Carbon Content Research Articles

Assessment and Delineation of GPS-GIS Based Soil Fertility Maps of Instructional Farm, Malegaon Tehsil Baramati

The present investigation was conducted in the year 2023-24 at division of Soil Science, Dr. Sharadchandra Pawar College of Agriculture, Baramati with an objectives to assess the soil available nutrient status and delineation of GIS based maps of soil available nutrients. Using Arc-GIS 10, Version 10.8, fertility maps of the available macro nutrients were created. The area under the Instructional Farm had soil pH ranged from 7.11 to 8.32, categorized into the slightly alkaline to moderately alkaline categories while the EC varied from 0.21 to 1.99 dSm-1, indicating that most of the soils were non-saline. The soil's organic carbon and calcium carbonate contents ranged from 0.21 to 0.97 per cent and 1.50 to 19.75 per cent and they were classified into low to high and low to very high categories respectively. In the Instructional Farm, the ranges of available nitrogen, phosphorus and potassium content were 85.50 to 360.75, 23.29 to 80.08 and 202.5 to 968.68 kg ha-1 respectively. The Instructional Farm soils had very low to moderate levels of available nitrogen, moderately high to very high levels of available phosphorus and moderately high to very high levels of available potassium. The implementation of GPS-GIS-based techniques for soil sampling represents a significant advancement that will allow researchers and institute officials to track changes in soil fertility over the years. The soil fertility maps created for the Instructional Farm will be invaluable for establishing a scientifically sound fertilization schedule.

Understanding how corn-yellow melilot intercropping combined with straw return increased stable organic carbon pool in Mollisols by reducing the application of chemical fertilizer

Long-term cultivation with persistent use of chemical fertilizers causes a rapid decline in organic matter content of Mollisols. But practicing intercropping along with straw return instead of the use of chemical fertilizer have the potential to reverse the decline and improve soil organic carbon (SOC) content. A field experiment with five treatments at two sites of Songnen Plain of Northeast China included the following treatments (1) corn monoculture with no chemical fertilizers and no straw return (c), (2) corn monoculture with chemical fertilizers and no straw return (c + F), (3) corn-yellow melilot intercropping and straw return combined with full application of chemical fertilizers (c&m + S + F), (4) corn-yellow melilot intercropping and straw return combined with half dose of chemical fertilizers (c&m + S + F/2), and (5) corn-yellow melilot intercropping and straw return without chemical fertilizers (c&m + S). The results showed that c&m + S + F, c + F, and c&m + S + F/2 decreased specific gravity and c&m + S + F increased water content. The c&m + S + F, c&m + S + F/2, and c&m + S improved SOC with 18.7%, 7.95%, and 8.17% (P < 0.05), respectively. The c&m + S + F and c&m + S + F/2 increased mineral-associated organic carbon, humus organic carbon, and heavy fraction organic carbon content. These findings provide a method for utilizing intercropping and straw return to replace chemical fertilizers to improve SOC and stable organic carbon content to ameliorate soil quality.

Functional properties of expanded austenite generated on AISI 316L by plasma nitrocarburizing using different active screen materials

Abstract This study investigates the functional properties of the expanded austenite layers generated on AISI 316L austenitic stainless steel resulting from active screen plasma nitrocarburizing using different active screen materials, i.e. steel or solid carbon. Treatments were conducted at 460 °C for 5 hours in a nitrogen-hydrogen feed gas, whereas for the treatments using a steel active screen, methane was added as carbon precursor. Additionally, the bias plasma conditions applied at the samples were varied between 0 kW and 1.25 kW. Samples were characterized by complementary microstructural and compositional investigations, surface roughness and hardness measurements, pin-on-disk tribological tests as well as potentiodynamic polarization tests in H2SO4 and NaCl electrolytes. The functional properties of the case are discussed based on the contents of nitrogen and carbon in the expanded austenite and on their effective diffusion depths. The results show that the usage of a carbon screen generally produces surfaces with uniform layer thickness, high hardness, improved wear resistance and a delayed tendency to pitting corrosion independent of the bias condition applied to the samples. When applying both screen materials at non-biased condition, the general corrosion resistance is slightly reduced under the conditions used, however, the layers generated using the carbon screen have a wear rate that is 3 times lower. It can be concluded that the carbon screen represents a robust treatment variant for austenitic stainless steels to produce sufficiently thick and wear-resistant surface layers in a short treatment duration, which still have the potential to maintain the corrosion resistance in different environments.

