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Applied Soil Ecology
Elsevier Science B.V.
Applied Soil Ecology

Elsevier Science B.V.

0929-1393

Applied Soil Ecology/Journal Applied Soil EcologySCIISTP
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    Loss in soil microbial diversity constrains microbiome selection and alters the abundance of N-cycling guilds in barley rhizosphere

    Saghai, AurelienWittorf, LeaPhilippot, LaurentHallin, Sara...
    10页
    查看更多>>摘要：Plant roots are shaping microbial communities that are distinct from the surrounding soil. These root-associated microbial communities can have both positive and negative effects on the host nutrient acquisition and thereby growth, yet how loss of soil microbial diversity will constrain the plant microbiome selection is relatively unknown. In this study, we manipulated the soil microbial community using a removal-by-dilution approach to examine how microbial diversity modulates microbiome selection in barley, including microbial guilds involved in nitrogen (N) cycling processes causing N loss, and its consequences for plant performance. We found that microbial diversity loss reduced the barley's ability to recruit specific microorganisms from the soil and only members of the Alphaproteobacteria and Bacteroidetes were enriched in both rhizosphere and root-associated compartments irrespective of dilution level. Loss in soil microbial diversity and the presence of plants affected the N-cycling communities, with the abundance of nitrous oxide reducers being 2-4 times higher in both barley compartments in the lower diversity soils. In these soils, the low abundance of bacterial ammonia oxidizers (close or below detection level in the barley compartments) was concomitant with an increase in leaf greenness (ca. 12%), an indicator of the plant N status. The reduction in soil microbial diversity was thus coupled to a change in functional traits of rhizosphere and root-associated communities, with consequences for plant performance. This work contributes to our understanding of plant-microbe interactions, which is needed to steer the crop microbiome towards increased N-use efficiency while minimizing negative environmental impact.
      原文链接:
    • NSTL
    • Elsevier

    Rapid redistribution and long-term aggregation of mulch residues by earthworms (Lumbricus terrestris)

    McTavish, Michael J.Murphy, Stephen D.
    9页
    查看更多>>摘要：There has been minimal study of how ecosystem engineering anecic earthworms such as Lumbricus terrestris L. may influence the distribution of mulch amendments across the soil surface by collecting residues into middens. The two primary research objectives of this study were: (1) to determine how rapidly earthworms change the surface distribution of mulch following amendment, and (2) to produce a more spatially explicit map of earthworm aggregation of mulch. This study used a microcosm experiment to assess the immediate, short-term impacts of earthworms on recently added mulch at a small scale, and an opportunistic field study of the longerterm impacts of earthworms on the distribution of corn 'stubble' mulch in a former agricultural field. In the microcosm experiment, earthworms rapidly redistributed mulch within the first week post amendment, decreasing initial ground cover (15-29% decrease). Over the subsequent five weeks, initial cover continued to decrease (20-45% decrease) as mulch was spread thinly onto adjacent, initially bare soil (49-69% increase). Higher mulch amendment mitigated losses in initial cover. In the field study, earthworms aggregated mulch across the soil surface, collecting 40% of the woody corn residues into 17% of the total area in regularly distributed middens. These results demonstrate the potential for L. terrestris to alter the distribution of mulch rapidly in the first several days and weeks following application and in the longer term over several years, increasing the spatial heterogeneity of soil resources. This physical redistribution has only been minimally investigated and may help inform models of earthworm impacts on various ecological processes and improve soil amendment and residue management in earthworm-occupied soils.
      原文链接:
    • NSTL
    • Elsevier

    Diverse crop rotations influence the bacterial and fungal communities in root, rhizosphere and soil and impact soil microbial processes

    Town, Jennifer R.Gregorich, Edward G.Drury, Craig F.Lemke, Reynald...
    12页
    查看更多>>摘要：Diverse crop rotations can improve crop productivity but impacts on the interaction of soil nutrient cycling and the soil and root-associated microbiomes are not well understood. Here, we analysed 16S rRNA and ITS DNA amplicons of soil, rhizosphere and roots from two Canadian long-term field experiments, wheat grown in Saskatchewan and corn grown Ontario. Together with soil biogeochemical analysis, we determined that long-term diverse rotations and cereal monocropping affected the composition of soil organic matter, nutrient cycling and selected bacterial and fungal microbiomes. Differential abundance analysis identified 27 bacterial amplicon sequence variants that were more abundant in the soil and rhizosphere of monocropped corn that were classified as Ktedonobacteria and Actinomycetales. Both wheat and corn samples showed significant variation in the abundance of several saprophytic Sordariomycetes. Monocropping increased lignin by 56% in corn and 25% in wheat, demonstrating shifts in soil organic matter composition in the two systems, although no differences in amino sugars were observed. Depending on sample type, soil total lignin and phosphatase enzyme activity were correlated (p < 0.05) with variation in bacterial and fungal community composition along with available N in corn and beta-glucosidase in wheat. Our results indicate that over the long-term, reduced cropping diversity altered soil nutrient cycling and soil, rhizosphere and root microbiomes corresponding with reduced yields in the monocropped corn and wheat systems.
      原文链接:
    • NSTL
    • Elsevier

