scholarly journals Effects of ageing under field conditions on soil organic matter in earthworm casts produced by the anecic earthworm Amynthas adexilis in northern Vietnam

2021 ◽  
Author(s):  
Nicolas Jean Bernard Puche ◽  
Cornelia Rumpel ◽  
Nicolas Bottinelli
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Soil Aggregates ◽  
Ct Images ◽  
Field Conditions ◽  
Strong Positive Correlation ◽  
Micro Ct ◽  
Earthworm Casts ◽  
Biogeochemical Models ◽  
And Control

<p>Carbon sequestration in soils became a major issue that governments have to face under their sustainable development objectives and the international 4p1000 program. Although, earthworms are recognized to play a key role in the structure and dynamics of organic matter (OM) in soils, their contribution to soil OM cycling is not taken into account in biogeochemical models nor well understood. In particular, the fate of OM protected in earthworm casts is unknown. In this study, we investigated the effects of ageing under field conditions on the OM dynamics contained in casts produced by the anecic earthworm Amynthas adexilis in North Vietnam. To this end we investigated (1) the microscale organisation of particulate organic matter and pores during the exposure of casts and control aggregates during 12 months and (2) compared it to the potential OM mineralisation during a laboratory incubation.</p><p>Our results indicated that fresh casts contained significantly more particulate organic matter (POM) than control soil aggregates and field aged earthworm casts. Conversely, the porosity was higher in soil control aggregates than in casts and the porosity of casts tended to increase with their ageing. The analyses of micro-CT images also revealed that POM and Pores contents between casts samples presented strong variabilities even in the youngest casts category. We found, on average, higher mineralisation rates for casts than for controls and a reduction of the OM mineralisation with the ageing of casts. Our results also highlighted a strong positive correlation (r<sup>2</sup> = 0.89) between POM contents determined by the segmentation of micro CT images and CO<sub>2</sub> emissions from the incubation experiment. We conclude that earthworms impact the microscale organisation of POM and pores in their casts and thereby influence soil OM dynamics.</p>

scholarly journals Two different microbial communities did not cause differences in occlusion of particulate organic matter in a sandy agricultural soil

2016 ◽  
Author(s):  
Frederick Büks ◽  
Philip Rebensburg ◽  
Peter Lentzsch ◽  
Martin Kaupenjohann
Keyword(s):  
Organic Matter ◽  
Microbial Communities ◽  
Particulate Organic Matter ◽  
Agricultural Soil ◽  
Agricultural Soils ◽  
Soil Aggregates ◽  
Soil Extract ◽  
Microbial Life ◽  
Physico Chemical ◽  
Airborne Microbes

Abstract. Apart from physico-chemical interactions between soil components, microbial life is assumed to be an important factor of soil structure forming processes. Bacterial exudates, the entanglement by fungal hypae and bacterial pseudomycelia as well as fungal glomalin are supposed to provide the occlusion of particulate organic matter (POM) through aggregation of soil particles. This work investigates the resilience of POM occlusion in face of different microbial communities under controlled environmental conditions. We hypothesized that the formation of different communities would cause different grades of POM occlusion. For this purpose samples of a sterile sandy agricultural soil were incubated for 76 days in bioreactors. Particles of pyrochar from pine wood were added as POM analogue. One variant was inoculated with a native soil extract, whereas the control was infected by airborne microbes. A second control soil remained non-incubated. During the incubation, soil samples were taken for taxon-specific qPCR to determine the abundance of Eubacteria, Fungi, Archaea, Acidobacteria, Actinobacteria, α-Proteobacteria and β-Proteobacteria. After the incubation soil aggregates (100–2000 μm) were collected by sieving and disaggregated using ultrasound to subject the released POM to an analysis of organic carbon (OC). Our results show, that the eubacterial DNA of both incubated variants reached a similar concentration after 51 days. However, the structural composition of the two communities was completely different. The soil-born variant was dominated by Acidobacteria, Actinobacteria and an additional fungal population, whereas the air-born variant mainly contained β-Proteobacteria. Both variants showed a strong occlusion of POM into aggregates during the incubation. Yet, despite the different population structure, there were only marginal differences in the release of POM along with the successive destruction of soil aggregates by ultrasonication. This leads to the tentative assumption that POM occlusion in agricultural soils could be resilient in face of changing microbial communities.

