Does Litter Quality Change Affect the Decomposition of Soil Organic Matter Under Elevated Atmospheric CO2 and Warming?

Abstract. Microbial decomposition of plant litter is a crucial process for the land carbon (C) cycle, as it directly controls the partitioning of litter C between CO2 released to the atmosphere versus the formation of new soil organic matter (SOM). Land surface models used to study the C cycle rarely considered flexibility in the decomposer C use efficiency (CUEd) defined by the fraction of decomposed litter C that is retained as SOM (as opposed to be respired). In this study, we adapted a conceptual formulation of CUEd based on assumption that litter decomposers optimally adjust their CUEd as a function of litter substrate C to nitrogen (N) stoichiometry to maximize their growth rates. This formulation was incorporated into the widely used CENTURY soil biogeochemical model and evaluated based on data from laboratory litter incubation experiments. Results indicated that the CENTURY model with new CUEd formulation was able to reproduce differences in respiration rate of litter with contrasting C : N ratios and under different levels of mineral N availability, whereas the default model with fixed CUEd could not. Using the model with flexible CUEd, we also illustrated that litter quality affected the long-term SOM formation. Litter with a small C : N ratio tended to form a larger SOM pool than litter with larger C : N ratios, as it could be more efficiently incorporated into SOM by microorganisms. This study provided a simple but effective formulation to quantify the effect of varying litter quality (N content) on SOM formation across temporal scales. Optimality theory appears to be suitable to predict complex processes of litter decomposition into soil C and to quantify how plant residues and manure can be harnessed to improve soil C sequestration for climate mitigation.

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Atmospheric CO2 enrichment and nutrient additions to planted soil increase mineralisation of soil organic matter, but do not alter microbial utilisation of plant- and soil C-sources

Soil Biology and Biochemistry ◽

10.1016/j.soilbio.2008.06.005 ◽

2008 ◽

Vol 40 (9) ◽

pp. 2434-2440 ◽

Cited By ~ 69

Author(s):

Eric Paterson ◽

Barry Thornton ◽

Andrew J. Midwood ◽

Shona M. Osborne ◽

Allan Sim ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Co2 Enrichment ◽

Atmospheric Co2 ◽

Soil C ◽

Nutrient Additions

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Controls on dissolved organic matter leaching from forest litter grown under elevated atmospheric CO2

Soil Biology and Biochemistry ◽

10.1016/j.soilbio.2007.01.038 ◽

2007 ◽

Vol 39 (7) ◽

pp. 1759-1769 ◽

Cited By ~ 52

Author(s):

Frank Hagedorn ◽

Miriam Machwitz

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Forest Litter ◽

Atmospheric Co2 ◽

Elevated Atmospheric Co2

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Effects of atmospheric CO2 enrichment on δ 13C, δ 15N values and turnover times of soil organic matter pools isolated by thermal techniques

Plant and Soil ◽

10.1007/s11104-007-9315-4 ◽

2007 ◽

Vol 297 (1-2) ◽

pp. 15-28 ◽

Cited By ~ 7

Author(s):

Maxim Dorodnikov ◽

Andreas Fangmeier ◽

Yakov Kuzyakov

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Co2 Enrichment ◽

Atmospheric Co2 ◽

Δ 13C ◽

Δ 15N ◽

Thermal Techniques

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Aridity-driven decoupling of δ13C between pedogenic carbonate and soil organic matter

Geology ◽

10.1130/g47241.1 ◽

2020 ◽

Vol 48 (10) ◽

pp. 981-985 ◽

Cited By ~ 2

Author(s):

Jiawei Da ◽

Yi Ge Zhang ◽

Gen Li ◽

Junfeng Ji

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Pore Space ◽

C4 Plants ◽

Atmospheric Co2 ◽

Chinese Loess Plateau ◽

Pedogenic Carbonate ◽

Chinese Loess ◽

Pedogenic Carbonates ◽

Soil Pore Space

Abstract Pedogenic carbonate is an invaluable archive for reconstructing continental paleoclimate and paleoecology. The δ13C of pedogenic carbonate (δ13Cc) has been widely used to document the rise and expansion of C4 plants over the Cenozoic. This application requires a fundamental presumption that in soil pores, soil-respired CO2 dominates over atmospheric CO2 during the formation of pedogenic carbonates. However, the decoupling between δ13Cc and δ13C of soil organic matter (δ13CSOM) have been observed, particularly in arid regions, suggesting that this presumption is not always valid. To evaluate the influence of atmospheric CO2 on soil δ13Cc, here we performed systematic δ13C analyses of paleosols across the Chinese Loess Plateau, with the sample ages spanning three intervals: the Holocene, the Late Pleistocene, and the mid-Pliocene warm period. Our paired δ13Cc and δ13CSOM data reveal broadly divergent trending patterns. Using a two-component CO2-mixing model, we show substantial incorporations of atmospheric CO2 (up to 60%) into soil pore space during carbonate precipitation. This result readily explains the enrichment of δ13Cc and its divergence from δ13CSOM. As a consequence, δ13C of pedogenic carbonates formed under semiarid and/or arid conditions are largely driven by regional aridity through its control on soil CO2 composition, and thus cannot be used to evaluate the relative abundance of C3 versus C4 plants. Nonetheless, these carbonates can be applied for atmospheric CO2 reconstructions, even for periods with low CO2 levels.

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Sustainability of Impacts of Poplar Growth on Soil Organic Matter in Eutric Cambisols

Soil Systems ◽

10.3390/soilsystems3020032 ◽

2019 ◽

Vol 3 (2) ◽

pp. 32

Author(s):

Christel Baum ◽

Martin Barth ◽

Kathrin Henkel ◽

Meike Siebers ◽

Kai-Uwe Eckhardt ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Mycorrhizal Fungi ◽

Litter Quality ◽

Phospholipid Fatty Acid ◽

Microbial Colonization ◽

Annual Crops ◽

No Till ◽

Poplar Growth

Short rotation coppices (SRC) with poplar on arable soils constitute no-till management in combination with a changed litter quality compared to annual crops. Both tillage and litter quality impact soil organic matter (SOM) composition, but little is known on the sustainability of this impact at the molecular level. We compared the microbial colonization and SOM quantity and quality of a young (4 years), old (17 years) and a former SRC with hybrid poplar (Populus maximoviczii × Populus nigra cv. Max) to adjacent arable sites with annual crops or grass. Total fungal and arbsucular mycorrhizal fungal phospholipid fatty acid (PLFA) markers were increased under no-till treatments with permanent crops (SRC and grass) compared to tilled cereals. Enrichments in fungal biomass coincided with C accumulation close to the soil surface (0–5 cm) but was abolished under former SRC after return to annual tillage. This management change altered the spatial distribution but not the accumulation of SOM within the topsoil (0–30 cm). However, lasting qualitative changes in SOM with increased proportions of lignin, lipids and sterols were found under current and former SRC. Increased colonization by arbuscular mycorrhizal fungi was correlated with increased invertase activity (R = 0.64; p < 0.05), carbohydrate consumption and a corresponding accumulation of lignins and lipids in the SOM. This link indicates a regulatory impact of mycorrhizal fungi on soil C dynamics by changing the quality of SOM. Increased stability of SOM to microbial degradation by higher portions of lipids and sterols in the SOM were assumed to be a sustainable effect of poplar growth at Eutric Cambisols.

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