Biology and Fertility of Soils最新文献

{"title":"Harnessing key bacteria from suppressive soil to mitigate banana Panama disease","authors":"Nana Lv, Mohammadhossein Ravanbakhsh, Shuqin Ling, Yannan Ou, Chengyuan Tao, Hongjun Liu, Rong Li, Zongzhuan Shen, Qirong Shen","doi":"10.1007/s00374-024-01836-7","DOIUrl":"https://doi.org/10.1007/s00374-024-01836-7","url":null,"abstract":"<p>Soil microbiomes play a pivotal role in shaping plant health and their ability to suppress the pathogens. However, the specific microbial features that confer disease suppression in agricultural soils have remained unknown. In this study, we aim to elucidate the mechanistic roles of soil key bacteria contributing to disease suppression in banana Panama disease by using a comprehensive soil survey focusing on suppressive, and conducive soils. Through an initial field survey across twelve paired locations, we identified five fields with significantly lower pathogen abundances compared to their co-located counterparts. Subsequent greenhouse experiments validated the disease-suppressive nature of soils collected from Jianfeng (JF) and Lingao (LG), both exhibiting low pathogen densities. Furthermore, four OTUs classified as <i>Massilia</i> (OTU44), <i>Flavisolibacter</i> (OTU396), <i>Brevundimonas</i> (OTU632) and <i>Pseudomonas</i> (OTU731), respectively, were identified as key players in suppressing pathogen invasion as they were significantly enriched in suppresive groups and pathogen inoculated treatments. The present results might suggest a vital link between these soil bacteria and pathogen inhibition in banana rhizosphere via a greenhouse experiment. The abundance of nonribosomal peptide synthetase (NRPS) genes, which was responsible for antibiotic synthesis and significantly enriched in the banana rhizosphere after beneficial microorganism inoculation, displayed a significant and negative correlation with pathogen abundance while a positive correlation with relative abundance of <i>Pseudomonas</i>. This result suggests that the up-regulation of NRPS genes may play a key role in bolstering banana plant immunity. These findings not only provide promising biocontrol strategies but also offer valuable insights into the dynamic relationship between soil microbiomes and plant physiology, paving the way for sustainable agriculture and disease management.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141315770","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":"Effects of military training, warfare and civilian ammunition debris on the soil organisms: an ecotoxicological review","authors":"Andrés Rodríguez-Seijo, David Fernández-Calviño, Manuel Arias-Estévez, Daniel Arenas-Lago","doi":"10.1007/s00374-024-01835-8","DOIUrl":"https://doi.org/10.1007/s00374-024-01835-8","url":null,"abstract":"<p>Civilian and military activities are sources of water and soil contamination by inorganic and organic contaminants caused by shooting practices, warfare, and/or mechanized military training. Lead poisoning and contaminant bioaccumulation due to spent shots or other related military contaminants have been widely studied for mammals, birds, and plants. Although there are different papers on the impact on earthworms, information on micro and mesofauna (i.e., collembola, nematodes, etc.) is still scarce. Here, we review the published data regarding the impact of civilian and military shooting activities, including war-impacted areas, focusing on soil organisms, from microbial communities to the ecotoxicological effects on terrestrial organisms. One hundred eleven studies were considered where earthworms and enchytraeids were widely studied, especially under ecotoxicological assays with Pb and energetic-related compounds from military explosives. There is a lack of information on soil organism groups, such as mites, ants, or gastropods, which play important roles in soil function. Data from combined exposures (e.g., PTEs + TNT and PTEs + PAHs) is scarce since several studies focused on a single contaminant, usually Pb, when combined contaminants would be more realistic. Ecotoxicological assays should also cover other understudied ammunition elements, such as Bi, Cu, or W.