Biological soil crusts significantly improve soil fertility and change soil microbiomes in Qinghai-Tibetan alpine grasslands.

Biological soil crusts (BSCs), a vital component of ecosystems, are pivotal in carbon sequestration, nutrient enrichment, and microbial diversity conservation. However, their impact on soil microbiomes in alpine regions remains largely unexplored. Therefore, this study aimed to determine the influence of BSCs on alpine grassland soil microbiomes, by collecting 24 pairs of soils covered by biological and physical crusts along a transect on the Qinghai-Tibetan Plateau. We found that BSCs significantly increased the contents of soil moisture, organic carbon, total nitrogen, and many available nutrients. They also substantially altered the soil microbiomes. Specifically, BSCs significantly increased the relative abundance of Cyanobacteria, Verrucomicrobiota, and Ascomycota, while decreasing the proportions of Gemmatimonadota, Firmicutes, Nitrospirae, Mortierellomycota, and Glomeromycota. By contrast, microbial abundance and α-diversity demonstrated low sensitivity to BSCs across most study sites. Under the BSCs, the assembly of prokaryotic communities was more affected by homogeneous selection and drift, but less affected by dispersal limitation. Conversely, soil fungal community assembly mechanisms showed an inverse trend. Overall, this study provides a comprehensive understanding of the effects of BSCs on soil properties and microbial communities, offering vital insights into the ecological roles of BSCs.

Spatial distribution characteristics and influencing factors of soil organic carbon based on the geographically weighted regression model.

Quantifying the effects of environmental factors on soil organic carbon and spatial distribution is fundamental to soil quality regulation, restoration, and response to climate change. The present study aims to explore the spatial distribution characteristics of the soil organic carbon (SOC) contents in Anhui Province, China, based on national soil data. In addition, we used the geographically weighted regression (GWR) model to quantify the influence degrees of environmental factors on the soil organic carbon density (SOCD). The results showed that the spatial distribution of SOCD in Anhui Province in both 1985 and 2018 was characterized by high in the south and low in the north. The GWR model prediction results of the 0-30cm SOCD showed local coefficients of determination (local R2) ranging from 0.21 to 0.96 and 0.14 to 0.96 in 1985 and 2018, respectively. Therefore, the predicted results were effective in evaluating the overall spatial distribution of the SOCD in Anhui Province. The regression coefficients of the normalized difference vegetation index (NDVI) and air temperature ranged from - 0.39 to 5.67 and - 0.17 to 3.11, respectively, demonstrating their strong controlling effects on the spatiotemporal variations in the 0-30cm SOCD in Anhui Province.

Effect of Air Pollutants and Environmental Noise on the Childhood Asthma Prevalence in Tehran, Iran

The purpose of this study is to investigate the effect of air pollutants and noise on the prevalence of childhood asthma in Tehran, Iran. The standardized questionnaire was completed by one of the parents of children aged 6–7 years or by adolescents aged 13–14 years. The asthma prevalence in ages 6-7 and 13–14 was found to be 8.8% and 17.44%, respectively. A significant positive association was observed between “ever wheezing” and monoxide carbon (CO) concentration (OR=1.84, 1.05-3.25 in 13–14 years), the occurrence of 4 to 12 wheezing attacks and sulfur dioxide (SO2) concentration (Odds Ratio [OR]=1.39, 1.04-1.91) and particulate matter less than 2.5 micron (PM2.5) concentration (OR=1.38, 1.05-1.98 and OR=1.13, 0.98-1.39 in 6-7 and 13–14 years, respectively), as well as one night per week of sleep disturbances and nitrogen dioxide (NO2) concentration (OR=1.09, 1.03-1.16 in 6–7 years, respectively). It was also found that there was a significant interaction between the noise level and particulate matter less than 10 microns (PM10) level. Based on the findings, exposure to certain outdoor air pollutants and noise can affect the prevalence of asthma symptoms in residents of Tehran. The simultaneous presence of air pollutants and noise has an aggravating effect on the prevalence of asthma symptoms. Therefore, controlling sources of pollutants for reducing asthma symptoms is suggested.

