Soil Biology & Biochemistry最新文献_第9页

The divergent role of straw return in soil O2 dynamics elucidates its confounding effect on soil N2O emission 秸秆还田在土壤氧气动力学中的不同作用阐明了其对土壤一氧化二氮排放的混杂效应

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-09 DOI: 10.1016/j.soilbio.2024.109620

Huanhuan Wei , Yue Li , Kun Zhu , Xiaotang Ju , Di Wu

The divergent effects of straw returns on nitrous oxide (N₂O) emissions from soil require elucidation of the underlying mechanisms and factors that explain the inconsistency in in-situ conditions. We conducted a field experiment based on a long-term trial under different regimes of nitrogen (N) fertilization and straw management, complemented by laboratory incubation experiments involving visualized O₂ dynamics imaging. In the field trial, we performed hourly basis high-time-resolution measurements of soil matrix oxygen (O₂), N₂O concentrations and fluxes during N₂O “hot moment” events. We found that straw return increased cumulative N₂O emissions by 32.7% under conventional high N input (N_con), but showed no effect on N₂O emission under optimized N input (N_opt). In situ O₂ content and further microcosm experiments with visualized O₂ spatiotemporal distribution suggested that long-term straw return increases porosity and soil O₂ content, which reduced N₂O emission under low N substrate conditions by improving soil pore structure and aeration during “hot moment” events. By contrast, straw return increased N₂O emission via creating short-term O₂ depletion zone and triggering denitrification in anoxic microsites when excess N substrate was available. Although straw return showed inconsistent effects on N₂O emission under different N application rates, it consistently decreased N₂O concentration in the soil matrix during the "hot moment" events, suggesting that straw return increases the transport of the produced N₂O in soil matrix to the soil surface. Our study underscores the multifaceted role of straw return in soil O₂ dynamics, i.e., stimulating O₂ consumption in a short-term microscale of soil, but increasing soil porosity in a long-term mesoscale of soil. This explains the confounding effects of straw management on the production and transportation of soil N₂O in situ and emphasizes the importance of optimized N fertilization for reducing the “hot moment” N₂O emissions when straw is incorporated.

秸秆还田对土壤中氧化亚氮（N2O）排放的不同影响需要阐明解释原位条件不一致的内在机制和因素。我们在氮肥施用和秸秆管理不同制度下的长期试验基础上进行了一项田间试验，并辅以可视化氧气动态成像的实验室培养试验。在田间试验中，我们对土壤基质氧气（O2）、一氧化二氮浓度以及一氧化二氮 "热点 "事件期间的通量进行了每小时一次的高时间分辨率测量。我们发现，在传统的高氮输入（Ncon）条件下，秸秆还田增加了 32.7% 的一氧化二氮累积排放量，但在优化氮输入（Nopt）条件下，秸秆还田对一氧化二氮排放量没有影响。原位 O2 含量和可视化 O2 时空分布的进一步小宇宙实验表明，长期秸秆还田增加了孔隙度和土壤中的 O2 含量，通过改善土壤孔隙结构和 "热时刻 "的通气性，减少了低氮基质条件下的 N2O 排放。与此相反，秸秆还田则会在氮基质过剩时，通过建立短期氧气耗竭区和引发缺氧微地的反硝化作用来增加一氧化二氮的排放。虽然秸秆还田在不同的氮施用率下对一氧化二氮排放的影响不一致，但在 "热时刻 "事件中，秸秆还田持续降低了土壤基质中的一氧化二氮浓度，这表明秸秆还田增加了土壤基质中产生的一氧化二氮向土壤表面的迁移。我们的研究强调了秸秆还田在土壤氧气动力学中的多方面作用，即在短期土壤微观尺度上刺激氧气消耗，但在长期土壤中观尺度上增加土壤孔隙度。这就解释了秸秆管理对土壤 N2O 在原位产生和运输的混杂效应，并强调了优化氮肥施用对减少秸秆还田时 "热时刻 "的 N2O 排放的重要性。

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引用次数: 0

Plant organ rather than cover crop species determines residue incorporation into SOC pools 决定残留物融入 SOC 池的是植物器官而非覆盖作物种类

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-05 DOI: 10.1016/j.soilbio.2024.109616

