scholarly journals Integrating microbial physiology and physiochemical principles in soils with the MIcrobial-MIneral Carbon Stabilization (MIMICS) model

2014 ◽  
Vol 11 (1) ◽  
pp. 1147-1185 ◽  
Author(s):  
W. R. Wieder ◽  
A. S. Grandy ◽  
C. M. Kallenbach ◽  
G. B. Bonan
Keyword(s):  
Litter Quality ◽  
Clay Content ◽  
Temperature Sensitive ◽  
Microbial Physiology ◽  
Carbon Stabilization ◽  
Physical Protection ◽  
Soil C ◽  
Substrate Quality ◽  
Functional Types ◽  
Microbial Residues

Abstract. Previous modeling efforts document divergent responses of microbial explicit soil biogeochemistry models when compared to traditional models that implicitly simulate microbial activity, particularly following environmental perturbations. However, microbial models are needed that capture current soil biogeochemical theories emphasizing the relationships between litter quality, functional differences in microbial physiology, and the physical protection of microbial byproducts in forming stable soil organic matter (SOM). To address these limitations we introduce the MIcrobial-MIneral Carbon Stabilization (MIMICS) model. In MIMICS, the turnover of litter and SOM pools are governed by temperature sensitive Michaelis–Menten kinetics and the activity of two physiologically distinct microbial functional types. The production of microbial residues through microbial turnover provides inputs to SOM pools that are considered physically or chemically protected. Soil clay content determines the physical protection of SOM in different soil environments. MIMICS adequately simulates the mean rate of leaf litter decomposition observed at a temperate and boreal forest sites, and captures observed effects of litter quality on decomposition rates. Initial results from MIMICS suggest that soil C storage can be maximized in sandy soils with low-quality litter inputs, whereas high-quality litter inputs may maximize SOM accumulation in finely textured soils that physically stabilize microbial products. Assumptions in MIMICS about the degree to which microbial functional types differ in the production, turnover, and stabilization of microbial residues provides a~mechanism by which microbial communities may influence SOM dynamics in mineral soils. Although further analyses are needed to validate model results, MIMICS allows us to begin exploring theoretical interactions between substrate quality, microbial community abundance, and the formation of stable SOM.

scholarly journals Integrating microbial physiology and physio-chemical principles in soils with the MIcrobial-MIneral Carbon Stabilization (MIMICS) model

2014 ◽  
Vol 11 (14) ◽  
pp. 3899-3917 ◽  
Author(s):  
W. R. Wieder ◽  
A. S. Grandy ◽  
C. M. Kallenbach ◽  
G. B. Bonan
Keyword(s):  
Litter Decomposition ◽  
Litter Quality ◽  
Clay Content ◽  
Temperature Sensitive ◽  
Microbial Physiology ◽  
Carbon Stabilization ◽  
Physical Protection ◽  
Soil C ◽  
Forest Sites

Abstract. A growing body of literature documents the pressing need to develop soil biogeochemistry models that more accurately reflect contemporary understanding of soil processes and better capture soil carbon (C) responses to environmental perturbations. Models that explicitly represent microbial activity offer inroads to improve representations of soil biogeochemical processes, but have yet to consider relationships between litter quality, functional differences in microbial physiology, and the physical protection of microbial byproducts in forming stable soil organic matter (SOM). To address these limitations, we introduce the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, and evaluate it by comparing site-level soil C projections with observations from a long-term litter decomposition study and soil warming experiment. In MIMICS, the turnover of litter and SOM pools is governed by temperature-sensitive Michaelis–Menten kinetics and the activity of two physiologically distinct microbial functional types. The production of microbial residues through microbial turnover provides inputs to SOM pools that are considered physically or chemically protected. Soil clay content determines the physical protection of SOM in different soil environments. MIMICS adequately simulates the mean rate of leaf litter decomposition observed at temperate and boreal forest sites, and captures observed effects of litter quality on decomposition rates. Moreover, MIMICS better captures the response of SOM pools to experimental warming, with rapid SOM losses but declining temperature sensitivity to long-term warming, compared with a more conventional model structure. MIMICS incorporates current microbial theory to explore the mechanisms by which litter C is converted to stable SOM, and to improve predictions of soil C responses to environmental change.

scholarly journals Stoichiometrically coupled carbon and nitrogen cycling in the MIcrobial-MIneral Carbon Stabilization model version 1.0 (MIMICS-CN v1.0)

