Soil Biology & Biochemistry最新文献_第4页

Soil food-web energy fluxes reveal diverse responses to smallholder land-use choices in temperate forests 土壤食物网能量通量揭示了温带森林中小农土地使用选择的不同反应

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-15 DOI: 10.1016/j.soilbio.2024.109619

Camila Pérez-Roig , Martín Videla , Verónica El Mujtar , Pablo A. Tittonell , Anton M. Potapov

The consequences of land-use change for soil fauna communities and soil functionality are hard to quantify and poorly understood. Energy fluxes provide a quantitative framework to link soil food webs to ecosystem functions. Here, we examined topsoil fauna in a forest-agriculture matrix in North Patagonia, Argentina, to assess the variation of soil food-web functioning across a gradient of land-use intensity. The sampled plots included reference forests, cattle grazing in forests, sheep grazing in meadows, perennial berry crops and seasonal vegetable crops. In each plot, we extracted soil fauna, measured their body sizes, estimated metabolic rates, and applied the soil food-web energy fluxes approach to assess associated trophic functions. Our findings revealed a greater total faunal biomass and energy flux in most land-use systems compared to native forests, while the number of interactions and the energetic inequality (unevenness in resource consumption) did not show a single pattern. Soil organic matter (SOM) consumption increased in sheep-grazed meadows and seasonal plots, while litter transformation decreased in the latter, and microbivory increased in most land-uses. The ratio between SOM consumption and faeces production, was greater in sheep-grazed meadows and seasonal plots, indicating a lower contribution to C sequestration by soil fauna. Herbivory and predation showed different patterns between seasons, but a reduced top-down herbivore control potential was found under sheep grazing. Overall, native and cattle-grazed forests showed lower energy fluxes but more balanced ecosystem functions. Perennial crops hosted more interactions and a similar potential for carbon storage and herbivore control as forests. In sheep-grazed meadows and seasonal crops, increased soil fauna biomass and energy flux were mainly reflected in higher SOM consumption. Our research shows how smallholder land-use choices result in different, often contrasting, effects on soil food-web structure and related functions, emphasizing the importance of human decisions for soil functional sustainability.

土地利用变化对土壤动物群落和土壤功能造成的后果难以量化，人们对其了解甚少。能量通量为将土壤食物网与生态系统功能联系起来提供了一个定量框架。在这里，我们研究了阿根廷北巴塔哥尼亚森林-农业矩阵中的表土动物群落，以评估土壤食物网功能在土地利用强度梯度上的变化。取样地块包括参照森林、在森林中放牧的牛、在草地上放牧的羊、多年生浆果作物和季节性蔬菜作物。在每块地里，我们提取了土壤中的动物，测量了它们的体型，估算了新陈代谢率，并采用土壤食物网能量通量法评估了相关的营养功能。我们的研究结果表明，与原生林相比，大多数土地利用系统中的动物总生物量和能量通量更大，而相互作用的数量和能量不平等（资源消耗的不均衡性）并没有显示出单一的模式。在羊群放牧的草地和季节性地块中，土壤有机质（SOM）消耗量增加，而在季节性地块中，枯落物转化量减少，在大多数土地利用系统中，微食性增加。在绵羊放牧的草地和季节性地块中，SOM 消耗量与粪便产生量之比更大，这表明土壤动物对固碳的贡献较小。草食动物和捕食动物在不同季节表现出不同的模式，但在羊群放牧的情况下，自上而下的草食动物控制潜力降低。总体而言，原生森林和牛放牧森林的能量通量较低，但生态系统功能更为平衡。多年生作物与森林的相互作用更多，碳储存和食草动物控制潜力也与森林相似。在羊群放牧的草地和季节性作物中，土壤动物群生物量和能量通量的增加主要体现在更高的 SOM 消耗量上。我们的研究表明，小农对土地利用的选择如何对土壤食物网结构和相关功能产生不同的、往往是截然相反的影响，从而强调了人类决策对土壤功能可持续性的重要性。