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141292719","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":"Aridity-driven divergence in soil microbial necromass carbon in alpine grasslands of the Tibetan Plateau","authors":"Yunfei Zhao, Xia Wang, Yazhen Li, Menghan Yuan, Jia Li, Huawei Zhu, Zhuoyun Cheng, Wenhui Duan, Junwu Wang","doi":"10.1007/s00374-024-01834-9","DOIUrl":"https://doi.org/10.1007/s00374-024-01834-9","url":null,"abstract":"<p>Soil microbial necromass carbon (MNC) contributes to the long-term stability of soil organic carbon (SOC). However, the response of MNC across aridity gradients remains unclear, especially in vulnerable alpine ecosystems. Here, we examined alpine grasslands from 180 sites spanning a 3,500 km aridity gradient on the Tibetan Plateau to investigate how MNC abundance and composition (contributions of bacterial and fungal necromass carbon) vary with climate. MNC was variable, ranging from 0.55 to 26.95 g kg⁻¹ soil, with higher content observed in humid and dry-subhumid regions than in arid and semiarid regions in the Western Tibetan Plateau. Soil properties were the dominant drivers of MNC, with soil fertility (cation exchange capacity and total phosphorus) and weathering products (clay, silt and iron/aluminum oxides) facilitating MNC accumulation, while a negative correlation was observed between MNC and soil pH. A pivotal aridity threshold of 0.60 underpinned a non-linear decrease in MNC with increasing aridity across soil condition gradients; MNC was negatively correlated with aridity below this threshold and showed no correlation beyond it. Given this pivotal aridity threshold, we delineated the drivers of MNC under conditions of low (aridity &lt; 0.6) versus high (aridity &gt; 0.6) aridity. In low-aridity conditions, MNC accumulation was governed by aridity, soil fertility, weathering products, and pH, whereas in high-aridity conditions, the interplay between soil properties and temperature took precedence. Species richness enhanced carbon accumulation from microbial residues under low-aridity conditions more so than under high-aridity conditions, with fungal necromass carbon consistently being a higher contributor to SOC than bacterial necromass carbon, particularly in humid regions. These findings highlight aridity-driven divergence in MNC and propose that conserving plant diversity may mitigate the adverse effects of aridification on MNC under low-aridity conditions in alpine grasslands.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141156719","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":"Nitrogen limitation in eucalypt roots: a cascading influence on the mobilization of soil organic matter","authors":"Luis Carlos Colocho Hurtarte, Ivan Francisco Souza, Rodrigo Teixeira Ávila, Luís Fernando J. Almeida, Gabriela Soares, Leonardus Vergütz, Ivo Ribeiro Silva","doi":"10.1007/s00374-024-01832-x","DOIUrl":"https://doi.org/10.1007/s00374-024-01832-x","url":null,"abstract":"<p>Emerging scientific evidence has shown that root exudates may trigger the mobilization of soil organic matter (SOM), particularly under nutrient limitation. However, the role of changes in root morphology, metabolism, exudation, and their impact on rhizospheric properties and SOM remain poorly known. To address this issue, we conducted a rhizobox experiment for 50 days in which pre-grown eucalypt plants (120 days-old) were supplied with nutrient solutions providing either limited (0.0 mg L^− 1) or normal N supply (196.0 mg L^− 1). After 48 days, we used a ¹³CO₂ pulse labeling to track the impact of N limitation on C translocation to roots and soil respiration. After the 50th day, we assessed root morphology and metabolism, rhizospheric pH, mineral crystallinity, C and N contents, and the molecular composition of SOM. Under N limitation, eucalypt plants showed reduced photosynthesis, increased their root-to-shoot ratio and root branching, with organic acids prevailing among root metabolites. Overall, N-limited eucalypt plants led to a cascading of changes in the rhizosphere: increased concentrations of recently fixed ¹³C-CO₂, citrate, and N-bearing compounds, whereas soil pH and Fe-bound SOM decreased. These results were not followed by significant changes in microbial biomass, neither fungi: bacteria nor Gram-positive: Gram-negative ratios. Our results show that under N limitation, eucalypt roots exhibited a cascade of morpho-physiological adjustments that ultimately increased the mobilization of some SOM pools. Therefore, the combined impacts of those root morpho-physiological traits on the mobilization of SOM may reduce the overall soil C sink of eucalypt forests under N limitation.