Soil Biology & Biochemistry最新文献

{"title":"Simulated erosion of A horizon influences the dissolved organic matter chemodiversity and carbon sequestration of B horizon in Mollisols","authors":"Meng Zhou, Yang Xiao, Yansheng Li, Jian Liu, Yueyu Sui, Xingyi Zhang, Xiaobing Liu","doi":"10.1016/j.soilbio.2024.109648","DOIUrl":"https://doi.org/10.1016/j.soilbio.2024.109648","url":null,"abstract":"Erosion of the A horizon of Mollisols is expected to change the dissolved organic matter (DOM) chemodiversity in the underlying B horizon. Three simulated erosion treatments, which had an A horizon of 30, 20, and 10 cm depth, were established for 9 years under a corn-soybean rotation on Mollisols. Compared to the A horizon that was 30 cm deep, the 20 cm treatment had 24–63% more dissolved lignin-like compounds, a significant increase, in the 0–10, 10–20, and 20–30 cm layers of the B horizon. When the A horizon was 10 cm deep, 41% more lignin-like compounds accumulated in the 10–20 cm layer of the B horizon and 22% more lignin-like compounds were detected in the 20–30 cm layer of the B horizon. Relative to the A horizon of 30 cm depth, the 20 and 10 cm treatments reduced the lipid- and protein-like compounds by 69–87% in 10–20 and 20–30 cm layers of the B horizon layers. Labile compounds increased in the 0–10 cm layer of the B horizon but decreased in the 10–20 and 20–30 cm layers of the B horizon. The DOM degradation degree, expressed in terms of the degradation index and Gibbs free energy, were related to the lignin accumulation, indicating that lignin, a recalcitrant compound, was degraded. Notably, variations in DOM chemodiversity in eroded Mollisols were primarily controlled by soil physicochemical properties and not microbial traits. Therefore, eroded Mollisols have less carbon sequestration potential in the B horizon. To prevent soil deterioration in corn-soybean rotations, we recommend to incorporate a combination of organic and mineral fertiliser to a 20–30 cm soil depth in erosion-susceptible Mollisols.","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"8 1","pages":""},"PeriodicalIF":9.7,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665534","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}

{"title":"Cropping systems and ecological groups of soil animals jointly affect the transfer of root-derived carbon and mineral nitrogen into the soil food web","authors":"Linlin Zhong ,&nbsp;Zhipeng Li ,&nbsp;Lingling Shi ,&nbsp;Thomas Larsen ,&nbsp;Stefan Scheu ,&nbsp;Melanie M. Pollierer","doi":"10.1016/j.soilbio.2024.109646","DOIUrl":"10.1016/j.soilbio.2024.109646","url":null,"abstract":"<div><div>Root-derived carbon (C) is a crucial resource fuelling soil food webs. However, the quantity of these resources varies with plant communities and may also influence the flux of mineral nitrogen (N) into belowground food webs. Yet, little is known about how different plant communities, especially in agricultural systems, influence the incorporation of plant C and mineral N into the soil macrofauna. Here, we combined pulse ¹³C-labelling of plants with ¹⁵N-labelling of soil in a crop monoculture (oilseed rape), a mixed grass community (grass and legume mixture) and a young tree plantation (willow) to trace the fluxes of root-derived C and mineral N into earthworms and centipedes as major soil decomposers and predators, respectively, over 28 days. Bulk stable isotope analysis and compound-specific stable isotope analysis of amino acids were used to quantify the uptake of ¹³C and ¹⁵N by soil macrofauna and to investigate the pathways by which these resources are channelled into soil macrofauna. Aligning with their use of plant-derived resources, epigeic and anecic earthworms incorporated more root-derived C than endogeic earthworms, with endogeic earthworms mainly relying on bacteria or bacterial necromass associated with soil organic matter. Generally, macrofauna incorporated both root-derived C and mineral N across cropping systems, but incorporation was more pronounced in rape and grass than in willow. Importantly, root-derived resources facilitated the incorporation of mineral N into soil animal food webs. Centipedes, as one of the most important predators in soil, mainly incorporated root-derived C and mineral N via preying on collembolans, whereas in willow epigeic earthworms likely also contributed to their diet. Overall, the fluxes of root-derived C and mineral N into the soil food web depended on plant communities and soil animal ecological groups, with higher fluxes in herbaceous crops than in tree plantations.