Pub Date : 2025-04-12DOI: 10.1016/j.soilbio.2025.109819
Bin Wu, Tongshuo Bai, Wenjuan Yu, Tongbin Zhu, Daming Li, Chenglong Ye, Manqiang Liu, Shuijin Hu
One central goal of global change research is to explore the potential to mitigate rising atmospheric CO2 by promoting carbon (C) sequestration in terrestrial ecosystems, particularly in low-C agricultural soils in tropical and subtropical regions. Existing evidence suggests that the application of organic amendments is not effective in promoting accrual of soil organic carbon (SOC) in weathered tropical soils like Acrisols, but the specific causes that constrain SOC sequestration are not exactly clear. Here, we synthesized data from 224 publications to assess changes in SOC stocks in response to organic amendments across Acrisols and five other soil orders (Anthrosols, Cambisols, Fluvisols, Luvisols, and Phaeozems). We found that Acrisols, characterized by the lowest soil pH, exhibited the lowest C retention efficiency of organic amendments among the six soil orders, whereas no significant differences were observed among the other five soil orders. Initial soil pH and mean annual precipitation (MAP) were key predictors of SOC retention efficiency, which increased with initial soil pH and decreased with MAP. In addition, low soil pH and high MAP also suppressed microbial growth in response to organic amendments, limiting the retention of mineral-associated organic C (MAOC), which was strongly linked to SOC retention efficiency. Together, these findings suggest that limited SOC accumulation in Acrisols likely results from rapid decomposition and inefficient microbial transformation under acidic and humid conditions. Developing viable practices to improve SOC retention in weathered tropical soils with high acidity should focus on both enhancing the microbial pathway of SOC formation (e.g., through liming) and reducing C decomposition (e.g., through reduced tillage or deep residue incorporation).
{"title":"Soil pH and precipitation controls on organic carbon retention from organic amendments across soil orders: A meta-analysis","authors":"Bin Wu, Tongshuo Bai, Wenjuan Yu, Tongbin Zhu, Daming Li, Chenglong Ye, Manqiang Liu, Shuijin Hu","doi":"10.1016/j.soilbio.2025.109819","DOIUrl":"https://doi.org/10.1016/j.soilbio.2025.109819","url":null,"abstract":"One central goal of global change research is to explore the potential to mitigate rising atmospheric CO<sub>2</sub> by promoting carbon (C) sequestration in terrestrial ecosystems, particularly in low-C agricultural soils in tropical and subtropical regions. Existing evidence suggests that the application of organic amendments is not effective in promoting accrual of soil organic carbon (SOC) in weathered tropical soils like Acrisols, but the specific causes that constrain SOC sequestration are not exactly clear. Here, we synthesized data from 224 publications to assess changes in SOC stocks in response to organic amendments across Acrisols and five other soil orders (Anthrosols, Cambisols, Fluvisols, Luvisols, and Phaeozems). We found that Acrisols, characterized by the lowest soil pH, exhibited the lowest C retention efficiency of organic amendments among the six soil orders, whereas no significant differences were observed among the other five soil orders. Initial soil pH and mean annual precipitation (MAP) were key predictors of SOC retention efficiency, which increased with initial soil pH and decreased with MAP. In addition, low soil pH and high MAP also suppressed microbial growth in response to organic amendments, limiting the retention of mineral-associated organic C (MAOC), which was strongly linked to SOC retention efficiency. Together, these findings suggest that limited SOC accumulation in Acrisols likely results from rapid decomposition and inefficient microbial transformation under acidic and humid conditions. Developing viable practices to improve SOC retention in weathered tropical soils with high acidity should focus on both enhancing the microbial pathway of SOC formation (e.g., through liming) and reducing C decomposition (e.g., through reduced tillage or deep residue incorporation).","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"20 1","pages":""},"PeriodicalIF":9.7,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824969","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}
Pub Date : 2025-04-11DOI: 10.1016/j.soilbio.2025.109816
Anna S. Wendel, Sara L. Bauke, Janadi Chamika Ileperuma, Karolin Funken, Katharina Frindte, Claudia Knief
Processes at the root-soil interface are essential for plant nutrient and water uptake, but the level of root-soil contact varies depending on root traits and soil properties. Implications of reduced root-soil contact for the rhizosphere, its microbiota and for plant performance remain largely unclear. Here, the consequences of root-soil contact reduction were analysed in maize microcosm experiments. Either soil porosity was modified by introducing artificial large-sized pores, or the contact area was reduced by a maize mutant (rth3) impaired in root hair development. Microscopic evaluation of roots grown in pores without soil contact revealed strongly reduced prokaryotic surface colonization. Bacterial abundance in the rhizosphere soil of remaining contact areas was also reduced (2.2×1010 vs. 1.0×109 16S rRNA gene copies per g dry soil), including the abundance of nitrogen cycling bacteria. The absence of root hairs decreased bacterial abundance likewise, though not of nitrogen cycling prokaryotes. 16S rRNA gene-based amplicon sequencing revealed bacterial community-compositional alterations in the rhizosphere (PERMANOVA R2=0.701, p=0.001) with lower relative abundances of Massilia and Paenibacillus for roots grown in pores. Community shifts in the rhizosphere of rth3 plants showed similar changes. No differences were evident upon root-soil contact reduction in the endosphere bacterial community. Combined manipulations revealed that root hairs improved root-soil contact in pores, whereas lateral roots reduced it, as validated with a maize mutant (lrt1) impaired in lateral root development. Plant growth and biomass allocation in the first three weeks were only weakly affected by root-soil contact reduction. Overall, the level of root-soil contact appears critical for bacterial life in the rhizosphere and rhizoplane, including the establishment of nitrifying bacteria and potential plant-beneficial taxa such as Massilia. Aiming at optimum root-soil contact by soil management and plant breeding strategies has thus the potential to contribute to the establishment of a functional rhizosphere microbiome.