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141096651","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":"Assessment of phosphorus use and availability by contrasting crop plants in a tropical soil","authors":"Lenir Fátima Gotz, Adila Natália França de Almeida, Rafael de Souza Nunes, Leo Murtagh Condron, Paulo Sergio Pavinato","doi":"10.1007/s00374-024-01833-w","DOIUrl":"https://doi.org/10.1007/s00374-024-01833-w","url":null,"abstract":"<p>Phosphorus (P) is a key element for energy transfer, and biosynthesis of nucleic acids and cell membranes. The objective of this study was to investigate and quantify P utilization by different grain—maize (<i>Zea mays</i> L.) and soybean (<i>Glycine max</i> L.)—and forage-cover crop brachiaria (<i>Brachiaria ruziziensis</i>) plant species in a low fertility highly weathered Oxisol. Two rates of P (25 and 50 mg kg⁻¹) were applied by water-soluble P fertilizer (triple superphosphate) to each of 12 crop cycles, together with a control (no P added). Measurements included plant biomass production and P uptake for each cycle, and analysis of soil P fractions (including labile and non-labile) and enzymes activities (acid phosphatase and β-glucosidase) were done at the beginning of the experiment and after 3, 6, and 12 cycles. Total biomass production and P uptake/removal were significantly higher for brachiaria than maize and soybean, which was reflected in the P use efficiency (PUE), being higher for brachiaria (57%), compared with maize (26%) and soybean (21%). The higher PUE by brachiaria was partly attributed to higher levels of acid phosphatase and β-glucosidase activities which indicated enhanced biological activity and P cycling under brachiaria. Data from the control treatment clearly demonstrated that all three plant species mobilized stable/occluded fractions of P throughout the experiment, however, brachiaria could produce more using less P. The findings of this study indicated the inclusion of brachiaria in crop rotations as a forage or cover crop/green manure may enhance overall P use efficiency.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141079380","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":"Microbial ammonium immobilization promoted soil nitrogen retention under high moisture conditions in intensively managed fluvo-aquic soils","authors":"Hui Wang, Zhifeng Yan, Zengming Chen, Xiaotong Song, Jinbo Zhang, Si-Liang Li, Christoph Müller, Xiaotang Ju, Xia Zhu-Barker","doi":"10.1007/s00374-024-01831-y","DOIUrl":"https://doi.org/10.1007/s00374-024-01831-y","url":null,"abstract":"<p>Quantifying the gross rates of individual nitrogen (N) processes is critical for understanding the availability, retention and loss of N and its eco-environmental impacts in agricultural ecosystems. Here, we carried out a ¹⁵N tracing study to quantify the influence of soil moisture on the gross rates of ten different N processes in two intensively managed fluvo-aquic soils. Results showed that the gross N mineralization rates were insensitive to changes in soil moisture, ranging from 40 to 120% water-filled pore space (WFPS). Contrarily, the gross ammonium (NH₄⁺) immobilization rates increased exponentially with elevated soil moisture. Specifically, under high soil moisture conditions (i.e., 90–120%WFPS), the gross NH₄⁺ immobilization rates (4.04 ± 0.83 and 0.88 ± 0.28 mg N kg^− 1d^− 1 for the two soils, respectively) were nearly four times higher than those under medium or low moisture conditions (i.e., 40–80%WFPS). Meanwhile, the high WFPS reduced the gross autotrophic nitrification rates (5.92 ± 2.15 and 12.31 ± 3.83 mg-N kg^− 1d^− 1 for the two soils, respectively) to only one-third to one-half of those that were observed under medium or low WFPS. By contrast, the rates of nitrate (NO₃⁻) immobilization increased in one soil whereas they decreased in another under high moisture conditions, and the other N processes (including heterotrophic nitrification and dissimilatory nitrate reduction to ammonium (DNRA)) were negligible throughout the different WFPS. Overall, our results suggest that under highly saturated conditions, the increase in microbial NH₄⁺ immobilization and decrease in autotrophic nitrification are critical for N retention in the fluvo-aquic soils. These findings provide valuable insights into potential alterations in soil N retention or loss under future climate change scenarios, where more intensive irrigation and extreme rainfall events are anticipated.