Tine Engedal , Veronika Hansen , Jim Rasmussen , Jakob Magid , Carsten W. Mueller , Sune Tjalfe Thomsen , Helle Sørensen , Lars Stoumann Jensen

The implementation of cover crops has emerged as a promising approach to improve soil organic carbon (SOC) stocks, with particular emphasis on the perceived higher carbon use efficiency displayed by high-quality residues such as from leguminous plants. In this study, we explored how different cover crop residues, specifically from a legume and a grass cover crop, affects SOC formation and its distribution across various soil carbon pools. Over a 7-month period, we incubated ¹⁴C-labeled winter rye and hairy vetch residues in microcosms containing soils of varying soil fertility levels from a long-term field trial. We tracked the fate of carbon into free and occluded particulate organic matter (fPOM, oPOM), mineral-associated organic matter (MAOM), and carbon deposited outside the detritusphere.

Despite notable differences in C:N ratio, chemical composition, and turnover rate, similar SOC formation efficiency between vetch and rye within each plant organ (shoots and roots) was observed. Interestingly, the plant organ appeared to exert a greater influence on the fate of cover crop carbon than whether the crop was leguminous or non-leguminous. This phenomenon seemed to be closely related to the lignin content.

At medium soil fertility, we found that the largest proportion of cover crop residue C remained as MAOM (20% for shoots, 15–18% for roots), followed by fPOM (5–6% for shoots, 10–12% for roots) and oPOM (2.7–3.0% for shoots, 1.5–1.6% for roots). Notably, fPOM and oPOM exhibited opposite responses to residue quality, indicating functional distinctions between these often-pooled POM pools.

Soil fertility exerted minimal influence on overall respiration rate patterns or SOC formation, although it did affect oPOM formation efficiency, likely due to differences in soil aggregation.

In conclusion, our findings challenge the assumption regarding the superiority of N rich leguminous cover crop residues for enhancing SOC accrual in C pools believed to have longer persistence.

种植覆盖作物已成为提高土壤有机碳（SOC）储量的一种很有前景的方法，尤其是豆科植物等优质残留物被认为具有更高的碳利用效率。在这项研究中，我们探讨了不同的覆盖作物残留物，特别是豆科和禾本科覆盖作物的残留物，如何影响 SOC 的形成及其在各种土壤碳库中的分布。在为期 7 个月的时间里，我们将 14C 标记的冬黑麦和毛茸茸的薇菜残留物放入含有来自长期田间试验的不同土壤肥力水平的土壤的微生态系统中进行培养。尽管在碳氮比、化学成分和周转率方面存在显著差异，但在每个植物器官（芽和根）内，我们观察到野豌豆和黑麦的 SOC 形成效率相似。有趣的是，植物器官似乎比豆科或非豆科作物对覆盖作物碳的去向影响更大。在中等肥力的土壤中，我们发现覆盖作物残留碳的最大比例是 MAOM（芽为 20%，根为 15-18%），其次是 fPOM（芽为 5-6%，根为 10-12%）和 oPOM（芽为 2.7-3.0%，根为 1.5-1.6%）。值得注意的是，fPOM 和 oPOM 对残留物质量的反应截然相反，这表明这些经常汇集在一起的 POM 池之间存在着功能差异。

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引用次数: 0

Rhizosphere priming and effects on mobilization and immobilization of multiple soil nutrients 根瘤菌引导及其对多种土壤养分动员和固定的影响

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-04 DOI: 10.1016/j.soilbio.2024.109615

Jiayu Lu , Jiangping Cai , Feike A. Dijkstra , Liming Yin , Peng Wang , Weixin Cheng