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引用次数: 0

Perennial crops shape the soil microbial community and increase the soil carbon in the upper soil layer 多年生作物塑造了土壤微生物群落，增加了土壤上层的土壤碳含量

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-13 DOI: 10.1016/j.soilbio.2024.109621

Shoujiao Li , Ana Barreiro , Juan Pablo Almeida , Thomas Prade , Linda-Maria Dimitrova Mårtensson

Soil biodiversity is threatened by intensive agriculture that relies on annual grain crop production, thus leading to a decline in soil functions and ecosystem services. Perennial grain crops have a positive impact on the soil microbial community, but the responsive microbial groups and the magnitude of their response remain uncertain. To elucidate this, we analysed soil microbial biomass and community composition, bacterial growth and soil total carbon in five crops: organic perennial intermediate wheatgrass (IWG, Thinopyrum intermedium, Kernza®), organic IWG-alfalfa intercrop, organic biennial grass-legume mixture, organic annual wheat or rye and conventional annual wheat. The analysis was carried out at three time points under two growing seasons at four different soil depths. Five years after establishment, IWG had greater amounts of soil total fungi and bacteria, and of arbuscular mycorrhizal (AM) fungi, saprotrophic fungi, gram-negative (G⁻) and gram-positive (G⁺) bacteria compared to annual wheat. Crop perenniality influenced the soil microbial community structure although precipitation, soil temperature and water content were the main drivers of the patterns of and temporal variations in the microbial community. Perennial crops, with reduced tillage and low nitrogen input management increased the proportions of fungi relative to bacteria, AM fungi to saprotrophic fungi, G⁻ bacteria to G⁺ bacteria, and the growth rate of total bacteria. This resulted in a more active soil microbial community with higher microbial biomass than annual wheat and contributed to the increased soil total carbon storage in the 0–5 cm soil layer in a humid continental climate. The findings emphasize the importance of combining a no tillage strategy with long-term vegetation cover to increase soil quality.

密集型农业依赖于一年一度的粮食作物生产，从而导致土壤功能和生态系统服务下降，土壤生物多样性受到威胁。多年生谷物作物对土壤微生物群落有积极影响，但对其有反应的微生物群体及其反应程度仍不确定。为了阐明这一点，我们分析了五种作物的土壤微生物生物量和群落组成、细菌生长和土壤总碳：有机多年生中间小麦草（IWG，Thinopyrum intermedium，Kernza®）、有机 IWG-紫花苜蓿间作、有机二年生草-豆科植物混合物、有机一年生小麦或黑麦以及常规一年生小麦。分析在四个不同土壤深度的两个生长季节的三个时间点进行。与一年生小麦相比，在建立五年后，IWG 的土壤真菌和细菌总数、丛枝菌根（AM）真菌、嗜渍真菌、革兰氏阴性菌（G-）和革兰氏阳性菌（G+）的数量都有所增加。虽然降水、土壤温度和含水量是微生物群落模式和时间变化的主要驱动因素，但多年生作物影响了土壤微生物群落结构。多年生作物在减少耕作和低氮输入管理的情况下，真菌与细菌的比例、AM 真菌与噬菌真菌的比例、G- 细菌与 G+ 细菌的比例以及细菌总数的增长率都有所增加。这使得土壤微生物群落比一年生小麦更活跃，微生物生物量更高，从而增加了湿润大陆性气候下 0-5 厘米土层的土壤总碳储量。研究结果强调了将免耕策略与长期植被覆盖相结合以提高土壤质量的重要性。

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引用次数: 0

Phosphorus limitation regulates the responses of microbial carbon metabolism to long-term combined additions of nitrogen and phosphorus in a cropland 磷限制调节耕地中微生物碳代谢对长期氮磷联合添加的反应

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-11 DOI: 10.1016/j.soilbio.2024.109614

Shuailin Li , Yongxing Cui , Daryl L. Moorhead , Feike A. Dijkstra , Lifei Sun , Zhuqing Xia , Yun Gao , Qiang Ma , Wantai Yu

