Soil Biology & Biochemistry最新文献

{"title":"First microscale data on depth profiles of microbial N₂O reduction, O2 availability, and pore networks inside contrasting single soil aggregates","authors":"S. Mitsunobu ,&nbsp;R. Wagai ,&nbsp;H. Shimada ,&nbsp;H. Kato ,&nbsp;K. Ito ,&nbsp;S. Sato ,&nbsp;M. Hayatsu ,&nbsp;K. Minamisawa","doi":"10.1016/j.soilbio.2024.109684","DOIUrl":"10.1016/j.soilbio.2024.109684","url":null,"abstract":"<div><div>A major greenhouse gas, nitrous oxide (N₂O) significantly emitted from agricultural soils, is reduced to innocuous N₂ gas by the activity of two groups of N₂O-reducing microbes (typical clade I and more recently discovered atypical clade II) having different enzymatic efficiency. Yet, basic information such as the locations of N₂O reduction hotspots and soil factors regulating their formations is still lacking. In addition, oxygen availability, which is strongly constrained by soil pore property, likely dictates their ecology in soil as N₂O reductase enzyme (coded by <em>nosZ</em> genes) is inhibited by O₂. Accordingly, the aim of this study was to assess the mechanistic linkage among soil pore networks, chemical microenvironments (pH, Eh, and O₂ and N₂O abundances), ecology of N₂O-reducing microbes, and the occurrence of N₂O reduction hotspots in single soil aggregates. Using water-stable macroaggregates from two contrasting soil types (highly porous Andosol and less porous clay-rich Acrisol), we determined microscale depth profiles of N₂O and O₂ dynamics, three-dimensional pore properties, and the two N₂O reducer populations in the single aggregates after 48-h lab incubation under a water-saturated condition. The N₂O and O₂ depth profiles showed the increase in N₂O production with O₂ depletion towards deeper part of the incubated aggregates, indicating denitrification N₂O production especially in Andosol aggregate where O₂ availability was higher. The gene distribution with depth clearly showed higher abundance of <em>nosZ</em> harboring microbes (including both clades I and II) in the Acrisol aggregate than Andosol aggregate especially towards the aggregate interior. In the Acrisol aggregate, the abundance of <em>nosZ</em> clade I harboring microbes was maximum at the middle depth corresponding to N₂O maxima, whereas the <em>nosZ</em> clade II harboring microbes had slightly different niche as their population monotonically increased towards the aggregate core, which were consistent with theoretical O₂ availability and pore connectivity. The current findings underscore the intimate connection between soil physical complexity and microbial ecology, which merits further investigation.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109684"},"PeriodicalIF":9.8,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142809591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coupling energy balance and carbon flux during cellulose degradation in arable soils","authors":"Johannes Wirsching ,&nbsp;Martin-Georg Endress ,&nbsp;Eliana Di Lodovico ,&nbsp;Sergey Blagodatsky ,&nbsp;Christian Fricke ,&nbsp;Marcel Lorenz ,&nbsp;Sven Marhan ,&nbsp;Ellen Kandeler ,&nbsp;Christian Poll","doi":"10.1016/j.soilbio.2024.109691","DOIUrl":"10.1016/j.soilbio.2024.109691","url":null,"abstract":"<div><div>Microbial carbon use efficiency (CUE) is an important metric for understanding the balance between anabolic and catabolic metabolism, while energy use efficiency (EUE) provides insight into microbial energy requirements. They are linked by the ratio between released heat and respiration (calorespirometric ratio, CR), which can be used to describe the efficiency of microbial growth. In this study, microbial C and energy use during the degradation of <span><math><mmultiscripts><mrow><mi>C</mi></mrow><none></none><none></none><mprescripts></mprescripts><none></none><mrow><mn>13</mn></mrow></mmultiscripts></math></span>-labeled cellulose in eight different soils was investigated experimentally and simulated using a process-based model. Our results show close agreement between the cumulative C and energy balances during the incubations, with a total C and energy release equal to 30–50% of the amount added as cellulose. Both energy and C fluxes indicated that a positive priming effect of soil organic matter (SOM) increased the release of heat and CO₂ by 10–32% relative to the added substrate. The CR-CUE relationship indicated that growth on cellulose was energy limited during the early but not the later stages of the incubation, especially in soils with high SOM content. We partly observed systematic differences between estimates for CUE based either on the <span><math><mmultiscripts><mrow><mi>C</mi></mrow><none></none><none></none><mprescripts></mprescripts><none></none><mrow><mn>13</mn></mrow></mmultiscripts></math></span> label or on the calorespirometric ratio. Both approaches were constrained by technical and methodological limitations and agreed best during the phase of microbial growth in the SOM-rich soils, with CUE values between 0.4 and 0.75 indicating efficient aerobic growth. During early stages or after transition to a maintenance phase, both estimates were less meaningful for cellulose degradation, a substrate with a lower turnover rate than glucose. Still, the coupled heat and mass balances during cellulose degradation in combination with process-based modeling provided additional information on growth yields as well as the contribution of SOM priming to microbial growth compared to considering mass balances alone.