Living roots and their rhizodeposition play a vital role in mediating soil organic carbon (SOC) decomposition and nutrient mobilization. It is virtually unknown how the rhizosphere effects on soil nutrient mobilization are connected with the rhizosphere priming on SOC decomposition. Here we investigated the rhizosphere effects of six grassland species (four grasses and two legumes) on soil nutrient mobilization and SOC decomposition with and without nitrogen (N) fertilization in a 95-day pot experiment. Plant nutrient acquisition, soil extractable nutrients, and net nutrient mobilization or immobilization were determined to evaluate the rhizosphere effect on soil nutrient dynamics. Primed SOC decomposition was measured as the difference in soil-derived CO₂–C between planted and unplanted treatments. Without N fertilization, all species consistently increased net phosphorus (P), sodium (Na), iron (Fe), and copper (Cu) mobilization and most species increased net N, sulfur (S), calcium (Ca), and zinc (Zn) mobilization and net potassium (K), magnesium (Mg), and manganese (Mn) immobilization compared to the unplanted soil. These results suggest that grassland species could induce both positive and negative rhizosphere effects on soil nutrient mobilization with different magnitude. With N fertilization, plant-induced net N mobilization increased, while plant-induced net P and S mobilization decreased. Further, plant biomass, plant N, P, and S acquisition, and plant-induced net N, P, and S mobilization (i.e., net nutrient mobilization in excess of the unplanted control), were positively correlated with primed SOC decomposition across six species, indicating that the mobilization of organically bound nutrients (N, P, and S) was connected with the rhizosphere priming on SOC decomposition. In contrast, plant-induced net nutrient mobilization of base cations and micronutrients was not related to primed SOC decomposition. Overall, our results demonstrate that a substantial portion of nutrient availability stems from rhizosphere processes and is plant species-specific, and that nutrient release of N, P and S are closely connected with rhizosphere priming on SOC decomposition.

活根及其根系沉积在介导土壤有机碳（SOC）分解和养分调动方面发挥着重要作用。根圈对土壤养分调动的影响与根圈对 SOC 分解的启动作用之间有何联系，目前几乎还不清楚。在此，我们在为期 95 天的盆栽实验中研究了六种草地物种（四种禾本科植物和两种豆科植物）在施氮肥和不施氮肥的情况下对土壤养分动员和 SOC 分解的根圈效应。通过测定植物养分获取量、土壤可提取养分以及净养分动员或固定情况，评估根圈对土壤养分动态的影响。以种植处理和未种植处理之间的土壤源 CO2-C 差值来衡量原始 SOC 分解情况。与未种植的土壤相比，在不施用氮肥的情况下，所有物种都持续增加了磷 (P)、钠 (Na)、铁 (Fe) 和铜 (Cu) 的净吸收量，大多数物种增加了氮、硫 (S)、钙 (Ca) 和锌 (Zn) 的净吸收量以及钾 (K)、镁 (Mg) 和锰 (Mn) 的净固定量。这些结果表明，草地物种可对土壤养分调动产生不同程度的正负根圈效应。施氮肥后，植物诱导的净氮动员增加，而植物诱导的净磷和净钾动员减少。此外，在六个物种中，植物生物量、植物氮、磷和硒的获取量以及植物诱导的氮、磷和硒净动员（即超过未种植对照的净养分动员）与SOC的初步分解呈正相关，表明有机结合养分（氮、磷和硒）的动员与根瘤菌层对SOC分解的初步作用有关。相比之下，植物诱导的基阳离子和微量营养元素的净养分动员与SOC的初步分解无关。总之，我们的研究结果表明，养分供应的很大一部分源于根瘤菌过程，并具有植物物种特异性，而且氮、磷和硒的养分释放与根瘤菌对 SOC 分解的促进作用密切相关。

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引用次数: 0

Extrinsic rather than intrinsic factors determine microbial colonization of deadwood 决定枯木微生物定殖的是外在因素而非内在因素

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-02 DOI: 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.

枯木分解主要归因于木材定殖真菌和细菌，主要由内在因素（如树种特性）而非外在因素驱动。最近的一项跨生态系统研究使用伽马射线灭菌的木块，将不同针叶树种和落叶树种的木块分别放置在 150 个森林和 150 个草原地点，结果显示，内在因素对分解率的影响最大。这些结果提出了一个问题：在木材上定居的微生物生物多样性是否遵循类似的组合模式。为此，我们使用代谢编码来分析木块上的真菌和细菌群落。我们发现，与内在因素（树种特征、木材 pH 值、木材质量损失）相比，生态系统类型和小气候（空气湿度、土壤 pH 值、土壤湿度、土壤温度）等外在因素对木材定殖群落的决定作用更大。虽然总体而言，这些结果似乎对真菌更为明显，但在这两个生态系统中，两个群落都由高度特化的木材定殖者组成。例如，真菌属 Mycena 和细菌属 Granulicella 在森林中的检出率更高，而 Exophiala 和 Sphingomonas 在草原中的检出率更高。木材质量损失与真菌多样性减少有更强的相关性，而细菌丰富度与质量损失没有关系，无论是在森林还是草地中都是如此。不过，两种定殖者群落的组成始终与木材质量损失有关。我们的研究系统表明，环境选择了不同的木材定殖群落，这些群落的分解效率差别很大；这一结果突出了跨生态系统分析对评估生态模式的重要性。

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引用次数: 0

Soil nematode community profiling using reference-free mito-metagenomics 利用无参照线粒体基因组学分析土壤线虫群落概况

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-02 DOI: 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.