Long-term effects of biochar amount on the content and composition of organic matter in soil aggregates under field conditions

2016 ◽  
Vol 16 (5) ◽  
pp. 1481-1497 ◽  
Author(s):  
Xinliang Dong ◽  
Tianyu Guan ◽  
Guitong Li ◽  
Qimei Lin ◽  
Xiaorong Zhao
Keyword(s):  
Organic Matter ◽  
Soil Aggregates ◽  
Field Conditions ◽  
Long Term Effects

scholarly journals Enzymatic biofilm digestion in soil aggregates facilitates the release of particulate organic matter by sonication

SOIL ◽  
2016 ◽  
Vol 2 (4) ◽  
pp. 499-509 ◽  
Author(s):  
Frederick Büks ◽  
Martin Kaupenjohann
Keyword(s):  
Organic Matter ◽  
Soil Quality ◽  
Particulate Organic Matter ◽  
Extracellular Polymeric Substances ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Enzyme Treatment ◽  
Rooting Depth ◽  
Experimental Proof ◽  
Biofilm Detachment

Abstract. The stability of soil aggregates against shearing and compressive forces as well as water-caused dispersion is an integral marker of soil quality. High stability results in less compaction and erosion and has been linked to enhanced water retention, dynamic water transport and aeration regimes, increased rooting depth, and protection of soil organic matter (SOM) against microbial degradation. In turn, particulate organic matter is supposed to support soil aggregate stabilization. For decades the importance of biofilm extracellular polymeric substances (EPSs) regarding particulate organic matter (POM) occlusion and aggregate stability has been canonical because of its distribution, geometric structure and ability to link primary particles. However, experimental proof is still missing. This lack is mainly due to methodological reasons. Thus, the objective of this work is to develop a method of enzymatic biofilm detachment for studying the effects of EPSs on POM occlusion. The method combines an enzymatic pre-treatment with different activities of α-glucosidase, β-galactosidase, DNAse and lipase with a subsequent sequential ultrasonic treatment for disaggregation and density fractionation of soils. POM releases of treated samples were compared to an enzyme-free control. To test the efficacy of biofilm detachment the ratio of bacterial DNA from suspended cells and the remaining biofilm after enzymatic treatment were measured by quantitative real-time PCR. Although the enzyme treatment was not sufficient for total biofilm removal, our results indicate that EPSs may attach POM within soil aggregates. The tendency to additional POM release with increased application of enzymes was attributed to a slight loss in aggregate stability. This suggests that an effect of agricultural practices on soil microbial populations could influence POM occlusion/aggregate stability and thereby carbon cycle/soil quality.

scholarly journals On the treatment of particulate organic matter sinking in large-scale models of marine biogeochemical cycles

2008 ◽  
Vol 5 (1) ◽  
pp. 55-72 ◽  
Author(s):  
I. Kriest ◽  
A. Oschlies
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Water Column ◽  
Size Distribution ◽  
Power Law ◽  
Particulate Organic Matter ◽  
Large Scale ◽  
Regional Patterns ◽  
Size Dependent ◽  
Biogeochemical Models

Abstract. Various functions have been suggested and applied to represent the sedimentation and remineralisation of particulate organic matter (POM) in numerical ocean models. Here we investigate some representations commonly used in large-scale biogeochemical models: a constant sinking speed, a sinking speed increasing with depth, a spectrum of particles with different size and different size-dependent sinking velocities, and a model that assumes a power law particle size distribution everywhere in the water column. The analysis is carried out for an idealised one-dimensional water column, under stationary boundary conditions for surface POM. It focuses on the intrinsic assumptions of the respective sedimentation function and their effect on POM mass, mass flux, and remineralisation profiles. A constant and uniform sinking speed does not appear appropriate for simulations exceeding a few decades, as the sedimentation profile is not consistent with observed profiles. A spectrum of size classes, together with size-dependent sinking and constant remineralisation, causes the sinking speed of total POM to increase with depth. This increase is not strictly linear with depth. Its particular form will further depend on the size distribution of the POM ensemble at the surface. Assuming a power law particle size spectrum at the surface, this model results in unimodal size distributions in the ocean interior. For the size-dependent sinking model, we present an analytic integral over depth and size that can explain regional variations of remineralisation length scales in response to regional patterns in trophodynamic state.

