Microbial immobilisation and turnover of 15N labelled substrates in two arable soils under field and laboratory conditions

WESSELSPERELO, L; Jimenez, Miguel; Munch, Jean Charles

doi:10.1016/j.soilbio.2005.07.013

Cited by 30 publications

(7 citation statements)

References 40 publications

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“…The first phase is likely a microbial response to the pulse of water soluble substrates released either as a result of soil disturbance in the case of soil incubation without maize leaves or as a direct result of added fresh substrates in the case of maize leaf addition. Microbial assimilation of the available substrates and associated growth of microbial biomass should dominate the first phase, causing the phenomenon of negative priming, possibly because the hypothesized “preferential substrate utilization” by which soil microbes switch to added substrates and use less of original substrates [ 32 ]. The negative correlation between the priming effect and microbial biomass carbon during the initial 60-days ( Fig 8C ) indeed supports this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

“…from r- to K-strategy) [ 35 ], the second phase should be dominated by microbes with K-strategy such as specialized bacteria and fungi which have been shown to be responsible for positive priming effects [ 36 ]. It is also likely that the C (and N) assimilated into microbial biomass during the first phase gets mineralized during the second phase due to the increased turnover of microbial biomass due to the die-out after the initial pulse of growth induced by the fresh substrate input [ 16 , 32 ]. Indeed, the second phase occurred during the transition period from relatively high microbial biomass C to a stabilized lower microbial biomass, indicating a faster microbial turnover rate ( Fig 8C ).…”

Section: Discussionmentioning

confidence: 99%

“…The weaker positive priming for the sable SOC in the two bare fallow soils during the second phase was reasonable as 23 years without fresh organic input would induce the soil microbial community to a greater level of “starvation” than the old-field soils. Consequently, the decomposer communities would assimilate more SOC, leading to less positive priming during the second phase [ 32 ]. The slightly more positive priming effect for the stable SOC in the bare fallow soil during the third phase might have resulted from the higher increase of total microbial biomass C in the bare fallow soil than in the old-field soil (232% vs. 208% on average) ( Fig 8 ).…”

Section: Discussionmentioning

confidence: 99%

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Priming effects on labile and stable soil organic carbon decomposition: Pulse dynamics over two years

Zhang

Han

et al. 2017

PLoS ONE

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Soil organic carbon (SOC) is a major component in the global carbon cycle. Yet how input of plant litter may influence the loss of SOC through a phenomenon called priming effect remains highly uncertain. Most published results about the priming effect came from short-term investigations for a few weeks or at the most for a few months in duration. The priming effect has not been studied at the annual time scale. In this study for 815 days, we investigated the priming effect of added maize leaves on SOC decomposition of two soil types and two treatments (bare fallow for 23 years, and adjacent old-field, represent stable and relatively labile SOC, respectively) of SOC stabilities within each soil type, using a natural 13C-isotope method. Results showed that the variation of the priming effect through time had three distinctive phases for all soils: (1) a strong negative priming phase during the first period (≈0–90 days); (2) a pulse of positive priming phase in the middle (≈70–160 and 140–350 days for soils from Hailun and Shenyang stations, respectively); and (3) a relatively stabilized phase of priming during the last stage of the incubation (>160 days and >350 days for soils from Hailun and Shenyang stations, respectively). Because of major differences in soil properties, the two soil types produced different cumulative priming effects at the end of the experiment, a positive priming effect of 3–7% for the Mollisol and a negative priming effect of 4–8% for the Alfisol. Although soil types and measurement times modulated most of the variability of the priming effect, relative SOC stabilities also influenced the priming effect for a particular soil type and at a particular dynamic phase. The stable SOC from the bare fallow treatment tended to produce a narrower variability during the first phase of negative priming and also during the second phase of positive priming. Averaged over the entire experiment, the stable SOC (i.e., the bare fallow) was at least as responsive to priming as the relatively labile SOC (i.e., the old-field) if not more responsive. The annual time scale of our experiment allowed us to demonstrate the three distinctive phases of the priming effect. Our results highlight the importance of studying the priming effect by investigating the temporal dynamics over longer time scales.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Priming effects on labile and stable soil organic carbon decomposition: Pulse dynamics over two years

Zhang

Han

et al. 2017

PLoS ONE

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“…Soil microorganisms and microbial extracellular enzymes involved in N cycling play a crucial role in sustaining soil quality, ecosystem processes, including the acquisition of essential soil nutrients [12], decomposition of organic matter [13], nitrogen (N) cycling and carbon (C) cycling [14]. These are measured as microbial biomass nitrogen (SMBN) and carbon (SMBC), primarily known as "biological traits", which are key indicators of soil health [15,16] and are also stated as the sensitive indicators of organic matter decomposition and N mineralization [17,18].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen Mineralization, Soil Microbial Biomass and Extracellular Enzyme Activities Regulated by Long-Term N Fertilizer Inputs: A Comparison Study from Upland and Paddy Soils in a Red Soil Region of China