2020 ◽  
Vol 13 (9) ◽  
pp. 4413-4434
Author(s):  
Emily Kyker-Snowman ◽  
William R. Wieder ◽  
Serita D. Frey ◽  
A. Stuart Grandy
Keyword(s):  
Environmental Change ◽  
Microbial Biomass C ◽  
N Losses ◽  
Microbial Physiology ◽  
Carbon Stabilization ◽  
Ecosystem Responses ◽  
Soil C ◽  
Continental Scale ◽  
Biogeochemical Models ◽  
C And N

Abstract. Explicit consideration of microbial physiology in soil biogeochemical models that represent coupled carbon–nitrogen dynamics presents opportunities to deepen understanding of ecosystem responses to environmental change. The MIcrobial-MIneral Carbon Stabilization (MIMICS) model explicitly represents microbial physiology and physicochemical stabilization of soil carbon (C) on regional and global scales. Here we present a new version of MIMICS with coupled C and nitrogen (N) cycling through litter, microbial, and soil organic matter (SOM) pools. The model was parameterized and validated against C and N data from the Long-Term Inter-site Decomposition Experiment Team (LIDET; six litter types, 10 years of observations, and 13 sites across North America). The model simulates C and N losses from litterbags in the LIDET study with reasonable accuracy (C: R2=0.63; N: R2=0.29), which is comparable with simulations from the DAYCENT model that implicitly represents microbial activity (C: R2=0.67; N: R2=0.30). Subsequently, we evaluated equilibrium values of stocks (total soil C and N, microbial biomass C and N, inorganic N) and microbial process rates (soil heterotrophic respiration, N mineralization) simulated by MIMICS-CN across the 13 simulated LIDET sites against published observations from other continent-wide datasets. We found that MIMICS-CN produces equilibrium values in line with measured values, showing that the model generates plausible estimates of ecosystem soil biogeochemical dynamics across continental-scale gradients. MIMICS-CN provides a platform for coupling C and N projections in a microbially explicit model, but experiments still need to identify the physiological and stoichiometric characteristics of soil microbes, especially under environmental change scenarios.

scholarly journals Stoichiometrically coupled carbon and nitrogen cycling in the MIcrobial-MIneral Carbon Stabilization model (MIMICS-CN)

2019 ◽  
Author(s):  
Emily Kyker-Snowman ◽  
William R. Wieder ◽  
Serita Frey ◽  
A. Stuart Grandy
Keyword(s):  
Environmental Change ◽  
Microbial Biomass C ◽  
N Losses ◽  
Microbial Physiology ◽  
Carbon Stabilization ◽  
Ecosystem Responses ◽  
Soil C ◽  
Continental Scale ◽  
Biogeochemical Models ◽  
C And N

Abstract. Explicit consideration of microbial physiology in soil biogeochemical models that represent coupled carbon-nitrogen dynamics presents opportunities to deepen understanding of ecosystem responses to environmental change. The MIcrobial-MIneral Carbon Stabilization (MIMICS) model explicitly represents microbial physiology and physicochemical stabilization of soil carbon (C) on regional and global scales. Here we present a new version of MIMICS with coupled C and nitrogen (N) cycling through litter, microbial, and soil organic matter (SOM) pools. The model was parameterized and validated against C and N data from the Long-Term Inter-site Decomposition Experiment Team (LIDET; 6 litter types, 10 years of observations, 13 sites across North America). The model simulates C and N losses from litterbags in the LIDET study with reasonable accuracy (C: R2 = 0.63, N: R2 = 0.29) results that are comparable with simulations from the DAYCENT model that implicitly represents microbial activity (C: R2 = 0.67, N: R2 = 0.30). Subsequently, we evaluated equilibrium values of stocks (total soil C and N, microbial biomass C and N, inorganic N) and microbial process rates (soil heterotrophic respiration, N mineralization) simulated by MIMICS-CN across the 13 simulated LIDET sites against published observations from other continent-wide datasets. We found that MIMICS-CN produces equilibrium values in line with measured values, showing that the model generates plausible estimates of ecosystem soil biogeochemical dynamics across continental-scale gradients. MIMICS-CN provides a platform for coupling C and N projections in a microbial-explicit model but experiments still need to identify the physiological and stoichiometric characteristics of soil microbes, especially under environmental change scenarios.

scholarly journals C and N urban soil budget and its spatial differentiation in comparison with natural areas in the Wroclaw region of Poland

