Long-term nitrogen addition suppresses microbial degradation, enhances soil carbon storage, and alters the molecular composition of soil organic matter

Wang, Junjian; Bowden, Richard D.; Lajtha, Kate; Washko, Susan; Wurzbacher, S.; Simpson, Myrna J.

doi:10.1007/s10533-018-00535-4

Cited by 77 publications

(78 citation statements)

References 71 publications

(100 reference statements)

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“…With long-term N-enrichment, we observed a 50% decline in soil microbial biomass in both the O and A horizons. Our companion study (Wang et al, 2019) and other studies have shown that N-enrichment reduces soil microbial biomass and the processing of soil C inputs (Frey et al, 2004Feng et al, 2010;Ramirez et al, 2012;Pisani et al, 2015;Morrison et al, 2016). Reduced soil pH may also reduce soil microbial biomass (Treseder, 2008;Boot et al, 2016); we did observe reductions in soil pH, likely due to deprotonation of added ammonium and possibly to increased nitrification, which we did not measure, but which likely increased as a consequence of N additions (Nave et al, 2009).…”

Section: Propertymentioning

confidence: 44%

“…root diameter treatment root mass c mass n mass n concentration g m -2 g C m -2 g N m -2 g kg -1 0- any difference in leaf chemistry at the onset of the year-long decomposition period is unlikely to be the major determinant of reduced decomposition. Rather, the decreased litter decomposition that we observed is likely due to changes in organic matter processes in soil (Wang et al, 2019), particularly reductions in microbial biomass and enzyme activity. Our evidence of reduced soil microbial biomass comes from the strong decline in soil PLFA concentrations and the accumulation of soil C. PLFAs are excellent indicators of living and active microbes because after cell death, PLFAs degrade in soil within days (Kindler et al, 2009;Dippold and Kuzyakov, 2016).…”

Section: Propertymentioning

confidence: 66%

“…We argue that most of the observed changes in soil C are probably driven by decreased organic matter decomposition at the surface and within mineral soil. A companion study (Wang et al, 2019) that analyzed the molecular composition of soil C from this experiment showed a suppression of plant litter processing with N addition. Furthermore, decomposition of fresh surface litter was significantly lower in the N-addition plots as measured during Years 9 and 22.…”

Section: Discussionmentioning

confidence: 86%

“…We also note, as others have found, evidence of a shift in the microbial community. Based on our PLFA data, gram-negative to gram-positive ratios were reduced in the N-addition plots by 25, 59, and 12% in the control plot O, A, and B horizons, respectively, and the fungal/bacterial ratio increased 75% in the A horizon (Wang et al, 2019). Our microbial results are consistent with efforts that show that microbial groups do not respond uniformly to N additions (Allison et al, 2008;Bhatnagar et al, 2018), and that carbon use efficiency (CUE) varies among microbial species and organic matter substrates (Frey et al, 2004;Billings and Ziegler, 2008;Allison et al, 2009;Liu et al, 2018).…”

Section: Propertymentioning

confidence: 87%

“…Phospholipid fatty acids (PLFAs) were extracted using a modified Bligh-Dyer method followed by identification and quantification using gas chromatography-mass spectrometry (GC-MS) (Frostegård and Bååth, 1996). Full details of the PLFA extraction and quantification by gas chromatography-mass spectrometry are given in Wang et al (2019). Concentrations of all compounds were normalized to soil C content for comparisons between different soil horizons.…”

Section: Microbial Analysesmentioning

confidence: 99%

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Long‐term Nitrogen Addition Decreases Organic Matter Decomposition and Increases Forest Soil Carbon

Bowden

Wurzbacher

Washko

et al. 2019

Soil Science Soc of Amer J

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Core Ideas N additions alter soil microbial community composition and reduce forest soil microbial biomass and enzyme activity. Litter decomposition and soil organic matter degradation was slowed by N additions. Reduced decomposition increases soil C, but long‐term effects on forest productivity are unknown. Eastern North American forests receive anthropogenically elevated nitrogen (N) deposition that alters soil processes and forest productivity. We examined N deposition effects on soil carbon (C) and N in temperate, N‐rich forest plots fertilized annually (100 kg N ha−1 y−1) since 1993. After nearly two decades, soil C in O, A, and upper 50 cm of B horizons of N‐addition plots was 17% greater (14.2 ± 0.7 kg C m−2) than control plots. Aboveground tree biomass growth and litterfall were not affected by fertilization. Fine root mass (0–1 mm) was 34% greater in N‐addition plots, but did not explain soil C increases. Rather, reduced decomposition of litter and soil organic matter drove C increases in N‐addition plots. Decomposition rates of black cherry, sugar maple, and mixed leaf litter were 43, 67, and 36%, greater, respectively, in control than N‐addition plots. Light fraction organic matter was greater in N‐addition plots than in control plots, due to either enhanced root production or decreased decomposition of soil organic matter. Soil respiration was reduced, and microbial biomass in O, A, and upper‐B horizons was lower in N‐addition plots than controls. The soil microbial community composition was also altered dramatically with N additions. Recalcitrant organic matter enzyme activity (peroxidase) was reduced in the O‐horizon by N addition. Available Ca, Mg, and K were reduced in O and A horizons by N fertilization. These results suggest that chronic elevated atmospheric N inputs can increase forest soil C storage by decreasing decomposition, however the long‐term stability of this additional C sequestration is unknown.

