Pore architecture and particulate organic matter in soils under monoculture switchgrass and restored prairie in contrasting topography

AbstractBioenergy cropping systems can substantially contribute to climate change mitigation. However, limited information is available on how they affect soil characteristics, including pores and particulate organic matter (POM), both essential components of the soil C cycle. The objective of this study was to determine effects of bioenergy systems and field topography on soil pore characteristics, POM, and POM decomposition under new plant growth. We collected intact soil cores from two systems: monoculture switchgrass (Panicum virgatum L.) and native prairie, at two contrasting topographical positions (depressions and slopes), planting half of the cores with switchgrass. Pore and POM characteristics were obtained using X-ray computed micro-tomography (μCT) (18.2 µm resolution) before and after new switchgrass growth. Diverse prairie vegetation led to higher soil C than switchgrass, with concomitantly higher volumes of 30–90 μm radius pores and greater solid-pore interface. Yet, that effect was present only in the coarse-textured soils on slopes and coincided with higher root biomass of prairie vegetation. Surprisingly, new switchgrass growth did not intensify decomposition of POM, but even somewhat decreased it in monoculture switchgrass as compared to non-planted controls. Our results suggest that topography can play a substantial role in regulating factors driving C sequestration in bioenergy systems.

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Changes in soil quality following humping/hollowing and flipping of pakihi soils on the West Coast, South Island New Zealand

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.2007.69.2666 ◽

2007 ◽

pp. 265-270 ◽

Cited By ~ 3

Author(s):

S.M. Thomas ◽

M.H.Beare C.D. Ford ◽

V. Rietveld

Keyword(s):

Organic Matter ◽

Soil Quality ◽

West Coast ◽

Land Development ◽

Hot Water ◽

Limited Information ◽

The West ◽

Organic Matter Quality ◽

Pasture Production ◽

Soil C

Humping/hollowing and flipping are land development practices widely used on the West Coast to overcome waterlogging constraints to pasture production. However, there is very limited information about how the resulting "new" soils function and how their properties change over time following these extreme modifications. We hypothesised that soil quality will improve in response to organic matter inputs from plants and excreta, which will in turn increase nutrient availability. We tested this hypothesis by quantifying the soil organic matter and nutrient content of soils at different stages of development after modification. We observed improvements in soil quality with increasing time following soil modification under both land development practices. Total soil C and N values were very low following flipping, but over 8 years these values had increased nearly five-fold. Other indicators of organic matter quality such as hot water extractable C (HWC) and anaerobically mineralisable N (AMN) showed similar increases. With large capital applications of superphosphate fertiliser to flipped soils in the first year and regular applications of maintenance fertiliser, Olsen P levels also increased from values

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Post-thinning soil organic matter evolution and soil CO2 effluxes in temperate radiata pine plantations: impacts of moderate thinning regimes on the forest C cycle

Canadian Journal of Forest Research ◽

10.1139/x2012-137 ◽

2012 ◽

Vol 42 (11) ◽

pp. 1953-1964 ◽

Cited By ~ 4

Author(s):

Irene Fernandez ◽

Juan Gabriel Álvarez-González ◽

Beatríz Carrasco ◽

Ana Daría Ruíz-González ◽

Ana Cabaneiro

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Radiata Pine ◽

Soil Samples ◽

Mitigation Strategies ◽

Change Scenario ◽

Soil C ◽

C Storage ◽

C Cycle ◽

C And N

Forest ecosystems can act as C sinks, thus absorbing a high percentage of atmospheric CO2. Appropriate silvicultural regimes can therefore be applied as useful tools in climate change mitigation strategies. The present study analyzed the temporal changes in the effects of thinning on soil organic matter (SOM) dynamics and on soil CO2 emissions in radiata pine ( Pinus radiata D. Don) forests. Soil C effluxes were monitored over a period of 2 years in thinned and unthinned plots. In addition, soil samples from the plots were analyzed by solid-state 13C-NMR to determine the post-thinning SOM composition and fresh soil samples were incubated under laboratory conditions to determine their biodegradability. The results indicate that the potential soil C mineralization largely depends on the proportion of alkyl-C and N-alkyl-C functional groups in the SOM and on the microbial accessibility of the recalcitrant organic pool. Soil CO2 effluxes varied widely between seasons and increased exponentially with soil heating. Thinning led to decreased soil respiration and attenuation of the seasonal fluctuations. These effects were observed for up to 20 months after thinning, although they disappeared thereafter. Thus, moderate thinning caused enduring changes to the SOM composition and appeared to have temporary effects on the C storage capacity of forest soils, which is a critical aspect under the current climatic change scenario.

