Geoderma最新文献

{"title":"Formation of placic horizons in soils of a temperate climate – The interplay of lithology and pedogenesis (Stołowe Mts, SW Poland)","authors":"Jarosław Waroszewski ,&nbsp;Łukasz Uzarowicz ,&nbsp;Marek Kasprzak ,&nbsp;Markus Egli ,&nbsp;Aleksandra Loba ,&nbsp;Artur Błachowski","doi":"10.1016/j.geoderma.2024.117118","DOIUrl":"10.1016/j.geoderma.2024.117118","url":null,"abstract":"<div><div>A placic horizon is a thin soil layer that is cemented or indurated by Fe, Mn, and/or Al compounds as well as by organic matter. The placic horizon is a hard, continuous, and nearly impermeable and impenetrable horizon that retards the vertical leaching of water and inhibits the growth of roots. Placic horizons can develop under different climates and in various ways. However, we do not fully understand the interactions between lithology and pedogenesis that might promote placic horizon formation. Therefore, to shed light on the mechanisms of placic genesis, we used an applied multiproxy approach (electrical resistivity tomography – ERT, XRD, ⁵⁷Fe Mössbauer spectroscopy, bulk geochemistry, soil micromorphology and ¹⁴C dating) for three soils developed from sandstone–mudstone parent materials in mountainous areas of SW Poland, to shed light on the mechanisms of placic horizon genesis. The ERT inversion models and soil survey data indicate lithic discontinuities in the profiles. Soil micromorphology data confirmed that a placic horizons formed slightly below the discontinuity. Radiocarbon ages of the placic horizon span from 2.2 to 4.8 ka and suggest that more humid conditions were favorable for the formation of a placic horizon, which aligns with our mineralogical results. Ferrihydrite is the major Fe oxyhydroxide in the placic horizon. Micromorphological data showed that after the formation of the placic horizon, a phase of clay migration might have occurred, while later, podzolisation took over as the main soil-forming process. This sequence shows that thin iron pans can develop independently of other processes and can exist (at least some of them) before the development of a spodic horizon. A placic horizon causes severe hydrological changes in the topsoil and subsurface horizons. Thus, water stagnation in the soil transforms it into a Stagnosol or Planosol and it’s responsible for the evolution of local plant communities and the ecosystem.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117118"},"PeriodicalIF":5.6,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Moroccan soil spectral library use framework for improving soil property prediction: Evaluating a geostatistical approach","authors":"Tadesse Gashaw Asrat ,&nbsp;Timo Breure ,&nbsp;Ruben Sakrabani ,&nbsp;Ron Corstanje ,&nbsp;Kirsty L. Hassall ,&nbsp;Abdellah Hamma ,&nbsp;Fassil Kebede ,&nbsp;Stephan M. Haefele","doi":"10.1016/j.geoderma.2024.117116","DOIUrl":"10.1016/j.geoderma.2024.117116","url":null,"abstract":"<div><div>A soil spectrum generated by any spectrometer requires a calibration model to estimate soil properties from it. To achieve best results, the assumption is that locally calibrated models offer more accurate predictions. However, achieving this higher accuracy comes with associated costs, complexity, and resource requirements, thus limiting widespread adoption. Furthermore, there is a lack of comprehensive frameworks for developing and utilizing soil spectral libraries (SSLs) to make predictions for specific samples. While calibration samples are necessary, there is the need to optimize SSL development through strategically determining the quantity, location, and timing of these samples based on the quality of the information in the library. This research aimed to develop a spatially optimized SSL and propose a use-framework tailored for predicting soil properties for a specific farmland context. Consequently, the Moroccan SSL (MSSL) was established utilizing a stratified spatially balanced sampling design, using six environmental covariates and FAO soil units. Subsequently, various criteria for calibration sample selection were explored, including a spatial autocorrelation of spectra principal component (PC) scores (spatial calibration sample selection), spectra similarity memory-based learner (MBL), and selection based on environmental covariate clustering. Twelve soil properties were used to evaluate these calibration sample selections to predict soil properties using the near