Recent Advances of Plastic Waste‐Derived Carbon Materials for Energy Storage, Environmental Remediation and Organic Synthesis Applications

AbstractThe escalating severity of plastic waste's impact on the ecological environment and human health emphasize the crucial importance of developing resource‐conserving disposal technologies for sustainable development. Carbon‐based materials possess extensive functional applications across various fields, however, their high production costs and heavy reliance on fossil fuels pose challenges. Plastic wastes serve as ideal precursors for the green and sustainable production of carbon‐based functional materials due to high carbon content and low‐cost. This review provides a comprehensive summary of recent research progress on plastic waste‐derived carbon materials (PWCMs) including primary strategies for constructing PWCMs and their current functional applications in energy storage, environmental remediation and organic synthesis.

Effect of Liquid Microbial Consortium on Physio Chemical Properties of Rice Field (Oryza Sativa) in a Vertisol

A study was conducted during kharif 2020 on "Effect of liquid microbial consortium (Azotobacter, Azospirillum, PSB (Pseudomonas mallei, Pseudomonas cepaceae, Penicillium sp.) and KSB) on physio chemical properties and microbial population of rice field (Oryza sativa) in a Vertisol" at the Indira Gandhi Krishi Vishwavidyalaya's Research cum instructional farm in Raipur (C.G.). Experiment included seven treatments viz. control (no fertilizer, no liquid NPK microbial consortia), two independent applications of 75 % RDF (90:45:30) and 100% RDF ((120: 60: 40) N, P2O5, and K2O kg ha-1 and four various combinations of seed and soil application of liquid NPK microbial consortia. Seed coating with NPK consortia @5ml kg-1, with 75% and 100% RDF and Seed coating with NPK consortia @5ml kg-1 + Soil application of NPK consortia @3 L ha-1 at 21 DAS with 75%RDF and 100%RDF. In the experiment, liquid biofertilizer products, such as liquid microbial NPK consortia were used. The population of Azotobacter, Azospirillum, phosphorous solubilizing bacteria (PSB), potassium solubilizing bacteria (KSB) and total bacterial population were significantly influenced by application of consortia as seed treatment @ 5ml kg-1 only and by a combination of seed treatment @ 5ml kg-1 seed + soil application @ 3 L ha-1 at 21 DAT with 75 or 100 % recommended dose of fertilizers and showed statistically significant higher microbial population in comparisons with the treatments of untreated alone applications of 75 or 100 % RDF. The results showed that the soil reaction, (pH) salt concentration (Electrical conductivity) and organic carbon status were not significantly influenced by the different treatments of fertilizer levels and microbial consortia applied. Slight decrease in the soil reaction (pH) and slight increase in the OC status after the harvesting of rice were observed from their initial soil values (before application of treatments). It might be due to the addition of organic matter as plant residues (straw and roots) of rice crop gown in the field. As compared to untreated- control (T1) a slight decrease in pH and increase in organic carbon content due to application of fertilizer and microbial consortia were also recorded. The residual available nitrogen in the soil after the harvesting of rice was not significantly influenced by the fertilizer levels and NPK consortia applied. The initial status of the experimental soil was low for available nitrogen (224 kg ha-1), medium for available phosphorus (24.5 kg ha-1) and high for available potassium (384 kg ha-1). Due to the addition of nitrogen through the fertilizer (90-120 kg ha-1) and less uptake of native nitrogen from the soil, a marginal increase in the residual available N in the soil from the initial level was observed in all treatments except the control (no fertilizer, no consortia). The residual status of available potassium was also not significantly influenced by the applied fertilizer doses and NPK consortia. A marginal decrease in the residual available K status after the harvesting of rice was observed in all treatments. A decrease was found in the control plot. A decrease in the K status (from the initial level) was observed less where a full dose of NPK fertilizers (100%) was applied with the NPK consortia. Ramlakshmi et al. [1], also observed slight reduction in soil pH and increase in organic carbon content in biofertilizer inoculated treatments as compared to the un-inoculated control soil [2].

