Pub Date : 2024-10-02DOI: 10.1016/j.soilbio.2024.109608
Julia Moll , Claus Bässler , François Buscot , Björn Hoppe , Nico Jehmlich , Harald Kellner , Sarah Muszynski , Matthias Noll
Deadwood decomposition is primarily attributed to wood-colonizing fungi and bacteria, driven mainly by intrinsic (e.g. tree species identity) rather than by extrinsic factors. A recent cross-ecosystem study, using gamma-sterilized wood blocks of different coniferous and deciduous tree species placed at 150 forest and 150 grassland sites, revealed that intrinsic factors most strongly influenced rate of decomposition. These results raised the question of whether the wood-colonizing microbial biodiversity follows similar assembly patterns. For this purpose, we used metabarcoding to analyse the fungal and bacterial communities colonizing the wood blocks. We discovered that the wood-colonizing communities were more strongly determined by extrinsic factors such as the ecosystem type and microclimate (air humidity, soil pH, soil moisture, soil temperature) than by intrinsic factors (tree species identity, wood pH, wood mass loss). Although overall these results seem to be more pronounced for fungi, both communities comprised highly specialized wood colonizers in both ecosystems. For instance, the fungal genus Mycena and the bacterial genus Granulicella were detected more frequently in forests, whereas Exophiala and Sphingomonas were more abundant in grasslands. Wood mass loss exhibited a stronger correlation with reduced fungal diversity, while bacterial richness displayed no association with mass loss, both within and across forest and grassland sites. However, the composition of both colonizers’ communities was consistently linked to wood mass loss. Our study suggests that the environment selects distinct wood-colonizing communities that differ greatly in their decomposition efficiency; this result highlights the importance of cross-ecosystem analyses to assess ecological patterns.
{"title":"Extrinsic rather than intrinsic factors determine microbial colonization of deadwood","authors":"Julia Moll , Claus Bässler , François Buscot , Björn Hoppe , Nico Jehmlich , Harald Kellner , Sarah Muszynski , Matthias Noll","doi":"10.1016/j.soilbio.2024.109608","DOIUrl":"10.1016/j.soilbio.2024.109608","url":null,"abstract":"<div><div>Deadwood decomposition is primarily attributed to wood-colonizing fungi and bacteria, driven mainly by intrinsic (e.g. tree species identity) rather than by extrinsic factors. A recent cross-ecosystem study, using gamma-sterilized wood blocks of different coniferous and deciduous tree species placed at 150 forest and 150 grassland sites, revealed that intrinsic factors most strongly influenced rate of decomposition. These results raised the question of whether the wood-colonizing microbial biodiversity follows similar assembly patterns. For this purpose, we used metabarcoding to analyse the fungal and bacterial communities colonizing the wood blocks. We discovered that the wood-colonizing communities were more strongly determined by extrinsic factors such as the ecosystem type and microclimate (air humidity, soil pH, soil moisture, soil temperature) than by intrinsic factors (tree species identity, wood pH, wood mass loss). Although overall these results seem to be more pronounced for fungi, both communities comprised highly specialized wood colonizers in both ecosystems. For instance, the fungal genus <em>Mycena</em> and the bacterial genus <em>Granulicella</em> were detected more frequently in forests, whereas <em>Exophiala</em> and <em>Sphingomonas</em> were more abundant in grasslands. Wood mass loss exhibited a stronger correlation with reduced fungal diversity, while bacterial richness displayed no association with mass loss, both within and across forest and grassland sites. However, the composition of both colonizers’ communities was consistently linked to wood mass loss. Our study suggests that the environment selects distinct wood-colonizing communities that differ greatly in their decomposition efficiency; this result highlights the importance of cross-ecosystem analyses to assess ecological patterns.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109608"},"PeriodicalIF":9.8,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369586","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 : 2024-10-02DOI: 10.1016/j.soilbio.2024.109613
Xue Qing , Michał Karlicki , Fan Guo , Anna Karnkowska , Hongmei Li
Nematodes are ubiquitous and diverse components of soil ecosystems worldwide. The 18S-based metabarcoding is known to have low species-level resolution and introduce bias in PCR. The mito-metagenomics (MMG) approach involves directly sequencing pooled samples, yields numerous mitochondrial reads that can be assembled into full or partial mitogenomes. This method circumvents the challenges associated with PCR-based metabarcoding and hold significant promise in biodiversity and phylogeny study. However, a reference database is typically required to extract mito-reads/contigs and provide taxonomic or phylogenetic context, thereby limiting its applicability. In this study, we introduced a novel reference-free pipeline for MMG assembly and diversity estimation. This pipeline has been integrated into a snakemake workflow, enabling the generation of output that is readily useable for phylogeny reconstruction in a single run. The performance tests have indicated that this new approach surpasses reference-based methods in soil nematode community profiling. We demonstrated that assembly quality improves with increasing sequencing depth, recommending an average of 1–2 Gb per species to achieve acceptable MMG assembly. Our pipeline presents an opportunity to create high-resolution phylogenies and assess diversity for poorly understood taxa, including neglected microscopic eukaryotes.
