首页期刊导航|Soil Biology & Biochemistry
期刊信息/Journal information
Soil Biology & Biochemistry
Pergamon Press.
Soil Biology & Biochemistry

Pergamon Press.

0038-0717

Soil Biology & Biochemistry/Journal Soil Biology & BiochemistrySCIISTPAHCI
正式出版
收录年代

    Do interactions between application rate and native soil organic matter content determine the degradation of exogenous organic carbon?

    Mendoza O.De Neve S.Deroo H.Li H....
    9页
    查看更多>>摘要：? 2021 Elsevier LtdAlthough the amendment of various forms of exogenous organic matter (EOM) is a common practice in cropland production, it is to date not clear if its mineralisation in soil depends on application rate. Previous research suggested that spatial concentration of EOM in soil positively impacts its degradability. Here, we seek to test these reports and furthermore to investigate if an interactive effect exists with native soil organic carbon (SOC) concentration. We hypothesised that at a low EOM dose, more EOM remains undecomposed in soil and that this effect becomes stronger at lower SOC level. Moreover, as a secondary goal, we explored if priming of native SOC mineralisation depends on EOM dose. Therefore, we set up seventy-day soil incubation experiments with six varying C4-maize residue (δ13C = ?12.7‰) doses (0–6 g kg?1) in soil mesocosms of loamy sand subsoils (δ13C = ?25.7‰) with three different native SOC levels (i.e. 0.1, 0.5, and 1.0%). Soil CO2 emissions and isotopic signature measurements of CO2 allowed to discern EOM and SOC mineralisation. We found that EOM-derived C mineralisation increased proportionally to EOM dose, refuting the hypothesised relative undecomposed EOM at low concentration. Volumes of larger pore neck size diameter classes (60–100 and >300 μm) almost doubled at high EOM dose, demonstrating formation of macropores. Yet, this apparently did not impact EOM mineralisation, probably because O2 supply was always sufficient to allow unlimited activity of EOM degraders, even at higher EOM doses, as indicated by generally higher measured redox potential. With EOM dose, fungal marker PLFA abundances increased in the 1% SOC soil and protozoan abundances increased in all three soils, but apparently these shifts did not result in an enhanced relative degradation of the EOM. Increasing EOM doses induced negative priming, e.g. EOM ≥1 g kg?1 reduced SOC mineralisation by >43% and >24% compared to the control in the 0.1 and 0.5% SOC soils, respectively; whereas no priming occurred in soil with 1% SOC. These results were largely explained by the amount of added C relative to microbial biomass carbon, and the theorised switch of slow decomposers (so called K-strategists and involved in recalcitrant compound decomposition) from SOM to preferentially decompose EOM at higher doses. We also postulate that at low SOC %, the obvious increased O2 consumption with higher EOM dose more readily results in local anaerobic conditions in finer pores, i.e. where SOC is located and mineralised. We conclude that on the short term, agricultural management for SOM thus does not need to consider EOM doses but only the total amount of EOM.
      原文链接:
    • NSTL
    • Elsevier

    Large-scale homogenization of soil bacterial communities in response to agricultural practices in paddy fields, China

    Wang H.Li H.Tao X.Zhang Z....
    12页
    查看更多>>摘要：? 2021 Elsevier LtdThe transformation of natural habitats into cropland is a major issue in ecological conservation. Of particular concern is the large-scale biotic homogenization (reduced β-diversity) of soil microbial communities. Paddy fields represent the largest anthropogenic ecosystem in the world; however, bacterial homogenization and reduced biodiversity in paddy fields caused by intensive modern agricultural practices have yet to be explored. Here, samples were collected from 257 sites in four typical rice-growing regions across a 4,000-km transect in China, including both paddy fields and adjacent natural habitats. These four regions follow a unique gradient of rice cultivation management, from modern mechanical to traditional manual practices. Distance–decay patterns of bacterial communities in paddy fields revealed reduced β-diversity compared to surrounding natural habitats. Modern rice farming practices (plowing with machines) caused stronger homogenization of soil bacterial communities than traditional farming (plowing by hand). Among the four paddy regions, plowing by hand retained the highest soil bacterial β-diversity. Moreover, a significant inverse correlation was observed between bacterial β-diversity and the agricultural mechanization level. Among multiple environmental factors, dramatic spatial homogenization of soil physicochemical properties, particularly soil nutrient contents, and reduced dispersal limitation caused by modern farming activities both strongly predict a reduction of bacterial β-diversity in modern paddy fields.
      原文链接:
    • NSTL
    • Elsevier