infrared (NIR) and mid infrared (MIR) ranges. Among the methods assessed, we observed distinct precision improvements resulting from spatial sample selection and MBL compared to the use of the entire MSSL. Notably, the Lin’s Concordance Correlation Coefficient (CCC) values using the spatial calibration sample selection was improved for Olsen extractable phosphorus (OlsenP) by 41.3% and Mehlich III extractable phosphorus (P_M3) by 8.5% for the MIR spectra and for CEC by 25.6%, pH by 13.0% and total nitrogen (Tot_N) by 10.6% for the NIR spectra in reference to use of the entire MSSL. Utilizing the spatial autocorrelation of the spectra PC scores proved beneficial in identifying appropriate calibration samples for a new sample location, thereby enhancing prediction performance comparable to, or surpassing that of the use of the entire MSSL. This study signifies notable advancement in crafting targeted models tailored for specific samples within a vast and diverse SSL.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117116"},"PeriodicalIF":5.6,"publicationDate":"2024-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial distributions and the main driving factors of soil total nitrogen in Zhejiang Province, China","authors":"Mi Tian ,&nbsp;Binbin Sun ,&nbsp;Chao Wu ,&nbsp;Xiaomeng Cheng ,&nbsp;Guohua Zhou ,&nbsp;Chunlei Huang ,&nbsp;Yining Zhou ,&nbsp;Qinghai Hu ,&nbsp;Longxue Li","doi":"10.1016/j.geoderma.2024.117112","DOIUrl":"10.1016/j.geoderma.2024.117112","url":null,"abstract":"<div><div>Nitrogen is an indispensable element in the growth and development stages of various crops, as well as an important component of soil nutrients. It plays an important role in farmland ecosystems. Studying the spatial distribution of soil total nitrogen (STN) is essential for improving the efficiency of soil fertility management and for a better understanding of the soil nitrogen cycle. In the study, the STN content data of surface soil (0–20 cm) were obtained from 19,119 sampling sites within an area of 7.47 × 10⁴ km² based on a multi-purpose regional geochemical survey established in Zhejiang Province, China, from 2002 to 2018. The spatial distribution and main driving factors of STN were determined using the random forest model. The results showed that the average STN content in the topsoil of the Zhejiang Province was 1.48 g⋅kg⁻¹. Among the different land-use types, grassland soil had the highest STN content of 1.55 g⋅kg⁻¹, and alfisol had the highest STN content of 2.59 g⋅kg⁻¹. The spatial distribution of STN content was high in the northern part and low in the southern part of the study area. The results of the random forest analysis showed that nitrogen deposition, pH, and mean annual precipitation (MAP) were the most important factors influencing the spatial variability of STN. The STN content exhibited a nonlinear decrease with an increase in pH and MAP and a nonlinear increase with an increase in nitrogen deposition. This study provides decision-makers with synthesized information on the spatial variability of STN and its driving factors in Zhejiang Province, which is important for accurately grasping the spatial distribution characteristics of STN to implement precision agriculture management measures.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117112"},"PeriodicalIF":5.6,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highway to health: Microbial pathways of soil organic carbon accrual in conservation farming systems","authors":"Sabine Huber ,&nbsp;Christoph Rosinger ,&nbsp;Gernot Bodner ,&nbsp;Luca Giuliano Bernardini ,&nbsp;Magdalena Bieber ,&nbsp;Axel Mentler ,&nbsp;Orracha Sae-Tun ,&nbsp;Bernhard Scharf ,&nbsp;Katharina Maria Keiblinger","doi":"10.1016/j.geoderma.2024.117115","DOIUrl":"10.1016/j.geoderma.2024.117115","url":null,"abstract":"<div><div>Increasing pressure on arable land related to climate change mitigation and adaptation within recent policy frameworks has generated widespread interest in the effect of sustainable agricultural management practices on soil organic carbon (SOC) storage. Current frameworks point to soil microorganisms and their functioning as the key drivers of SOC accrual. This study provides a comprehensive on-farm assessment of changes in SOC formation pathways (physico-chemical and microbial) and the underlying drivers comparing three soil use systems: conservation and conventional farming systems as well as permanently vegetated adjacent reference soils (i.e., field margins) without agricultural land-use.