    Organic substrate availability and enzyme activity affect microbial-controlled carbon dynamics in areas disturbed by a mining dam failure

    de Souza, Josemara KarinaSilva, Aline OliveiraBarbosa, Marisangela Vianados Santos, Jesse Valentim...
    7页
    查看更多>>摘要：We investigated key ecophysiological traits of microbial communities across different disturbance levels for two upper horizon depths (A1: 0-3 cm and A2: 10-13 cm) in areas disturbed by Funda tilde o dam failure across Gualaxo do Norte river. We found that lower microbial growth (microbial biomass) and higher microbial-C losses (high qCO2) were linked to both decreases in organic substrate availability and enzyme activity suggesting important feedbacks on C dynamics in areas disturbed by Funda tilde o dam failure. Basal respiration was not affected by organic substrate availability but increased with enzyme activity at A2 suggesting an enzymatic compensation in response to a lower plant-derived input. Lower degradative activity of extracellular enzymes (expressed as GMean index) was linked to lower organic matter content in mine tailings. Our results suggest that changes in organic substrate availability reflect changes in the microbial-controlled C dynamics in mine tailings. Thus, the design of restorative strategies based on microbial traits has the potential to accelerate the rehabilitation in areas disturbed by Funda tilde o dam failure.
      原文链接:
    • NSTL
    • Elsevier

    Land-use affects soil microbial co-occurrence networks and their putative functions

    Xue, PeipeiMinasny, BudimanMcBratney, Alex B.
    11页
    查看更多>>摘要：Soil microbial interactions are crucial in performing ecosystem functions. The microbial co-occurrence network could shed a new understanding of microbial functioning as affected by land management. Current studies on microbial community interactions mainly considered surface soils, thus the understanding of the microbial interactions and functions in the subsoils is still limited. We investigated soil samples from undisturbed remnant forests and disturbed vineyards in top-(0-25 cm) and subsoils (40-100 cm) in the Hunter Valley region, New South Wales, Australia. Soil microbial communities of bacteria and fungi were characterized by analyses of 16S rRNA and ITS amplicon sequencing, respectively. Land use differences caused the variances of soil properties, as resulted in the differences of microbial community composition and diversity, especially for the topsoils. Moreover, we found that agriculture activities had influenced the microbial networks for both the top-and subsoils. Widely connected bacterial networks were found in forest soils but they appeared as highly centralized clusters in vineyards for both layers. Although the interactions within those network clusters were enhanced in cropping soils, the connections between the clusters decreased or even isolated. We also characterized bacterial functions for element cycling based on their putative functions. Agricultural disturbances decreased the variability of C cycling bacteria for both surface and below layers, and reduced bacteria abundances working for C cycling in the topsoils. Additionally, soil bacterial co-occurrence network clusters were found to be correlated with microbial functions for element cycling, which demonstrated the significant influences of microbial network structure for microbial biological functions.
      原文链接:
    • NSTL
    • Elsevier

    Combined selective gamma irradiation and pulverized soil inoculation for ecologically relevant soil microfauna studies

    Hu, JunweiGebremikael, Mesfin TsegayeDumack, KennethHassi, Ummehani...
    12页
    查看更多>>摘要：The separate and collective role of soil nematodes and protists at community level in soil biogeochemical processes remains poorly quantified due to the lack of appropriate methodologies to study them independently from other soil biota under conditions emulating natural soil. Here we present a methodological exploration for the selective removal of nematodes and protists using gamma irradiation and the subsequent reinoculation with metazoan-free soil powder inoculum that allows reconstructing a complex microbial food web comprising the native microflora and soil protist communities, without other fauna. Nematodes, and culturable flagellates and ciliates were removed from 6 kGy onwards, while a small fraction of the amoebae survived (8% of the entire protist population) at 16 kGy but were totally removed at 27 kGy. Reinoculation with pulverized soil powder successfully established a protist community of similar size and composition as the control soil as assessed by both amplicon sequencing-based detection and microscopic observation after cultivation. A viable native microflora community remained from 6 to 16 kGy doses, but microbial activity was completely inhibited at 27 kGy. We suggest that, in ecological relevant experiments where selective removal of nematodes or other fauna is the purpose and protist community is meant to be kept intact, gamma irradiation needs to be followed routinely by soil powder inoculation in order to restore the suppressed protist community. This experiment also opens up new perspectives for studying the ecological roles of the entire protist community or specific groups thereof (flagellates and ciliates) in real soil and in the presence of a viable native microflora community.
      原文链接:
    • NSTL
    • Elsevier