{"title":"Soil nematode community profiling using reference-free mito-metagenomics","authors":"Xue Qing , Michał Karlicki , Fan Guo , Anna Karnkowska , Hongmei Li","doi":"10.1016/j.soilbio.2024.109613","DOIUrl":"10.1016/j.soilbio.2024.109613","url":null,"abstract":"<div><div>Nematodes are ubiquitous and diverse components of soil ecosystems worldwide. The 18S-based metabarcoding is known to have low species-level resolution and introduce bias in PCR. The mito-metagenomics (MMG) approach involves directly sequencing pooled samples, yields numerous mitochondrial reads that can be assembled into full or partial mitogenomes. This method circumvents the challenges associated with PCR-based metabarcoding and hold significant promise in biodiversity and phylogeny study. However, a reference database is typically required to extract mito-reads/contigs and provide taxonomic or phylogenetic context, thereby limiting its applicability. In this study, we introduced a novel reference-free pipeline for MMG assembly and diversity estimation. This pipeline has been integrated into a snakemake workflow, enabling the generation of output that is readily useable for phylogeny reconstruction in a single run. The performance tests have indicated that this new approach surpasses reference-based methods in soil nematode community profiling. We demonstrated that assembly quality improves with increasing sequencing depth, recommending an average of 1–2 Gb per species to achieve acceptable MMG assembly. Our pipeline presents an opportunity to create high-resolution phylogenies and assess diversity for poorly understood taxa, including neglected microscopic eukaryotes.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109613"},"PeriodicalIF":9.8,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369585","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 : 2024-10-02DOI: 10.1016/j.soilbio.2024.109610
Jin Ho Lee , Tayler C. Ulbrich , Maik Geers-Lucas , G. Philip Robertson , Andrey K. Guber , Alexandra N. Kravchenko
Switchgrass (Panicum virgatum L.) is a promising feedstock for biofuel production, with diverse cultivars representing several ecotypes adapted to different environmental conditions within the contiguous USA. Multiple field studies have demonstrated that monoculture switchgrass cultivation leads to slow to negligible soil carbon (C) gains, an outcome unexpected for such a deep-rooted perennial. We hypothesize that different switchgrass cultivars have disparate impacts on soil C gains, and one of the reasons is variations in physical characteristics of their roots, where roots directly and indirectly influence formation of soil pores. We tested this hypothesis at Great Lakes Bioenergy Research Center's research site in Michigan using two lowland cultivars (Alamo and Kanlow) and four upland cultivars (Southlow, Cave-in-Rock, Blackwell, and Trailblazer). Three types of soil samples were collected: 20 cm diameter (Ø) intact cores used for root analyses; 5 cm Ø intact cores subjected to X-ray computed tomography scanning used for pore characterization; and disturbed soil samples used for microbial biomass C (MBC) and soil C measurements. Path analysis was used to explore interactive relationships among roots, soil pores, and their impact on MBC, and ultimately, on soil C contents across six cultivars. The abundance of very fine roots (<200 μm Ø) was positively associated with fractions of pores in the same size range, but negatively with distances to pores and particulate organic matter. Higher abundance of such roots also led to greater MBC, while greater volumes of medium pores (50–200 μm Ø) and shorter distances to pores increased MBC. Results suggest that the greater proportion of very fine roots is a trait that can potentially stimulate soil C gains, with pore characteristics serving as links for the relationship between such roots and C gains. However, at present, ten years of cultivation generated no differences in soil C among the studied cultivars.
开关草(Panicum virgatum L.)是一种很有前景的生物燃料生产原料,其栽培品种多种多样,代表了美国毗连地区适应不同环境条件的几种生态型。多项实地研究表明,单一种植开关草会导致土壤碳(C)的缓慢增加,甚至可以忽略不计,对于这种深根多年生植物来说,这种结果是出乎意料的。我们假设,不同的开关草栽培品种对土壤碳增量的影响不同,原因之一是其根系的物理特性不同,根系直接或间接影响土壤孔隙的形成。我们在密歇根州大湖生物能源研究中心的研究基地使用两个低地栽培品种(阿拉莫和坎洛)和四个高地栽培品种(南洛、岩洞、布莱克威尔和开拓者)对这一假设进行了测试。采集了三种类型的土壤样本:用于根系分析的直径为 20 厘米(Ø)的完整土芯;用于孔隙特征描述的经过 X 射线计算机断层扫描的直径为 5 厘米(Ø)的完整土芯;以及用于微生物生物量 C (MBC) 和土壤碳测量的扰动土壤样本。利用路径分析探讨了根系、土壤孔隙之间的交互关系,以及它们对微生物生物量C的影响,并最终影响了六个栽培品种的土壤C含量。极细根系(直径 200 微米)的丰度与相同大小范围的孔隙比例呈正相关,但与孔隙距离和颗粒有机物呈负相关。此类根的数量越多,中型气孔(直径 50-200 微米)的体积越大,与气孔的距离越短,中型气孔的体积就越大。研究结果表明,较多的细根有可能促进土壤碳的增加,而孔隙特征则是细根与碳增加之间关系的纽带。然而,目前,十年的栽培并未在所研究的栽培品种之间产生土壤碳的差异。
{"title":"Very fine roots differ among switchgrass (Panicum virgatum L.) cultivars and differentially affect soil pores and carbon processes","authors":"Jin Ho Lee , Tayler C. Ulbrich , Maik Geers-Lucas , G. Philip Robertson , Andrey K. Guber , Alexandra N. Kravchenko","doi":"10.1016/j.soilbio.2024.109610","DOIUrl":"10.1016/j.soilbio.2024.109610","url":null,"abstract":"<div><div>Switchgrass (<em>Panicum virgatum</em> L.) is a promising feedstock for biofuel production, with diverse cultivars representing several ecotypes adapted to different environmental conditions within the contiguous USA. Multiple field studies have demonstrated that monoculture switchgrass cultivation leads to slow to negligible soil carbon (C) gains, an outcome unexpected for such a deep-rooted perennial. We hypothesize that different switchgrass cultivars have disparate impacts on soil C gains, and one of the reasons is variations in physical characteristics of their roots, where roots directly and indirectly influence formation of soil pores. We tested this hypothesis at Great Lakes Bioenergy Research Center's research site in Michigan using two lowland cultivars (Alamo and Kanlow) and four upland cultivars (Southlow, Cave-in-Rock, Blackwell, and Trailblazer). Three types of soil samples were collected: 20 cm diameter (Ø) intact cores used for root analyses; 5 cm Ø intact cores subjected to X-ray computed tomography scanning used for pore characterization; and disturbed soil samples used for microbial biomass C (MBC) and soil C measurements. Path analysis was used to explore interactive relationships among roots, soil pores, and their impact on MBC, and ultimately, on soil C contents across six cultivars. The abundance of very fine roots (<200 μm Ø) was positively associated with fractions of pores in the same size range, but negatively with distances to pores and particulate organic matter. Higher abundance of such roots also led to greater MBC, while greater volumes of medium pores (50–200 μm Ø) and shorter distances to pores increased MBC. Results suggest that the greater proportion of very fine roots is a trait that can potentially stimulate soil C gains, with pore characteristics serving as links for the relationship between such roots and C gains. However, at present, ten years of cultivation generated no differences in soil C among the studied cultivars.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109610"},"PeriodicalIF":9.8,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369584","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 : 2024-09-30DOI: 10.1016/j.soilbio.2024.109611
A.R.G. Mason , A.J. Lowe , C. Brien , N. Jewell , T.R. Cavagnaro , M.J. Salomon
The sequestration of atmospheric CO₂ in soil is suggested as an effective climate change mitigation strategy. Biochar application shows promise in this regard, while the role of fungi in soil carbon cycling and sequestration is also under investigation. Using a novel high-throughput plant phenomics approach, we explore the impact of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on wheat growth and soil carbon, guided by one of the leading global carbon credit schemes. Wheat was successfully colonised by AMF, achieving an average root length colonisation of 35.9%. We uncover an indirect fungal-mediated pathway to soil carbon sequestration, with mycorrhizal plants generating more biomass across all soil treatments without yield penalties, suggesting colonised plants deliver more plant derived carbon to the soil, potentially leading to long-term soil carbon gains. Conversely, fungal-driven carbon loss occurred, significantly reducing soil carbon accumulation in unamended soil, but not in biochar-amended soil, suggesting that biochar moderates fungal activity and positively impacts the soil carbon balance. While both biochar and AMF enhance plant growth, their direct effects on soil carbon are complex. Although biochar did not significantly increase soil carbon stocks beyond its own contribution, its ability to regulate fungal activity could play an important role in influencing soil carbon sequestration.