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Temperature sensitivity of simulated soils with biochars produced at different temperatures

Soil Research ◽

10.1071/sr18226 ◽

2019 ◽

Vol 57 (3) ◽

pp. 294 ◽

Cited By ~ 1

Author(s):

Xiaojie Wang ◽

Guanhong Chen ◽

Renduo Zhang

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Temperature Sensitivity ◽

Pyrolysis Temperature ◽

Soil C ◽

Ambient Temperatures ◽

C Pools ◽

C Cycle ◽

Microbial Enzyme ◽

Different Temperatures

The temperature sensitivity of multiple carbon (C) pools in the soil plays an important role in the C cycle and potential feedback to climate change. The aim of this study was to investigate the temperature sensitivity of different biochars in soil to better understand the temperature sensitivity of different soil C pools. Biochars were prepared using sugarcane residue at temperatures of 300, 500 and 800°C (representing different C pools) and C skeletons (representing the refractory C pool in biochar) were obtained from each biochar. The sugarcane residue, biochars and C skeletons were used as amendments in a simulated soil with microbes but without organic matter. The temperature sensitivity of the amended soils was characterised by their mineralisation rate changes in response to ambient temperatures. The temperature sensitivity of treatments with relatively refractory biochars was higher than that with labile biochars. The temperature sensitivity of treatments with biochars was lower than for their corresponding C skeletons. The different temperature sensitivity of treatments was attributable to the different internal C structures (i.e. the functional groups of C=C and aromatic structure) of amendments, determining the biodegradability of substrates. Dissolved organic matter and microbial enzyme activity of biochars were lower than those of corresponding C skeletons, and decreased with increasing pyrolysis temperature. The temperature sensitivities of treatments with biochars, C skeletons and sugarcane residue were negatively correlated with the properties of dissolved organic matter and microbial enzyme activities (especially dehydrogenase) in soil.

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Influence of climate change factors on carbon dynamics in northern forested peatlands

Canadian Journal of Soil Science ◽

10.4141/s05-089 ◽

2006 ◽

Vol 86 (Special Issue) ◽

pp. 269-280 ◽

Cited By ~ 28

Author(s):

C. C. Trettin ◽

R. Laiho ◽

K. Minkkinen ◽

J. Laine

Keyword(s):

Climate Change ◽

Organic Matter ◽

Management Practices ◽

Atmospheric Temperature ◽

Soil C ◽

Altered Hydrology ◽

Biogeochemical Models ◽

C Dynamics ◽

C Balance ◽

C Cycle

Peatlands are carbon-accumulating wetland ecosystems, developed through an imbalance among organic matter production and decomposition processes. Soil saturation is the principal cause of anoxic conditions that constrain organic matter decay. Accordingly, changes in the hydrologic regime will affect the carbon (C) dynamics in forested peatlands. Our objective is to review ecological studies and experiments on managed peatlands that provide a basis for assessing the effects of an altered hydrology on C dynamics. We conclude that climate change influences will be mediated primarily through the hydrologic cycle. A lower water table resulting from altered precipitation patterns and increased atmospheric temperature may be expected to decrease soil CH4 and increase CO2 emissions from the peat surface. Correspondingly, the C balance in forested peatlands is also sensitive to management and restoration prescriptions. Increases in soil CO2 efflux do not necessarily equate with net losses from the soil C pool. While the fundamentals of the C balance in peatlands are well-established, the combined affects of global change stressors and management practices are best considered using process-based biogeochemical models. Long-term studies are needed both for validation and to provide a framework for longitudinal assessments of the peatland C cycle. Key words: Peatland, carbon cycle, methane, forest, wetland.