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140919639","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":"Modulation of volatile emissions in olive trees: sustained effect of Trichoderma afroharzianum T22 on induced plant defenses after simulated herbivory","authors":"Martin Aguirrebengoa, Beatriz Moreno, Rafael Alcalá-Herrera, Rafael Núñez, Nuria Guirado, Juan M. García, María J. Pozo, Emilio Benítez","doi":"10.1007/s00374-024-01830-z","DOIUrl":"https://doi.org/10.1007/s00374-024-01830-z","url":null,"abstract":"<p>We explored the activation of defense genes and the changes in volatile profiles in olive (<i>Olea europaea</i> var. Picual) plants subjected to mechanical wounding and prior soil inoculation with the fungus <i>Trichoderma afroharzianum</i> T22. Our findings indicate a sustained effect of the inoculant in olive plants, which shifted the constitutive volatile emission more significantly towards an aldehyde-dominated blend than the mechanical damage alone. Furthermore, we found that wounding alone did not alter the expression of hydroperoxide lyase genes associated with aldehyde biosynthesis. However, this expression was significantly enhanced when combined with prior T22 inoculation. Mechanical wounding amplified the plant’s immediate defensive response by enhancing the upregulation of the direct defense enzyme acetone cyanohydrin lyase. <i>Trichoderma afroharzianum</i> T22 also modulated direct defense, although to a lesser extent, and its effect persisted 9 months after inoculation. Metagenomic analyses revealed that aerial mechanical damage did influence specific root bacterial functions. Specifically, an upregulation of predicted bacterial functions related to various metabolic processes, including responses to biotic and abiotic stresses, was observed. On the contrary, T22’s impact on bacterial functional traits was minor and/or transient.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140919724","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":"Fates of slurry-nitrogen applied to mountain grasslands: the importance of dinitrogen emissions versus plant N uptake","authors":"Michael Dannenmann, Irina Yankelzon, Svenja Wähling, Elisabeth Ramm, Mirella Schreiber, Ulrike Ostler, Marcus Schlingmann, Claus Florian Stange, Ralf Kiese, Klaus Butterbach-Bahl, Johannes Friedl, Clemens Scheer","doi":"10.1007/s00374-024-01826-9","DOIUrl":"https://doi.org/10.1007/s00374-024-01826-9","url":null,"abstract":"<p>Intensive fertilization of grasslands with cattle slurry can cause high environmental nitrogen (N) losses in form of ammonia (NH₃), nitrous oxide (N₂O), and nitrate (NO₃⁻) leaching. Still, knowledge on short-term fertilizer N partitioning between plants and dinitrogen (N₂) emissions is lacking. Therefore, we applied highly ¹⁵N-enriched cattle slurry (97 kg N ha⁻¹) to pre-alpine grassland field mesocosms. We traced the slurry ¹⁵N in the plant-soil system and to denitrification losses (N₂, N₂O) over 29 days in high temporal resolution. Gaseous ammonia (NH₃), N₂ as well N₂O losses at about 20 kg N ha⁻¹ were observed only within the first 3 days after fertilization and were dominated by NH₃. Nitrous oxide emissions (0.1 kg N ha⁻¹) were negligible, while N₂ emissions accounted for 3 kg of fertilizer N ha⁻¹. The relatively low denitrification losses can be explained by the rapid plant uptake of fertilizer N, particularly from 0–4 cm depth, with plant N uptake exceeding denitrification N losses by an order of magnitude already after 3 days. After 17 days, total aboveground plant N uptake reached 100 kg N ha⁻¹, with 33% of N derived from the applied N fertilizer. Half of the fertilizer N was found in above and belowground biomass, while at about 25% was recovered in the soil and 25% was lost, mainly in form of gaseous emissions, with minor N leaching. Overall, this study shows that plant N uptake plays a dominant role in controlling denitrification losses at high N application rates in pre-alpine grassland soils.