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109691"},"PeriodicalIF":9.8,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142804871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrogen input alleviates the priming effects of biochar addition on soil organic carbon decomposition","authors":"Xuhui Zhou ,&nbsp;Zhiqiang Feng ,&nbsp;Yixian Yao ,&nbsp;Ruiqiang Liu ,&nbsp;Junjiong Shao ,&nbsp;Shuxian Jia ,&nbsp;Yining Gao ,&nbsp;Kui Xue ,&nbsp;Hongyang Chen ,&nbsp;Yuling Fu ,&nbsp;Yanghui He","doi":"10.1016/j.soilbio.2024.109689","DOIUrl":"10.1016/j.soilbio.2024.109689","url":null,"abstract":"<div><div>The combination of biochar and nitrogen (N) addition has been proposed as a potential strategy to sustain crop productivity and mitigate climate change by increasing soil fertility, sequestering carbon (C), and reducing soil greenhouse gas emissions. However, our current knowledge about how biochar and N additions interactively alter mineralization of native soil organic C (SOC), which is referred to priming effects (PEs), is largely limited. To address this uncertainty, C₃ biochar (pyrolyzing rice straw at 300, 550, and 800 °C) and its combination with N fertilizer (urea) were incubated in a C₄-derived soils at 25 °C. All these 3 types of biochar with different addition rates caused positive priming of native soil organic matter decomposition (up to +58.4%). The maximum negative priming effects (up to −25.4%) occurred in soil treated with 1% of N-bound biochar pyrolyzed at 300 °C. In addition, a negative correlation was found between the priming intensity and soil inorganic N content across all treatments. The decrease in biochar-induced PEs was related with a shift in microbial community composition and reduction in microbial biomass determined by chloroform-fumigation. Such a reduction, however, was not confirmed by PLFA analysis. These findings advance our understanding on the microbial mechanisms mediating net soil C balance with the adequate biochar use for blending traditional mineral fertilizers.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109689"},"PeriodicalIF":9.8,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Increased soil pH and enhanced microbial activity stimulate the gradual immobilisation of selenate added to soils","authors":"C. Vermeiren ,&nbsp;J. Ceulemans ,&nbsp;Y. Thiry ,&nbsp;E. Smolders","doi":"10.1016/j.soilbio.2024.109688","DOIUrl":"10.1016/j.soilbio.2024.109688","url":null,"abstract":"<div><div>In recent years, a global interest in selenium (Se) has arisen, both in the light of crop biofortification and risk assessments of ⁷⁹Se present in nuclear waste. In both cases, a profound understanding of the fate of Se in soils is required. The objectives of this study were to evaluate the fate of selenate (Se(VI)) added to soil and to relate the rate and extent of its immobilisation in the months after soil spiking, termed ageing, to soil properties. The underlying hypothesis is that Se mobility can be reduced by incorporation in microbial biomass and by pH-dependent adsorption to oxyhydroxides. Ageing of Se was studied in 14 soils with contrasting properties after spiking with an enriched ⁷⁷Se(VI) isotope tracer. During six months of incubation, subsamples of the soils were collected and extracted to monitor the mobile, adsorbed and NaOH-extractable fractions of soil-native Se and spiked ⁷⁷Se. After 182 days, the mobile concentration of the ⁷⁷Se spike was reduced by a factor 2–300, with the largest factors consistently found in soils with a pH above 6. The decrease in Se availability with time was described by first-order kinetics, which allowed to derive a rate and extent of Se ageing in soils. Distinct but gradual ageing was mainly promoted by high soil pH, whereas Se immobilisation was faster but less pronounced in low pH soils. Amendment of five soils with a carbon source enhanced microbial activity, thereby increasing the rate and/or extent of Se ageing. Also among the unamended soils, the immobilisation rate constant increased with increasing measured soil respiration rates. This study showed a pronounced effect of both soil pH and biochemical reactions on the time-dependent solid:liquid distribution of Se, which should be considered in biofortification practices and risk assessments.