Microorganisms play central roles in the decomposition and retention of soil organic carbon (SOC), but how nutrient addition in intensively managed croplands influences microbial C metabolism remains uncertain. Here, we investigated the effects of coupled phosphorus (P) and nitrogen (N) additions on microbial respiration, growth rate, C use efficiency (CUE), and biomass turnover time in a continuously managed Zea mays cropland, by combining an 18-year field fertilization experiment with the ¹⁸O–H₂O labeling approach. Results showed that adding P at 50 and 100 kg P ha⁻¹, combined with 150 kg N ha⁻¹, increased respiration by 109% and 50.7%, increased growth rate by 207% and 135%, and increased CUE from approximately 0.26 without P addition to around 0.33 and 0.35, respectively. Conversely, adding N at varying rates (0, 100, 150, and 250 kg N ha⁻¹), combined with 50 kg P ha⁻¹, generated variable responses. These findings underscore the significance of P as the primary limiting element for microbial metabolism in this system. Ecoenzyme stoichiometry analysis further revealed that P addition decreased microbial P vs. N limitation, as well as decreased relative C limitation. In total, changes in P vs. N limitation with P and N additions accounted for 39.6% of the variation in microbial respiration, and in conjunction with relative C limitation, co-explained 51.4% of variations in growth rate and 44.0% of variations in CUE. Furthermore, our investigation identified positive associations of CUE with the activities of N and P-acquiring enzymes, but not with SOC. These results demonstrate flexible responses of microbial C metabolism to long-term anthropogenic N and P additions, highlighting their dependence on soil nutrient limitation. Consequently, optimizing the P-to-N fertilization ratio to alleviate relative P and C limitations may maximize microbial C assimilation and SOC retention in agroecosystems.

微生物在土壤有机碳（SOC）的分解和保留过程中发挥着核心作用，但密集管理的耕地中养分的添加如何影响微生物的碳代谢仍不确定。在此，我们结合 18 年田间施肥试验和 18O-H2O 标记方法，研究了磷氮（N）耦合添加对连续管理的玉米耕地中微生物呼吸、生长速率、碳利用效率（CUE）和生物量周转时间的影响。结果表明，以每公顷 50 和 100 千克 P 和每公顷 150 千克 N 的比例添加 P，呼吸作用分别提高了 109% 和 50.7%，生长速度分别提高了 207% 和 135%，CUE 分别从未加 P 时的约 0.26 提高到约 0.33 和 0.35。相反，添加不同比例的氮（0、100、150 和 250 千克氮公顷-1）和 50 千克磷公顷-1 会产生不同的反应。这些发现强调了 P 作为该系统微生物代谢主要限制元素的重要性。生态酶化学计量分析进一步表明，添加 P 会降低微生物对 P 和 N 的限制，并降低对 C 的相对限制。总的来说，添加磷和氮后磷与氮限制的变化占微生物呼吸变化的 39.6%，与相对碳限制共同解释了 51.4%的生长率变化和 44.0%的 CUE 变化。此外，我们的调查还发现，CUE 与氮和磷获取酶的活性呈正相关，但与 SOC 无关。这些结果表明了微生物碳代谢对长期人为添加氮和磷的灵活反应，突出了它们对土壤养分限制的依赖性。因此，优化氮磷施肥比以缓解相对的氮磷限制，可最大限度地提高农业生态系统中微生物的碳同化和 SOC 保持率。

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引用次数: 0

Arctic tundra soil depth, more than seasonality, determines active layer bacterial community variation down to the permafrost transition 北极冻土层土壤深度比季节性更能决定活动层细菌群落的变化，直至永久冻土过渡阶段

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-10 DOI: 10.1016/j.soilbio.2024.109624

Casper T. Christiansen , Katja Engel , Michael Hall , Josh D. Neufeld , Virginia K. Walker , Paul Grogan

