Microbial utilization of mineral-associated nitrogen in soils

Turner, Stephanie; Meyer-Stüve, Sandra; Schippers, Axel; Guggenberger, Georg; Schaarschmidt, Frank; Wild, Birgit; Richter, Andreas; Dohrmann, R.; Mikutta, Robert

doi:10.1016/j.soilbio.2016.10.010

Cited by 35 publications

(26 citation statements)

References 50 publications

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“…In this “cycling downwards” concept, the microbial processing of weakly mineral-bound organic matter might be initiated by microbial taxa colonizing organically coated minerals 36 . Incubation of topsoil MOM along the age gradient also demonstrated that a fraction of the mineral-bound organic matter can be re-mobilized and processed by microorganisms 45 . The high soil biological activity and annual precipitation of >3,600 mm along the chronosequence make dissolved organic matter transported with percolating water a major source for the formation of MOM, especially in subsoil.…”

Section: Resultsmentioning

confidence: 93%

Microbial and abiotic controls on mineral-associated organic matter in soil profiles along an ecosystem gradient

Mikutta

Turner

Schippers

et al. 2019

Sci Rep

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Formation of mineral-organic associations is a key process in the global carbon cycle. Recent concepts propose litter quality-controlled microbial assimilation and direct sorption processes as main factors in transferring carbon from plant litter into mineral-organic associations. We explored the pathways of the formation of mineral-associated organic matter (MOM) in soil profiles along a 120-ky ecosystem gradient that developed under humid climate from the retreating Franz Josef Glacier in New Zealand. We determined the stocks of particulate and mineral-associated carbon, the isotope signature and microbial decomposability of organic matter, and plant and microbial biomarkers (lignin phenols, amino sugars and acids) in MOM. Results revealed that litter quality had little effect on the accumulation of mineral-associated carbon and that plant-derived carbon bypassed microbial assimilation at all soil depths. Seemingly, MOM forms by sorption of microbial as well as plant-derived compounds to minerals. The MOM in carbon-saturated topsoil was characterized by the steady exchange of older for recent carbon, while subsoil MOM arises from retention of organic matter transported with percolating water. Overall, MOM formation is not monocausal but involves various mechanisms and processes, with reactive minerals being effective filters capable of erasing chemical differences in organic matter inputs.

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Section: Resultsmentioning

confidence: 93%

Microbial and abiotic controls on mineral-associated organic matter in soil profiles along an ecosystem gradient

Mikutta

Turner

Schippers

et al. 2019

Sci Rep

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“…To evaluate the effect of specific soil characteristics (O 2 status, soil fraction, soil age, C, and P addition) on microbial abundances and community composition we set up a microcosm incubation experiment with soils of the Franz Josef chronosequence (Supplementary Figure S3 ; Turner et al, 2017 ). Therefore, we used different soil fractions (bulk soil, mineral-associated OM, and particulate OM) of A horizons of four soil ages (0.5, 5, 12, and 120 kyr).…”

Section: Methodsmentioning

confidence: 99%

Microbial Community Dynamics in Soil Depth Profiles Over 120,000 Years of Ecosystem Development

et al. 2017

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Along a long-term ecosystem development gradient, soil nutrient contents and mineralogical properties change, therefore probably altering soil microbial communities. However, knowledge about the dynamics of soil microbial communities during long-term ecosystem development including progressive and retrogressive stages is limited, especially in mineral soils. Therefore, microbial abundances (quantitative PCR) and community composition (pyrosequencing) as well as their controlling soil properties were investigated in soil depth profiles along the 120,000 years old Franz Josef chronosequence (New Zealand). Additionally, in a microcosm incubation experiment the effects of particular soil properties, i.e., soil age, soil organic matter fraction (mineral-associated vs. particulate), O2 status, and carbon and phosphorus additions, on microbial abundances (quantitative PCR) and community patterns (T-RFLP) were analyzed. The archaeal to bacterial abundance ratio not only increased with soil depth but also with soil age along the chronosequence, coinciding with mineralogical changes and increasing phosphorus limitation. Results of the incubation experiment indicated that archaeal abundances were less impacted by the tested soil parameters compared to Bacteria suggesting that Archaea may better cope with mineral-induced substrate restrictions in subsoils and older soils. Instead, archaeal communities showed a soil age-related compositional shift with the Bathyarchaeota, that were frequently detected in nutrient-poor, low-energy environments, being dominant at the oldest site. However, bacterial communities remained stable with ongoing soil development. In contrast to the abundances, the archaeal compositional shift was associated with the mineralogical gradient. Our study revealed, that archaeal and bacterial communities in whole soil profiles are differently affected by long-term soil development with archaeal communities probably being better adapted to subsoil conditions, especially in nutrient-depleted old soils.

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“…Nitrogen-mining could explain the higher C:N ratios of the largest POM size fraction in the Lplots. Mineralisation rates of C and N in the sand fractions can be higher than in the silt or clay fractions (Turner et al 2017) and in our study, the largest changes in C:N ratios occurred in the 2000-200 lm fraction (equivalent to the coarse sand fraction), which is generally the least stabilised and potentially the most vulnerable to degradation (Lehmann et al 2001;Hofmockel et al 2011;Giannetta et al 2019). Indeed, POM-N may be the dominant source of N to microbiota (Lavallee et al 2020) and greater fungal abundance in POM (Gude et al 2012) could increase N mineralisation (Fontaine et al 2011), which would explain the higher C:N ratio in the 2000-200 lm POM fraction.…”

Section: Discussionmentioning

confidence: 94%

Altered litter inputs modify carbon and nitrogen storage in soil organic matter in a lowland tropical forest

et al. 2020

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Soil organic matter (SOM) in tropical forests is an important store of carbon (C) and nutrients. Although SOM storage could be affected by global changes via altered plant productivity, we know relatively little about SOM stabilisation and turnover in tropical forests compared to temperate systems. Here, we investigated changes in soil C and N within particle size fractions representing particulate organic matter (POM) and mineral-associated organic matter (MAOM) after 13 years of experimental litter removal (L−) and litter addition (L+) treatments in a lowland tropical forest. We hypothesized that reduced nitrogen (N) availability in L− plots would result in N-mining of MAOM, whereas long-term litter addition would increase POM, without altering the C:N ratio of SOM fractions. Overall, SOM-N declined more than SOM-C with litter removal, providing evidence of N-mining in the L− plots, which increased the soil C:N ratio. However, contrary to expectations, the C:N ratio increased most in the largest POM fraction, whereas the C:N ratio of MAOM remained unchanged. We did not observe the expected increases in POM with litter addition, which we attribute to rapid turnover of unprotected SOM. Measurements of ion exchange rates to assess changes in N availability and soil chemistry revealed that litter removal increased the mobility of ammonium-N and aluminium, whereas litter addition increased the mobility of nitrate-N and iron, which could indicate SOM priming in both treatments. Our study suggests that altered litter inputs affect multiple processes contributing to SOM storage and we propose potential mechanisms to inform future work.

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Microbial utilization of mineral-associated nitrogen in soils

Cited by 35 publications

References 50 publications

Microbial and abiotic controls on mineral-associated organic matter in soil profiles along an ecosystem gradient

Microbial and abiotic controls on mineral-associated organic matter in soil profiles along an ecosystem gradient

Microbial Community Dynamics in Soil Depth Profiles Over 120,000 Years of Ecosystem Development

Altered litter inputs modify carbon and nitrogen storage in soil organic matter in a lowland tropical forest

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