scholarly journals On the treatment of particulate organic matter sinking in large-scale models of marine biogeochemical cycles

2007 ◽  
Vol 4 (4) ◽  
pp. 3005-3040
Author(s):  
I. Kriest ◽  
A. Oschlies
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Water Column ◽  
Size Distribution ◽  
Power Law ◽  
Particulate Organic Matter ◽  
Large Scale ◽  
Regional Patterns ◽  
Size Dependent ◽  
Biogeochemical Models

Abstract. Various functions have been suggested and applied to represent the sedimentation and remineralisation of particulate organic matter (POM) in numerical ocean models. Here we investigate some representations commonly used in large-scale biogeochemical models: a constant sinking speed, a sinking speed increasing with depth, a spectrum of particles with different size and different size-dependent sinking velocities, and a model that assumes a power-law particle size distribution everywhere in the water column. The analysis is carried out for an idealised one-dimensional water column, under stationary boundary conditions for surface POM. It focuses on the intrinsic assumptions of the respective sedimentation function and their effect on POM mass, mass flux, and remineralisation profiles. A constant and uniform sinking speed does not appear appropriate for simulations exceeding a few decades, as the sedimentation profile is not consistent with observed profiles. A spectrum of size classes, together with size-dependent sinking and constant remineralisation, causes the sinking speed of total POM to increase with depth. This increase is not strictly linear with depth. Its particular form will further depend on the size distribution of the POM ensemble at the surface. Assuming a power-law particle size spectrum at the surface, this model results in unimodal size distributions in the ocean interior. For the size-dependent sinking model, we present an analytic integral over depth and size that can explain regional variations of remineralisation length scales in response to regional patterns in trophodynamic state.

scholarly journals Particles under stress: Ultrasonication causes size and recovery rate artifacts with soil derived POM, but not with microplastics

2020 ◽  
Author(s):  
Frederick Büks ◽  
Gilles Kayser ◽  
Antonia Zieger ◽  
Friederike Lang ◽  
Martin Kaupenjohann
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Particulate Organic Matter ◽  
Recovery Rate ◽  
Soil Aggregates ◽  
Terrestrial Ecosystems ◽  
Physiochemical Properties ◽  
Average Factor ◽  
Carry Over ◽  
Physical Stabilization

Abstract. The breakdown of soil aggregates and the extraction of particulate organic matter (POM) by ultrasonication and density fractionation is a method widely used in soil organic matter (SOM) analyses. It has recently also been used for the extraction of microplastic from soil samples. However, the investigation of some POM physiochemical properties and ecological functions might be biased, if particles are comminuted during the treatment. In this work, different types of POM, which are representative for different terrestrial ecosystems and anthropogenic influences, were tested for their structural stability in face of ultrasonication in a range of 0 to 500 J ml−1. The occluded particulate organic matter (oPOM) of an agricultural and forest soil as well as pyrochar showed a significant reduction of particle size at ≥ 50 J ml−1 by an average factor of 1.37 ± 0.16 and a concurrent reduction of recovery rates by an average of 21.7 ± 10.7 % when being extracted. Our results imply that ultrasonication causes an imitated carry-over of POM to more strongly bound fractions or to the mineral-associated organic matter (MOM) due to enhanced attraction to the mineral phase, which could e.g. lead to a false estimation of physical stabilization. In contrast, neither fresh nor weathered polyethylene (PE), polyethylene terephthalate (PET) and polybutylene adipate terephthalate (PBAT) microplastics showed a reduction of particle size or the recovery rate after application of ultrasound. We conclude that ultrasonication applied to soils has no impact on microplastic size distribution and thus provides a valuable tool for the assessment of microplastics in soils and soil aggregates.