Enhanced microbial decomposition of the Arctic's vast soil carbon pool due to climate warming could result in globally significant CO₂/CH₄ emissions. Our understanding of tundra soil microbial communities is generally based on studies of either the top surface or the deep frozen permafrost. In contrast, there has been relatively little exploration of bacterial communities and soil biogeochemistry down through entire soil depth profiles to the permafrost, and none that has specifically incorporated temporal dynamics with depth as the summer thaw proceeds. Here we report bacterial community composition in 10-cm increments from the surface to the permafrost from late winter through to autumn, at a mesic low Arctic tundra site. Bacterial community composition and phylogenetic diversity varied substantially with soil depth and much less among sampling times. Correlation analysis indicated that the surface organic, subsoil mineral, and permafrost transition soil layers each had distinct community interaction networks. Acidobacteriota-affiliated taxa dominated surface communities but declined significantly with soil depth and increasing pH, while Bacteroidetes taxa relative abundances were also associated with pH, and were largest in the carbon-restricted permafrost transition layer. Thus, patterns in community assembly were primarily associated with depth and correlated with edaphic factors, with relatively little impact of the seasonal changes between frozen and thawed assemblages within each sampling depth interval. Nevertheless, total microbial biomass within each depth interval generally declined during the seasonal transition from frozen to thawed state. Finally, our data indicate that soil pH, which is known to govern tundra microbial community composition horizontally across the surface organic layer at multiple spatial scales, is also an important determinant of vertical differences in bacterial community composition from the top surface down to the permafrost.

由于气候变暖，北极地区巨大的土壤碳库的微生物分解作用增强，这可能导致全球范围内大量的二氧化碳/四氧化二氮排放。我们对苔原土壤微生物群落的了解通常基于对表层或深冻永久冻土的研究。与此相反，对整个土壤深度剖面到永久冻土层的细菌群落和土壤生物地球化学的研究相对较少，也没有专门研究夏季解冻时随着深度变化的时间动态。在这里，我们报告了从冬末到秋季，在一个中低纬度北极苔原地点，从地表到永久冻土层以 10 厘米为单位的细菌群落组成。细菌群落组成和系统发育多样性随土壤深度变化很大，而采样时间的变化则小得多。相关性分析表明，表层有机土壤、底层矿物土壤和永久冻土过渡土壤层各有不同的群落相互作用网络。酸性菌群类群在表层群落中占主导地位，但随着土壤深度和 pH 值的增加，酸性菌群类群的数量明显减少，而类杆菌群类群的相对丰度也与 pH 值有关，在碳限制的永久冻土过渡层中，类杆菌群类群的数量最多。因此，群落的组合模式主要与深度有关，并与土壤环境因子相关，而在每个取样深度区间内，冰冻和解冻群落之间的季节性变化影响相对较小。不过，在从冻结状态向解冻状态的季节性过渡期间，每个深度区间内的微生物总生物量普遍下降。最后，我们的数据表明，已知土壤 pH 值在多个空间尺度上支配着整个表层有机层的苔原微生物群落水平组成，它也是决定从表层到永久冻土层的细菌群落垂直组成差异的重要因素。

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引用次数: 0

Soil function-microbial diversity relationship is impacted by plant functional groups under climate change 土壤功能与微生物多样性之间的关系受到气候变化下植物功能群的影响。

IF 9.8 1区农林科学 Q1 SOIL SCIENCE

Soil Biology & Biochemistry

Pub Date : 2024-10-10 DOI: 10.1016/j.soilbio.2024.109623

Ramesha H. Jayaramaiah , Catarina S.C. Martins , Eleonora Egidi , Catriona A. Macdonald , Jun-Tao Wang , Hongwei Liu , Peter B. Reich , Manuel Delgado-Baquerizo , Brajesh K. Singh