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"200 ","pages":"Article 109646"},"PeriodicalIF":9.8,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142599667","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":"Plant community composition and traits modulate the impacts of drought intensity on soil microbial community composition and function","authors":"Natalie J. Oram ,&nbsp;Fiona Brennan ,&nbsp;Nadine Praeg ,&nbsp;Richard D. Bardgett ,&nbsp;Paul Illmer ,&nbsp;Johannes Ingrisch ,&nbsp;Michael Bahn","doi":"10.1016/j.soilbio.2024.109644","DOIUrl":"10.1016/j.soilbio.2024.109644","url":null,"abstract":"<div><div>Terrestrial ecosystems are increasingly threatened by extreme drought events. Soil microbial communities are central to terrestrial ecosystem function via their role in regulating biogeochemical cycling. Consequently, the impact of increasingly intense drought events on soil microbial communities will have knock-on effects for how ecosystems cope with climate change. In an outdoor grassland mesocosm experiment, we determined how increasing drought intensity affects bacterial and fungal community composition, and functioning, during and after drought. We also tested whether plant community resource acquisition strategy (fast-versus slow-strategy plant communities), plant community composition, and plant functional traits mediate soil microbial responses to increasing drought intensity. We found that increasing drought intensity markedly shifted bacterial and fungal community composition, and these effects persisted until the end of the experiment (two months after re-wetting). Bacterial and fungal communities that experienced severe droughts did not return to baseline composition, while those that experienced a mild drought did. Microbial community functioning (potential extracellular enzyme activity) was reduced at peak drought and shortly after re-wetting. While drought intensity effects on bacterial or fungal communities were insensitive to plant community resource acquisition strategy, functional group abundance (aboveground biomass of grass or forb plant species) composition (grass:forb ratio) and leaf traits (leaf dry matter content and leaf nitrogen concentration) explained significant variation in bacterial and fungal community composition during and after drought. Notably, plant community leaf dry matter content and soil nitrogen were the key factors mediating the effect of increasing drought intensity on microbial indicator taxa (ASVs). We conclude that increasing drought intensity affects grassland soil microbial communities during and after drought, and this impact is influenced by plant community composition and functional traits.</div></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"200 ","pages":"Article 109644"},"PeriodicalIF":9.8,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142566133","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":"What controls the availability of organic and inorganic P sources in top- and subsoils? A 33P isotopic labeling study with root exudate addition","authors":"Juanjuan Ai ,&nbsp;Callum C. Banfield ,&nbsp;Guodong Shao ,&nbsp;Kazem Zamanian ,&nbsp;Tobias Stürzebecher ,&nbsp;Lingling Shi ,&nbsp;Lichao Fan ,&nbsp;Xia Liu ,&nbsp;Sandra Spielvogel ,&nbsp;Michaela A. Dippold","doi":"10.1016/j.soilbio.2023.109129","DOIUrl":"10.1016/j.soilbio.2023.109129","url":null,"abstract":"<div><p>Phosphorus (P) is a major limiting nutrient for plant growth implying an often-intensive competition between microorganisms and plants in the rhizosphere. Increasing the P availability in subsoils may help to mitigate potential future P fertilizer shortages and to overcome P limitations due to droughts, which mainly affect topsoils. Root exudates provide easily available carbon and energy sources for microorganisms to mobilize soil nutrients. Nonetheless, details regarding the distinct processes underlying P mobilization from various P sources (free vs. sorbed PO₄³⁻; low molecular vs. complex organic P, e.g. ATP vs. plant litter P) as affected by root exudates are poorly understood, especially in subsoils. This study aimed to identify the controlling factors and microbial processes regulating the availability of organic and inorganic P in top- and subsoils by ³³P isotopic labeling. The focus was on the potential key role of root exudates in P mobilization. We found that microbial communities in top- and subsoils used high- and low-available mineral P to a similar extent, but that the subsoil communities were much more efficient in mobilizing and incorporating complex litter-derived organic P. This capability of subsoil communities was even enhanced when root exudates were present. Microbial activity and nutrient-mobilizing mechanisms (e.g., P-related enzymes) clearly increased by root exudate addition, an effect that was generally higher in sub-than in topsoils. We conclude that subsoil communities are well capable of mobilizing and using complex organic P sources, especially if root exudates accelerate overall activity and P cycling. Thus, high root exudation is highly relevant for crops, which depend on subsoil nutrients and litter-derived P. Accordingly, detritusphere P, e.g. in subsoil root channels, is likely to be plant-available because of exudate-induced microbial P (re-)cycling processes.