soil respiration was high at the beginning of the fire but decreased gradually, and then the initial value also increased in the last months of sampling. In this research, the amount of basic respiration in the soil of burned areas is not higher than that of unburned areas despite the occurrence of fire and the negative effect on soil organic carbon. According to the results, the amount of substrate-induced respiration decreases under and outside the crown (burnt and control) with the passage of time and the decrease in temperature. According to the ANOVA results, the effects of fire and the sampling location were significant on the microbial metabolic quotient of the soil, although no significant interaction effects on the microbial metabolic quotient were observed in February and June. The highest and the lowest microbial metabolic quotients were measured under (0.94 mg C/mg MBC.day) and outside (0.26 mg C/mg MBC.day) the unburned crown, respectively. With the passage of time and a decrease in temperature, the amount of this parameter decreased in the treatment under the crown of the unburnt area and increased in the three treatments under and outside the burned crown and outside the unburnt crown. At the end of the period, the highest and the lowest microbial metabolic quotients were measured under (0.72 mg C/ mg MBC. day) and outside (0.59 mg C/ mg MBC. day) the crown of the burned area, respectively. Conclusion: The results showed that the fire was superficial in both places under and outside the crown and did not significantly affect the soil’s chemical and biological characteristics. Therefore, no significant changes occurred in indicators such as soil organic carbon and EC, and the fire only increased phosphorus in the burned areas compared to the control. Due to the occurrence of surface fire, combustion did not significantly increase biological indicators. The results of this research demonstrate that the fire changes the soil’s chemical and biological characteristics when it occurs with a higher intensity and at a higher temperature.

Extended Abstract Background: Soil organic carbon is one of the important parameters to determine soil fertility, and production ability and a mind index for showing soil quality of dry and semi-dry lands. On the other hand, rangelands are one of the main dry ecosystems of carbon reservoirs. Knowing about carbon reservoir distribution and changes for detecting the controller mechanisms of the carbon world cycle and carbon stability is vital for managing ranges. Since field operations include soil sampling from different places and depths to measure the amount of soil carbon sequestration, it is very time-consuming and costly., On the other hand, different soil characteristics may be measured and available in many rangeland areas for other purposes using modeling and prediction under various inputs, including soil properties such as texture, acidity, electrical conductivity, etc. Researchers in the rangeland field can estimate and evaluate soil carbon. Novel prediction methods, including artificial intelligence, are of high interest in this field. The present research aims to study the ability of the adaptive neuro-fuzzy inference system (ANFIS) to predict the carbon sequestration (CS) of rangeland soil. Methods: The studied area in this research includes the rangelands of the southwestern slopes of Mount Damavand in the Lar watershed with an area of about 2000 hectares and an altitude between 2500 and 3460. With a statistical climate period of 36 years, it is a semi-humid to ultra-cold region where the average rainfall is 550 mm. Dominant plant species in the region are Onobrychis cornuta, Astragalus ochrodeucus, Astragalus microcephalus, Thymus pubescens, etc. Considering the Lar watershed region geographic conditions, four height groups relative to sea level, including height group 1 (2500-2700 m), group 2 (2700-2900 m), group 3 (2900-3100 m), and group 4 (3100-up m) were selected for sampling soil at different depths in this research. Thirteen random points were determined at all height groups, and three samples from each point were dug at depths 0-15 cm and 15-30 cm. In total, 312 soil samples were collected in the entire region and transferred to a soil science laboratory, where soil characteristics (texture, organic carbon, and bulk gravity) were measured as an average of three repetitions. These characteristics were used to calculate the amount of soil carbon deposition. After soil sampling and measuring the amount of carbon sequestration under the effect of soil depth and height in the sampling location at the Mount Damavand rangelands at the Lar watershed region, the regression and ANFIS prediction equations were developed and their accuracy was compared together for CS prediction plus introducing the more accurate approach. The root mean square error (RMSE) and correlation coefficient (R2) were applied to evaluate the regression and ANFIS models. The regression analysis was performed using the SPSS20 software. Excel software was used to draw descriptive charts. ANFIS modeling was created in MATLAB software and is based on the input/output dataset of a fuzzy inference system (FIS). This system is based on the combination of three components: membership functions of input and output variables (fuzzification), fuzzy rules (rule base), mechanism inference (a combination of rules with fuzzy input), output characteristics, and results of the system (de-fuzzification). Results: The results of the analysis of variance (ANOVA) revealed that only soil sampling depth significantly affected the soil CS, but the effect of sampling location and the interaction effect of depth and height were not significant. More amount of CS was obtained at a depth of 15-30 cm than at a depth of 0-15 cm, and the utmost amount of CS was measured in gang 4 of height (3119-3545 m) at both depths. The highest amount of CS (604656) belonged to gang 4 of height and a depth of 15-30 cm. In fact, the amount of soil CS increased at higher and lower altitudes while its amount decreased at medium altitudes. After gang 4 of height, the second most CS was recorded for the gang 1 of height. In the modeling part, the ANFIS model with higher accuracy (R2 = 0.4736) and lower error (RMSE = 0.0274) predicted the soil CS related to a regression model with lower accuracy (R2 = 0.4308) and higher error (RMSE = 0.069). This result indicates the higher ability of the ANFIS model than the regression model in creating a relationship between input and output and its proximity to the measured values. Conclusion: The increase in the correlation coefficient and the reduction of the mean error deviation in the ANFIS method compared to the linear multivariate regression show that the ANFIS method is more successful in estimating the amount of soil CS under the effects of various factors in the studied land use. The better performance of the ANFIS model than statistical regression methods can be found in its estimation and prediction capability for the nonlinear estimation with a small amount of data. This is despite the fact that the performance and accuracy of regression methods strongly depend on the sample size, and a small sample size can be a limiting factor in such statistical models. The adaptive neuro-fuzzy inference system (ANFIS) satisfied operation in predicting rangeland soil CS under the different sampling depths and heights. Furthermore, it will be used as an intelligent tool for predicting different parameters in studied ranges and rangeland science, such as above and underground biomass volume, distribution of rangeland plant species, and so on.