</div><div>Overall, our results indicated substantial increases in extractable organic carbon (+22 %), microbial biomass carbon (+29 %) and necromass carbon stocks (+11 %) in soils of conservation farming systems as compared to conventional farming systems. Differences between all three soil use systems were strongly pronounced in the surface soil (0–5 cm) and declined in deeper soil layers. Structural equation modelling revealed a varying influence of SOC storage pathways among soil use systems, with microbial-mediated (<em>‘in-vivo’</em>) turnover and direct sorption being the most dominant pathways. Moreover, diversity of crop rotation and tillage intensity were identified as the most important factors influencing extractable organic carbon and carbon-liberating enzyme activity within conservation farming management. Our on-farm approach demonstrates that enhanced bioavailable carbon inputs and reduced soil disturbance are the key drivers for microbially-controlled SOC accrual in arable soils and that conservation farming systems with extended plant coverage and increased crop diversity can substantially advance the restoration of soil health.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117115"},"PeriodicalIF":5.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of anecic Amynthas aspergillum on the proportion and depth of straw-derived carbon input into soil","authors":"Xiangdong Li ,&nbsp;Na Mao ,&nbsp;Tong Liu ,&nbsp;Jiong Cheng ,&nbsp;Xiaorong Wei ,&nbsp;Ming’an Shao","doi":"10.1016/j.geoderma.2024.117114","DOIUrl":"10.1016/j.geoderma.2024.117114","url":null,"abstract":"<div><div>Straw mulching significantly affects the soil organic carbon (OC) pool, but its positive effect on soil OC is limited by the slow decomposition rate and shallow depth. Increasing the conversion rate of straw-derived carbon (C) to soil OC and the depth affected are important for enhancing soil carbon storage and mitigating global climate change. Anecic earthworms feed on surface organic residues and dwell underground; and thus, they can carry surface straw directly underground. However, previous studies have focused on European earthworms, and it is still unclear how Chinese widely distributed earthworms, such as the anecic <em>Amynthas aspergillum</em>, affect the conversion rate of straw-derived C into soil OC and the depth affected, and whether these effects are related to soil properties. Using ¹³C tracing technology, we established treatments with and without <em>A. aspergillum</em> in soil with added straw to examine how <em>A. aspergillum</em> regulate the distribution of straw-derived OC in soil profiles during incubation for 31 days. Soil samples from the plow layer (PL) and plow pan layer (PP) of subtropical corn land were used in this study to represent two soils of different properties. Visible earthworm casts were not observed on the surface soil. <em>A. aspergillum</em> significantly increased the loss of surface straw by 86.1 % and 43.1 % in the PL and PP soils, respectively (<em>p</em> &lt; 0.05). The conversion rate of straw-derived C into soil OC was 21.8 ± 0.5 % in the presence of earthworms in the PL soils, which was significantly greater than that without earthworms (7.9 ± 0.5 %, <em>p</em> &lt; 0.05). The conversion rates were 8.0 % and 12.8 % in the absence and presence of earthworms, respectively, in the PP soils. The <em>A. aspergillum</em> increased the soil depth affected by straw-derived C input in the profiles of both the PL (to 10–20 cm) and PP soils (to 5–10 cm) compared with the treatments without earthworms (0–5 cm). Thus, anecic <em>A. aspergillum</em> promoted the decomposition of straw, enhanced the conversion of straw-derived C into soil OC and depth affected, and the effects of <em>A. aspergillum</em> were greater in the fertile soils. The underground casting behavior of <em>A. aspergillum</em>, may enhance the effects of incorporation of surface straw-derived C in deep soils. We suggest that earthworm regulation combined with straw return could be considered in sustainable agriculture.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117114"},"PeriodicalIF":5.