</p></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"185 ","pages":"Article 109129"},"PeriodicalIF":9.7,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42105145","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}

{"title":"Corrigendum to “Population energetics of bacterial-feeding nematodes: Stage-specific development and fecundity rates” [Soil Biology and Biochemistry 28 (3) 271–280, 1996]","authors":"H. Ferris ,&nbsp;R.C. Venette ,&nbsp;S. Sánchez Moreno","doi":"10.1016/j.soilbio.2023.109116","DOIUrl":"10.1016/j.soilbio.2023.109116","url":null,"abstract":"<div><p>Nematodes play significant roles in carbon and nitrogen biogeochemical cycles in soils. The contributions of individual species to these processes depend, in part, on differences in their population ecology. Formatting errors were discovered that made portions of our previously published work on this subject nearly unintelligible. Herein, we correct those errors.</p></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"185 ","pages":"Article 109116"},"PeriodicalIF":9.7,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48716628","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}

{"title":"Revegetation promotes soil mineral-associated organic carbon sequestration and soil carbon stability in the Tengger Desert, northern China","authors":"Yunfei Li ,&nbsp;Xue Zhang ,&nbsp;Bingyao Wang ,&nbsp;Xudong Wu ,&nbsp;Zhanjun Wang ,&nbsp;Lichao Liu ,&nbsp;Haotian Yang","doi":"10.1016/j.soilbio.2023.109155","DOIUrl":"10.1016/j.soilbio.2023.109155","url":null,"abstract":"<div><p>Ecological restoration is considered an effective strategy for increasing soil carbon storage and mitigating climate change. However, the impact of revegetation in desert areas on the stability of soil organic carbon (SOC) is still unclear. We investigated the content and stability of SOC in restoration sites along a chronosequence in the Tengger Desert, focusing on the mineral-associated organic carbon (MAOC) and particulate organic carbon (POC) fractions. The content of SOC significantly increased with site age from 0.37 g kg⁻¹ at year 0–5.32 g kg⁻¹ at year 66. Revegetation significantly changed the SOC fraction and improved SOC stability as a factor of site age. In the 66-year-old site, the levels of MAOC and POC were increased by 255.67 and 9.24 times, respectively. The percentage of MAOC was increased from 1.50% to 28.92%, whereas that of POC was decreased from 98.50% to 71.08%. Based on our findings, the content and proportion of MAOC and POC are closely related to plant input, soil variables, and the soil microbial community. We estimate that the maximum content and proportion of MAOC are 2.65 g kg⁻¹ and 36.71% with continuous succession, based on the soil clay and silt contents. Overall, revegetation improved the stability of SOC. Our study highlights the importance of the revegetation of temperate desert areas to further mitigate climate change.</p></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"185 ","pages":"Article 109155"},"PeriodicalIF":9.7,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44987801","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}

{"title":"Intercropping increases soil macroaggregate carbon through root traits induced microbial necromass accumulation","authors":"Xupeng Zhao ,&nbsp;Cunkang Hao ,&nbsp;Ruqiang Zhang ,&nbsp;Nianyuan Jiao ,&nbsp;Jing Tian ,&nbsp;Hans Lambers ,&nbsp;Chao Liang ,&nbsp;Wen-Feng Cong ,&nbsp;Fusuo Zhang","doi":"10.1016/j.soilbio.2023.109146","DOIUrl":"10.1016/j.soilbio.2023.109146","url":null,"abstract":"<div><p>Microbial necromass, as part of persistent soil organic matter, plays a significant role in maintaining soil fertility and sustainability of agroecosystems. Intercropping, planting multiple crop species in the same field at approximately the same time, has been demonstrated to increase soil organic matter through enhanced biomass input. Nonetheless, little is known as to how intercropping affects microbial necromass accumulation in soils and the underlying microbiological mechanisms, particularly about microbial life strategies and network stability. Here, we investigated the carbon (C) accumulation mechanism of microbe-aggregate interactions using aggregate fractionation combined with microbial biomarkers as well as high-throughput sequencing in an 11-year maize/peanut intercropping field experiment. We found that intercropping increased soil organic carbon (SOC) and microbial necromass C in macroaggregates (&gt;250 μm) compared with sole crops, and it was mostly accounted for by fungal necromass C. Within small macroaggregates (250–2000 μm), bacterial necromass C was positively correlated with <em>r</em>-strategy bacteria, and fungal necromass C was positively correlated with <em>K</em>-strategy fungi. Microbial inter-kingdom co-occurrence network analysis showed higher proportions of positive links in intercropping system than in sole crops, and the proportions of positive links positively correlated with fungal necromass C in macroaggregates (&gt;250 μm). Path analysis revealed that intercropping increased SOC mainly through root traits induced microbial life strategies and microbial network stability, resulting in increased microbial necromass. In conclusion, crop diversity-driven changes in root traits induced microbial traits promote microbial necromass accumulation. A new mechanism elucidating the positive crop diversity effect on soil C sequestration is proposed.</p></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"185 ","pages":"Article 109146"},"PeriodicalIF":9.7,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43157972","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}

{"title":"A new concept for modelling the moisture dependence of heterotrophic soil respiration","authors":"Zhongdong Huang ,&nbsp;Yuan Liu ,&nbsp;Pengfei Huang ,&nbsp;Zhongyang Li ,&nbsp;Xiaoxian Zhang","doi":"10.1016/j.soilbio.2023.109147","DOIUrl":"10.1016/j.soilbio.2023.109147","url":null,"abstract":"<div><p>The moisture dependence of heterotrophic soil respiration is a key factor affecting the uncertainty in predicting the response of soil organic carbon (SOC) to global warming. Considering that heterotrophic respiration from unsaturated soils is primarily driven by microbial reduction of oxygen (O₂), we propose a new concept to model the respiration by tracking dissolution of gaseous O₂ and its subsequent diffusion and microbial reduction at hydrated microsite in the pore space of soil. Total respiration from a soil sample is calculated by summing the O₂ reduced by all microbes in the soil. This allows us to separate physical processes and microbial activity occurring at microsites and incorporate pore-scale substrate heterogeneity, macropores and other factors explicitly into the model. We show that scaling up these microscopic physical processes over a soil sample makes soil moisture, temperature, and other factors inherently integrated in their influence on microbial respiration, and that a change in one of them affects the response of the respiration to the change in others. Comparison with experimental data shows the model can reproduce the diverse moisture-respiration relationships observed from various experiments and predict the change in soil respiration with temperature. It is noteworthy to point out that previous studies had attributed the variations in the moisture and temperature sensitivity of heterotrophic soil respiration to microbial adaptation; herein we demonstrate that changes in soil structure and physical processes can also give rise to such variations. Distinguishing between physical and microbial effects in data analysis and modelling is therefore crucial, as mistaking physical effects for microbial adaptation would lead to errors in predicting the response of SOC to environmental changes.</p></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"185 ","pages":"Article 109147"},"PeriodicalIF":9.7,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44164261","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}

{"title":"Long-term fertilization enhances the activity of anaerobic oxidation of methane coupled to nitrate reduction and associated microbial abundance in paddy soils","authors":"Yuling Yang ,&nbsp;Lidong Shen ,&nbsp;Xu Zhao ,&nbsp;Evgenios Agathokleous ,&nbsp;Shuwei Wang ,&nbsp;Bingjie Ren ,&nbsp;Wangting Yang ,&nbsp;Jiaqi Liu ,&nbsp;Jinghao Jin ,&nbsp;Hechen Huang ,&nbsp;Hongsheng Wu","doi":"10.1016/j.soilbio.2023.109130","DOIUrl":"10.1016/j.soilbio.2023.109130","url":null,"abstract":"<div><p>Anaerobic oxidation of methane coupled to nitrate reduction (nitrate-coupled AOM) is performed by <em>Candidatus Methanoperedens</em> nitroreducens (<em>M. nitroreducens</em>)-related archaea, and is recently recognized as a crucial component of the global carbon cycle. The input of fertilizers