Carbon Stock Estimation of Poplar Plantations Based on Additive Biomass Models

Accurate estimation of biomass and carbon stocks in forest ecosystems is critical for understanding their roles in carbon sequestration and climate change mitigation. Currently, the development of stand biomass models and carbon stock estimation at the regional scale has emerged as a prominent research priority. In this study, 225 Populus spp. (poplar) trees in Shandong Province, China, were destructively sampled to obtain the biomass of their components. Two models (MS1 and MS2) were developed using allometric equations and the seemingly unrelated regression (SUR) method to ensure additive properties across tree components. The model evaluation employed the leave-one-out jackknife (LOO) method, considering statistics such as adjusted R-squared (Ra2), root mean square error (RMSE), mean absolute percent error (MAPE), and mean absolute error (MAE). The results from our models demonstrated high accuracy, with MS2 slightly outperforming MS1 after incorporating tree height as an independent variable. The models reliably estimated component-specific biomass and carbon stocks, with distinct variations observed in the carbon content among foliage (47.14 ± 2.07%), branches (47.26 ± 2.48%), stems (47.67 ± 2.21%), and roots (46.37 ± 2.78%). Carbon stocks in poplar plantations increased with the diameter class, ranging from 5 to 35 cm and correspondingly from 3.670 to 172.491 Mg C ha−1. As the diameter class increases, the carbon allocation strategy of poplars aligns with the CSR strategy, transitioning from prioritizing growth competition to emphasizing self-stabilization. Our research proposes a robust framework for assessing biomass and carbon stocks in poplar plantations, which is essential for evidence-based forest management strategies.

Experimental Study of Erosion Prevention Model by Bio-Cement Sand

Microbially induced carbonate precipitation (MICP) technology is employed to reinforce the surface soil of a dam, aiming to prevent erosion caused by water flow and damage to the dam slope. The relationship between penetration depth, calcium carbonate content, and bonding depth was investigated at eight measuring points on the sand slope surface of a mold under different reinforcement durations. It was observed that as grouting reinforcement times increased, there was a gradual increase in calcium carbonate content but a rapid rise in penetration resistance. Moreover, the bonding depth of sand on the bio-reinforced sand slope increased with higher levels of calcium carbonate content. Microbial grouting reinforcement enhanced soil particle bonding force, requiring water flow to overcome this force for activation of sand particles. Consequently, microbial grouting reinforcement significantly improved shear strength and critical starting flow velocity on sand slope surfaces. The experimental results demonstrated that after MICP surface treatment through spraying, a dense and water-stable hard shell layer composed of bonded calcium carbonate and soil particles formed continuously on sample surfaces, effectively enhancing the strength and erosion resistance of sandy soils. These findings provide reliable evidence for silt slope reinforcement and dam erosion prevention.

Effect of Soil Amendments on the Aggregate Stability, Biological Activity, and Yield of Canola (Brassica napus L.) in Degraded Soils

ABSTRACT Recycling organic waste and water treatment residues in nanoform is a promising technology in various farming systems, and its effect on aggregate stability, biological activity, and canola production in degraded soils is largely unknown. Hence, we evaluated the effect of nano-biochar (nB) and nano-water treatment residues (nWTR) at levels 50, 100, and 250 mg kg−1 as compared to soil without amendments on the aggregate stability, biological activity, and canola yield in degraded soil. The results showed that the structure coefficient (SC) values are higher when nB and nWTR are added at 100 mg kg−1 soil than at levels 50 and 250 mg kg−1. In our study, the high aggregate stability in the soil treated with nB and nWTR is likely due to their higher content of nutrients, organic carbon, clay, and CEC. The seed weight of the canola plant increased with increasing nB by more than 64%, while it decreased with increasing nWTR. Microbial biomass carbon (MBC) and the activity of dehydrogenase (DHA) and catalase (CLA) increased significantly in the treated pots with the addition of nB and nWTR at various rates. The results of the pot experiment recommended that the applications of nWTR and nB could be used as a promising strategy to improve soil quality and crop yield while also increasing the recycled efficiency of WTR and rice straw.