{"title":"Implications of reduced root-soil contact for microbial rhizosphere establishment and early plant growth performance","authors":"Anna S. Wendel, Sara L. Bauke, Janadi Chamika Ileperuma, Karolin Funken, Katharina Frindte, Claudia Knief","doi":"10.1016/j.soilbio.2025.109816","DOIUrl":"https://doi.org/10.1016/j.soilbio.2025.109816","url":null,"abstract":"Processes at the root-soil interface are essential for plant nutrient and water uptake, but the level of root-soil contact varies depending on root traits and soil properties. Implications of reduced root-soil contact for the rhizosphere, its microbiota and for plant performance remain largely unclear. Here, the consequences of root-soil contact reduction were analysed in maize microcosm experiments. Either soil porosity was modified by introducing artificial large-sized pores, or the contact area was reduced by a maize mutant (<em>rth3</em>) impaired in root hair development. Microscopic evaluation of roots grown in pores without soil contact revealed strongly reduced prokaryotic surface colonization. Bacterial abundance in the rhizosphere soil of remaining contact areas was also reduced (2.2×10<sup>10</sup> vs. 1.0×10<sup>9</sup> 16S rRNA gene copies per g dry soil), including the abundance of nitrogen cycling bacteria. The absence of root hairs decreased bacterial abundance likewise, though not of nitrogen cycling prokaryotes. 16S rRNA gene-based amplicon sequencing revealed bacterial community-compositional alterations in the rhizosphere (PERMANOVA R<sup>2</sup>=0.701, <em>p</em>=0.001) with lower relative abundances of <em>Massilia</em> and <em>Paenibacillus</em> for roots grown in pores. Community shifts in the rhizosphere of <em>rth3</em> plants showed similar changes. No differences were evident upon root-soil contact reduction in the endosphere bacterial community. Combined manipulations revealed that root hairs improved root-soil contact in pores, whereas lateral roots reduced it, as validated with a maize mutant (<em>lrt1</em>) impaired in lateral root development. Plant growth and biomass allocation in the first three weeks were only weakly affected by root-soil contact reduction. Overall, the level of root-soil contact appears critical for bacterial life in the rhizosphere and rhizoplane, including the establishment of nitrifying bacteria and potential plant-beneficial taxa such as <em>Massilia</em>. Aiming at optimum root-soil contact by soil management and plant breeding strategies has thus the potential to contribute to the establishment of a functional rhizosphere microbiome.","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"39 1","pages":""},"PeriodicalIF":9.7,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143823076","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}
Pub Date : 2025-04-10DOI: 10.1016/j.soilbio.2025.109818
Xiang Li , Junwei Luan , Siyu Li , Pengsen Sun , Jinglei Zhang , Yi Wang , Shalom D. Addo-Danso , Shaowen Mei , Baoliang Niu , Shirong Liu
Extreme climatic events, such as drought, are projected to alter soil carbon (C) and nitrogen (N) cycling in forest ecosystems. However, how the effects of drought are modulated by tree roots and their associated mycorrhizal fungi remains poorly understood. Over 144 days of in-situ incubation, using mesocosms with different mesh sizes in an oak forest subjected to six consecutive years of throughfall rain reduction treatment, we distinguished the drought effects on soil organic C and N accumulations via root-pathway and mycorrhizal hypha-pathway. These effects were assessed within different stability fractions of soil organic matter, i.e., particulate organic matter (POM) and mineral-associated organic matter (MAOM). Drought led to greater accumulations of soil organic C and N via the hypha-pathway compared to the root-pathway. This outcome arose because the hypha-pathway drove greater accumulation in POM than losses in MAOM due to reduced decomposition rates, whereas the root-pathway led to greater POM losses relative to MAOM accumulation, primarily attributable to an enhanced root priming effect. Moreover, plants utilized more soil inorganic N relative to organic N through the hypha-pathway in response to drought, which may partly account for the inconsistent changes in C and N within different labile fractions. These findings emphasize the importance of distinguishing divergent roles of roots and mycorrhizal hyphae in modulating soil C and N processes in the context of future climate change scenarios.