Understanding the interactions between plant and soil microbial diversity is crucial for predicting ecosystem responses to environmental changes. While the individual roles of plant and microbial diversity in driving ecosystem functions have been widely investigated, their interplay especially under stress conditions remains largely underexplored. This study investigated how interactions between plant and microbial diversity affect key soil functions during and after drought. We simultaneously manipulated soil microbial diversity and plant species richness, while also considering the influence of plant functional groups (PFGs), to investigate their interactions and effects on key soil functions. Our results revealed independent and interactive effects of plant and microbial diversity in shaping soil functions. Microbial diversity loss significantly altered microbial community structure and impacted microbially-driven soil N and P pools and processes such as N-mineralization. These effects were modulated by plant species richness and varied across different PFGs. The relative influence of plant and microbial diversity on soil functions was context-dependent. Microbial diversity showed stronger effects on specific functions, such as phosphatase activity, and under the drought condition. Plant diversity, particularly through PFGs (e.g. legumes), played an independent role in shaping the microbial-driven soil functions. These findings advance mechanistic insights and highlight the importance of considering both above- and belowground biodiversity, along with their interactions, in shaping soil functions and ecosystem resilience, particularly under environmental stress. Further, it emphasizes the need to explicitly consider PFGs, along with above- and belowground biodiversity, as a strategy for preserving essential belowground functions in the face of ongoing environmental changes.

了解植物和土壤微生物多样性之间的相互作用对于预测生态系统对环境变化的反应至关重要。虽然植物和微生物多样性在驱动生态系统功能方面的各自作用已得到广泛研究，但它们之间的相互作用，尤其是在压力条件下的相互作用，在很大程度上仍未得到充分探索。本研究调查了植物和微生物多样性之间的相互作用如何影响干旱期间和干旱后的关键土壤功能。我们同时操纵了土壤微生物多样性和植物物种丰富度，同时还考虑了植物功能群（PFGs）的影响，以研究它们之间的相互作用及其对关键土壤功能的影响。我们的研究结果表明，植物和微生物多样性在塑造土壤功能方面具有独立和交互作用。微生物多样性的丧失极大地改变了微生物群落结构，影响了由微生物驱动的土壤氮、磷池和氮矿化等过程。这些影响受到植物物种丰富度的调节，并且在不同的植物群落中各不相同。植物和微生物多样性对土壤功能的相对影响取决于具体情况。在干旱条件下，微生物多样性对磷酸酶活性等特定功能的影响更大。植物多样性，特别是通过全缘植物（如豆科植物），在塑造微生物驱动的土壤功能方面发挥了独立作用。这些研究结果推进了对机理的认识，并强调了考虑地上和地下生物多样性及其相互作用对塑造土壤功能和生态系统恢复力的重要性，尤其是在环境压力下。此外，该研究还强调，在面对持续的环境变化时，有必要明确考虑 PFGs 以及地上和地下生物多样性，将其作为一种保护地下基本功能的策略。

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引用次数: 0

Moisture-mineral interactions drive bacterial and organic matter turnover in glacier-sourced riparian sediments undergoing pedogenesis 水分与矿物质的相互作用推动了冰川源河岸沉积物中细菌和有机物的更替，这些沉积物正经历着植被形成过程

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.2024.109617

A. Peyton Smith , Kenton A. Rod , Tayte Campell , Kaizad F. Patel , Alice Dohnalkova , Malak Tfaily , Lupita Renteria , Vanessa L. Bailey , Ryan Renslow

Glacial recession is occurring at unprecedented rates resulting in increased sediment accumulations in some riverine ecosystems providing new mineral surfaces for soil formation. Soils and sediments have an enormous potential to retain carbon (C), predominantly due to sorption to mineral surfaces. However, C persistence may be sensitive to climate-change induced temperature and moisture variations. We coupled ultrahigh resolution organic matter composition classification with bacterial characterization and respiration measurements to test the combined pedogenic effects of temperature (4 vs 20 °C) and moisture (50 vs 100% water-filled pore space) on C turnover in sediments maintained under different mineralogical conditions (illite-amended vs non-amended). Here we show that the inhibition of CO₂ emissions from the combined effect of increased moisture content and illite was reflected in the turnover of key molecular signatures, such as the nominal oxidation state of C, often irrespective of temperature. However, shifts in bacterial communities from a coupled moisture-mineral interaction, were temperature-dependent. Our results highlight the importance of moisture in driving mineral-organic interactions and suggest that C in clay-rich, water-saturated sediments is both thermodynamically unfavorable and mineral-protected from microbial consumption.