Utilizing Coconut Biochar as a Bio‐reinforcing Agent in Natural Rubber Composites

AbstractThis research investigates the pyrolysis of biochar from different parts of residual aromatic young coconut waste, namely coconut fruit, coconut bunch, and coconut leaf, to be used as fillers in natural rubber (NR). Scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy reveals that biochar has a flake‐like structure with a high carbon content (67%–77%). The biochar is mixed with NR using a two‐roll mill at filler contents of 0, 10, 20, 30, and 40 phr (part per hundred of rubber). Adding coconut fruit biochar at 40 phr increases the Shore A hardness to 59.62, a remarkable 47% improvement compared with unfilled NR. The maximum tensile strength occurs at 20 phr, while the highest tensile modulus (4.53 MPa) and tear strength (17,344 N m−1) are observed at 40 phr. Moreover, the swelling index of composites in toluene decreases slightly as biochar content increases, and the crosslink density is higher for NR filled with coconut fruit biochar than for other biochar types. Based on these results, coconut fruit biochar is identified as the most effective reinforcement filler for NR among the biochar types studied. Consequently, it can be used as a bio‐reinforcing agent in NR composites, contributing to sustainability and eco‐friendliness.

Investigation of the Dependence of the Strength Characteristics of Silicon Carbide-Based Ceramics on the Initial Carbon Content

Investigation of the Dependence of the Strength Characteristics of Silicon Carbide-Based Ceramics on the Initial Carbon Content

Micro-facies characterization of the Cane Creek Shale, Paradox Basin, Utah: implications of diagenetic controls on reservoir quality

The fine-grained Pennsylvanian Cane Creek Shale of the Paradox Formation, Paradox Basin, Utah exhibits relatively thin cyclic interbeds of contrasting lithologies including fine sandstone to siltstone, organic-rich carbonate and dolomitic mudstone, and evaporites. As such, it provides a unique opportunity to evaluate micro-facies and the fluid storage capacity potential of mixed fine-grained systems. Micro-facies descriptions were performed using core and petrographic analyses, including scanning electron microscopy with energy dispersive spectroscopy. The study leverages core-based porosity and permeability data, as well as previous core description. These data are used together to explore mineralogical depositional and diagenetic controls on porosity and permeability. Twelve micro-facies were described based on sedimentological textures, grain size, lithology, and mineralogy categorized into three groups: 1) sandstone to siltstone, 2) mudstone, and 3) evaporitic micro-facies. Sandstone to siltstone micro-facies exhibit variable porosity and permeability. Porosity connectivity is dependent on the degree of authigenic cementation and compaction that negatively impacts porosity. Mudstone micro-facies show less variability in porosity and permeability; and are characterized by carbonate content, organic-matter, and clay nanopores. The development of early carbonate grains maintains porosity in mudstone and dolomitic siltstone micro-facies. Evaporitic micro-facies represented by evaporitic sabkha-like conditions are characterized by pore-reducing anhydrite and halite cement. A diagenetic paragenetic sequence was developed to assess the timing and impact of mineralogy on reservoir quality. Early (eogenetic), Middle (mesogenetic), and Late (telogenetic) stages correspond with diagenetic stages and known tectonic basin events. Syndepositional dolomite and diagenetic illite/smectite authigenic cements are the main controls on reservoir quality and have opposing effects related to porosity and permeability by preserving early pore space or reducing porosity and permeability.

Extraction of Aluminum Oxide from Local Kaolin Clay Deposits in Ethiopia

The need for aluminum is growing worldwide, which has sparked interest in finding alternate ways to make alumina from materials other than bauxite, particularly clays. This article examines the use of sodium carbonate as a leaching agent in the lime sintering process to recover alumina from kaolin. Excavated from Tarmaber, Ethiopia, kaolin clay contains a content of 32.88%, which has a relatively good composition. Collecting and grounding raw kaolin to micrometer-level particle size is the first task. The recovery of kaolin alumina was studied at sintering temperatures of (T&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;=800°C, T&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;= 900°C &amp; T&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;=1000°C) at different sintering times of (t&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;=1 hr, t&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;=2 hrs &amp; t&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;=3 hrs). After the raw material was burned at the given temperatures and times, it was cooled for the night in the furnace and leached with different concentrations of sodium carbonate (M&amp;lt;sub&amp;gt;1&amp;lt;/sub&amp;gt;=50 g/l, M&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;=60 g/l &amp; M&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;=70 g/l). The response surface methodology (RSM) in combination with the central composite design was used to optimize the operating parameters. The optimization result shows that the optimal conditions were a calcination temperature of 953.84°C, a sintering time of 2.99 h, and a leaching agent concentration of 70 g/l. At this optimal condition, the yield of Alumina was 1.05 g of 20 g of Kaolin clay. The resulting Alumina was crystalline in structure (from XRD analysis), contains 89.05% Al&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; (from silicate analysis) and a large broad band between 400-1000 cm&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt; is attributed to Al-O-Al stretching of Alumina (from FT-IR analysis). So, it is possible to conclude that alumina production from no bauxite ores is possible.