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140902885","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":"Soil contribution to the cobalamin (vitamin B12) supply of terrestrial organisms","authors":"Arne Matteo Jörgensen, Rainer Georg Joergensen","doi":"10.1007/s00374-024-01828-7","DOIUrl":"https://doi.org/10.1007/s00374-024-01828-7","url":null,"abstract":"<p>Cobalamin (Vitamin B₁₂) is a cofactor for many enzymes, including those in bacteria, archaea, algae, and mammals. In humans, cobalamin deficiency can lead to pernicious anaemia as well as gastrointestinal and neurological disorders. In contrast to marine ecosystems, there is a great paucity of information on the role of soils and terrestrial plants in the supply of cobalt and cobalamin to microorganisms and animals. The content of cobalt cations in most soils is usually sufficient to maintain growth, and the density of cobalamin-producing soil prokaryotes is high in comparison to water bodies. The cobalt content of most soils is usually sufficient in comparison with water, and the density of cobalamin-producing soil prokaryotes is high. Therefore, terrestrial plants are an important cobalt source for cobalamin-producing rumen and gut prokaryotes. The major source of cobalamin for most other animals is the meat of ruminants as well as other animal-derived products, bacteria in insects, and coprophagy, e.g., by rodents. In addition, faecal deposits, and fertilizers as well as soil bacteria add to the cobalamin supply. However, those archaea and bacteria that do not produce cobalamin obtain this coenzyme or its analogues from the environment. Therefore, presence or absence of cobalamin-producing species in soil affects the whole soil microbiome. However, our knowledge concerning microbial producers and consumers of cobalamin in soils is still limited, despite some recent advances. The main reasons are a low cobalamin content in soils and challenging methods of determination. In this regard, advanced analytical knowledge and technical equipment are required, which are usually unavailable in soil laboratories. This review provides relevant methodological information on sample homogenization, extraction, concentration, and purification as well as analysis of cobalamin.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140895380","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":"Root mucilage nitrogen for rhizosphere microorganisms under drought","authors":"Meisam Nazari, Samuel Bickel, Yakov Kuzyakov, Nataliya Bilyera, Mohsen Zarebanadkouki, Birgit Wassermann, Michaela A. Dippold","doi":"10.1007/s00374-024-01827-8","DOIUrl":"https://doi.org/10.1007/s00374-024-01827-8","url":null,"abstract":"<p>Nitrogen (N) is a crucial nutrient for the growth and activity of rhizosphere microorganisms, particularly during drought conditions. Plant root-secreted mucilage contains N that could potentially nourish rhizosphere microbial communities. However, there remains a significant gap in understanding mucilage N content, its source, and its utilization by microorganisms under drought stress. In this study, we investigated the impact of four maize varieties (DH02 and DH04 from Kenya, and Kentos and Keops from Germany) on the secretion rates of mucilage from aerial roots and explored the origin of mucilage N supporting microbial life in the rhizosphere. We found that DH02 exhibited a 96% higher mucilage secretion rate compared to Kentos, while Keops showed 114% and 89% higher secretion rates compared to Kentos and DH04, respectively. On average, the four maize varieties released 4 μg N per root tip per day, representing 2% of total mucilage secretion. Notably, the natural abundance of ¹⁵N isotopes increased (higher δ¹⁵N signature) with mucilage N release. This indicates a potential dilution of the isotopic signal from biological fixation of atmospheric N by mucilage-inhabiting bacteria as mucilage secretion rates increase. We proposed a model linking mucilage secretion to a mixture of isotopic signatures and estimated that biological N fixation may contribute to 45 - 75% of mucilage N per root tip. The N content of mucilage from a single maize root tip can support a bacterial population ranging from 10⁷ to 10¹⁰ cells per day. In conclusion, mucilage serves as a significant N-rich resource for microbial communities in the rhizosphere during drought conditions.</p>","PeriodicalId":9210,"journal":{"name":"Biology and Fertility of Soils","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140895555","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}