{"title":"Mycorrhizal hyphae, but not fine roots modulate drought effects on soil organic matter accumulation in a temperate forest","authors":"Xiang Li , Junwei Luan , Siyu Li , Pengsen Sun , Jinglei Zhang , Yi Wang , Shalom D. Addo-Danso , Shaowen Mei , Baoliang Niu , Shirong Liu","doi":"10.1016/j.soilbio.2025.109818","DOIUrl":"10.1016/j.soilbio.2025.109818","url":null,"abstract":"<div><div>Extreme climatic events, such as drought, are projected to alter soil carbon (C) and nitrogen (N) cycling in forest ecosystems. However, how the effects of drought are modulated by tree roots and their associated mycorrhizal fungi remains poorly understood. Over 144 days of in-situ incubation, using mesocosms with different mesh sizes in an oak forest subjected to six consecutive years of throughfall rain reduction treatment, we distinguished the drought effects on soil organic C and N accumulations via root-pathway and mycorrhizal hypha-pathway. These effects were assessed within different stability fractions of soil organic matter, i.e., particulate organic matter (POM) and mineral-associated organic matter (MAOM). Drought led to greater accumulations of soil organic C and N via the hypha-pathway compared to the root-pathway. This outcome arose because the hypha-pathway drove greater accumulation in POM than losses in MAOM due to reduced decomposition rates, whereas the root-pathway led to greater POM losses relative to MAOM accumulation, primarily attributable to an enhanced root priming effect. Moreover, plants utilized more soil inorganic N relative to organic N through the hypha-pathway in response to drought, which may partly account for the inconsistent changes in C and N within different labile fractions. These findings emphasize the importance of distinguishing divergent roles of roots and mycorrhizal hyphae in modulating soil C and N processes in the context of future climate change scenarios.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"206 ","pages":"Article 109818"},"PeriodicalIF":9.8,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820017","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}
Pub Date : 2025-04-09DOI: 10.1016/j.soilbio.2025.109817
Chunhui Liu , Baorong Wang , Jiaqi Liu , Chenming Guo , Huijun Li , Haolin Zhang , Yang Hu , Deng Ao , Zhijing Xue , Shaoshan An , Zhaolong Zhu
Robinia pseudoacacia plantations are an effective strategy for preventing soil erosion, enhancing soil fertility, and stimulating carbon (C) sequestration in barren systems, supported by symbioses with arbuscular mycorrhizal (AM) fungi and rhizobia. However, the effects of AM fungal diversity and hyphal density on microbial necromass and SOC accumulation after long-term Robinia pseudoacacia plantations remain unclear. We hypothesize that increased AM fungal diversity and hyphal density after afforestation stimulate SOC formation by facilitating fungal and bacterial necromass C (FNC and BNC), glomalin (GRSP), and extracellular polymeric substances (EPS), with the contributions increasing as forest age. To test this hypothesis, microbial necromass, SOC, AM fungal diversity, and hyphal density were measured in surface soil (0–20 cm) and subsurface soil (20–40 cm) of Robinia pseudoacacia plantations aged 10, 15, 20, 35, and >50 years. Results showed that SOC accumulation was largely confined to surface soil, predominantly as mineral-associated organic C (MAOC). The content of FNC, GRSP, and EPS-polysaccharide in surface soil also increased with stand age, which is closely associated with MAOC. This emphasizes that long-term Robinia pseudoacacia plantations primarily stimulate C accumulation in surface soil, likely due to GRSP and EPS-polysaccharide aiding in the aggregation and protection of microbial necromass C. Although the AM fungal diversity in surface soil decreased with stand age, the hyphal density increased alongside root biomass. The increase in hyphal density could facilitate FNC and EPS formation, thereby contributing to the MAOC and SOC accumulation. In contrast, the content of SOC and microbial necromass C in subsurface soil showed an absence of differences or was reduced. Overall, this study reveals that microbial necromass and SOC accumulation after Robinia pseudoacacia plantations occur in surface soil, with AM fungal hyphal density and associated exudates, rather than AM fungal diversity, serving as key predictors.