Evaluating soil quality and carbon storage in Western Ghats Forests, Karnataka, India, for sustainable forest management.

Monitoring soil quality index (SQI) and soil organic carbon (SOC) stock status of the Western Ghats (WG) forests in India is crucial for providing vital ecosystem services alongside sustainable forest management practices. However, comprehensive profile data on SQI and SOC stock across different forest types under WG forests are limited. The study evaluated SQI and SOC stock under three forest types, i.e. tropical wet evergreen (TWE), tropical semi-evergreen (TSE), and tropical moist deciduous (TMD) across WG in Karnataka. SQI was assessed using principal component analysis with two indexing approaches and scoring methodologies, with weightage indexing through nonlinear scoring functions (NLSF) showing superiority over other methodologies. TMD forests exhibited the highest SQI, followed by TWE and TSE, while the lowest was observed in Rippon Pet RF (0.36 surface, 0.28 control section), primarily due to limitations in organic carbon and clay content. SOC stock mirrored SQI trends (TMD > TWE > TSE), with the highest values in Kollegal RF (339.3 MG ha-1) and lowest in Rippon Pet RF (102.5 MG ha-1). Although SOC and SQI were established to be ideal indicators for dynamic ecosystem services (ESs), high OC content in surface soils of Poomale NF induces pedogenic acidification and Al toxicities, indicating potential forest soil degradation. Significant correlation with control section SQI and SOC (p < 0.05) emphasises monitoring subsurface soil status to identify soil degradation, sustainable forestry practices, and complex ESs in forest systems.

Enhancing the Growth of Chili Plants and Soil Health: Synergistic Effects of Coconut Shell Biochar and Bacillus Sp. Strain Ya-1 on Rhizosphere Microecology and Plant Metabolism

To mitigate soil degradation and decrease dependency on chemical inputs in agriculture, this study examined the joint effects of coconut shell biochar and Bacillus strain Ya-1 on soil fertility, rhizosphere bacterial communities, and the growth of chili (Capsicum annuum L.). A controlled pot experiment with four treatments was conducted: control (CK), biochar only (C), Bacillus strain Ya-1 only (B), and a combination of both (BC). The BC treatment significantly enhanced the soil carbon and available phosphorus contents by approximately 20% and the soil nitrogen content and pH by 18% and 0.3 units, respectively, compared to the control. It also increased microbial biomass carbon and nitrogen by 25% and 30%, respectively, indicating improved soil microbial diversity as shown by the highest Pielou evenness index and Shannon index values. The combined application of biochar and the Ya-1 strain resulted in a 15% increase in chili plant height and a 40% improvement in root dehydrogenase activity, suggesting enhanced nutrient uptake and metabolism. Metabolic profiling showed shifts in stress response and nutrient assimilation under different treatments. Collectively, these results indicate the potential of biochar and microbial inoculants to significantly promote soil and plant health, providing a sustainable strategy to improve agricultural productivity and reduce reliance on chemical inputs.