On low-lying soils with a high clay content and poor water conductivity, excess water regularly appears after almost every rainy winter causing soil degradation, which leads to yield failures and/or losses. To outlet the harmful excess surface, waters needs appropriate ameliorative and agrotechnical operations. Among them, scraping represents a suitable intervention into soil structure involving the complete conversion of the micro-topography of the land. The humus content of the soil is a determining factor in terms of soil fertility; therefore, it must be preserved even when drastic tillage operations are carried out on a plot. Our research aimed to assess the effect of scraping on the humus content of the soil on three plots with a heavy textured Vertisol endangered by excess waters. Scraping was used on these plots to create a homogeneous topography and surface with a slight slope to get rid of excess water when it appears. It was established that scraping did not cause humus loss on a plot scale, and it resulted in an evener organic matter distribution, hence a potentially more homogenous yield within the ameliorated plots.

Abstract Trait heritability and the response to selection depend on genetic variation, a prerequisite to developing sorghum varieties with desirable agronomic traits and high carbon sequestration for sustainable crop production and soil health. The present study aimed to assess the extent of genetic variability and associations among agronomic and carbon storage traits in selected sorghum genotypes to identify the best candidates for production or breeding. Fifty genotypes were evaluated at Ukulinga, Bethlehem and Silverton sites in South Africa during the 2022/23 growing season. The following agronomic and carbon storage traits were collected: days to 50% heading (DTH), days to 50% maturity (DTM), plant height (PH), total plant biomass (PB), shoot biomass (SB), root biomass (RB), root-to-shoot biomass ratio (RS), grain yield (GY), harvest index (HI), shoot carbon content (SCc), root carbon content (RCc), grain carbon content (GCc), total plant carbon stock (PCs), shoot carbon stock (SCs), root carbon stock (RCs), and root-to-shoot carbon stock ratio (RCs/SCs), and grain carbon stock (GCs). Higher genotypic coefficient of variations (GCVs) were recorded for GY at 45.92%, RB (39.24%), RCs/SCs (38.45), and RCs (34.62). Higher phenotypic coefficient of variations (PCVs) were recorded for PH (68.91%), followed by GY (51.8%), RB (50.51%), RS (41.96%), RCs/SCs (44.90%), and GCs (41.90%). High broad-sense heritability and genetic advance were recorded for HI (83.76 and 24.53%), GY (78.59 and 9.98%), PB (74.14 and 13.18%) and PCs (53.63 and 37.57%), respectively, suggesting a marked genetic contribution to the traits. Grain yield exhibited positive association with HI (r = 0.76; r = 0.79), DTH (r = 0.13; r = 0.31), PH (r = 0.1; r = 0.27), PB (r = 0.01; r = 0.02), RB (r = 0.05; r = 0.06) based on genotypic and phenotypic correlations, respectively. Further, the path analysis revealed significant positive direct effects of SB (0.607) and RB (0.456) on GY. The RS exerted a positive and significant indirect effect (0.229) on grain yield through SB. The study revealed that PB, SB, RB, RS, RCs, and RCs/SCs are the principal traits when selecting sorghum genotypes with high yield and carbon storage capacity.