{"title":"Arbuscular mycorrhizal fungi hyphal density rather than diversity stimulates microbial necromass accumulation after long-term Robinia pseudoacacia plantations","authors":"Chunhui Liu , Baorong Wang , Jiaqi Liu , Chenming Guo , Huijun Li , Haolin Zhang , Yang Hu , Deng Ao , Zhijing Xue , Shaoshan An , Zhaolong Zhu","doi":"10.1016/j.soilbio.2025.109817","DOIUrl":"10.1016/j.soilbio.2025.109817","url":null,"abstract":"<div><div><em>Robinia pseudoacacia</em> plantations are an effective strategy for preventing soil erosion, enhancing soil fertility, and stimulating carbon (C) sequestration in barren systems, supported by symbioses with arbuscular mycorrhizal (AM) fungi and rhizobia. However, the effects of AM fungal diversity and hyphal density on microbial necromass and SOC accumulation after long-term <em>Robinia pseudoacacia</em> plantations remain unclear. We hypothesize that increased AM fungal diversity and hyphal density after afforestation stimulate SOC formation by facilitating fungal and bacterial necromass C (FNC and BNC), glomalin (GRSP), and extracellular polymeric substances (EPS), with the contributions increasing as forest age. To test this hypothesis, microbial necromass, SOC, AM fungal diversity, and hyphal density were measured in surface soil (0–20 cm) and subsurface soil (20–40 cm) of <em>Robinia pseudoacacia</em> plantations aged 10, 15, 20, 35, and >50 years. Results showed that SOC accumulation was largely confined to surface soil, predominantly as mineral-associated organic C (MAOC). The content of FNC, GRSP, and EPS-polysaccharide in surface soil also increased with stand age, which is closely associated with MAOC. This emphasizes that long-term <em>Robinia pseudoacacia</em> plantations primarily stimulate C accumulation in surface soil, likely due to GRSP and EPS-polysaccharide aiding in the aggregation and protection of microbial necromass C. Although the AM fungal diversity in surface soil decreased with stand age, the hyphal density increased alongside root biomass. The increase in hyphal density could facilitate FNC and EPS formation, thereby contributing to the MAOC and SOC accumulation. In contrast, the content of SOC and microbial necromass C in subsurface soil showed an absence of differences or was reduced. Overall, this study reveals that microbial necromass and SOC accumulation after <em>Robinia pseudoacacia</em> plantations occur in surface soil, with AM fungal hyphal density and associated exudates, rather than AM fungal diversity, serving as key predictors.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"206 ","pages":"Article 109817"},"PeriodicalIF":9.8,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143806186","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}
Pub Date : 2025-04-07DOI: 10.1016/j.soilbio.2025.109813
Jing Fang , Jie Ma , Tao Wen , Guoqing Niu , Shuli Wei , Shaofeng Su , Liuxi Yi , Yuchen Cheng , Jun Yuan , Xiaoqing Zhao , Zhanyuan Lu
In response to drought, plants modulate their morphology and orchestrate a range of functional adaptations. However, the intricate relationships between plants and their microbiome in response to drought stress are not fully understood. Herein, we used transcriptome and untargeted metabolomics technologies to study genetic and metabolic changes associated with drought resistance in spring wheat, as well as amplicon sequencing and metagenomic approaches were employed to investigate the influence of rhizosphere microorganisms on this process. Results indicated that plant functions of osmotic adjustment, oxidative stress, and stomatal regulation were enriched during drought conditions. Meanwhile, the relative abundances of trehalose, sucrose, gentiobiose, and abscisic acid in root exudates increased by 18.7 %, 21.1 %, 4.8 %, and 121.0 %, respectively. Cross-domain network construction with four omics data revealed that a significant increase in abundance of the trehalose biosynthetic pathway and sugar transporter SWEET gene promoted sucrose and trehalose secretion, respectively, leading to an enrichment of Pseudomonas and Streptomyces in the subsequent validation assay. Pseudomonas extremorientalis LS-8 and Streptomyces cinereoruber LW-5 were isolated to reveal that both strains could improve drought resistance by increasing the average aboveground fresh weight by more than 33.0 % and upregulating the expression of TaLEA2, TaBADHb, TaWRKY10, and TaERF3 in spring wheat. Taken together, our study reveals novel drought resistance insights of spring wheat by the collaboration of self-rescue and cry for help from rhizosphere strategy, providing new opportunities to enhance drought resilience of spring wheat.