2018 ◽  
Vol 45 ◽  
pp. 00085
Author(s):  
Izabela Sówka ◽  
Yaroslav Bezyk ◽  
Maxim Dorodnikov
Keyword(s):  
Urban Soil ◽  
Spatial Differentiation ◽  
Clay Content ◽  
Dry Mass ◽  
Microbial Biomass C ◽  
Natural Areas ◽  
Soil C ◽  
Soil C And N ◽  
C And N ◽  
Natural Grassland

An assessment of C and N balance in urban soil compared to the natural environment was carried out to evaluate the influence of biological processes along with human-induced forcing. Soil C and N stocks were quantified on the samples (n=18) collected at 5 - 10 cm depth from dominated green areas and arable lands in the city of Wroclaw (Poland) and the relatively natural grassland located ca. 36 km south-west. Higher soil carbon and nitrogen levels (C/N ratio = 11.8) and greater microbial biomass C and N values (MBC = 95.3, MBN = 14.4 mg N kg-1) were measured in natural grassland compared with the citywide lawn sites (C/N ratio = 15.17, MBC = 84.3 mg C kg-1, MBN = 11.9 mg N kg-1), respectively. In contrast to the natural areas, the higher C and N concentration was measured in urban grass dominated soils (C = 2.7 % and N = 0.18 % of dry mass), which can be explained mainly due to the high soil bulk density and water holding capacity (13.8 % clay content). The limited availability of soil C and N content was seen under the arable soil (C = 1.23 %, N = 0.13 %) than in the studied grasslands. In fact, the significantly increased C/N ratios in urban grasslands are largely associated with land conversion and demonstrate that urban soils have the potential to be an important reservoir of C.

Increased atmospheric CO2 and litter quality

1998 ◽  
Vol 6 (1) ◽  
pp. 1-12 ◽  
Author(s):  
M Francesca Cotrufo ◽  
Björn Berg ◽  
Werner Kratz
Keyword(s):  
Chemical Composition ◽  
Leaf Litter ◽  
Decomposition Rate ◽  
Litter Quality ◽  
Castanea Sativa ◽  
Plant Litter ◽  
Decomposition Rates ◽  
Chemical Changes ◽  
Substrate Quality ◽  
N Concentration

There is evidence that N concentration in hardwood leaf litter is reduced when plants are raised in an elevated CO2 atmosphere. Reductions in the N concentration of leaf litter have been found for tree species raised under elevated CO2, with reduction in N concentration ranging from ca. 50% for sweet chestnut (Castanea sativa) to 19% for sycamore (Acer platanoides). However, the effects of elevated CO2 on the chemical composition of litter has been investigated only for a limited number of species. There is also little information on the effects of increased CO2 on the quality of root tissues. If we consider, for example, two important European forest ecosystem types, the dominant species investigated for chemical changes are just a few. Thus, there are whole terrestrial ecosystems in which not a single species has been investigated, meaning that the observed effects of a raised CO2 level on plant litter actually has a large error source. Few reports present data on the effects of elevated CO2 on litter nutrients other than N, which limits our ability to predict the effects of elevated CO2 on litter quality and thus on its decomposability. In litter decomposition three separate steps are seen: (i) the initial stages, (ii) the later stages, and (iii) the final stages. The concept of "substrate quality," translated into chemical composition, will thus change between early stages of decomposition and later ones, with a balanced proportion of nutrients (e.g., N, P, S) being required in the early decomposition phase. In the later stages decomposition rates are ruled by lignin degradation and that process is regulated by the availability of certain nutrients (e.g., N, Mn), which act as signals to the lignin-degrading soil microflora. In the final stages the decomposition comes to a stop or may reach an extremely low decomposition rate, so low that asymptotic decomposition values may be estimated and negatively related to N concentrations. Studies on the effects of changes in chemical composition on the decomposability of litter have mainly been made during the early decomposition stages and they generally report decreased litter quality (e.g., increased C/N ratio), resulting in lower decomposition rates for litter raised under elevated CO2 as compared with control litter. No reports are found relating chemical changes induced by elevated CO2 to litter mass-loss rates in late stages. By most definitions, at these stages litter has turned into humus, and many studies demonstrated that a raising of the N level may suppress humus decomposition rate. It is thus reasonable to speculate that a decrease in N levels in humus would accelerate decomposition and allow it to proceed further. There are no experimental data on the long-term effect of elevated CO2 levels, and a decrease in the storage of humus and nutrients could be predicted, at least in temperate and boreal forest systems. Future works on the effects of elevated CO2 on litter quality need to include studies of a larger number of nutrients and chemical components, and to cover different stages of decomposition. Additionally, the response of plant litter quality to elevated CO2 needs to be investigated under field conditions and at the community level, where possible shifts in community composition (i.e., C3 versus C4 ; N2 fixers versus nonfixers) predicted under elevated CO2 are taken into account.Key words: climate change, substrate quality, carbon dioxide, plant litter, chemical composition, decomposition.