    Pathways of biogenically excreted organic matter into soil aggregates

    Guhra T.Totsche K.U.Stolze K.
    18页
    查看更多>>摘要：? 2021 The AuthorsSoil organisms are recognized as ecosystem engineers and key for aggregation in soil due to bioturbation, organic matter (OM) decomposition, and excretion of biogenic OM. The activity of soil organisms is beneficial for soil quality, functions, and nutrient cycling. These attributions are based on field-scale observations that link the presence and activity of organisms to spatiotemporal changes in soil properties and can be traced back to the formation of biogenic aggregates. This biogenic formation pathway encompasses a cascade of processes so far not discussed comprehensively. A more general approach needs to consider the activity and feedback loops between soil biota, the active release of biogenic OM by excretion, the interaction of biogenic OM with soil constituents, the formation of organo-mineral associations, and how these become incorporated in aggregated structures. Especially the function of biogenically excreted OM, which is quite complex in composition, is controversial as it permits or inhibits aggregation. This review analyzes the various roles of biogenically excreted OM may take as an aggregation agent. We will show that its function depends on the interplay of numerous factors, including environmental conditions, variety of OM producers, composition and availability of biogenically excreted OM, and type of interacting mineral phase. We consider biogenically excreted OM to affect aggregate formation in three different ways: (I) as a bridging agent which promotes the aggregation due to surface modifications and attraction, (II) as a separation agent which favors the formation, mobility, and transport of organo-mineral associations and inhibits their further inclusion into aggregates, and (III) as a gluing agent which mediates aggregate stability, after an external force provokes a close approach of soil particles. We conclude that biogenically excreted OM takes these functional roles simultaneously and to a varying extent across spatiotemporal scales. Hence, biogenically excreted OM is involved in the surface modification of soil particles, in the enmeshment and gluing of particles into soil aggregates, in the (im-)mobilization, and in facilitating the transport of particles. All that depends on the interplay of a hierarchy of factors comprising the local soil community's composition, the properties of biogenically excreted OM, and the conditions of the immediate environment.
      原文链接:
    • NSTL
    • Elsevier

    Disentangling the effects of nitrogen availability and soil acidification on microbial taxa and soil carbon dynamics in natural grasslands

    Bai Y.Lu X.Xing W.Ying J....
    13页
    查看更多>>摘要：? 2021Although nitrogen (N) enrichment enhances both soil N availability and soil acidification, it is difficult to isolate their effects on microbial taxa that drive the soil carbon (C) dynamics under different microbial C limitation conditions in natural ecosystems. Based on long-term field N addition, field acid addition, and laboratory incubation experiments in the Inner Mongolian grassland, we disentangled the effects of increased N availability and soil acidification on relative abundance of bacterial and fungal taxa under the mild (soil incubation for 28 days) and strong microbial C limitations (soil incubation for 191 days). Bacterial and fungal taxa are grouped into four ecological categories (N sensitive, acid sensitive, N and acid sensitive, N and acid insensitive) with multiple levels of N addition. In the context of the mild microbial C limitation, increased N availability promoted the relative abundance of the fungal class Eurotiomycetes (N positive sensitivity) under the low–medium levels of N addition, with an associated decrease in soil labile carbonyl C content. Conversely, increased N availability reduced the relative abundance of fungal class Sordariomycetes (N negative sensitivity) and bacterial gene copies (N and acid negative sensitivity) under the high levels of N addition, with associated increases in labile O-alkyl C and di-O-alkyl C content, making soil C more labile. In the context of the strong microbial C limitation, increased soil acidification promoted the abundance of acidophilous fungal classes Sordariomycetes and Eurotiomycetes under the low–medium levels of N addition, with an associated decrease in soil labile carbonyl C content. However, increased N availability promoted the relative abundance of the bacterial phylum Thaumarchaeota (N positive sensitivity equal to acid negative sensitivity), with associated low labile O-alkyl C and di-O-alkyl C content, leaving C chemistry more resistant. By applying the ecological category concept to soil microbes, our findings highlight that the N enrichment-induced shifts in abundance of N- and/or acid-sensitive categories are tightly associated with the changes in soil organic carbon (SOC) chemical composition, and the relationship between microbial function groups and SOC chemistry varied substantially under the mild versus strong microbial C limitations.
      原文链接:
    • NSTL
    • Elsevier

    Limited effects of century-old biochar on taxonomic and functional diversities of collembolan communities across land-uses