{"title":"Cry for help from rhizosphere microbiomes and self-rescue strategies cooperatively alleviate drought stress in spring wheat","authors":"Jing Fang , Jie Ma , Tao Wen , Guoqing Niu , Shuli Wei , Shaofeng Su , Liuxi Yi , Yuchen Cheng , Jun Yuan , Xiaoqing Zhao , Zhanyuan Lu","doi":"10.1016/j.soilbio.2025.109813","DOIUrl":"10.1016/j.soilbio.2025.109813","url":null,"abstract":"<div><div>In response to drought, plants modulate their morphology and orchestrate a range of functional adaptations. However, the intricate relationships between plants and their microbiome in response to drought stress are not fully understood. Herein, we used transcriptome and untargeted metabolomics technologies to study genetic and metabolic changes associated with drought resistance in spring wheat, as well as amplicon sequencing and metagenomic approaches were employed to investigate the influence of rhizosphere microorganisms on this process. Results indicated that plant functions of osmotic adjustment, oxidative stress, and stomatal regulation were enriched during drought conditions. Meanwhile, the relative abundances of trehalose, sucrose, gentiobiose, and abscisic acid in root exudates increased by 18.7 %, 21.1 %, 4.8 %, and 121.0 %, respectively. Cross-domain network construction with four omics data revealed that a significant increase in abundance of the trehalose biosynthetic pathway and sugar transporter <em>SWEET</em> gene promoted sucrose and trehalose secretion, respectively, leading to an enrichment of <em>Pseudomonas</em> and <em>Streptomyces</em> in the subsequent validation assay. <em>Pseudomonas extremorientalis</em> LS-8 and <em>Streptomyces cinereoruber</em> LW-5 were isolated to reveal that both strains could improve drought resistance by increasing the average aboveground fresh weight by more than 33.0 % and upregulating the expression of <em>TaLEA2</em>, <em>TaBADHb</em>, <em>TaWRKY10</em>, and <em>TaERF3</em> in spring wheat. Taken together, our study reveals novel drought resistance insights of spring wheat by the collaboration of self-rescue and cry for help from rhizosphere strategy, providing new opportunities to enhance drought resilience of spring wheat.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"206 ","pages":"Article 109813"},"PeriodicalIF":9.8,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143789816","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}
Although earthworms play a crucial role in soil biogeochemical processes, the importance of their traits in shaping the physicochemical properties of their casts remain poorly understood. This study aimed (1) to evaluate the influence of earthworm species and soil types on cast properties and (2) investigate the relationship between earthworm morphological, anatomical, physiological and behavioral traits and the physicochemical properties of their casts. Nine temperate earthworm species were studied under controlled conditions in two contrasting soil types (Luvisol and Cambisol), and 21 traits were determined for each species. Casts were analyzed for their physicochemical properties, total and available organic carbon and nitrogen, and compared to control soil incubated under similar conditions without earthworms. Results showed that earthworm activity modulated soil pH depending on soil type, increasing pH in Cambisol while decreasing pH in Luvisol. Species-specific effects on cast properties revealed a physicochemical gradient: L. castaneus and L. terrestris produced casts with the highest nitrate, dissolved organic carbon, total organic carbon, and moisture levels, whereas endogeic species had the lowest values. Moreover, earthworm species exerted a stronger overall influence on cast properties than soil type (59% vs. 24%), underscoring the dominant role of species-specific traits in shaping cast characteristics. We identified nine key traits related to the earthworm’s morphology, anatomy, physiology and behavior, that influenced cast properties directly or indirectly. Direct effect traits included mouth area, gizzard size and location, typhlosole complexity, intestinal mucus and cast production. Indirect effect traits, such as pigmentation, litter ingestion and litter-to-cast ratio, reflected the ecological behavior of earthworm species. This trait-based approach provides a promising avenue to future studies of the role of earthworms in soil biogeochemical cycling and a framework for advancing our understanding of their impact on soil organic matter dynamics.
{"title":"Let’s get functional: relationship between earthworm traits and physicochemical cast properties","authors":"Yacouba ZI, Nicolas BOTTINELLI, Malalatiana RAZAFINDRAKOTO, Yvan CAPOWIEZ, Alessandro FLORIO, Chao SONG, Cornelia RUMPEL, D.I.G.N.A.C. Marie-France","doi":"10.1016/j.soilbio.2025.109809","DOIUrl":"https://doi.org/10.1016/j.soilbio.2025.109809","url":null,"abstract":"Although earthworms play a crucial role in soil biogeochemical processes, the importance of their traits in shaping the physicochemical properties of their casts remain poorly understood. This study aimed (1) to evaluate the influence of earthworm species and soil types on cast properties and (2) investigate the relationship between earthworm morphological, anatomical, physiological and behavioral traits and the physicochemical properties of their casts. Nine temperate earthworm species were studied under controlled conditions in two contrasting soil types (Luvisol and Cambisol), and 21 traits were determined for each species. Casts were analyzed for their physicochemical properties, total and available organic carbon and nitrogen, and compared to control soil incubated under similar conditions without earthworms. Results showed that earthworm activity modulated soil pH depending on soil type, increasing pH in Cambisol while decreasing pH in Luvisol. Species-specific effects on cast properties revealed a physicochemical gradient: <em>L. castaneus</em> and <em>L. terrestris</em> produced casts with the highest nitrate, dissolved organic carbon, total organic carbon, and moisture levels, whereas endogeic species had the lowest values. Moreover, earthworm species exerted a stronger overall influence on cast properties than soil type (59% vs. 24%), underscoring the dominant role of species-specific traits in shaping cast characteristics. We identified nine key traits related to the earthworm’s morphology, anatomy, physiology and behavior, that influenced cast properties directly or indirectly. Direct effect traits included mouth area, gizzard size and location, typhlosole complexity, intestinal mucus and cast production. Indirect effect traits, such as pigmentation, litter ingestion and litter-to-cast ratio, reflected the ecological behavior of earthworm species. This trait-based approach provides a promising avenue to future studies of the role of earthworms in soil biogeochemical cycling and a framework for advancing our understanding of their impact on soil organic matter dynamics.","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"25 1","pages":""},"PeriodicalIF":9.7,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143775932","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}
The calorespirometric ratio is a metabolic indicator that can be useful in soil science for understanding thermodynamics and the carbon use efficiency of soil microbial metabolism. Calculating calorespirometric ratios for soil microbial metabolism involves the development of calorespirometric procedures using calorimeters of the heat conduction type. The calorespirometric measurements for soil microbial metabolism are recent and their calculation requires sensitive calorimeters and accurate measurements. Their interpretation for soils has been developing during the last years, but accuracy of the methods involved in their calculation are still under question. This paper analyses the precision of the traditional calorespirometric method to yield these calorespirometric ratios by comparison with analysis of respiration measured in parallel using chromatography. Results indicated that the CO2 data obtained by chromatography and calorespirometry are significantly correlated with each other and with the heat rate of the soil microbial metabolism. The comparison of the CO2 data from both methods by the paired sample Wilcoxon signed rank test yielded no statistically significant differences. Nevertheless, small changes in the CO2 determinations, due to the method of measurement or to the reproducibility of these indices in the soil replicates, affected the experimental quantitative values of the calorespirometric ratios. Differences in the quantitative values were large enough in some of the samples to yield distinct interpretations of the results.