is an essential agricultural practice that greatly impacts methane (CH₄) production and emission. However, the significance of nitrate-coupled AOM in CH₄ cycling and its response to fertilization in rice fields remain unclear. In this study, the potential nitrate-coupled AOM rates and the communities of <em>M. nitroreducens</em>-related archaea in rice fields were examined at different soil layers (0–10, 10–20, and 30–40 cm) at tillering, elongation, flowering, and ripening stages under three long-term fertilization treatments (CK-without fertilizer, CF-chemical fertilization, or CFS-chemical fertilization with straw incorporation). The results indicated that both CF (1.07 nmol ¹³CO₂ g⁻¹ d⁻¹) and CFS (1.21 nmol ¹³CO₂ g⁻¹ d⁻¹) treatments significantly promoted the potential nitrate-coupled AOM rates compared to CK (0.53 nmol ¹³CO₂ g⁻¹ d⁻¹). A greater response of potential activity to fertilization was observed at plough layer (upper 20 cm) and during elongation stage. The abundance of <em>M. nitroreducens</em>-related archaea under CF (1.12 × 10⁷ copies g⁻¹) and CFS (1.62 × 10⁷ copies g⁻¹) treatments was significantly greater than that under CK (6.93 × 10⁶ copies g⁻¹). Conversely, the growth response of these archaeal to fertilization was stronger at deeper layer (30–40 cm). Moreover, no significant change was observed in the community composition of <em>M. nitroreducens</em>-related archaea among treatments. Correlation analysis suggested that the variations of soil organic carbon, NH₄⁺, and NO₃⁻ contents caused by fertilization were key factors influencing the potential nitrate-coupled AOM rates and <em>M. nitroreducens</em>-related archaeal abundance. Our findings provide the first evidence for positive response of nitrate-coupled AOM to long-term fertilization, demonstrating its potential to act as an important process for mitigating CH₄ emission in rice fields.</p></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"185 ","pages":"Article 109130"},"PeriodicalIF":9.7,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41750476","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}

{"title":"Thirty years of increased precipitation modifies soil organic matter fractions but not bulk soil carbon and nitrogen in a mesic grassland","authors":"Katherine S. Rocci ,&nbsp;Michael Bird ,&nbsp;John M. Blair ,&nbsp;Alan K. Knapp ,&nbsp;Chao Liang ,&nbsp;M. Francesca Cotrufo","doi":"10.1016/j.soilbio.2023.109145","DOIUrl":"10.1016/j.soilbio.2023.109145","url":null,"abstract":"<div><p>Grassland ecosystems, which are known to be sensitive to climate change, have shown minimal responses of soil carbon (C) and nitrogen (N) pools to increased moisture availability, despite moisture-induced changes in plants and soil microbes (e.g., expected drivers of soil C and N). However, it is not clear if this apparent limited response is due to an unresponsive belowground system or because alterations in multiple soil organic matter (SOM) component pools and fluxes offset each other. To investigate potential responses of C and N in SOM to decadal increases in precipitation, we sampled soils from a 30-year precipitation augmentation experiment in an annually burned mesic grassland. We measured C and N in three SOM fractions which vary in their plant and microbial controls 1) free particulate OM (fPOM), 2) occluded POM plus heavy, coarse OM (oPOM + hcOM), and 3) mineral-associated OM (MAOM), as well as amino sugars, pyrogenic C and N, and root quality metrics. We found no changes in bulk C or N under increased precipitation, but SOM fractions were modified. Altered plant inputs and soil N availability appeared to drive the responses of fPOM N and oPOM + hcOM C:N, which were increased and decreased, respectively, by increased precipitation. In contrast, the observed increase in MAOM C and N under increased precipitation could not be connected to a specific driver, suggesting additional plant, microbial, or mineral measurements may be required. Regardless, our results indicate that investigating SOM fractions may more directly connect soil C and N pools and their drivers, compared to measuring only bulk SOM. Further, our finding of greater stable OM (MAOM) under increased precipitation suggests soil C storage could provide a negative feedback to climate change with increased moisture availability, but the lack of bulk SOM response suggests that this feedback is not strong in mesic grasslands.</p></div>","PeriodicalId":21888,"journal":{"name":"Soil Biology & Biochemistry","volume":"185 ","pages":"Article 109145"},"PeriodicalIF":9.7,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47949453","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}