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controlled soil monolith experiment for studying the effects of waterlogging on redox processes","authors":"Reija Kronberg ,&nbsp;Sanna Kanerva ,&nbsp;Markku Koskinen ,&nbsp;Tatu Polvinen ,&nbsp;Jussi Heinonsalo ,&nbsp;Mari Pihlatie","doi":"10.1016/j.geoderma.2024.117110","DOIUrl":"10.1016/j.geoderma.2024.117110","url":null,"abstract":"<div><div>Climate change induced mild and rainy winters may expose soils to more frequent and prolonged waterlogging in boreal regions. Resulting oxygen depletion induces reductive dissolution of iron (Fe) oxides further altering the stability of Fe-associated organic matter. Thus far, the impact of waterlogging on the coupled cycling of Fe and carbon (C) in upland arable soils remains unknown. We constructed a monolithic experimental system with 32 soil profiles (l = 63 cm, d = 15.2 cm) collected from two agricultural fields (silty clay, sandy loam) to study the effects of off-season waterlogging, overwintering cover crop and soil type on soil redox potential (E_h), Fe solubility, and movement of C and nitrogen (N) within the soil–plant-atmosphere continuum. Soil moisture, temperature, electrical conductivity, and E_h were continuously monitored, and soil pore water samples were collected at three soil depths. Here, we assess the systems suitability for studying coupled Fe and C dynamics in boreal climate, and investigate the treatment impacts on soil E_h, pH, reductive Fe dissolution and N concentration in pore water. Waterlogging led to reducing conditions in both soils down to 30 cm depth at the soil temperature (+4 to 12 °C) matching those of spring and autumn in southern Finland. The declining E_h and the slightly rising Fe concentration in porewater (max ∼ 10 µmol l⁻¹) suggest that reductive dissolution of Fe could proceed even during mild winters if the duration of waterlogging exceeds 1–2 weeks. The study demonstrated that cover crops may accelerate the drop in soil E_h by removing bioavailable N_, and hence controlling the availability of alternative electron acceptors (nitrate) in the soil. Thus, the simultaneous effects of cover crops on C inputs, and on N and water dynamics, all influencing redox reactions, emphasize the importance of incorporating vegetation into studies exploring the impacts of waterlogging on coupled dynamics of Fe and C.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117110"},"PeriodicalIF":5.6,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of invasive alien tree species on symbiotic soil fungal communities in pine-dominated forest ecosystems in central Europe","authors":"Robin Wilgan ,&nbsp;Marta Brygida Kujawska ,&nbsp;Tomasz Leski","doi":"10.1016/j.geoderma.2024.117111","DOIUrl":"10.1016/j.geoderma.2024.117111","url":null,"abstract":"<div><div>Biological invasions are a serious threat to nature conservation and sustainable forest management. Invasive trees can reduce biodiversity, modify nutrient cycles and transform native forests into novel ecosystems determined by invaders. Almost all European trees form ectomycorrhizal (ECM) symbiosis with fungi, which is crucial for tree development. However, the impact of invasive trees on ECM fungi in native forests has scarcely been studied.</div><div>We aimed to determine how an invasion of the widespread alien trees <em>Robinia pseudoacacia</em> (which hosts arbuscular mycorrhizal (AM) fungi), <em>Prunus serotina</em> (which forms AM associations and potentially can ECM symbiosis), and <em>Quercus rubra</em> (ECM-dominated, can form AM associations) influences symbiotic fungi in soil. We collected soil samples along a gradient of increasing density of invasive species in 81 stands in pine-dominated forests in Western Poland, identifying fungi through high-throughput sequencing of the ITS2 rDNA, a barcode region for fungi. Each invasive tree was examined independently.</div><div><em>Robinia pseudoacacia</em> had the strongest negative impact, almost eliminating ECM fungi from the soil. Among soil compounds, N-NO3 and N-NH4 significantly influenced diversity and taxa composition of ECM fungal communities. Uninvaded pine stands near <em>R</em>. <em>pseudoacacia</em> had significantly lower richness and abundance of ECM fungi, and several-fold higher N-NO3 concentrations, than uninvaded stands elsewhere. That indicates, that the negative impact of <em>Robinia</em> trees extends beyond stands containing <em>Robinia</em> to influence surrounding forests. <em>Prunus serotina</em> had significant negative impact on ECM taxa abundance, but not on ECM taxa richness and diversity indices, while <em>Quercus rubra</em> enhanced the abundance and richness of ECM fungi, but had no significant influence on the diversity indices.