    Pollet S.Burgeon V.Cornelis J.-T.Chabert A....
    11页
    查看更多>>摘要：? 2021 Elsevier LtdBiochar is often considered as a promising climate-smart agricultural tool capable of stabilizing carbon overtime in soils while improving crop productivity. However, long-term consequences for soil biodiversity have barely been addressed. The main aim of this study was to investigate the effects of centennial biochar on the total collembolan densities, the taxonomic and functional diversities of collembolan communities. We sampled preindustrial charcoal kiln sites across three land-uses (cropland, grassland and forest) in temperate soils as model for aged biochar. The complementarity use of total collembolan densities, a taxonomic approach (species richness, Pielou evenness) and a functional approach (functional richness, Rao quadratic entropy, community-weighted means of the functional traits) showed that charcoal enrichment had little effect on collembolan communities. Yet, there was a systematic shift in traits composition of collembolan communities towards traits adapted to life at depth in the presence of charcoal across land-uses. In cropland soils, charcoal induced minor species and abundance changes that significantly shifted the traits composition. In grassland soils, charcoal significantly decreased the taxonomic evenness of communities and host new species with more diverse functional profiles. In forest soils, charcoal was suggested to induce a species domination and a functional homogenization of collembolan communities. Our results suggest that the long-term effect of biochar on soil fauna are related to slight direct or indirect modifications of soil habitat, which hinges on land-use. Indeed, the land-use was a much stronger driver in shaping soil collembolan communities than centennial charcoal. We advocate furthering functional traits studies on the ecological and edaphic mechanisms driving Collembola long-term responses to biochar amendment.
      原文链接:
    • NSTL
    • Elsevier

    The importance of rare versus abundant phoD-harboring subcommunities in driving soil alkaline phosphatase activity and available P content in Chinese steppe ecosystems

    Xu L.Cao H.Yao M.Zhou S....
    11页
    查看更多>>摘要：? 2021 Elsevier LtdThe alkaline phosphatase-harboring community (the phoD community hereafter) plays an important role in organic P mineralization. Here, we comparatively studied the biogeographical patterns of abundant and rare phoD subcommunities and their roles in mediating soil phosphatase (ALP) activity and available P content in three representative steppe regions in China, namely the Inner Mongolian Plateau, the Loess Plateau, and the Qinghai-Tibetan Plateau. The results indicated that soil ALP activity, available P content, soil and microbial biomass C:P, N:P ratios varied significantly among steppe regions. Significant differences in diversity, metabolic energy and assembly processes were observed between abundant and rare phoD subcommunities. First, richness of the rare taxa was significantly higher than that of the abundant subcommunities. Second, testing of metabolic theory of ecology showed that rare subcommunities had a higher metabolic activation energy than the abundant taxa. Thirdly, deterministic other than stochastic processes dominated in the community assembly of both subcommunities. Soil pH was the key environmental determinant in community assembly processes for both subcommunities. The relationships among P-cycling parameters and between these parameters and phoD diversity were scale-dependent. The phylogenetic beta diversity of the rare phoD taxa had higher correlations with P-cycling parameters than that with the abundant taxa. More rare than abundant genera were significantly correlated with P limitation and ALP activity at different spatial scales. The rare Frankia was the key genus detecting P limitation, producing ALP and enhancing soil available P in Qinghai-Tibet.
      原文链接:
    • NSTL
    • Elsevier

    Soil-atmosphere exchange of CH4 in response to nitrogen addition in diverse upland and wetland ecosystems: A meta-analysis

    Wu J.Xing W.Liu G.Cheng X....
    11页
    查看更多>>摘要：? 2021Reactive nitrogen (N) addition may profoundly impact the global CH4 budget through its substantial effects on soil CH4 uptake and emission. However, the magnitude and direction of soil CH4 uptake and emission rates in response to N addition on a global scale are still unclear. Here, to investigate the effects of N addition on soil CH4 uptake and emission rates in various upland and wetland ecosystems, we synthesized a large dataset comprising 878 paired observations from 178 studies. Across these studies, we found that N addition significantly reduced soil CH4 uptake rate in upland ecosystems but significantly increased soil CH4 emission rate in wetland ecosystems. The magnitude of the effects was ecosystem-type dependent. Following N addition, reduction of soil CH4 uptake rate and increase in CH4 emission rate were significantly higher in natural ecosystems (with the exception of grassland ecosystems) than in agricultural ecosystems. However, reduction in soil CH4 uptake rate increased with N addition rate in only natural ecosystems. Moreover, the soil CH4 uptake rate in N-limited ecosystems (cold temperate zone and Tibet Plateau) was less sensitive to N addition compared to N-rich ecosystems (subtropical and tropical zones). Additionally, organic N addition had a lower reduction effect on soil CH4 uptake in upland ecosystems and a lower stimulatory effect on soil CH4 emission rate in wetland ecosystems compared to the addition of inorganic N forms. Overall, our results shed light on the magnitude and direction of the effect of N addition on soil CH4 uptake and emission rates in diverse upland and wetland ecosystems and will help improve ecosystem models for predicting soil CH4 flux caused by N addition.
      原文链接:
    • NSTL
    • Elsevier