scholarly journals Assessment of Water Quality and Soil Salinity in the Agricultural Coastal Plain (Ravenna, North Italy)

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 369 ◽  
Author(s):  
Livia Vittori Antisari ◽  
Maria Speranza ◽  
Chiara Ferronato ◽  
Mauro De Feudis ◽  
Gilmo Vianello ◽  
...  
Keyword(s):  
Oxygen Demand ◽  
Clay Content ◽  
Field Capacity ◽  
Soil Salinization ◽  
Soil Samples ◽  
Winter Period ◽  
Negative Effects ◽  
Soil C ◽  
Salt Leaching ◽  
Water Volumes

To improve knowledge on salt leaching suitability on different soils, in Arenosols and Cambisols croplands in the coastal area of Ravenna (Italy), soil samples were collected in the non-irrigation winter period and irrigation summer period. Concurrently, waters of the canal network were also investigated. Soil samples were analyzed for pH, carbonate, total organic carbon (TOC), particle size distribution, electrical conductivity (EC), bulk density (BD) and water content at field capacity (FC). Water samples were investigated for pH, EC, biological and chemical oxygen demand, sodium adsorption ratio, phosphorus, nitrogen, sulfates and chlorides. All soils had low TOC concentrations and Arenosols showed the lowest clay content, BD and FC. Soils had similar EC values in winter, but in summer the lowest ones were observed in Arenosols, suggesting that irrigation mitigated salinization in Arenosols, while the high clay content, BD and FC prevented or limited the salt leaching in Cambisols. In summer, the increase of total nitrogen and biological oxygen demand, especially in drainage channels, might suggest the leaching of soluble nutrients and organic matter from soils due to the high irrigation water volumes. Finally, our findings stress the need to consider soil type and properties to contrast soil salinization without negative effects on soil C leaching caused by salt leaching practice.

scholarly journals Modeling the effects of litter stoichiometry and soil mineral N availability on soil organic matter formation using CENTURY-CUE (v1.0)

2018 ◽  
Vol 11 (12) ◽  
pp. 4779-4796 ◽  
Author(s):  
Haicheng Zhang ◽  
Daniel S. Goll ◽  
Stefano Manzoni ◽  
Philippe Ciais ◽  
Bertrand Guenet ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Litter Quality ◽  
Plant Litter ◽  
Climate Mitigation ◽  
N Availability ◽  
Mineral N ◽  
Microbial Decomposition ◽  
Soil C ◽  
C Cycle

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.

Changes in soil carbon and soil nitrogen after tree clearing in the semi-arid rangelands of Queensland

2005 ◽  
Vol 53 (7) ◽  
pp. 639 ◽  
Author(s):  
B. P. Harms ◽  
R. C. Dalal ◽  
A. P. Cramp
Keyword(s):  
Soil Carbon ◽  
Soil Depth ◽  
Woody Debris ◽  
Soil Phosphorus ◽  
Basal Area ◽  
Clay Content ◽  
Strongly Correlated ◽  
Soil N ◽  
Soil C ◽  
C Stocks

Changes in soil carbon (C) and nitrogen (N) stocks following tree clearing were estimated at 32 rangeland sites in central and southern Queensland by using paired-site sampling. When corrected for soil bulk-density differences at each site, average soil C across all sites decreased after tree clearing by 8.0% for 0–0.3-m soil depth, and by 5.4% for 0–1.0-m depth; there were corresponding declines in soil C of 2.5 and 3.5tha–1, respectively. Mean soil C stocks (excluding surface litter, extractable roots and coarse charcoal) at uncleared sites were 29.5tha–1 for 0–0.3-m soil depth, and 62.5tha–1 for 0–1.0-m depth. Mean soil C stocks (0–0.3m) were 41% of the mean total C for the soil–plant system (soil + litter/woody debris + stand biomass) at uncleared sites. Soil C decline (0–0.3m) accounted for approximately 7% of the average total C lost because of land clearing across all sites. Soil C stocks at uncleared sites were correlated with tree basal area, clay content and soil phosphorus (P) content. Changes in soil C after tree clearing were strongly correlated to initial soil C contents at the uncleared sites, and were associated with particular vegetation groups and soil types. Changes in soil N were strongly correlated with changes in soil C; however, the average change in soil N across all sites was not significant. Given the size of the C and N pools in rangeland soils, the factors that influence soil C and soil N dynamics in rangeland systems need to be better understood for the effective management of C stocks in these soils.