{"title":"Response of wheat to arbuscular mycorrhizal fungi inoculation and biochar application: Implications for soil carbon sequestration","authors":"A.R.G. Mason , A.J. Lowe , C. Brien , N. Jewell , T.R. Cavagnaro , M.J. Salomon","doi":"10.1016/j.soilbio.2024.109611","DOIUrl":"10.1016/j.soilbio.2024.109611","url":null,"abstract":"<div><div>The sequestration of atmospheric CO₂ in soil is suggested as an effective climate change mitigation strategy. Biochar application shows promise in this regard, while the role of fungi in soil carbon cycling and sequestration is also under investigation. Using a novel high-throughput plant phenomics approach, we explore the impact of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on wheat growth and soil carbon, guided by one of the leading global carbon credit schemes. Wheat was successfully colonised by AMF, achieving an average root length colonisation of 35.9%. We uncover an indirect fungal-mediated pathway to soil carbon sequestration, with mycorrhizal plants generating more biomass across all soil treatments without yield penalties, suggesting colonised plants deliver more plant derived carbon to the soil, potentially leading to long-term soil carbon gains. Conversely, fungal-driven carbon loss occurred, significantly reducing soil carbon accumulation in unamended soil, but not in biochar-amended soil, suggesting that biochar moderates fungal activity and positively impacts the soil carbon balance. While both biochar and AMF enhance plant growth, their direct effects on soil carbon are complex. Although biochar did not significantly increase soil carbon stocks beyond its own contribution, its ability to regulate fungal activity could play an important role in influencing soil carbon sequestration.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109611"},"PeriodicalIF":9.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369588","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}
Pub Date : 2024-09-30DOI: 10.1016/j.soilbio.2024.109607
Weimin Song , Yan Zhao , Jian Zhou , Jianxiang Feng , Zhonglei Wang , Guangxuan Han , Elise Pendall , Guanghui Lin
The paucity of studies on nitrous oxide (N2O) dynamics with rising temperatures and nitrogen (N)-based eutrophication makes it challenging to evaluate the role of mangroves in mitigating climate change. Here, a 3-year mesocosm experiment was conducted to investigate the effects of climate warming (+3 °C) and excessive N input (25 mg N L−1) on soil N2O emissions from two mangroves (Avicennia marina and Bruguiera gymnorrhiza). We found that warming and N input alone significantly increased soil N2O emissions from both mangroves, while the interactive effects of warming and N input on soil N2O emissions were affected by mangrove species. Warming mitigated the positive effect of N input on soil N2O emissions from A. marina; and amplified the effect of N input on soil N2O emissions from B. gymnorrhiza, suggesting that the response of soil N2O emissions to these global change factors is species-dependent. Stable isotopic signature analysis revealed that both warming and N input significantly increased the relative contribution of nitrification to N2O emissions from A. marina; whereas N input, rather than warming, significantly changed the relative contribution of nitrification in B. gymnorrhiza. This could be attributed to the differential changes in soil environmental conditions, plant growth and the microbial structure of the two mangroves. Overall, this study highlights the role of mangrove species in modifying the effects of warming and N input on soil N2O emissions, which should be considered when accurately projecting N2O emissions from mangroves. Furthermore, considering the low N2O emissions from background sediments and the common N limitation across mangroves, our findings suggest that climate warming and exogenous N input may lead to a surge of N2O emissions from mangroves, especially those that are seriously affected by human activities.