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109688"},"PeriodicalIF":9.8,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biochar strategy for long-term N2O emission reduction: Insights into soil physical structure and microbial interaction","authors":"Yeye Zhang ,&nbsp;Chun Yan ,&nbsp;Tao Wang ,&nbsp;Guangxin Zhang ,&nbsp;Michael Bahn ,&nbsp;Fei Mo ,&nbsp;Juan Han","doi":"10.1016/j.soilbio.2024.109685","DOIUrl":"10.1016/j.soilbio.2024.109685","url":null,"abstract":"<div><div>Applying biochar to agricultural soils is a promising strategy for mitigating nitrous oxide (N₂O) emissions. Nitrogen (N) fertilizers are essential for crop production but also represent a significant source of N₂O emissions. The effectiveness of biochar in reducing N₂O emissions depends on the amount of N fertilizer applied and the morphological structure of the biochar. However, few studies have examined the impact of field-aged biochar on N₂O emissions under different N application levels, especially concerning the mechanisms by which biochar's morphological properties and soil characteristics influence microbial-driven N₂O production. We conducted a long-term field experiment over three winter wheat seasons, applying two N fertilizer doses (113.25 and 226.5 kg N ha⁻¹) and four biochar doses (0, 5, 10, 20 t ha⁻¹). In-situ N₂O measurements, combined with amplicon sequencing (16S rRNA, ITS rRNA), metagenomic sequencing, scanning electron microscopy, and Brunauer-Emmett-Teller analysis, were performed to explore the effects of combined application of biochar with N fertilizer on soil N₂O emissions and potential soil physicochemical and microbial mechanisms. The study demonstrated that biochar aged for several years consistently reduced soil N₂O emissions, likely due to modifications in soil physical properties such as specific surface area, pore size, and pore volume. The dose of N fertilizer had a significant effect on how biochar regulated soil pore structure, consequently impacting the abundance of N cycle genes and microbes. The intermediate biochar dose of 10 t ha⁻¹ biochar significantly increased soil mesopore size and the abundance of N₂O-reducing genes such as <em>nosZ</em>, while simultaneously suppressing the N₂O production genes such as <em>napA</em> and <em>norB</em> through enhanced soil specific surface area and pore volume, but further increasing the dose did not result in sustained improvement. The functional diversity of N-cycling genes proved to be a more reliable predictor of N₂O emissions than the diversity of fungal and bacterial taxa. Our findings advance the understanding of how biochar influences physical-microbial interactions that determine N₂O production in agricultural soils. These mechanistic insights are crucial for developing integrated biochar and fertilization management strategies to mitigate climate change effectively.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109685"},"PeriodicalIF":9.8,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rhizosphere priming effects and trade-offs among root traits, exudation and mycorrhizal symbioses","authors":"He Wang ,&nbsp;Jiayu Lu ,&nbsp;Feike A. Dijkstra ,&nbsp;Lijuan Sun ,&nbsp;Liming Yin ,&nbsp;Peng Wang ,&nbsp;Weixin Cheng","doi":"10.1016/j.soilbio.2024.109690","DOIUrl":"10.1016/j.soilbio.2024.109690","url":null,"abstract":"<div><div>The influence of living roots on soil organic matter decomposition is termed the rhizosphere priming effect (RPE). Although root traits are critical for understanding the RPE, it is unclear how the trade-offs among root traits, exudation and mycorrhizal symbioses mediate the RPE. The RPEs of 12 grassland species were quantified using a natural ¹³C tracer method in a mesocosm experiment. Ten root functional traits were measured to examine the trade-offs among root traits, and their linkage with the RPEs. All species produced positive RPEs, with legumes and forbs showing larger RPEs than grasses. The magnitude varied from 32% to 350% compared to the unplanted soil. After accounting for root biomass effect, specific RPEs were positively correlated with specific root length, specific root surface area, root exudation rate, and specific rhizosphere respiration, while negatively correlated with root diameter and arbuscular mycorrhizal fungi colonization. These results demonstrate that plants with thinner roots show efficient root morphology and/or more exudation by inducing larger specific RPEs, while plants with thicker roots associate more with mycorrhizal symbioses and induce smaller specific RPEs. Overall, root functional traits play key roles in mediating the species-specific RPEs and have implications for predicting soil organic matter dynamics.