{"title":"Validation of the traditional calorespirometric procedure using external respirometry to quantify the calorespirometric ratio of soil microbial metabolism","authors":"Verónica Piñeiro , Yago Lestido-Cardama , César Pérez-Cruzado , Nieves Barros","doi":"10.1016/j.soilbio.2025.109812","DOIUrl":"10.1016/j.soilbio.2025.109812","url":null,"abstract":"<div><div>The calorespirometric ratio is a metabolic indicator that can be useful in soil science for understanding thermodynamics and the carbon use efficiency of soil microbial metabolism. Calculating calorespirometric ratios for soil microbial metabolism involves the development of calorespirometric procedures using calorimeters of the heat conduction type. The calorespirometric measurements for soil microbial metabolism are recent and their calculation requires sensitive calorimeters and accurate measurements. Their interpretation for soils has been developing during the last years, but accuracy of the methods involved in their calculation are still under question. This paper analyses the precision of the traditional calorespirometric method to yield these calorespirometric ratios by comparison with analysis of respiration measured in parallel using chromatography. Results indicated that the CO<sub>2</sub> data obtained by chromatography and calorespirometry are significantly correlated with each other and with the heat rate of the soil microbial metabolism. The comparison of the CO<sub>2</sub> data from both methods by the paired sample Wilcoxon signed rank test yielded no statistically significant differences. Nevertheless, small changes in the CO<sub>2</sub> determinations, due to the method of measurement or to the reproducibility of these indices in the soil replicates, affected the experimental quantitative values of the calorespirometric ratios. Differences in the quantitative values were large enough in some of the samples to yield distinct interpretations of the results.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"206 ","pages":"Article 109812"},"PeriodicalIF":9.8,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776160","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}
The degradation of large biopolymers, such as cellulose, in soil requires several enzymatic hydrolysis steps to produce simpler substrates for microbial uptake. The synthesis of these enzymes requires energy and takes time until they are fully expressed. However, the heat release associated with enzymatic hydrolysis and the temporal delay between this initial heat release and the final carbon mineralization to CO2 is largely unknown. In this study, we investigated the dynamics of heat and CO2 release during the sequential decomposition of cellulose to its building blocks, cellobiose and glucose, in soil and related these processes to activities of cellobiohydrolase and β-glucosidase driving the corresponding steps of cellulose decomposition. Moreover, we estimated catabolic heat release during the stepwise enzymatic production of oligo- and monomers in soil by employing fluorogenically labeled substrates. This amounted to the absolute value of 26.5 kJ mol C−1, approximately 6.5 % of the total combustion enthalpy stored in the applied cellulose.
By three complementary approaches, we confirmed that cellobiohydrolase rather than β-glucosidase is the bottleneck step of enzymatic hydrolysis. First, a 36 h temporal decoupling between the heat and CO2 formation peaks occurred during step-wise enzymatic hydrolysis of cellulose performed by cellobiohydrolase and β-glucosidase towards final mineralization. This decoupling was not observed in the next sequential step of cellobiose hydrolysis by β-glucosidase. Remarkably, heat and CO2 release evolved more slowly during cellulose degradation compared to that of its building blocks, cellobiose and glucose. Second, the enzyme activity of β-glucosidase more than doubled that of cellobiohydrolase during cellulose degradation. Third, heat release after the addition of flurogenically labeled substrate to soil, which mimics the steps of cellulose degradation, was faster in the step of glucose production than that of cellobiose production. This study highlights the novel mechanistic insights facilitated by calorespiroemetric monitoring of carbon decomposition at high temporal resolution.