Development and characterization of sustainable epoxy resin composites reinforced with palm kernel shell particulate and sisal fiber

This study explores the development and characterization of epoxy resin composites reinforced with palm kernel shell (PKS) particulate and sisal fibers, aiming to create sustainable and high-performance materials. Elemental composition analysis using energy dispersive X-ray revealed significant increases in carbon and oxygen content with higher PKS particulate content, indicating successful reinforcement integration. The mechanical properties were evaluated through Brinell hardness, impact energy, impact strength, tensile stress, and wear resistance tests. The Brinell hardness increased from 31.8 kg/mm2 in the control sample to a peak of 60.6 kg/mm2 in sample SP4, demonstrating enhanced hardness with PKS particulate addition. Impact tests identified an optimal reinforcement level in sample SP3, which achieved the highest impact energy (83 J) and impact strength (47.43 kJ/m2). Tensile stress analysis showed a maximum tensile stress of 28.7991 MPa for SP3, while excessive PKS content in SP4 reduced this to 20.4612 MPa. Wear tests indicated a trade-off between mechanical reinforcement and wear resistance, with the control sample exhibiting the lowest wear rates and SP4 the highest having a 91.9% increase. Based on the obtained results, SP3 with 0.8 g PKS particulate, 0.2 g sisal fiber in epoxy resin matrix seems the optimized composite with enhance mechanical properties without compromising wear resistance.

Stand Characteristics, Leaf Traits and Growth of Threatened Conifer Pilgerodendron uviferum (Cupressaceae) in Southern Patagonia, Argentina

Pilgerodendron uviferum is an endemic Cupressaceae of Patagonia (Argentina) that is restricted to a small group of individual trees, growing in isolated populations (relicts) along its distribution. The main objective was to evaluate the habitat, forest structure, leaf traits, leaf nutrient reabsorption and growth of four relicts (area between 0.3 and 0.86 ha) in the Santa Cruz province (Argentina) to improve the available information for forest conservation purposes. Principal components analysis was conducted to determine the separation between relict populations based on their ecological characteristics (individual and habitat levels). We found contrasting environmental and forest structure conditions among the four studied relicts. For example, two relicts associated with Nothofagus antarctica showed higher values of P. uviferum tree density, DBH and dominant height at the stand level. Alongside that, these relicts presented a higher sapling density (1950–3167 ind ha−1) and understory plant diversity compared to pure P. uviferum relicts growing near the ecotone with the steppe grassland. Specific leaf area, carbon and nutrient concentrations in P. univerum leaves varied depending on the relict conditions and tree age of the individuals. The mean nutrient resorption efficiency varied according to relicts and particular nutrients, ranging from 18.1% to 49.5% for Ca and P, respectively. The diameter growth of the dominant P. univerum trees ranged from 0.33 to 0.46 mm yr−1, indicating that the species follows a stress-tolerant strategy. The information of this work may assist in the conservation of marginal P. uviferum forest communities spatially disconnected with continuous forests, growing in relicts.

Response of soil nitrogen mineralization, nitrification and denitrification to milk vetch (Astragalus sinicus L.) application in a paddy field

We conducted incubation experiments with a paddy soil collected from a long-term field experiment to explore the effect of Chinese milk vetch (Astragalus sinicus L., CMV) application on potential nitrogen (N) denitrification (PDA), nitrification (PNA), mineralization (PNM), soil chemical properties, microbial communities, enzyme activities, yields and nutrient uptake of rice under different fertilization treatments. Five treatments were included: no chemical fertilizers (C0), chemical fertilizers (C100), Chinese milk vetch (M), CMV combined with 100% chemical fertilizers (MC100) and with 80% chemical fertilizers (MC80). Results showed that the M, MC100, and MC80 treatments significantly increased PNM and PNA compared with the C100 treatment (P &lt; 0.05). Meanwhile, the CMV application significantly increased total N, microbial biomass N, and carbon (C) concentrations, the abundances of the bacterial phylum Actinobacteria, and the genera Bradyrhizobium, Mycobacterium, Streptomyces and Reyranella, N-acetyl-glucosaminidase (NAG) activity, yields and N nutrient uptake of rice grain compared with the C100 treatment (P &lt; 0.05). Correlation analyses indicated that grain yield and N uptake of rice, soil total N, microbial biomass C and N, the bacterial phylum Actinobacteria, the genera Bradyrhizobium, Mycobacterium, Streptomyces, Reyranella, and NAG were significantly correlated with PNM under different fertilization regimes, while microbial biomass C and N, Actinobacteria, Bradyrhizobium, and Reyranella were positively related to PNA (P &lt; 0.05). Together, the application of CMV alone or in combination with chemical fertilizers can improve soil properties and rice growth, which may accelerate N mineralization and nitrification in this soil.