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109690"},"PeriodicalIF":9.8,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142797377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Visualization of soil aggregate structures provides insights into their formation mechanisms induced by litter inputs","authors":"Milda Pucetaite ,&nbsp;Per Persson ,&nbsp;Julia Parker ,&nbsp;Ulf Johansson ,&nbsp;Edith C. Hammer","doi":"10.1016/j.soilbio.2024.109686","DOIUrl":"10.1016/j.soilbio.2024.109686","url":null,"abstract":"<div><div>Soil aggregation is a dynamic process influenced by physical, chemical and biological factors; however, their individual and combined effect on the formation and turnover of aggregates is not well understood. The aim of this study was to examine incorporation of fresh litter inputs of different physicochemical properties including their carbon-to-nitrogen (C/N) ratio – maize (C/N = 12) and straw (C/N = 103) - into aggregates, <em>de novo</em> formed from mineral soil with or without the presence of microbiota. Using rare-earth element oxides, we labelled structures formed during a four-week incubation with a single litter type and traced their incorporation into newly formed aggregates after mixing them together and incubating for a subsequent seven-week period. To visualize them, we used synchrotron-based X-ray fluorescence microspectroscopy, which allowed us to demonstrate that presence of the plant-derived particulate organic matter was the key factor for the aggregate formation. Within the timescale of the experiment, neither microbial abundance nor the community composition had any significant effect. However, the relative increase in straw-associated soil in aggregates larger than 250 μm provided support for our hypothesis regarding impact of carbon-rich organic matter on macroaggregation, likely via promotion of fungal growth and hyphal enmeshing. Phospholipid fatty acid analysis further confirmed relatively higher abundance of fungi in macroaggregates in straw-containing soil. All in all, our study provides insights into the initial stages of aggregate formation following litter additions and development of associated microbial community. The spatial analysis enabled by the X-ray fluorescence microspectroscopy enabled visualization of internal aggregate structures, shedding light on the processes involved, which is not possible with bulk analysis alone.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109686"},"PeriodicalIF":9.8,"publicationDate":"2024-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142793592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrification inhibitor induced microbial NH4+-N immobilization improves maize nitrogen use efficiency in strong ammonia oxidation soil","authors":"Si-Yi Liu ,&nbsp;Di Wu ,&nbsp;Xiao-Tang Ju ,&nbsp;Ju-Pei Shen ,&nbsp;Yi Cheng ,&nbsp;Na Deng ,&nbsp;Xiao-Tong Song ,&nbsp;Hong-Jie Di ,&nbsp;Pei-Pei Li ,&nbsp;Li-li Han ,&nbsp;An-Hui Ge ,&nbsp;Chuan-Fa Wu ,&nbsp;Li-Mei Zhang","doi":"10.1016/j.soilbio.2024.109687","DOIUrl":"10.1016/j.soilbio.2024.109687","url":null,"abstract":"<div><div>Nitrification inhibitors (NIs) have been acknowledged since 1970s for their potential to mitigate N₂O emissions, enhance fertilizer nitrogen use efficiency (NUE), and improve crop productivity. However, their effectiveness in improving yield and NUE varies significantly across different soil types, with the underlying mechanisms largely unexplored. This study integrates laboratory ¹⁵N labeling incubation experiments with field trials to evaluate the influence of a specific NI, nitraprin, on soil gross N transformation rates, N₂O emissions, maize yield and NUE across three distinct soil types prevalent in China's major crop production zones. These soils include acidic black soil at GZL site, alkaline fluvo-aquic soil at XC site, and acidic red soil at QJ site. The alkaline fluvo-aquic soil (XC) exhibited the highest gross nitrification rates (<em>O</em>_<em>NH4</em>) and cumulative N₂O emissions, while also showing the lowest immobilization rate of NH₄⁺-N (<em>I</em>_<em>NH4</em>). Conversely, the acidic black soil (GZL) had opposite trends. NI application lead to a significant reduction in <em>O</em>_<em>NH4</em> by 23–53% and in N₂O emissions by 48–85%. Notably an increase in maize yield (by 18.7%) and NUE (by 30.3 %) were observed exclusively at XC. NI addition notably enhanced <em>I</em>_<em>NH4</em> at XC, due to the suppression of a high nitrification rate, reduced the N losing risk (N/I ratio) and consequently supported higher maize yield. Further analyses highlighted that autotrophic nitrification, predominantly mediated by ammonia-oxidizing bacteria (AOB), particularly the AOB <em>Nitrosospira</em> cluster 3a.2 (D11), is pivotal in regulating soil N₂O emissions and is sensitive to NI addition. This study underscores the significant role that the interplay between <em>O</em>_<em>NH4</em> and <em>I</em>_<em>NH4</em> plays in influencing maize yield, NUE, and the effectiveness of NIs across various soil types. These insights are crucial for developing tailored N management strategies that aim to maximize NUE and minimize N₂O emissions.