关于一氧化二氮(N2O)随温度升高和氮(N)富营养化而变化的研究很少,这使得评估红树林在减缓气候变化方面的作用具有挑战性。在此,我们进行了一项为期 3 年的中观实验,研究气候变暖(+3 °C)和过量氮输入(25 毫克 N L-1)对两种红树林(Avicennia marina 和 Bruguiera gymnorrhiza)土壤氧化亚氮排放的影响。我们发现,单独升温和过量氮的输入会显著增加两种红树林的土壤一氧化二氮排放量,而升温和过量氮的输入对土壤一氧化二氮排放量的交互影响则受红树林物种的影响。变暖减轻了氮输入对A. marina土壤N2O排放的积极影响;放大了氮输入对B. gymnorrhiza土壤N2O排放的影响,这表明土壤N2O排放对这些全球变化因素的反应取决于物种。稳定同位素特征分析表明,气候变暖和氮输入都显著增加了A. marina的硝化作用对N2O排放的相对贡献;而氮输入(而不是气候变暖)显著改变了B. gymnorrhiza的硝化作用对N2O排放的相对贡献。这可能是由于两种红树林的土壤环境条件、植物生长和微生物结构发生了不同的变化。总之,这项研究强调了红树林物种在改变气候变暖和氮输入对土壤一氧化二氮排放的影响方面所起的作用,在准确预测红树林的一氧化二氮排放时应考虑到这一点。此外,考虑到背景沉积物的 N2O 排放量较低以及红树林普遍存在的 N 限制,我们的研究结果表明,气候变暖和外源 N 输入可能会导致红树林的 N2O 排放量激增,尤其是那些受到人类活动严重影响的红树林。
{"title":"The effects of climate warming and exogenous nitrogen input on soil N2O emissions from mangroves","authors":"Weimin Song , Yan Zhao , Jian Zhou , Jianxiang Feng , Zhonglei Wang , Guangxuan Han , Elise Pendall , Guanghui Lin","doi":"10.1016/j.soilbio.2024.109607","DOIUrl":"10.1016/j.soilbio.2024.109607","url":null,"abstract":"<div><div>The paucity of studies on nitrous oxide (N<sub>2</sub>O) dynamics with rising temperatures and nitrogen (N)-based eutrophication makes it challenging to evaluate the role of mangroves in mitigating climate change. Here, a 3-year mesocosm experiment was conducted to investigate the effects of climate warming (+3 °C) and excessive N input (25 mg N L<sup>−1</sup>) on soil N<sub>2</sub>O emissions from two mangroves (<em>Avicennia marina</em> and <em>Bruguiera gymnorrhiza</em>). We found that warming and N input alone significantly increased soil N<sub>2</sub>O emissions from both mangroves, while the interactive effects of warming and N input on soil N<sub>2</sub>O emissions were affected by mangrove species. Warming mitigated the positive effect of N input on soil N<sub>2</sub>O emissions from <em>A</em>. <em>marina</em>; and amplified the effect of N input on soil N<sub>2</sub>O emissions from <em>B. gymnorrhiza</em>, suggesting that the response of soil N<sub>2</sub>O emissions to these global change factors is species-dependent. Stable isotopic signature analysis revealed that both warming and N input significantly increased the relative contribution of nitrification to N<sub>2</sub>O emissions from <em>A</em>. <em>marina</em>; whereas N input, rather than warming, significantly changed the relative contribution of nitrification in <em>B. gymnorrhiza</em>. This could be attributed to the differential changes in soil environmental conditions, plant growth and the microbial structure of the two mangroves. Overall, this study highlights the role of mangrove species in modifying the effects of warming and N input on soil N<sub>2</sub>O emissions, which should be considered when accurately projecting N<sub>2</sub>O emissions from mangroves. Furthermore, considering the low N<sub>2</sub>O emissions from background sediments and the common N limitation across mangroves, our findings suggest that climate warming and exogenous N input may lead to a surge of N<sub>2</sub>O emissions from mangroves, especially those that are seriously affected by human activities.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109607"},"PeriodicalIF":9.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369589","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 : 2024-09-30DOI: 10.1016/j.soilbio.2024.109612
Shengxian Chen , Junjie Guo , Ruijia Guo , Baiqing Huang , Jian Huang , Min Wang , Qirong Shen , Ning Ling , Shiwei Guo
The soil priming effect, which refers to the alteration of soil organic matter (SOM) decomposition due to labile carbon (C) inputs, is widely acknowledged for its impact on C storage in terrestrial ecosystems. However, the impact of chronic nitrogen (N) fertilizer on soil priming effect, particularly in agroecological systems, remains unclear. Here, we utilized soils subjected to varying levels of N fertilization (0, 140, 280, 470, and 660 kg N ha−1 y−1), which were collected from a long-term experimental site. Enzyme activity related to C, N, and phosphorus (P) acquisition was measured using the fluorometric method. Additionally, DNA-based stable isotope probing with 13C-labeled glucose was conducted to explore the role of active bacterial communities (16S rRNA gene analysis) on the priming effect in soils with different N fertilization histories. Glucose addition enhanced the decomposition of native SOM and induced positive priming effects in all soils, which were amplified by the historical N application level. Activity of C-related enzymes essential for soil C decomposition increased following glucose addition, which was positively correlated with the soil priming effect. Active bacterial taxa, primarily Firmicutes, Actinobacteria, and Proteobacteria, were capable of assimilating exogenous glucose-C or native SOM-C. Notably, bacteria assimilating glucose exhibited higher abundance-weighted average ribosomal RNA gene operon copy number than those assimilating SOM, indicating the role of r-strategists in accelerating SOC turnover and increasing C loss. These findings highlight the role of active microbial community attributes on the soil priming effects. This study provides new insights into the intricate processes of C transformation in soils subjected to long-term N management in agroecosystems.