    Linking soil biodiversity and ecosystem function in a Neotropical savanna

    Gatto, AlcidesPereira, Reginaldo S.Inkotte, JonasBomfim, Barbara...
    10页
    查看更多>>摘要：Conserving the remaining savanna ecosystems in the Brazilian savanna (Cerrado) - a global biodiversity hotspot that stores carbon and provides water to a large portion of South America - requires understanding the ecological processes maintaining their function. Nutrient cycling supports savanna function via plant litter production and decomposition by soil fauna, releasing nutrients for plant and soil organism uptake. Soil biodiversity and biogeochemistry linkages with litter dynamics in Neotropical savannas under a changing climate are poorly understood. Here, we combined two years of rainfall seasonality, leaf and wood litter production and decomposition with soil epigeic fauna abundance - the number of ground-surface dwelling invertebrates collected through pitfall traps - taxa richness, Shannon's diversity and Pielou's evenness, and 16 soil biogeochemical variables measured in 12 plots of preserved savanna. Rainfall seasonality modulated the mean soil epigeic fauna diversity and evenness across all plots, which were highest in the rainy season, in contrast to litterfall rates, which peaked in the dry season. In the dry season (April to September), the Formicidae family was the most abundant with 50% of all individuals, while in the rainy season (October to March), the Isoptera order was the most abundant with approximately 39% of individuals. Wood litter decomposition grouped with annual Hemiptera abundance, co-varying with soil epigeic fauna diversity and evenness per plot and against soil fertility variables. Leaf litter decomposition co-varied with the total epigeic fauna abundance and soil pH. We speculate that the specific need to decompose wood litter may be associated with a greater need for diversity than an abundance of soil epigeic fauna. Our work highlights the role of rainfall seasonality on soil biodiversity and physicochemistry, which is also tightly linked with litter production and decomposition. This study advances our understanding of the mechanisms governing nutrient cycling in savanna ecosystems on nutrient-impoverished soils, with implications for achieving sustainable conservation and restoration goals.
      原文链接:
    • NSTL
    • Elsevier

    Assessing the effects of Salicornia brachiata Roxb. growth on coastal saline soil quality over temporal and spatial scales

    Rathore, Aditya P.Chaudhary, Doongar R.Jha, Bhavanath
    13页
    查看更多>>摘要：Global climate change and human interference gradually increase the salt-affected land; hence the availability of agricultural land is decreasing day by day. Higher salinity severely affects the physical, chemical and biological characteristics of the soil. Various studies investigated the effects of growing crop plants on soil quality but such investigations on halophytic plants in their natural habitat are limited. Salicornia brachiata was selected to assess its effects on the soil quality over temporal and spatial scales because of its highest importance value index among the naturally growing coastal halophytes at the studied sites. The root zone soil of S. brachiata was sampled (six times in one growing period) from six different coastal sites in Gujarat, India. Soil characteristics, microbial community composition (ester linked-fatty acid methyl ester profiling) and genes (16S rRNA, nifH and cbbL) abundance in comparison with control soil (without vegetation) were studied. The root zone soil of S. brachiata had significantly higher pH, K+ and P, and lower EC, NO3--N, NH4+-N and Na+ contents than control soil. The contents of total, GM+ve, GM-ve, total bacterial, fungal and actinomycetes FAMEs (fatty acid methyl esters) were higher in the S. brachiata covered soils (37.98, 6.44, 10.38, 16.35, 1.74 and 2.12 nmol g(-1), respectively) than control soils (22.22, 3.81, 5.47, 9.30, 0.77 and 1.23 nmol g(-1), respectively). Among the studied sites, mot zone soil from Diu possessed the highest total, bacterial (GM+ve and GM-ye), fungal and actinomycetes FAMEs, whereas the Vivaniya site exhibited the lowest. Among the sampling periods, S. brachiata soil exhibited significantly elevated contents of total FAME and FAME biomarkers of microbial taxonomic groups in the initial two sampling months (August and October), followed by December and the least in June. Compared with control soil, S. brachiata covered soil possessed the microbial community shift related to the enhanced abundance of total bacterial, GM-ye and fungal FAMEs. The abundance of 16S rRNA, cbbL and nifH genes was higher in S. brachiata covered soils (1.64 x 10(9), 5.06 x 10(6) and 2.53 x 10(7), respectively) compared with control soil (6.78 x 10(8), 1.55 x 10(6) and 6.99 x 10(6), respectively). In the August and October months, the abundance of all three genes was highest in S. brachiata and control soils. The findings of this study confirm the significant effects of S. brachiata on saline soil properties (soil characteristics, microbial activities and genes abundance) over temporal and spatial scales. The results strongly suggest the potentials of S. brachiata for the restoration of salt-affected degraded lands for healthy ecosystem functioning.
      原文链接:
    • NSTL
    • Elsevier