Abstract Exposure assessments to metalworking fluids (MWF) is difficult considering the complex nature of MWF. This study describes a comprehensive exposure assessment to straight and water-based MWFs among workers from 20 workshops. Metal and organic carbon (OC) content in new and used MWF were determined. Full-shift air samples of inhalable particulate and gaseous fraction were collected and analysed gravimetrically and for metals, OC, and aldehydes. Exposure determinants were ascertained through observations and interviews with workers. Determinants associated with personal inhalable particulate and gaseous fractions were systematically identified using mixed models. Similar inhalable particle exposure was observed for straight and water-based MWFs (64–386 µg/m3). The gaseous fraction was the most important contributor to the total mass fraction for both straight (322–2362 µg/m3) and water-based MWFs (101–699 µg/m3). The aerosolized particles exhibited low metal content irrespective of the MWF type; however, notable concentrations were observed in the sumps potentially reaching hazardous concentrations. Job activity clusters were important determinants for both exposure to particulate and gaseous fractions from straight MWF. Current machine enclosures remain an efficient determinant to reduce particulate MWF but were inefficient for the gaseous fraction. Properly managed water-based MWF meaning no recycling and no contamination from hydraulic fluids minimizes gaseous exposure. Workshop temperature also influenced the mass fractions. These findings suggest that exposures may be improved with control measures that reduce the gaseous fraction and proper management of MWF.

Abstract Pesticide contamination and soil degradation present significant challenges in agricultural ecosystems, driving extensive exploration of biochar (BC) and nano-biochar (NBC) as potential solutions. This study examines their effects on soil properties, microbial communities, and the fate of two key pesticides: the hydrophilic methomyl (MET) and the hydrophobic lambda-cyhalothrin (LCT), at different concentrations (1%, 3%, and 5% w w−1) in agricultural soil. Through a carefully designed seven-week black bean pot experiment, the results indicated that the addition of BC/NBC significantly influenced soil dynamics. Soil pH and moisture content (MC) notably increased, accompanied by a general rise in soil organic carbon (SOC) content. However, in BC5/NBC5 treatments, SOC declined after the 2nd or 3rd week. Microbial populations, including total plate count (TPC), phosphate-solubilizing bacteria (PSB), and nitrogen-fixing bacteria (NFB), showed dynamic responses to BC/NBC applications. BC1/NBC1 and BC3/NBC3 applications led to a significant increase in microbial populations, whereas BC5/NBC5 treatments experienced a decline after the initial surge. Furthermore, the removal efficiency of both MET and LCT increased with higher BC/NBC concentrations, with NBC demonstrating greater efficacy than BC. Degradation kinetics, modeled by a first-order equation, revealed that MET degraded faster than LCT. These findings underscore the profound impact of BC/NBC on pesticide dynamics and microbial communities, highlighting their potential to transform sustainable agricultural practices.

Abstract Maize cultivation is under the growing threat of charcoal rot (Macrophomina phaseolina). Chemical control of diseases imparts serious health hazards to humans and the ecosystem. Biochar as an alternative disease management approach has been under consideration of the researchers for some time now. The biochar utilized in this study was derived from maize stalks and cobs. Crystallographic structure, inorganic minerals content and size of maize biochar were analyzed by powder X-ray diffractometer, while scanning electron microscopy revealed rough, irregular, tubular structure of the biochar surface. EDX spectra revealed that the maize biochar composition was dominated by ‘C’ followed by ‘O’. The current study was designed to determine the synergistic effect of maize biochar (MB), and biocontrol agent (BCA) Trichoderma viride as soil amendments on the suppression of M. phaseolina. In vitro bioassays were conducted to check the efficiency of antagonistic effect of Trichoderma spp., in combination with maize biochar. On the basis of maximum mycelial growth inhibition T. viride was selected for a glasshouse experiment. Maize plants were grown in pots containing a mixture of soil with MB at application at the rate of 3 and 6% (v/v) separately, associated with or without T. viride. Treatments amended with 3% MB inoculated with M. phaseolina significantly reduced the percentage disease severity index by 40%. While in the presence of T. viride, 3% MB showed maximum disease suppression and a minimum percentage severity index i.e. 60 and 20%, respectively. Highest nitrogen contents were 18.4 g kg−1 observed in treatment 6% MB, while highest phosphorus and potassium contents were 3.11 and 15.2 g kg−1, respectively in the treatment with 3% MB. Conclusively, the effect of variable concentrations of maize biochar and T. viride as soil amendment was evident on the development of charcoal rot, growth and physiology of maize plants. According to the available literature, our report is the first on the implementation of biochar in synergism with T. viride to suppress the charcoal rot in maize.