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

Geoscientific Model Development ◽

10.5194/gmd-11-4779-2018 ◽

2018 ◽

Vol 11 (12) ◽

pp. 4779-4796 ◽

Cited By ~ 6

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.

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Modeling the effects of litter stoichiometry and soil mineral N availability on soil organic matter formation

10.5194/gmd-2018-173 ◽

2018 ◽

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 adapted CUEd formulation, we also illustrated that litter quality affected the long-term SOM formation crucially. 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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Characterization of Soil Organic Matter along an elevation gradient at Stelvio Pass (Italian Alps).

10.5194/egusphere-egu2020-10750 ◽

2020 ◽

Author(s):

Roberta Zangrando ◽

Maria del Carmen Villoslada Hidalgo ◽

Clara Turetta ◽

Nicoletta Cannone ◽

Francesco Malfasi ◽

...

Keyword(s):

Climate Change ◽

Organic Matter ◽

Soil Organic Matter ◽

Organic Carbon ◽

Elevation Gradient ◽

Total Carbon ◽

Plant Component ◽

Soil C ◽

C Cycle ◽

C Stocks

Climate Change (CC) has evident impacts on the biotic and abiotic components of ecosystems.Soil is the third largest reservoir of carbon, next to the lithosphere and the oceans, and stores approximately 1500 Gt in the top1 m depth. &#160;Even small changes in soil C stocks could have a vast impact on atmospheric CO2 concentration. Elevated surface temperature can substantially affect global C budgets and produce positive or negative feedbacks to climate change. Therefore, understanding the response of soil organic carbon (SOC) stocks to warming is of critical importance to evaluate the feedbacks between terrestrial C cycle and climate change.In comparison to other ecosystems, the areas at high altitudes and latitudes are the most vulnerable. In permafrost areas of the Northern Hemisphere the CC has already determined an increase in greenhouse gas emissions, shrub vegetation and variation in the composition of microbial communities. While numerous studies have been performed in Arctic, much less numerous are available for high altitude areas. These areas are a quarter of the emerged lands &#160;and have suffered strong impacts from the CC. Mountain permafrost makes up 14% of global permafrost, stores large quantities of organic carbon (SOC), and can release large quantities of CO2 due to climate change. However, permafrost contribution to the IPCC global budget has not yet been correctly quantified, in particular for ecosystems of prairie and shrubland, which alone could incorporate over 80Pg of C between soil and biomass. In the last decades, the plant component has undergone migration of species to higher altitudes, expansion of shrubs, variations in floristic composition and dominance, variations in area distribution. The expansion of the shrubs accelerates the regression of alpine meadows and snow valleys.The sampling activities have been carried out in July and September, from September 2017 to July 2019 in an area near Stelvio Pass (2,758 m a.s.l.) (Italian Central-Eastern Alps) along an altitude gradient. &#160;&#160;Two sampling sites located at 2600 m a.s.l. and 2200 m a.s.l. in altitude, corresponding to about 3&#176; C difference in the average annual air temperature were chosen. At the 2600 m site, warming experiments using open-top chambers (OTCs) to investigate how climate warming affects SOC were performed.In order to characterize the SOM (Soil Organic Matter), Total carbon (TC), Organic carbon (OC), Total Nitrogen (TN) and Dissolved Organic Carbon (DOC) were determined in soils. TC and TN were determined in biomass. In both soils and biomass were analyzed to quantify the distribution of stable isotopes of C and N, &#948;13C and &#948;15N.

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Land-use perturbations in ley grassland decouple the degradation of ancient soil organic matter from the storage of newly derived carbon inputs

SOIL ◽

10.5194/soil-6-435-2020 ◽

2020 ◽

Vol 6 (2) ◽

pp. 435-451

Author(s):

Marco Panettieri ◽

Denis Courtier-Murias ◽

Cornelia Rumpel ◽

Marie-France Dignac ◽

Gonzalo Almendros ◽

...