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117111"},"PeriodicalIF":5.6,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SOC: clay ratio: A mechanistically-sound, universal soil health indicator across ecological zones and land use categories?","authors":"Walter W. Wenzel,&nbsp;Alireza Golestanifard,&nbsp;Olivier Duboc","doi":"10.1016/j.geoderma.2024.117080","DOIUrl":"10.1016/j.geoderma.2024.117080","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The European Union has recently launched a proposal for a soil monitoring and resilience directive (“soil monitoring law”, SML), defining the SOC: clay ratio as descriptor of the soil organic carbon (SOC) status, with a ratio of 1/13 separating “healthy” from “unhealthy” soils. Using data of the Lower Austrian soil database, this article explores the mechanistic foundation and applicability of the SOC: clay ratio in the ecologically diverse study region. We observe considerable variation of the SOC: clay ratio among agroecological regions because clay content and SOC are driven by different ecological variables, with clay content related to the texture of parent materials. After stratification by land use (cropland versus grassland), we built multiple regression models starting with an initial set of predictor variables including mean annual precipitation (MAP) and temperature (MAT), clay content, CaCO&lt;sub&gt;3&lt;/sub&gt; equivalent, amorphous oxyhydroxides of Al (Al&lt;sub&gt;o&lt;/sub&gt;) and Fe (Fe&lt;sub&gt;o&lt;/sub&gt;), and pH to identify the main drivers of SOC and their relative importance. The final models explain between 23 and 77  % of the overall SOC variation, and reveal that SOC is primarily controlled by Al&lt;sub&gt;o&lt;/sub&gt; and the CaCO&lt;sub&gt;3&lt;/sub&gt; equivalent across the entire study region and within most agroecological and soil units, with smaller contributions of clay content and MAP. The set of relevant SOC drivers and their relative importance vary with spatial scale (entire study region versus agroecological and soil units), the aridity index (defined as MAT: MAP) and the state of soil development, as reflected by soil pH. With some notable exceptions, Al&lt;sub&gt;o&lt;/sub&gt; is most important in more humid regions and acidic soils, whereas the relevance of CaCO&lt;sub&gt;3&lt;/sub&gt; equivalent and clay content increases with pH and aridity.&lt;/div&gt;&lt;div&gt;The limited importance of clay content indicates that the SOC: clay ratio is a poor descriptor of soil health in the study region. Moreover, we could not confirm a meaningful functional relation between the SOC: clay ratio and the quality of soil structure derived from visual assessment. These findings challenge the universal use of the SOC: clay ratio as descriptor of soil health, and its threshold of 1/13 to distinguish the soil health status across different ecological zones. If SOC is not primarily driven by clay content, also the use of correction factors to the SOC: clay threshold as suggested by the SML is not appropriate.&lt;/div&gt;&lt;div&gt;To derive meaningful regional benchmarks of SOC, we suggest to employ multiple regression analysis with the main SOC drivers as input variables. The regression equation can be used to predict the SOC levels expected for the average management regime of the region at any given values of the relevant main soil and climate drivers. This approach can be further refined by scaling down to the soil unit level, and by developing relations for different, clearly defined categories of soil manage","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117080"},"PeriodicalIF":5.6,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbial necromass accrual from newly added labile and native soil carbon in the rhizosphere vs. non-rhizosphere of broadleaved and coniferous trees","authors":"Juan Jia ,&nbsp;Guoqing Zhai ,&nbsp;Yufu Jia ,&nbsp;Xiaojuan Liu ,&nbsp;Keping Ma ,&nbsp;Xiaojuan Feng","doi":"10.1016/j.geoderma.2024.117107","DOIUrl":"10.1016/j.geoderma.2024.117107","url":null,"abstract":"<div><div>Microbe-mediated carbon (C) transformation plays a crucial role in the accumulation of soil organic C (SOC). However, microbial conversion efficiency of newly-added labile C and native SOC to necromass remain under-investigated. Here we collected the rhizosphere and