土壤诱导效应是指由于可变碳(C)的输入而改变土壤有机质(SOM)的分解,它对陆地生态系统中 C 储存的影响已得到广泛认可。然而,长期施用氮肥对土壤初始效应的影响,尤其是在农业生态系统中的影响,仍不清楚。在这里,我们利用了从一个长期实验地采集的不同施氮水平(0、140、280、470 和 660 kg N ha-1 y-1)的土壤。采用荧光测定法测量了与碳、氮和磷(P)获取相关的酶活性。此外,还用 13C 标记的葡萄糖进行了基于 DNA 的稳定同位素探测,以探索活跃细菌群落(16S rRNA 基因分析)在不同氮肥施用历史的土壤中对引诱效应的作用。在所有土壤中,葡萄糖的添加都促进了原生 SOM 的分解,并诱导了积极的引诱效应,这种效应随着历史氮肥施用水平的提高而扩大。添加葡萄糖后,土壤中 C 分解所必需的 C 相关酶的活性增加,这与土壤的启动效应呈正相关。活跃的细菌类群(主要是固氮菌、放线菌和变形菌)能够同化外源葡萄糖-C 或本地 SOM-C。值得注意的是,与同化 SOM 的细菌相比,同化葡萄糖的细菌表现出更高的丰度加权平均核糖体 RNA 基因操作子拷贝数,这表明 r-strategists 在加速 SOC 转化和增加 C 损失方面的作用。这些发现凸显了活跃的微生物群落属性对土壤引诱效应的作用。这项研究为了解农业生态系统中长期氮管理土壤中复杂的碳转化过程提供了新的视角。
{"title":"Deciphering the active bacteria involving glucose-triggered priming effect in soils with gradient N inputs","authors":"Shengxian Chen , Junjie Guo , Ruijia Guo , Baiqing Huang , Jian Huang , Min Wang , Qirong Shen , Ning Ling , Shiwei Guo","doi":"10.1016/j.soilbio.2024.109612","DOIUrl":"10.1016/j.soilbio.2024.109612","url":null,"abstract":"<div><div>The soil priming effect, which refers to the alteration of soil organic matter (SOM) decomposition due to labile carbon (C) inputs, is widely acknowledged for its impact on C storage in terrestrial ecosystems. However, the impact of chronic nitrogen (N) fertilizer on soil priming effect, particularly in agroecological systems, remains unclear. Here, we utilized soils subjected to varying levels of N fertilization (0, 140, 280, 470, and 660 kg N ha<sup>−1</sup> y<sup>−1</sup>), which were collected from a long-term experimental site. Enzyme activity related to C, N, and phosphorus (P) acquisition was measured using the fluorometric method. Additionally, DNA-based stable isotope probing with <sup>13</sup>C-labeled glucose was conducted to explore the role of active bacterial communities (16S rRNA gene analysis) on the priming effect in soils with different N fertilization histories. Glucose addition enhanced the decomposition of native SOM and induced positive priming effects in all soils, which were amplified by the historical N application level. Activity of C-related enzymes essential for soil C decomposition increased following glucose addition, which was positively correlated with the soil priming effect. Active bacterial taxa, primarily <em>Firmicutes</em>, <em>Actinobacteria</em>, and <em>Proteobacteria</em>, were capable of assimilating exogenous glucose-C or native SOM-C. Notably, bacteria assimilating glucose exhibited higher abundance-weighted average ribosomal RNA gene operon copy number than those assimilating SOM, indicating the role of r-strategists in accelerating SOC turnover and increasing C loss. These findings highlight the role of active microbial community attributes on the soil priming effects. This study provides new insights into the intricate processes of C transformation in soils subjected to long-term N management in agroecosystems.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109612"},"PeriodicalIF":9.8,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369587","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 : 2024-09-28DOI: 10.1016/j.soilbio.2024.109605
Kurt O. Reinhart , Lance T. Vermeire , Chad J. Penn , Ylva Lekberg
Calcareous dryland soils are rich in precipitated phosphate and represent >30% of Earth's land, yet the relative importance of phosphorus-acquisition strategies (PAS) among plant species in these systems is not well known. No experiment has investigated potential interactions between varying amounts of added calcium carbonate (CaCO3) and arbuscular mycorrhizal fungi (AMF) on plant performance and PAS which could test for potential mechanisms without the limitations of in-situ comparisons along natural gradients. To fill this knowledge gap, we conducted an experiment with CaCO3 addition, AMF inoculation, and three invasive and five native grassland plants. We expected an increase in soil [CaCO3] of an alkaline subsoil to 1) reduce soil-available phosphorus (P), 2) reduce plant biomass and P uptake, and 3) shift PAS toward increased root mining as Ca-bound P increases. The largest CaCO3 addition reduced available P by as much as 57%. On average, the largest addition of CaCO3 reduced total biomass of plants by 19% and plant uptake of P by 15%. The PAS seemed to have changed, and CaCO3 additions tended to increase an indicator of root exudation (shoot [Mn]) to mobilize Ca-bound P, suggesting plasticity for some inducible root mining, especially Artemisia frigida and Poa secunda. However, CaCO3 and plant species interacted to affect shoot [Mn]. The invasive grass Bromus tectorum was superior at acquiring P (> P uptake, > shoot [Mn]) and thus tolerating low soluble P conditions. Rarely did AMF and CaCO3 interact to affect plant biomass. When they did, mycorrhizal responsiveness did not increase where P was less available, suggesting AMF become less beneficial upon P and Ca coprecipitation. In dryland soils with less soluble P, plants are thus likely to rely more on root mining PAS than mycorrhizal scavenging, except for the invasive forb Euphorbia esula that always benefitted from AMF inoculation.