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Section: Propertymentioning

confidence: 44%

Section: Propertymentioning

confidence: 66%

Section: Discussionmentioning

confidence: 86%

Section: Propertymentioning

confidence: 87%

Section: Microbial Analysesmentioning

confidence: 99%

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Long‐term Nitrogen Addition Decreases Organic Matter Decomposition and Increases Forest Soil Carbon

Bowden

Wurzbacher

Washko

et al. 2019

Soil Science Soc of Amer J

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Stability of needle‐ and root‐derived biomarkers during litter decomposition

Altmann

Jansen

Palviainen

et al. 2020

J. Plant Nutr. Soil Sci.

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Background and aims: Plant‐derived, ester‐bound substituted fatty acids have been used for decades as biomarkers to identify input of plant materials in sediments and soils. However, the long‐term decomposition patterns of these biomarker compounds under natural conditions are not well understood, although this is a basic prerequisite for quantitative biomarker applications. Methods: For this study, we analyzed the decomposition patterns of root‐ and needle‐specific compounds of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) in a litterbag study conducted over 3 years. Samples were analyzed by methanolic KOH extraction with previous removal of free extractable lipids. Results: The concentrations of most detectable compounds had decreased after three years of incubation. The observed changes of concentrations followed a non‐linear path and cannot be explained by microbial uptake and metabolism alone. Other factors controlling the breakdown of ester‐bound lipids, like lipid oxidation must play a role. Between similar plant parts and different plant parts of the same species, the observed degradation patterns were heterogeneous. The estimated ratio of remaining root and needle biomass that may arise with the choice of a particular biomarker varies in this study between 0.6 and 40 times after three years. Conclusion: This range of variation does not allow reliable conclusions about the contribution of roots and needles to decomposed organic matter based on biomarkers ratios.

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Effects of nutrient addition on the composition and chemical characteristics of soil dissolved organic matter in a desert steppe in northern China

Liu,

Wu,

Xue

et al. 2023

Land Degrad Dev

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Dissolved organic matter (DOM) plays a critical role in ecosystem function and productivity, particularly in carbon (C) cycling in grassland ecosystems. However, changes in the structural complexity of DOM in a desert steppe following long‐term treatment with nitrogen (N) and phosphorus (P) remain unclear; this limits our understanding of the nutrient‐related soil C cycle in a desert steppe. In the present study, soil experiments were conducted in the 0–10 cm soil layer of a desert steppe in northern China from 2017 to 2021, and four treatments were established: P, N, N + P (NP), and no nutrient addition (CK). The content and chemical composition of soil DOM were determined by ultraviolet–visible absorbance, fluorescence, and Fourier transform infrared spectroscopy. Compared to CK treatment, nutrient addition increased soil DOM content by 2.86%–53.84%. NP addition increased the average molecular weight, aromaticity, and humification degree of soil DOM. The DOM source was attributed to the combination of foreign and local sources. Fluorescent components of the DOM samples were mainly proteins and humic acids; the humic acid content decreased after N addition and increased after P and NP addition. Nutrient availability and pH were the key factors affecting the changes in the source and average molecular weight of the DOM, respectively. The soil organic matter content was significantly positively correlated with the humification index (r = 0.96). These results imply that nutrient addition accelerates the accumulation of DOM and influences its structural complexity; this potentially benefits soil C sequestration in a desert steppe.

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Long-term nitrogen addition suppresses microbial degradation, enhances soil carbon storage, and alters the molecular composition of soil organic matter

Abstract: Long-term nitrogen addition suppresses microbial degradation, enhances soil carbon storage, and alters the molecular composition of soil organic matter

Cited by 77 publications

References 71 publications

Long‐term Nitrogen Addition Decreases Organic Matter Decomposition and Increases Forest Soil Carbon

Long‐term Nitrogen Addition Decreases Organic Matter Decomposition and Increases Forest Soil Carbon

Stability of needle‐ and root‐derived biomarkers during litter decomposition

Effects of nutrient addition on the composition and chemical characteristics of soil dissolved organic matter in a desert steppe in northern China

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