scholarly journals Tillage Effects on Spatiotemporal Variability of Particulate Organic Matter

2009 ◽  
Vol 2009 ◽  
pp. 1-14 ◽  
Author(s):  
Juhwan Lee ◽  
Emilio A. Laca ◽  
Chris van Kessel ◽  
Dennis E. Rolston ◽  
Jan W. Hopmans ◽  
...  
Keyword(s):  
Organic Matter ◽  
Clay Content ◽  
Farming System ◽  
Spatiotemporal Variability ◽  
Reduced Tillage ◽  
Short Term ◽  
Soil C ◽  
No Till ◽  
C And N ◽  
Term Field

This study was performed to evaluate effects of no-till (NT) and standard tillage (ST) on POM in two 15-ha neighboring fields from 2003 to 2004. We also evaluated the effects of minimum tillage (MT) on POM after both NT and ST fields were converted to MT in the summer of 2005. We quantified C and N stocks of three size fractions (53–250, 250–1000, and 1000–2000 μm) of POM (0–0.15 m depth). The POM-C 53–250 μmand 250–1000 μmfractions decreased by 25% and 36% after six months under ST, whereas relatively little change occurred under NT, suggesting significant tillage effects over the period 2003-2004. Only small changes in POM content then occurred under MT on both fields. Changes in POM-N were similar to POM-C changes upon tillage conversions. This suggests that reduced tillage did not lead to soil C increase compared to ST but may help maintain the level of soil C for a typical California farming system. Short-term, field level variability of POM was primarily affected by tillage and was further influenced by clay content, bulk density, and scale of observation.

Texture effects on carbon stabilisation and storage in New Zealand soils containing predominantly 2 : 1 clays

Soil Research ◽  
2016 ◽  
Vol 54 (1) ◽  
pp. 30 ◽  
Author(s):  
Denis Curtin ◽  
Michael H. Beare ◽  
Weiwen Qiu
Keyword(s):  
New Zealand ◽  
Clay Fraction ◽  
Clay Content ◽  
Soil C ◽  
Particle Size Fractions ◽  
C Storage ◽  
Physico Chemical ◽  
Wide Range ◽  
Mass Proportion ◽  
C And N

Developing strategies to sequester carbon (C) in soils requires an understanding of the key factors that influence C stabilisation. Although fine mineral particles, especially clay, play a key role in stabilising soil organic matter (SOM), the relationship between SOM and texture is often not strong. We examined the role of the fine mineral fraction in C storage in sedimentary soils in New Zealand. Soils, representing two soil Orders (Brown and Recent) and different land use histories (total of 58 soils; 0–15 cm depth) were sampled. The concentration of C (and N) in four particle size fractions (<5, 5–20, 20–50, >50 µm) was determined (soils fractionated after dispersion by sonication). The soils had a wide range of textures and SOM; the mass proportion of clay (<5 µm) ranged from 10 to 60 g 100 g–1 and soil C from 16 to 45 g kg–1. Across both soil Orders and all land uses (dairy, sheep or beef, arable and vegetable cropping), the majority of soil C (57 to 66%) was stored in the clay fraction. However, there was no correlation (R2 = 0.02; P > 0.05) between the C concentration in whole soil and clay content. The concentration of C in the clay fraction, which varied over a wide range (35 to 135 g kg–1 clay), decreased as the mass proportion of clay increased. A similar trend in C concentration was observed for the fine (5–20 µm) silt fraction. Because of this inverse relationship between the mass of the fine fractions and their C concentration, there was little change in amount of stable C (defined as C in the <20 µm fraction) as the mass proportion of fine (<20 µm) particles increased. Differences in pyrophosphate extractable aluminium explained part of the variability in C concentration in the fine fractions; however, we were unable to identify any specific physico-chemical factor that would account for the relatively low C concentrations observed in the <5 and 5–20 µm fractions of fine-textured soils. We concluded that such soils may be under-saturated and potential may exist to store additional stable C.

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