钙质旱地土壤含有丰富的沉淀磷酸盐,占地球陆地面积的 30%,但这些系统中植物物种的磷获取策略(PAS)的相对重要性却鲜为人知。目前还没有任何实验研究过不同添加量的碳酸钙(CaCO3)和丛枝菌根真菌(AMF)对植物表现和磷获取策略的潜在相互作用。为了填补这一知识空白,我们进行了一项实验,加入 CaCO3、接种 AMF 以及 3 种入侵植物和 5 种本地草地植物。我们预计,碱性底土中土壤[CaCO3]的增加会:1)减少土壤中可利用的磷(P);2)减少植物的生物量和 P 吸收量;3)随着 Ca 结合的 P 的增加,PAS 向增加根系挖掘的方向转变。CaCO3 的最大添加量使可用磷减少了 57%。平均而言,CaCO3 的最大添加量使植物的总生物量减少了 19%,植物对 P 的吸收量减少了 15%。PAS 似乎发生了变化,CaCO3 的添加往往会增加根系渗出的指标(芽[Mn]),以调动与 Ca 结合的钾,这表明一些诱导性根系开采具有可塑性,特别是蒿属植物和 Poa secunda。然而,CaCO3 和植物物种相互作用影响嫩枝[Mn]。入侵性禾本科植物 Bromus tectorum 在获取钾(钾吸收,嫩枝[Mn])方面更胜一筹,因此可以耐受低可溶性钾条件。AMF 和 CaCO3 很少相互作用影响植物的生物量。当它们发生作用时,菌根的反应能力并没有在可获得的钾较少的地方增加,这表明在钾和钙共沉淀时,AMF 的益处较少。因此,在可溶性钙较少的旱地土壤中,植物可能会更多地依赖于根采矿PAS,而不是菌根的清除作用。
{"title":"Experimental evidence that poor soil phosphorus (P) solubility typical of drylands due to calcium co-precipitation favors autonomous plant P acquisition over collaboration with mycorrhizal fungi","authors":"Kurt O. Reinhart , Lance T. Vermeire , Chad J. Penn , Ylva Lekberg","doi":"10.1016/j.soilbio.2024.109605","DOIUrl":"10.1016/j.soilbio.2024.109605","url":null,"abstract":"<div><div>Calcareous dryland soils are rich in precipitated phosphate and represent >30% of Earth's land, yet the relative importance of phosphorus-acquisition strategies (P<sub>AS</sub>) among plant species in these systems is not well known. No experiment has investigated potential interactions between varying amounts of added calcium carbonate (CaCO<sub>3</sub>) and arbuscular mycorrhizal fungi (AMF) on plant performance and P<sub>AS</sub> which could test for potential mechanisms without the limitations of <em>in-situ</em> comparisons along natural gradients. To fill this knowledge gap, we conducted an experiment with CaCO<sub>3</sub> addition, AMF inoculation, and three invasive and five native grassland plants. We expected an increase in soil [CaCO<sub>3</sub>] of an alkaline subsoil to 1) reduce soil-available phosphorus (P), 2) reduce plant biomass and P uptake, and 3) shift P<sub>AS</sub> toward increased root mining as Ca-bound P increases. The largest CaCO<sub>3</sub> addition reduced available P by as much as 57%. On average, the largest addition of CaCO<sub>3</sub> reduced total biomass of plants by 19% and plant uptake of P by 15%. The P<sub>AS</sub> seemed to have changed, and CaCO<sub>3</sub> additions tended to increase an indicator of root exudation (shoot [Mn]) to mobilize Ca-bound P, suggesting plasticity for some inducible root mining, especially <em>Artemisia frigida</em> and <em>Poa secunda</em>. However, CaCO<sub>3</sub> and plant species interacted to affect shoot [Mn]. The invasive grass <em>Bromus tectorum</em> was superior at acquiring P (> P uptake, > shoot [Mn]) and thus tolerating low soluble P conditions. Rarely did AMF and CaCO<sub>3</sub> interact to affect plant biomass. When they did, mycorrhizal responsiveness did not increase where P was less available, suggesting AMF become less beneficial upon P and Ca coprecipitation. In dryland soils with less soluble P, plants are thus likely to rely more on root mining P<sub>AS</sub> than mycorrhizal scavenging, except for the invasive forb <em>Euphorbia esula</em> that always benefitted from AMF inoculation.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109605"},"PeriodicalIF":9.8,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369590","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 : 2024-09-28DOI: 10.1016/j.soilbio.2024.109609
Elizabeth Gachibu Wangari , Ricky Mwangada Mwanake , Tobias Houska , David Kraus , Hanna-Marie Kikowatz , Benjamin Wolf , Gretchen M. Gettel , Lutz Breuer , Per Ambus , Ralf Kiese , Klaus Butterbach-Bahl
The natural abundance of plant and bulk soil 15N isotopic signatures provides valuable insights into the magnitude of nitrogen cycling and loss processes within terrestrial ecosystems. However, 15N isotopic signatures are highly variable in space due to natural and anthropogenic factors affecting N cycling processes and losses. To date, most studies on foliar and bulk soil 15N isotopic signatures have focused on N-limited forest ecosystems at relatively large spatial scales, while similar studies in N-enriched ecosystems at finer spatial scales are lacking. To address this gap and evaluate links between soil 15N isotopic signatures and ecosystem N cycling and loss processes (plant N uptake, N leaching, and gaseous loss), this study quantified foliar and bulk soil 15N isotopic signatures, soil physicochemical parameters, gaseous (N2O), and hydrological (NO3) N losses at 80 sites distributed across a heterogeneous landscape (∼5.8 km2). To account for the spatial-temporal heterogeneity, the measurements were performed in four campaigns (March, June, September 2022, and March 2023) at sites that considered different land uses, soil types, and topography. Results indicated that foliar and bulk soil 15N isotopic signatures were significantly (P < 0.05) more enriched in arable and grassland ecosystems than forests, suggesting a more open N cycle with significant N cycling and losses due to higher N inputs from fertilizers. Similar to soil inorganic N, N2O fluxes, and NO3 leaching rates, landscape-scale foliar and soil 15N isotopic signatures varied widely spatially, particularly at grassland and arable land (−3 to 9.0‰), with bivariate and multivariate analyses also showing significant relationships between landscape-scale soil 15N isotopic signatures and the aforementioned parameters (r2: 0.29 to 0.82). Based on these relationships, our findings suggested that foliar and bulk 15N isotopic signatures may capture fine-scale areas with persistently high and low environmental N losses (N2O fluxes and NO3 leaching) within a heterogeneous landscape.