Keyword(s):

Land Use ◽

Organic Matter ◽

Soil Organic Matter ◽

Temperate Climate ◽

Soil C ◽

Legacy Effect ◽

C Cycle ◽

13C Nuclear Magnetic Resonance ◽

Microbial Proliferation ◽

Soil C Cycle

Abstract. In a context of global change, soil has been identified as a potential carbon (C) sink, depending on land-use strategies. To detect the trends in carbon stocks after the implementation of new agricultural practices, early indicators, which can highlight changes in short timescales, are required. This study proposes the combined use of stable isotope probing and chemometrics applied to solid-state 13C nuclear magnetic resonance (NMR) spectra to unveil the dynamics of the storage and mineralization of soil carbon (C) pools. We focused on light organic matter fractions isolated by density fractionation of soil water stable aggregates because they respond faster to changes in land use than the total soil organic matter (SOM). Samples were collected from an agricultural field experiment with grassland, continuous maize cropping, and ley grassland under temperate climate conditions. Our results indicated contrasting aggregate dynamics depending on land-use systems. Under our experimental conditions, grassland returns larger amounts of C as belowground inputs than maize cropping, evidencing a different distribution of light C fractions between aggregate classes. Coarse aboveground inputs from maize contributed mostly to larger macroaggregates. Land-use changes with the introduction of ley grassland provoked a decoupling of the storage and/or degradation processes after the grassland phase. The newly derived maize inputs were barely degraded during the first 3 years of maize cropping, whereas grassland-derived material was depleted. As a whole, results suggest large microbial proliferation as shown by 13C NMR under permanent grassland, then reduced within the first years after the land-use conversion, and finally restored. The study highlighted a fractal structure of the soil, determining a scattered spatial distribution of the cycles of storage and degradation of soil organic matter related to detritusphere dynamics. As a consequence, vegetal inputs from a new land use are creating new detritusphere microenvironments that may be disconnected from the dynamics of C cycle of the previous land use. The formation of those different and unconnected microenvironments may explain the observed legacy effect of the previous land use, since each microenvironment type contributes separately to the overall soil C cycle. The effects of the new land use on the soil C cycle are delayed until the different detritusphere microenvironments remain unconnected, and the ones from the previous land use represent the predominant microenvironment type. Increasing knowledge of the soil C dynamics at a fine scale will be helpful in refining the prediction models and land-use policies.

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Soil aggregate stability index and particulate organic matter in response to differently afforested lands in the temperate regions of Iran

Journal of Forest Science ◽

10.17221/20/2021-jfs ◽

2021 ◽

Vol 67 (No. 8) ◽

pp. 376-384

Author(s):

Masoomeh Soleimany ◽

Jamshid Eslamdoust ◽

Moslem Akbarinia ◽

Yahya Kooch

Keyword(s):

Organic Matter ◽

Particulate Organic Matter ◽

Aggregate Stability ◽

Stability Index ◽

Surface Layers ◽

Northern Iran ◽

Soil C ◽

Soil Aggregate Stability ◽

Land Use And Management ◽

Positive Effect

Aggregate Stability Index (ASI) and particulate organic matter (POM) are strongly influenced by land use and management. This work illustrates the effects of plantations on ASI and POM-C and POM-N in northern Iran. Three plantations of P. deltoides (PD), T. distichum (TD), A. subcordata (AS), and a fourth site ‒ adjacent abandoned lands (BL, as control) were selected. Soil samples were taken within 16 quadrats of each plantation and BL from the two depths of 0–15 cm and 15–30 cm during the summer. Soil C was signiﬁcantly higher under TD (2.10%) than under BL (2.02%) > PD (1.61%) > AS (1.30%). Soil N was found in ranked order of AS (8.99%) > TD (7.82%) > PD (5.30%) > BL (3.68%) (P < 0.019). The significantly higher ASI was found under TD (57.49) in comparison with PD (53.10), BL (51.23), and AS (36.57). The POM-C was as follows: TD (0.209%) > PD (0.141%) > AS (0.139%) > BL (0.075%) (P = 0.020). The highest POM-N was found under TD (0.035), followed by AS (0.0284%), PD (0.0288%), and BL (0.007%). The results indicate the positive effect of afforestation on soil ASI and POM-C and POM-N, especially in the surface layers of soil.

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