    Competition within low-density bacterial populations as an unexpected factor regulating carbon decomposition in bulk soil

    Coche A.de Dreuzy J.-R.Babey T.Rapaport A....
    13页
    查看更多>>摘要：? 2021 Elsevier LtdBacterial decomposition of organic matter in soils is generally believed to be mainly controlled by the access bacteria have to organic substrate. The influence of bacterial traits on this control has, however, received little attention. Using the substrate-dependent Monod growth model, we develop a bioreactive transport model to screen the interactive impacts of spatial dispersion and bacterial traits on mineralization. Bacterial traits primarily involved in the bacterial response to the substrate concentration, such as the maximum specific uptake rate and efficiency, the adaptation time of the uptake rate and the initial population density, are considered. We compare the model results with two sets of previously performed cm-scale soil-core experiments in which the mineralization of the pesticide 2,4-D was measured under well-controlled initial distributions and transport conditions. Bacterial dispersion away from the initial substrate location induced a significant increase in 2,4-D mineralization. It reveals an increase of specific uptake rates at lower bacterial densities, more than compensating the decrease of specific uptake rates caused by substrate dilution. This regulation of bacterial activities by density, caused by the local depletion of substrate by competing bacteria, becomes dominant for bacteria with an efficient uptake of substrate at low substrate concentrations (a common feature of oligotrophs). Such oligotrophs, commonly found in soils, compete with each other for substrate even at remarkably low population densities. The ratio-dependent Contois growth model, which includes a density regulation in the expression of the uptake efficiency, is more accurate and convenient to calibrate than the substrate-dependent Monod model, at least under these conditions. In view of their strong interactions, bioreactive and transport processes cannot be handled independently but should be integrated, in particular when reactive processes of interest are carried out by oligotrophs.
      原文链接:
    • NSTL
    • Elsevier

    Measurements of fine root decomposition rate: Method matters

    Li X.Zheng X.Zhou Q.McNulty S....
    5页
    查看更多>>摘要：? 2021Fine root decomposition plays a major role in biogeochemical cycle in forests. Litterbags and intact cores are predominant methods for measuring fine root decomposition rate. However, their efficacies have not been critically reviewed. In this study, we identify six sources of error for both methods including use of unrepresentative substrates, changes in decomposer community composition, altered effects of living roots and mycorrhizal fungi, differences in experimental duration length and sampling regime, confounding of spatiotemporal resolution, and limited temporal resolution. We present an indirect method to quantify fine root decomposition rate by integrating soil core and minirhizotron measurements into a new equation. The indirect method requires measuring more fine root parameters but can generally overcome the weaknesses associated with litterbag and intact core methods. Directly measuring the decomposition rate inevitably disturbs interactions between roots, soil fauna and rhizosphere microbes, which could significantly undermine the credibility of the estimates. Indirect measurement based on fine root growth and death rates, biomass and necromass that can be assessed reliably should be the future choice.
      原文链接:
    • NSTL
    • Elsevier

    Predicting measures of soil health using the microbiome and supervised machine learning

    Wilhelm R.C.van Es H.M.Buckley D.H.
    12页
    查看更多>>摘要：? 2021 Elsevier LtdSoil health encompasses a range of biological, chemical, and physical soil properties that sustain the commercial and ecological value of agroecosystems. Monitoring soil health requires a comprehensive set of diagnostics that can be cost-prohibitive for routine analyses. The soil microbiome provides a rich source of information about soil properties, which can be assayed in a high-throughput, cost-effective way. We evaluated the accuracy of random forest (RF) and support vector machine (SVM) regression and classification models in predicting 12 measures of soil health, tillage status, and soil texture from 16S rRNA gene amplicon data with an operationally relevant sample set. We validated the efficacy of the best performing models against independent datasets and also tested best practices for processing microbiome data for use in machine learning. Soil health metrics could be predicted from microbiome data with the best models achieving a Kappa value of ～0.65, for categorical assessments, and a R2 value of ～0.8, for numerical scores. Biological health ratings were better predicted than chemical or physical ratings. Validation with independent datasets revealed that models had general predictive value for soil properties, including yield. The ecological profiles of several taxa important for model accuracy matched the observed relationships with soil health, including Pyrinomonadaceae, Nitrososphaeraceae, and Candidatus Udeaobacter. Models trained at the highest taxonomic resolution proved most accurate, with losses in accuracy resulting from rarefying, sparsity filtering, and aggregating at higher taxonomic ranks. Our study provides the groundwork for developing scalable technology to use microbiome-based diagnostics for the assessment of soil health.
      原文链接:
    • NSTL
    • Elsevier