    Natural attenuation and bioremediation of chlorpyrifos and endosulfan in periurban horticultural soils of Buenos Aires (Argentina) using microcosms assays

    Montserrat, Javier M.Zubillaga, MartaCabrera, Sonia
    9页
    查看更多>>摘要：Chlorpyrifos and endosulfan degradations were compared at laboratory scale in three different soils: a conventional horticultural (SH), an accredited 25 year organic horticultural (SA) and a reference soil (SR) used as control. Chlorpyrifos and alpha-endosulfan degradation half-lives were, respectively, in the range 7.2 d - 9.8 d and 4.4 d - 6.6 d, finding no statistical difference for any soil. In the case of beta-endosulfan, a difference was found in degradation half-lives, being: SR (25.8 d) < SA (49.1 d) < SH (102.1 d), indicating some difficulty, in the case of the traditional horticultural soil, to biodegrade this isomer. Three different biostimulants: poultry litter (CP), bokashi (fermented organic matter, BKS) and ramial chipped wood (BRF) were added to soil to explore the increase of chlorpyrifos and endosulfan biodegradation. While no improvement was observed for chlorpyrifos, all biostimulants favoured endosulfan degradation. In the case of BKS endosulfan half-life was reduced ca. three times (considering both isomers). Seed germination bioassays were performed using soil and biostimulant to evaluate potential ecotoxicological impacts. CP had a significant inhibitory effect on germination, hypocotyl elongation, radicle length and hypocotyl length, while BKS and BRF parameters were more similar to the control performance.
      原文链接:
    • NSTL
    • Elsevier

    Acid stress and compost addition decouple carbon and nitrogen cycling in an agricultural soil: An incubation study

    Lazicki, PatriciaRodrigues, Jorge L. MazzaGeisseler, Daniel
    11页
    查看更多>>摘要：Agricultural practices can lead to fluctuations in soil pH and salinity, likely affecting soil nutrient cycling. Compost addition may reduce the impact of these stresses, leading to more stable and resilient systems. We tested nitrogen (N) and carbon (C) cycling responses to the imposition and relief of an acute stress in an agricultural soil, and whether these responses were moderated by compost. In greenhouse pots, we mixed soil with elemental sulfur (S) and compost in a complete 2-way factorial design and incubated at ambient temperatures. Sulfur induced strong acidity and mild salinity stress. After 70 d, stress was partially alleviated by leaching with liquid lime. We took samples 21 and 42 d after S addition and one week after alleviation, measured enzyme activity, microbial biomass, and soluble organic C and N, and performed N and C cycle assays by incubating subsamples with and without ground legume residues to stimulate mineralization and microbial growth. Net N minerali-zation increased in response to the applied stress, and declined after alleviation. Conversely, stress reduced most C cycling indicators and inhibited nitrification. Stress limited microbial growth more than respiration. Unex-pectedly, compost additions to the stressed soils consistently stimulated net N mineralization compared to stressed soils without compost. Compost thus exacerbated rather than buffered the effects of stress on net N mineralization. Compost addition did not affect microbial growth or respiration in any treatment, or how any C cycle parameter responded to stress. The decoupled C and N responses suggest that the localized stresses asso-ciated with intensive agriculture may have important implications for C and N turnover in these systems, and warrant further study. Additionally, they demonstrate that biogeochemical processes should be evaluated concurrently when accessing the effect of stressors in soil systems.
      原文链接:
    • NSTL
    • Elsevier