{"title":"Spatial-temporal patterns of foliar and bulk soil 15N isotopic signatures across a heterogeneous landscape: Linkages to soil N status, nitrate leaching, and N2O fluxes","authors":"Elizabeth Gachibu Wangari , Ricky Mwangada Mwanake , Tobias Houska , David Kraus , Hanna-Marie Kikowatz , Benjamin Wolf , Gretchen M. Gettel , Lutz Breuer , Per Ambus , Ralf Kiese , Klaus Butterbach-Bahl","doi":"10.1016/j.soilbio.2024.109609","DOIUrl":"10.1016/j.soilbio.2024.109609","url":null,"abstract":"<div><div>The natural abundance of plant and bulk soil <sup>15</sup>N isotopic signatures provides valuable insights into the magnitude of nitrogen cycling and loss processes within terrestrial ecosystems. However, <sup>15</sup>N isotopic signatures are highly variable in space due to natural and anthropogenic factors affecting N cycling processes and losses. To date, most studies on foliar and bulk soil <sup>15</sup>N isotopic signatures have focused on N-limited forest ecosystems at relatively large spatial scales, while similar studies in N-enriched ecosystems at finer spatial scales are lacking. To address this gap and evaluate links between soil <sup>15</sup>N isotopic signatures and ecosystem N cycling and loss processes (plant N uptake, N leaching, and gaseous loss), this study quantified foliar and bulk soil <sup>15</sup>N isotopic signatures, soil physicochemical parameters, gaseous (N<sub>2</sub>O), and hydrological (NO<sub>3</sub>) N losses at 80 sites distributed across a heterogeneous landscape (∼5.8 km<sup>2</sup>). To account for the spatial-temporal heterogeneity, the measurements were performed in four campaigns (March, June, September 2022, and March 2023) at sites that considered different land uses, soil types, and topography. Results indicated that foliar and bulk soil <sup>15</sup>N isotopic signatures were significantly (P < 0.05) more enriched in arable and grassland ecosystems than forests, suggesting a more open N cycle with significant N cycling and losses due to higher N inputs from fertilizers. Similar to soil inorganic N, N<sub>2</sub>O fluxes, and NO<sub>3</sub> leaching rates, landscape-scale foliar and soil <sup>15</sup>N isotopic signatures varied widely spatially, particularly at grassland and arable land (−3 to 9.0‰), with bivariate and multivariate analyses also showing significant relationships between landscape-scale soil <sup>15</sup>N isotopic signatures and the aforementioned parameters (r<sup>2</sup>: 0.29 to 0.82). Based on these relationships, our findings suggested that foliar and bulk <sup>15</sup>N isotopic signatures may capture fine-scale areas with persistently high and low environmental N losses (N<sub>2</sub>O fluxes and NO<sub>3</sub> leaching) within a heterogeneous landscape.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109609"},"PeriodicalIF":9.8,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369626","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}
Earthworms are pivotal in shaping soil ecological processes through their bioturbation activity and organic matter consumption. Earthworm species are known to have different impacts on soil structure, but only a small number of species have been studied so far, and few studies have examined how earthworms simultaneously affect soil functions. Here, we measured the impact of different earthworm species on soil structure (bioturbation function), carbon (C) and nitrogen (N) dynamics and the microbial community (organic matter transformation function), while exploring the links between these functions, across distinct soil compartments (surface casts, below-ground drilosphere, and bulk soil). Six earthworm species (Lumbricus terrestris, Allolobophora chlorotica, Octolasion cyaneum, Octodrilus complanatus, Aporrectodea caliginosa meridionalis and Microscolex dubius) of different ecological categories and functional groups were incubated in soil cores with soil and alfalfa litter for 6 weeks. Our results on the bioturbation function illustrated a great diversity of behaviors and confirmed the relevance of a functional classification based on bioturbation metrics. The main microbial hotspots were surface casts, whose characteristics allowed to distinguish two groups of species. Octod. complanatus, L. terrestris and M. dubius induced high humidity (respectively, +57, +48, +74%), high C (respectively, 19.9, 24.8, 33.2 g kg⁻1 dry soil) and N (respectively, 2, 2.3, 3.2 g kg⁻1 dry soil) content and microbial community selection, promoting C and N mineralization. The three other species had a lower impact. The below-ground drilosphere only showed specific characteristics in the case of L. terrestris. The effects of the studied species on the organic matter transformation function did not align with their bioturbation activities nor with their ecological category. These findings show that the contribution of earthworms to C and N turnover is only partially dependent on their bioturbation effects and suggest the usefulness of developing distinct functional groups based on the specific soil functions under consideration.
蚯蚓通过其生物扰动活动和有机物消耗在塑造土壤生态过程中起着关键作用。众所周知,蚯蚓物种对土壤结构有不同的影响,但迄今为止只研究了少数物种,很少有研究探讨蚯蚓如何同时影响土壤功能。在这里,我们测量了不同蚯蚓物种对土壤结构(生物扰动功能)、碳(C)和氮(N)动态以及微生物群落(有机物转化功能)的影响,同时探索了这些功能在不同土壤区系(表层蚯蚓、地下蚯蚓圈和块状土壤)之间的联系。我们将不同生态类别和功能群的六种蚯蚓(Lumbricus terrestris、Allolobophora chlorotica、Octolasion cyaneum、Octodrilus complanatus、Aporrectodea caliginosa meridionalis 和 Microscolex dubius)与土壤和苜蓿废弃物一起放入土芯中培养 6 周。我们对生物扰动功能的研究结果表明了行为的多样性,并证实了基于生物扰动指标的功能分类的相关性。主要的微生物热点是地表菌落,其特征可以区分出两组物种。Octod. complanatus、L. terrestris 和 M. dubius 引发了高湿度(分别为 +57%、+48% 和 +74%)、高 C(分别为 19.9、24.8 和 33.2 g kg-1 干土)和 N(分别为 2、2.3 和 3.2 g kg-1 干土)含量和微生物群落选择,促进了 C 和 N 的矿化。其他三个物种的影响较小。只有 L. terrestris 的地下钻孔层表现出特殊的特征。研究物种对有机物转化功能的影响与其生物扰动活动和生态类别并不一致。这些研究结果表明,蚯蚓对碳和氮转化的贡献仅部分取决于它们的生物扰动作用,并表明根据所考虑的特定土壤功能建立不同的功能组是有用的。
{"title":"The effects of earthworm species on organic matter transformations and soil microbial communities are only partially related to their bioturbation activity","authors":"Luna Vion-Guibert , Yvan Capowiez , Gonzague Alavoine , Ludovic Besaury , Olivier Delfosse , Mickaël Hedde , Claire Marsden , Gwenaëlle Lashermes","doi":"10.1016/j.soilbio.2024.109606","DOIUrl":"10.1016/j.soilbio.2024.109606","url":null,"abstract":"<div><div>Earthworms are pivotal in shaping soil ecological processes through their bioturbation activity and organic matter consumption. Earthworm species are known to have different impacts on soil structure, but only a small number of species have been studied so far, and few studies have examined how earthworms simultaneously affect soil functions. Here, we measured the impact of different earthworm species on soil structure (bioturbation function), carbon (C) and nitrogen (N) dynamics and the microbial community (organic matter transformation function), while exploring the links between these functions, across distinct soil compartments (surface