non-rhizosphere soils under broadleaved and coniferous trees of varying nutrient availability, and conducted an 80-day soil incubation with ¹³C-labelled glucose to evaluate ‘microbial C pump’ (MCP) capacity (new C-derived biomass and necromass), phospholipid fatty acids (PLFAs)-based C use efficiency (i.e., new C-derived PLFAs relative to respiration, referred as CUE′ to differentiate from microbial biomass C-based CUE) and amino sugar (reflecting necromass) accumulation efficiency (AAE; new C-derived amino sugars relative to respiration). We found that MCP capacity, microbial AAE and CUE′ had different variation patterns and influencing factors. The amount of added glucose played a decisive role in determining MCP capacity. The key predictors of AAE were the ratio of inorganic nitrogen (N) to added glucose (reflecting N limitation) and bacterial PLFAs, while ratios of fungi to bacteria and C to N were important for predicting CUE′. Furthermore, we found that glucose addition stimulated microbial transformation of native SOC into necromass in C- but not N-limited soils (with a high AAE) without invoking a priming effect, potentially enhancing microbe-mediated SOC sequestration. These findings suggest that the efficiency of microbial necromass accumulation is strongly influenced by N availability and decoupled from biomass synthesis, highlighting nutrient regulations on SOC sequestration via plant–microbe interactions. We argue that AAE is a more reliable indicator to assess the efficiency of MCP fueled by labile C.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117107"},"PeriodicalIF":5.6,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142700398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon dioxide exchange and temperature sensitivity of soil respiration along an elevation gradient in an arctic tundra ecosystem","authors":"Wenyi Xu ,&nbsp;Andreas Westergaard-Nielsen ,&nbsp;Anders Michelsen ,&nbsp;Per Lennart Ambus","doi":"10.1016/j.geoderma.2024.117108","DOIUrl":"10.1016/j.geoderma.2024.117108","url":null,"abstract":"<div><div>Generally, with increasing elevation, there is a corresponding decrease in annual mean air and soil temperatures, resulting in an overall decrease in ecosystem carbon dioxide (CO₂) exchange. However, there is a lack of knowledge on the variations in CO₂ exchange along elevation gradients in tundra ecosystems. Aiming to quantify CO₂ exchange along elevation gradients in tundra ecosystems, we measured ecosystem CO₂ exchange in the peak growing season along an elevation gradient (9–387 m above sea level, m.a.s.l) in an arctic heath tundra, West Greenland. We also performed an <em>ex-situ</em> incubation experiment based on soil samples collected along the elevation gradient, to assess the sensitivity of soil respiration to changes in temperature and soil moisture. There was no apparent temperature gradient along the elevation gradient, with the lowest air and soil temperatures at the second lowest elevation site (83 m). The lowest elevation site exhibited the highest net ecosystem exchange (NEE), ecosystem respiration (ER) and gross ecosystem production (GEP) rates, while the other three sites generally showed intercomparable CO₂ exchange rates. Topography aspect-induced soil microclimate differences rather than the elevation were the primary drivers for the soil nutrient status and ecosystem CO₂ exchange. The temperature sensitivity of soil respiration above 0 °C increased with elevation, while elevation did not regulate the temperature sensitivity below 0 °C or the moisture sensitivity. Soil total nitrogen, carbon, and ammonium contents were the controls of temperature sensitivity below 0 °C. Overall, our results emphasize the significance of considering elevation and microclimate when predicting the response of CO₂ balance to climate change or upscaling to regional scales, particularly during the growing season. However, outside the growing season, other factors such as soil nutrient dynamics, play a more influential role in driving ecosystem CO₂ fluxes. To accurately upscale or predict annual CO₂ fluxes in arctic tundra regions, it is crucial to incorporate elevation-specific microclimate conditions into ecosystem models.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"452 ","pages":"Article 117108"},"PeriodicalIF":5.6,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142673095","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}