et al. 2021

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A long-term experiment (38 years) was conducted to elucidate the effects of long-term N addition on the net N mineralization in both paddy and upland soils, based on their initial soil N status, with and in connection with soil microbial biomass and N cycling extracellular enzyme activities. Two treatments without N addition CK (No fertilizer) and K (inorganic potassium fertilizer) and two treatments with N addition N (inorganic nitrogen fertilizer) and NK (inorganic nitrogen and potassium fertilizer) were placed in incubation for 90 days. Results showed that the total N and soil organic carbon (SOC) contents were higher in the treatments with N application compared to the treatments without N in both paddy and upland soils. The SOC content of paddy soil was increased relative to upland soil by 56.2%, 45.7%, 61.1% and 62.2% without N (CK, K) and with N (N and NK) treatments, respectively. Site-wise, total N concentration in paddy soil was higher by 0.06, 0.10, 0.57 and 0.60 times under the CK, K, N and NK treatments, respectively, compared with upland soil. In paddy soil, soil microbial biomass nitrogen (SMBN) was higher by 39.6%, 2.77%, 29.5% and 31.4%, and microbial biomass carbon (SMBC) was higher by 11.8%, 11.9%, 10.1% and 12.3%, respectively, in CK, K, N and NK treatment, compared with upland soil. Overall, compared to upland soil, the activities of leucine-aminopeptidase (LAP) were increased by 31%, 18%, 20% and 11%, and those of N-acetyl-b-D-glucosaminidase (NAG) were increased by 70%, 21%, 13% and 18% by CK, K, N and NK treatments, respectively, in paddy soil. A significantly linear increase was found in the NO3−-N and NH4+-N concentrations during the 90 days of the incubation period in both soils. NK treatment showed the highest N mineralization potential (No) along with mineralization rate constant, k (NMR) at the end of the incubation. SMBC, SMBN, enzyme activities, NO3−-N and NH4+-N concentrations and the No showed a highly significant (p ≤ 0.05) positive correlation. We concluded that long-term N addition accelerated the net mineralization by increasing soil microbial activities under both soils.

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“…Earthworms not only stimulate organic matter (OM) decomposition, but they also promote SOM stabilization within soil aggregates [9,10]. Decomposition is enhanced both by increasing the access of microbial decomposers to OM substrates through mixing and fragmentation of litter [9,[11][12][13][14] and by stimulating the activity of the ingested soil-derived earthworm gut microbiome, which accelerates the breakdown of earthworm-ingested OM during gut passage. This latter is referred to as 'the sleeping beauty paradox' [3,15].…”

Section: Introductionmentioning

confidence: 99%

Assessing the efficacy of antibiotic treatment for the creation of axenic earthworms

Ho¹,

Swart

Tp³

et al. 2021

Preprint

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Earthworms are an integral part of soil ecosystems, especially for their role in soil functions such as organic matter (OM) decomposition and nutrient cycling. Earthworms and microorganisms are interdependent, and a considerable portion of the contribution earthworms make to influencing OM fate is through interactions with microorganisms. However, the importance of the earthworm-associated microbiome is not fully understood, because it is difficult to separate the direct influence of the earthworms from the indirect influence of their microbiome. Here, we evaluated an antibiotic-based procedure for producing axenic ecologically-contrasting earthworm species (E. fetida, L. terrestris, A. chlorotica) as the first step towards soil studies aimed at understanding the importance of the earthworm microbiome for host health and function. Individual earthworms were exposed to antibiotics: cycloheximide (150 μg ml-1), ampicillin (100 μg ml-1), ciprofloxacin (50 μg ml-1), nalidixic acid (μg ml-1), and gentamicin (μg ml-1) either singly or in a cocktail via culture (96 h) in a semi-solid agar carrier. Compared to the non-antibiotic treated control, the cocktail (for all three species) and ciprofloxacin (for E. fetida and A. chlorotica) treatments significantly reduced (P<0.05) culturable microbial abundance on nutrient agar and potato dextrose agar. The microbial counts were reduced to below detection (<50 CFU individual-1) for E. fetida and A. chlorotica receiving the cocktail. Illumina 16S rDNA amplicon sequence analysis of culturable L. terrestris -associated bacteria showed that antibiotic treatment influenced community composition revealing putative sensitive (Comomonas, Kosakonia and Sphingobacterium) and insensitive (Aeromonas, Pseudochrobactrum) taxa. Overall, we report a rapid, with minimal earthworm- handling, process of creating axenic E. fetida and A. chlorotica individuals or L. terrestris with a suppressed microbiome as a tool to be used in future ecological studies of earthworm microbial interactions affecting host health and function.

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Microbial immobilisation and turnover of 15N labelled substrates in two arable soils under field and laboratory conditions

Cited by 30 publications

References 40 publications

Priming effects on labile and stable soil organic carbon decomposition: Pulse dynamics over two years

Priming effects on labile and stable soil organic carbon decomposition: Pulse dynamics over two years

Nitrogen Mineralization, Soil Microbial Biomass and Extracellular Enzyme Activities Regulated by Long-Term N Fertilizer Inputs: A Comparison Study from Upland and Paddy Soils in a Red Soil Region of China

Assessing the efficacy of antibiotic treatment for the creation of axenic earthworms

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