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109687"},"PeriodicalIF":9.8,"publicationDate":"2024-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142789804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Opposite priming responses to labile carbon versus oxygen pulses in anoxic peat","authors":"Namid Krüger,&nbsp;Klaus-Holger Knorr,&nbsp;Peter Mueller","doi":"10.1016/j.soilbio.2024.109682","DOIUrl":"10.1016/j.soilbio.2024.109682","url":null,"abstract":"<div><div>Vegetation shifts in peatlands might change the stability of soil organic carbon (SOC) stocks via rhizosphere priming effects. However, mechanisms and magnitude of priming effects in peat soils are poorly understood. Beyond supplying C-rich root exudates - a central driver of priming in upland soils - wetland vascular plants supply oxygen to reducing soil systems.</div><div>We evaluated priming effects in anoxic peat soils driven by labile C-exudate inputs (glucose), oxygen inputs and their interaction. Using incubation experiments, we mimicked oxygen loss and exudation rates of wetland plants and separated peat SOC- and glucose-derived respiration rates using a C stable isotope approach.</div><div>Oxygen pulses and oxygen + glucose pulses stimulated SOC mineralization through positive priming of &gt; + 350% and &gt; + 200%, respectively. By contrast, glucose pulses alone caused negative priming, with the most negative effect (&lt; - 70%) at maximum glucose input. However, even glucose-C inputs smaller than the estimated microbial biomass C led to negative or no priming. Both positive and negative priming effects continued for several weeks after inputs stopped and increased in magnitude.</div><div>We demonstrate that labile C inputs into an anoxic soil can strongly suppress SOC mineralization, in contrast to positive priming effects often observed in oxic upland soils. We hypothesize that negative priming driven by preferential substrate usage is amplified in anoxic soils due to electron-acceptor exhaustion through exudate-fueled respiration. Our results imply that expansion of vascular plants into peatlands could stimulate SOC mineralization through root oxygen loss, while labile C inputs might stabilize SOC.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109682"},"PeriodicalIF":9.8,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142782656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Distinct N-cycling microbial communities contribute to microtopographic variation in soil N2O emissions from denitrification","authors":"Alexander H. Krichels ,&nbsp;Robert A. Sanford ,&nbsp;Joanne C. Chee-Sanford ,&nbsp;Lynn Connor ,&nbsp;Rachel Van Allen ,&nbsp;Angela D. Kent ,&nbsp;Wendy H. Yang","doi":"10.1016/j.soilbio.2024.109683","DOIUrl":"10.1016/j.soilbio.2024.109683","url":null,"abstract":"<div><div>Climate change is increasing the frequency and intensity of large precipitation events that flood soils and establish anoxic conditions that promote microbial denitrification, a predominant source of atmospheric nitrous oxide (N₂O, a strong greenhouse gas). Denitrification may be favored within topographic depressions in otherwise flat fields that are prone to ponding, establishing “hotspots” of N₂O emissions. The location of N₂O hotspots may also depend on the distribution of soil microbial communities that are responsible for the production and consumption of N₂O in soils. Yet, relating soil microbial community composition to N₂O emissions remains challenging. To assess how spatial variation in soil microbial communities affects N₂O emissions, we measured the community composition of active microorganisms using amplicon-based sequencing of cDNA generated from mRNA transcripts associated with N-cycling processes in response to experimentally flooding and draining soils in the lab. We also used stable isotope tracers to relate microbial communities to process rates. Consistent with the hypothesis that denitrifying microbial communities are not functionally redundant, we found that the diversity of microbial taxa expressing nitrite reduction genes (<em>nirK</em>) and N₂O reduction genes (Clade I <em>nosZ)</em> were correlated with denitrifier-derived N₂O emissions. Depressional soils had more diverse active N₂O consuming communities (assessed using Clade I <em>nosZ</em>) under flooded conditions, limiting net N₂O emissions compared to upslope soils. Our results show that depressional soils maintain distinct microbial communities that likely promote higher rates of N₂O reduction compared to upslope soils. Soil microtopography can, therefore, select for distinct microbial communities that emit different amount of N₂O in response to large precipitation events.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"202 ","pages":"Article 109683"},"PeriodicalIF":9.8,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142782731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}