冰川正在以前所未有的速度消退，导致一些河流生态系统中的沉积物堆积增加，为土壤的形成提供了新的矿物表面。土壤和沉积物具有保留碳（C）的巨大潜力，这主要归功于矿物表面的吸附作用。然而，碳的持久性可能对气候变化引起的温度和湿度变化很敏感。我们将超高分辨率有机物成分分类与细菌特征描述和呼吸测量结合起来，测试了温度（4˚C 与 20˚C）和湿度（50% 与 100% 水填充孔隙空间）对在不同矿物学条件（伊利石改良与非改良）下保持的沉积物中碳周转的综合影响。我们在此表明，湿度增加和伊利石的共同作用对二氧化碳排放的抑制反映在关键分子特征（如 C 的名义氧化态）的变化上，通常与温度无关。然而，细菌群落在水分和矿物质耦合作用下的变化与温度有关。我们的研究结果突显了湿度在驱动矿物-有机物相互作用中的重要性，并表明富含粘土的水饱和沉积物中的碳在热力学上是不利的，而且矿物保护作用使其不会被微生物消耗。

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引用次数: 0

Scaling up taxon-specific microbial traits to predict community-level microbial activity in agricultural systems 扩大分类群特异性微生物特征，预测农业系统中群落水平的微生物活动

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.2024.109622

Jeth G. Walkup , Ember M. Morrissey

Soil microorganisms perform many important ecosystem functions including nitrogen (N) cycling which dictates plant productivity in agricultural ecosystems. Despite the importance of these communities, connecting microbial composition with ecosystem function has been a long standing challenge. Taxon-specific substrate assimilation traits, measured with quantitative stable isotope probing (qSIP), may provide a means to scale from microbial community composition to community-level process rates. To test the potential for scaling up taxon-specific N assimilation to predict community-level rates of carbon mineralization, N mineralization, and N immobilization we measured soil properties, microbial activity, and N assimilation using ¹⁵N qSIP in soils from six distinct farm systems. N assimilation, measured as DNA ¹⁵N enrichment, varied among taxa and within taxa across farms. Taxon specific N assimilation was aggregated to calculate a community-weighted mean, which when combined with measures of microbial biomass was used to estimate new microbial biomass N production. This estimate of new microbial biomass production reflects the growth of active microbes over the incubation period and related to microbial activity. The new microbial biomass N produced was predictive of soil C and N mineralization rates, explaining 37–47% of the observed variation across the six farming systems. This approach highlights the ability of trait-based methods to relate microbial community structure data to microbially mediated functional process rates. Such advances may enhance our ability to understand and manage microbially mediated processes, such as N cycling, in both natural and agricultural ecosystems.

土壤微生物发挥着许多重要的生态系统功能，包括氮（N）循环，它决定着农业生态系统中植物的生产力。尽管这些群落非常重要，但将微生物组成与生态系统功能联系起来一直是一个长期的挑战。利用定量稳定同位素探针（qSIP）测量的分类群特异性基质同化特征，可能为从微生物群落组成到群落级过程速率的扩展提供一种方法。为了测试扩大分类群特异性氮同化作用以预测群落级碳矿化率、氮矿化率和氮固定化率的可能性，我们在六个不同农场的土壤中使用 15N qSIP 测量了土壤特性、微生物活动和氮同化作用。以 DNA 15N 富集度衡量的氮同化作用在不同农场的分类群之间和分类群内部都存在差异。分类群的特定氮同化量经过汇总，计算出群落加权平均值，再与微生物生物量的测量值相结合，估算出新的微生物生物量氮产量。新微生物生物量的估计值反映了培养期间活跃微生物的生长情况，并与微生物活动有关。新产生的微生物生物量氮可预测土壤碳和氮的矿化率，可解释六种耕作制度中观察到的变化的 37-47%。这种方法强调了基于性状的方法将微生物群落结构数据与微生物介导的功能过程速率联系起来的能力。这种进步可能会提高我们理解和管理自然和农业生态系统中微生物介导过程（如氮循环）的能力。

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引用次数: 0

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