{"title":"Decoupling of heat and CO2 release during decomposition of cellulose and its building blocks in soil","authors":"Fatemeh Dehghani , Thomas Reitz , Steffen Schlüter , Matthias Kästner , Evgenia Blagodatskaya","doi":"10.1016/j.soilbio.2025.109801","DOIUrl":"10.1016/j.soilbio.2025.109801","url":null,"abstract":"<div><div>The degradation of large biopolymers, such as cellulose, in soil requires several enzymatic hydrolysis steps to produce simpler substrates for microbial uptake. The synthesis of these enzymes requires energy and takes time until they are fully expressed. However, the heat release associated with enzymatic hydrolysis and the temporal delay between this initial heat release and the final carbon mineralization to CO<sub>2</sub> is largely unknown. In this study, we investigated the dynamics of heat and CO<sub>2</sub> release during the sequential decomposition of cellulose to its building blocks, cellobiose and glucose, in soil and related these processes to activities of cellobiohydrolase and β-glucosidase driving the corresponding steps of cellulose decomposition. Moreover, we estimated catabolic heat release during the stepwise enzymatic production of oligo- and monomers in soil by employing fluorogenically labeled substrates. This amounted to the absolute value of 26.5 kJ mol C<sup>−1</sup>, approximately 6.5 % of the total combustion enthalpy stored in the applied cellulose.</div><div>By three complementary approaches, we confirmed that cellobiohydrolase rather than β-glucosidase is the bottleneck step of enzymatic hydrolysis. First, a 36 h temporal decoupling between the heat and CO<sub>2</sub> formation peaks occurred during step-wise enzymatic hydrolysis of cellulose performed by cellobiohydrolase and β-glucosidase towards final mineralization. This decoupling was not observed in the next sequential step of cellobiose hydrolysis by β-glucosidase. Remarkably, heat and CO<sub>2</sub> release evolved more slowly during cellulose degradation compared to that of its building blocks, cellobiose and glucose. Second, the enzyme activity of β-glucosidase more than doubled that of cellobiohydrolase during cellulose degradation. Third, heat release after the addition of flurogenically labeled substrate to soil, which mimics the steps of cellulose degradation, was faster in the step of glucose production than that of cellobiose production. This study highlights the novel mechanistic insights facilitated by calorespiroemetric monitoring of carbon decomposition at high temporal resolution.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"206 ","pages":"Article 109801"},"PeriodicalIF":9.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758410","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}
Elevated temperature significantly impacts arsenic (As) bioavailability and speciation in soils. Methane (CH4)-dependent arsenate reduction (M-AsR), a process in which As(V) reduction coupled with aerobic or anaerobic methane oxidation, has been extensively demonstrated in paddy soils. However, the intricacies of M-AsR under future global warming scenarios remain unclear. In this study, we aimed to investigate the effect of elevated temperature on M-AsR by conducting incubations with soil inocula and microcosm. Our findings indicated that M-AsR was highly sensitive to elevated temperature. Specifically, the generation rates of 13CO2 and As(III) increased by 72.6 % and 36.1 %, respectively, when the temperature rose from 28 °C (the average daytime temperature in the rice-growing regions) to 33 °C (the future temperature condition). Quantitative polymerase chain reaction (qPCR) analysis revealed a positive correlation between temperature and the abundance of the arrA gene, the pmoA2 gene and the ANME-mcrA gene. Additionally, microbial community composition at 33 °C differed markedly from 28 °C. It was characterized by a greater relative abundance of type II methanotrophs (e.g., Beijerinckiaceae) and anaerobic methanotrophic archaea (e.g., Methanosarcinaceae), and by a decrease in type I methanotrophs (e.g., Methylomonaceae). Overall, our results highlight the importance of temperature in regulating M-AsR in paddy soils. Elevated temperature has the potential to significantly enhance the M-AsR pathway by changing the abundance of functional microorganisms and reshaping the microbial community.