线虫是全球土壤生态系统中无处不在的多种多样的组成部分。众所周知，基于 18S 的代谢编码的物种级分辨率较低，并且会在 PCR 中产生偏差。线粒体-基因组学（MMG）方法包括直接对集合样本进行测序，产生大量线粒体读数，并可将其组装成完整或部分有丝分裂基因组。这种方法规避了与基于 PCR 的代谢编码相关的挑战，在生物多样性和系统发育研究中大有可为。然而，提取有丝分裂读数/序列片段和提供分类学或系统发育背景通常需要参考数据库，从而限制了其适用性。在这项研究中，我们引入了一种新型的无参考文献管道，用于 MMG 组装和多样性估计。该流程已集成到 snakemake 工作流程中，只需一次运行即可生成可用于系统发育重建的输出结果。性能测试表明，在土壤线虫群落剖析中，这种新方法超越了基于参考的方法。我们证明，随着测序深度的增加，组装质量也会提高，建议每个物种平均使用 1-2 Gb 的数据来实现可接受的 MMG 组装。我们的方法为建立高分辨率的系统进化和评估了解不多的类群（包括被忽视的微小真核生物）的多样性提供了机会。

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引用次数: 0

Very fine roots differ among switchgrass (Panicum virgatum L.) cultivars and differentially affect soil pores and carbon processes 开关草（Panicum virgatum L.）不同栽培品种的细根对土壤孔隙和碳过程有不同影响

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-02 DOI: 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。

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引用次数: 0

Response of wheat to arbuscular mycorrhizal fungi inoculation and biochar application: Implications for soil carbon sequestration 小麦对接种丛枝菌根真菌和施用生物炭的反应：对土壤固碳的影响

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-09-30 DOI: 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.

在土壤中封存大气中的二氧化碳被认为是一种有效的减缓气候变化的策略。生物炭的应用在这方面显示出前景，而真菌在土壤碳循环和固碳中的作用也在研究之中。在全球领先的碳信用计划的指导下，我们利用一种新型的高通量植物表型组学方法，探讨了接种丛枝菌根真菌（AMF）和施用生物碳对小麦生长和土壤碳的影响。小麦成功地被AMF定殖，平均根长定殖率达到35.9%。我们发现了一条由真菌直接介导的土壤固碳途径，在所有土壤处理中，菌根植物都能产生更多的生物量，而不会影响产量，这表明定殖植物向土壤提供了更多的植物碳，可能会带来长期的土壤碳增益。相反，真菌导致碳损失，显著减少了未改良土壤中的土壤碳积累，但生物炭改良土壤中的碳积累却没有减少，这表明生物炭能缓和真菌活动，并对土壤碳平衡产生积极影响。虽然生物炭和 AMF 都能促进植物生长，但它们对土壤碳的直接影响却很复杂。虽然生物炭在增加土壤碳储量方面的作用并不明显，但其调节真菌活动的能力可在影响土壤固碳方面发挥重要作用。

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引用次数: 0

The effects of climate warming and exogenous nitrogen input on soil N2O emissions from mangroves 气候变暖和外源氮输入对红树林土壤一氧化二氮排放的影响

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-09-30 DOI: 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。

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引用次数: 0

Deciphering the active bacteria involving glucose-triggered priming effect in soils with gradient N inputs 解密有氮梯度输入的土壤中涉及葡萄糖触发引物效应的活性细菌

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-09-30 DOI: 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。

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引用次数: 0

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 实验证明，由于钙共沉淀作用，干旱地区典型的土壤磷（P）溶解度低，这有利于植物自主获取磷，而不是与菌根真菌合作获取磷

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-09-28 DOI: 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 (P_AS) 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 P_AS 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 P_AS 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 P_AS 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 P_AS 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。

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引用次数: 0