Stream and floodplain restoration is a popular billion‐dollar industry in the United States, with many restorations being conducted to satisfy water pollution regulations and nutrient reduction goals. The long‐term efficacy of these restorations is, however, not well studied, and key soil metrics that can be used for performance assessments have not been developed. We evaluated a chronosequence of 12 restoration sites spanning an age range of 0–22 years to assess changes in denitrification rates and associated soil parameters. Restored versus unrestored reaches were compared for denitrification rate and functional gene nosZ, bulk soil δ15N, soil organic carbon (SOC), soil organic matter (SOM), bulk density, and soil moisture. Denitrification, SOM, SOC, and soil moisture were all found to increase with site age at restored sites, with the largest increase for the 10–22 age category. Bulk density decreased with time, with a significant decrease in restored floodplain soils. Bulk soil δ15N was highest immediately after restoration, decreased with restoration age, and was not positively correlated with denitrification. This may reduce its potential as a proxy for denitrification. Overall, this study reveals that selected soil metrics (SOC, SOM, soil moisture, and bulk density) could serve as a valuable proxy for denitrification and could help assess the denitrification effectiveness of floodplain restorations at the decadal time scales. Ideally, the soil metrics should be combined with other short‐term assessment measures, such as those for stream and groundwaters, for a robust performance assessment of restored floodplains. [ABSTRACT FROM AUTHOR]

Aim Methods Results Conclusion Composts made from food waste will soon become more widespread on the market thanks to the upcoming enforcement of the legal obligation to sort biowaste. Our experiment aims at improving knowledge on the short‐term effects of these composts on soils’ physicochemical properties and vegetable crops.Three composts with contrasting characteristics were tested: a 100% v/v green waste compost (C1), and two composts composed of 50% v/v food waste and 50% v/v green waste, one prepared directly on the soil (C2) and the other from a competing producer who have the French NFU 44‐051 (AFNOR NF U 44‐051, 2006) certification for an organic amendment (C3). They were applied at a rate of 100 t ha−1 (dry matter) on two cropped soils with contrasting textures. Soil‐and‐compost mixes and compost‐free soil were planted with lettuce, radish, and potato.Seventy‐four days after planting, composts improved some soil physicochemical properties. The compost‐amended soils had better saturated hydraulic conductivity (Ks, 1 10−3–2.5 10−3 cm s−1) than the compost‐free soil (0.5 10−3 cm s−1), and water‐stable aggregates were higher than the initial value in C3 soil, equal to it in C2 soil, and lower in C1 soil. pH, total nitrogen, and organic carbon increased in all compost‐amended soils. Food waste compost stimulated crop production. The yields (dry matter) of all three crops were two to three times higher in the two soils amended with food waste compost compared to unamended soil, whereas they decreased almost two times in the soil amended with green waste compost due to nitrogen immobilization. Trace metals (particularly Pb and Cd) added by the composts, although present in edible parts of the plants, did not exceed the European rules for trace metals.Thus, food waste composts have positive effects on soils and vegetable crops, and the higher their organic matter content, the higher these positive effects. [ABSTRACT FROM AUTHOR]

Understanding the vertical distributions of organic carbon (OC) is crucial for predicting and simulating the influences of soil units on the terrestrial carbon cycle. The OC in the fine earth fraction was calculated for the soil units Anthrosols, Cambisols, Fluvisols, Leptosols, and Regosols in the municipality of Ponte de Lima, Portugal, at depths of 0–30 cm, 0–100 cm, 0–200 cm, and 0–2590 cm. In the study area, over 40% of the OC is concentrated in the Regosol unit, followed by the Anthrosols with over 23% OC at all depths, and the Leptosols with over 22% OC at all depths. The soil units Cambisols and Fluvisols have a lower representation in the territory, with values below 1.5% and 6.5% respectively at all depths. The obtained results contribute to assessing the potential of the soil units present in the municipality to sequester CO2, promoting the development of carbon inventories and analyzing the distribution of OC through accurate and reliable estimates of current C reserves as an essential tool for analyzing and modeling the effects of different factors involved in the potential of soil OC sequestration. [ABSTRACT FROM AUTHOR]