{"title":"Elevated temperature promotes methane-dependent arsenate reduction in paddy soils","authors":"Yujie Zhou , Zhaofeng Yuan , Ouyuan Jiang , Dan Chen , Williamson Gustave , Jianming Xu , Xianjin Tang","doi":"10.1016/j.soilbio.2025.109800","DOIUrl":"10.1016/j.soilbio.2025.109800","url":null,"abstract":"<div><div>Elevated temperature significantly impacts arsenic (As) bioavailability and speciation in soils. Methane (CH<sub>4</sub>)-dependent arsenate reduction (M-AsR), a process in which As(V) reduction coupled with aerobic or anaerobic methane oxidation, has been extensively demonstrated in paddy soils. However, the intricacies of M-AsR under future global warming scenarios remain unclear. In this study, we aimed to investigate the effect of elevated temperature on M-AsR by conducting incubations with soil inocula and microcosm. Our findings indicated that M-AsR was highly sensitive to elevated temperature. Specifically, the generation rates of <sup>13</sup>CO<sub>2</sub> and As(III) increased by 72.6 % and 36.1 %, respectively, when the temperature rose from 28 °C (the average daytime temperature in the rice-growing regions) to 33 °C (the future temperature condition). Quantitative polymerase chain reaction (qPCR) analysis revealed a positive correlation between temperature and the abundance of the <em>arrA</em> gene, the <em>pmoA2</em> gene and the ANME-<em>mcrA</em> gene. Additionally, microbial community composition at 33 °C differed markedly from 28 °C. It was characterized by a greater relative abundance of type II methanotrophs (e.g., <em>Beijerinckiaceae</em>) and anaerobic methanotrophic archaea (e.g., <em>Methanosarcinaceae</em>), and by a decrease in type I methanotrophs (e.g., <em>Methylomonaceae</em>). Overall, our results highlight the importance of temperature in regulating M-AsR in paddy soils. Elevated temperature has the potential to significantly enhance the M-AsR pathway by changing the abundance of functional microorganisms and reshaping the microbial community.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"206 ","pages":"Article 109800"},"PeriodicalIF":9.8,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745151","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}
Pub Date : 2025-04-01DOI: 10.1016/j.soilbio.2025.109799
Sneha P. Couvillion, Isabella H. Yang, Dylan Hermosillo, Damon Leach, Josie Eder, Sheryl Bell, Kirsten S. Hofmockel
Root-derived carbon has been shown to contribute more to soil carbon stocks than aboveground litter. Yet the molecular chemodiversity of root exudates remains poorly understood due to limited characterization and annotation. In this study, we characterized the molecular chemodiversity and production of metabolites and lipids in root exudates from field grown mature tall wheatgrass (Thinopyrum ponticum). We discovered a diversity of lipids, including substantial levels of triacylglycerols (∼19 μg/g fresh root per min), fatty acyls, sphingolipids, sterol lipids, and glycerophospholipids, some of which have not been previously documented in root exudates. By integrating tandem mass spectral library searching and deep learning-based chemical class assignment, our metabo-lipidomics approach significantly expanded the known molecular diversity of root exudates. Rates of lipid derived carbon production were approximately double that of polar metabolites (lipids: 81.52 ± 13.81 vs polar metabolites: 38.41 ± 5.93 μg C g−1 fresh root mass min−1) with an order of magnitude higher carbon to nitrogen ratios (lipids: 459 ± 90 vs polar metabolites: 14.40 ± 0.58). Exudate lipids displayed highly negative nominal oxidation state of carbon (−1.182 to −1.909), indicating that these compounds may be less favorable for microbial decomposition. Together our results suggest the potential of root exudate lipids to contribute to stable carbon pools in soil, supporting long-term carbon storage. This work advances understanding of plant-derived lipid inputs to soil and underscores the need for future studies on the functional roles of lipids in shaping root-microbe-soil interactions, microbial activity, soil structure, and nutrient availability – contributing to soil health.
{"title":"Root exudate lipids: Uncovering chemodiversity and carbon stability potential","authors":"Sneha P. Couvillion, Isabella H. Yang, Dylan Hermosillo, Damon Leach, Josie Eder, Sheryl Bell, Kirsten S. Hofmockel","doi":"10.1016/j.soilbio.2025.109799","DOIUrl":"10.1016/j.soilbio.2025.109799","url":null,"abstract":"<div><div>Root-derived carbon has been shown to contribute more to soil carbon stocks than aboveground litter. Yet the molecular chemodiversity of root exudates remains poorly understood due to limited characterization and annotation. In this study, we characterized the molecular chemodiversity and production of metabolites and lipids in root exudates from field grown mature tall wheatgrass (<em>Thinopyrum ponticum</em>). We discovered a diversity of lipids, including substantial levels of triacylglycerols (∼19 μg/g fresh root per min), fatty acyls, sphingolipids, sterol lipids, and glycerophospholipids, some of which have not been previously documented in root exudates. By integrating tandem mass spectral library searching and deep learning-based chemical class assignment, our metabo-lipidomics approach significantly expanded the known molecular diversity of root exudates. Rates of lipid derived carbon production were approximately double that of polar metabolites (lipids: 81.52 ± 13.81 vs polar metabolites: 38.41 ± 5.93 μg C g<sup>−1</sup> fresh root mass min<sup>−1</sup>) with an order of magnitude higher carbon to nitrogen ratios (lipids: 459 ± 90 vs polar metabolites: 14.40 ± 0.58). Exudate lipids displayed highly negative nominal oxidation state of carbon (−1.182 to −1.909), indicating that these compounds may be less favorable for microbial decomposition. Together our results suggest the potential of root exudate lipids to contribute to stable carbon pools in soil, supporting long-term carbon storage. This work advances understanding of plant-derived lipid inputs to soil and underscores the need for future studies on the functional roles of lipids in shaping root-microbe-soil interactions, microbial activity, soil structure, and nutrient availability – contributing to soil health.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"206 ","pages":"Article 109799"},"PeriodicalIF":9.8,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745231","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}
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