casts, below-ground drilosphere, and bulk soil). Six earthworm species <em>(Lumbricus terrestris</em>, <em>Allolobophora chlorotica</em>, <em>Octolasion cyaneum, Octodrilus complanatus</em>, <em>Aporrectodea caliginosa meridionalis</em> and <em>Microscolex dubius</em>) of different ecological categories and functional groups were incubated in soil cores with soil and alfalfa litter for 6 weeks. Our results on the bioturbation function illustrated a great diversity of behaviors and confirmed the relevance of a functional classification based on bioturbation metrics. The main microbial hotspots were surface casts, whose characteristics allowed to distinguish two groups of species. <em>Octod. complanatus, L. terrestris</em> and <em>M. dubius</em> induced high humidity (respectively, +57, +48, +74%), high C (respectively, 19.9, 24.8, 33.2 g kg⁻<sup>1</sup> dry soil) and N (respectively, 2, 2.3, 3.2 g kg⁻<sup>1</sup> dry soil) content and microbial community selection, promoting C and N mineralization. The three other species had a lower impact. The below-ground drilosphere only showed specific characteristics in the case of <em>L. terrestris</em>. The effects of the studied species on the organic matter transformation function did not align with their bioturbation activities nor with their ecological category. These findings show that the contribution of earthworms to C and N turnover is only partially dependent on their bioturbation effects and suggest the usefulness of developing distinct functional groups based on the specific soil functions under consideration.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109606"},"PeriodicalIF":9.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369627","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 : 2024-09-26DOI: 10.1016/j.soilbio.2024.109603
George D. Mercer , Bede S. Mickan , Deirdre B. Gleeson , Megan H. Ryan
Soil carbon supports desirable ecosystem functions for global agricultural productivity and climate resilience objectives. Wastewater biosolids can be transformed into soil amendments that return carbon and nutrients to agricultural systems in stoichiometric ratios that support carbon stabilisation. However, practicable delivery that enhances stable soil carbon and plant yield remains challenging. Soil carbon stability and nutrient availability are mediated partly by microbial community composition and function, which are poorly understood in soils amended with transformed biosolids. We conducted a 56-day study in a temperature-controlled glasshouse, growing perennial ryegrass (Lolium perenne) in pasture soil amended with straw, straw supplemented with nutrients, or transformed biosolids (composted biosolids, dried biosolids or biosolids biochar), all with equal added carbon (3500 kg ha−1). Control soils, with and without supplementary nutrients, were also included. Plant dry mass, soil chemical characteristics, and soil carbon fractions were measured at harvest. 16S rRNA sequencing was used to infer the composition and putative function of rhizosphere bacterial communities. Shoot dry mass increased for composted biosolids (236%) and dried biosolids (559%), but total carbon in rhizosphere soil decreased for composted biosolids (16.3%), dried biosolids (13.3%) and biosolids biochar (12.7%) when compared to unamended soils. Fine-fraction carbon in rhizosphere soil decreased for straw with supplementary nutrients (6.8%), dried biosolids (6.3%) and biosolids biochar (4.6%). Rhizosphere bacterial communities clustered by treatment, with populations correlated with fine-fraction carbon distinct from those populations correlated with shoot and root dry mass. Path analysis linked fine-fraction carbon loss with increased putative carbon cycling genes, driven by available nutrients and plant growth. Transformed biosolids can trigger a microbial response that reallocates nutrients from organic matter to plants, disrupting soil carbon-nutrient stoichiometry and facilitating carbon loss. Understanding the carbon cost of this ecosystem service is fundamental when translating benefits of transformed biosolids to end users.
{"title":"Transformed biosolids promote ryegrass growth and microbial carbon cycling at the ‘cost’ of soil carbon","authors":"George D. Mercer , Bede S. Mickan , Deirdre B. Gleeson , Megan H. Ryan","doi":"10.1016/j.soilbio.2024.109603","DOIUrl":"10.1016/j.soilbio.2024.109603","url":null,"abstract":"<div><div>Soil carbon supports desirable ecosystem functions for global agricultural productivity and climate resilience objectives. Wastewater biosolids can be transformed into soil amendments that return carbon and nutrients to agricultural systems in stoichiometric ratios that support carbon stabilisation. However, practicable delivery that enhances stable soil carbon and plant yield remains challenging. Soil carbon stability and nutrient availability are mediated partly by microbial community composition and function, which are poorly understood in soils amended with transformed biosolids. We conducted a 56-day study in a temperature-controlled glasshouse, growing perennial ryegrass (<em>Lolium perenne</em>) in pasture soil amended with straw, straw supplemented with nutrients, or transformed biosolids (composted biosolids, dried biosolids or biosolids biochar), all with equal added carbon (3500 kg ha<sup>−1</sup>). Control soils, with and without supplementary nutrients, were also included. Plant dry mass, soil chemical characteristics, and soil carbon fractions were measured at harvest. 16S rRNA sequencing was used to infer the composition and putative function of rhizosphere bacterial communities. Shoot dry mass increased for composted biosolids (236%) and dried biosolids (559%), but total carbon in rhizosphere soil decreased for composted biosolids (16.3%), dried biosolids (13.3%) and biosolids biochar (12.7%) when compared to unamended soils. Fine-fraction carbon in rhizosphere soil decreased for straw with supplementary nutrients (6.8%), dried biosolids (6.3%) and biosolids biochar (4.6%). Rhizosphere bacterial communities clustered by treatment, with populations correlated with fine-fraction carbon distinct from those populations correlated with shoot and root dry mass. Path analysis linked fine-fraction carbon loss with increased putative carbon cycling genes, driven by available nutrients and plant growth. Transformed biosolids can trigger a microbial response that reallocates nutrients from organic matter to plants, disrupting soil carbon-nutrient stoichiometry and facilitating carbon loss. Understanding the carbon cost of this ecosystem service is fundamental when translating benefits of transformed biosolids to end users.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"199 ","pages":"Article 109603"},"PeriodicalIF":9.8,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142417622","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}