The Impact of Corn Residue Removal on Soil Aggregates and Particulate Organic Matter

2014 ◽  
Vol 7 (2) ◽  
pp. 559-567 ◽  
Author(s):  
Shannon L. Osborne ◽  
Jane M. F. Johnson ◽  
Virginia L. Jin ◽  
Amber L. Hammerbeck ◽  
Gary E. Varvel ◽  
...  
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Soil Aggregates ◽  
Residue Removal ◽  
Corn Residue ◽  
The Impact

Preliminary remarks on porosity of soil aggregates in air-dry state and at pF 2.

1961 ◽  
Vol 9 (3) ◽  
pp. 168-173 ◽  
Author(s):  
H. Kuipers
Keyword(s):  
Organic Matter ◽  
Moisture Content ◽  
Water Content ◽  
Pore Volume ◽  
Pore Space ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Field Conditions ◽  
Swelling Properties ◽  
Air Voids

In pycnometer determinations of the pore volume of 2-5-mm air-dry aggregates from various soils of 1.5-2.5 and 2.6-3.5% organic-matter levels and various clay contents, the use of kerosene (S. & F. XVII [1897]) gave as good values as, and was more convenient than, the use of sand or mercury (the latter giving low porosities). The pore-space percentage of aggregates could be calculated from the water content at pF 2, when no air voids in the small aggregates are likely to occur and water between the aggregates is of no importance. Dry aggregates were only slightly denser in cores of light soils than under field conditions, and swelling was small; dry aggregates were very dense in heavy soils in which moisture content and density of aggregates appeared so closely related that it was difficult to distinguish between the effect of either on the strength of aggregates. Swelling properties and aggregate size are likely to be important factors in the structure of heavy soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Examples of energy self-sufficient municipal nutrient removal plants

2011 ◽  
Vol 64 (1) ◽  
pp. 1-6 ◽  
Author(s):  
O. Nowak ◽  
S. Keil ◽  
C. Fimml
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Nutrient Removal ◽  
Energy Efficient ◽  
Aeration Tank ◽  
Sludge Digestion ◽  
Self Sufficiency ◽  
And Control ◽  
Aerobic Sludge ◽  
Aeration Control

In Austria, two municipal WWTPs (the Strass TP and Wolfgangsee-Ischl TP) operated with nutrient removal and aerobic sludge digestion are now energy self-sufficient. This is the result of a long-standing and on-going optimisation process at both plants including optimal aeration control and control of the aerobic section of the aeration tank to optimise denitrification and prevent degradation of particulate organic matter that should be degraded in the digester. Both TPs are now equipped with energy-efficient CHP units. However, it is maybe more sustainable to use the biogas as bio-methane/bio-fuel than in conventional CHP at the WWTP. It is shown that energy self-sufficiency should be in reach at other municipal WWTPs, too.

scholarly journals Particles under stress: ultrasonication causes size and recovery rate artifacts with soil-derived POM but not with microplastics

2021 ◽  
Vol 18 (1) ◽  
pp. 159-167
Author(s):  
Frederick Büks ◽  
Gilles Kayser ◽  
Antonia Zieger ◽  
Friederike Lang ◽  
Martin Kaupenjohann
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Particulate Organic Matter ◽  
Recovery Rate ◽  
Soil Aggregates ◽  
Terrestrial Ecosystems ◽  
Physiochemical Properties ◽  
The Face ◽  
Average Factor ◽  
Physical Stabilization

Abstract. The breakdown of soil aggregates and the extraction of particulate organic matter (POM) by ultrasonication and density fractionation is a method widely used in soil organic matter (SOM) analyses. It has recently also been used for the extraction of microplastic from soil samples. However, the investigation of POM physiochemical properties and ecological functions might be biased if particles are comminuted during the treatment. In this work, different types of POM, which are representative of different terrestrial ecosystems and anthropogenic influences, were tested for their structural stability in the face of ultrasonication in the range of 0 to 500 J mL−1. The occluded particulate organic matter (oPOM) of an agricultural and forest soil as well as pyrochar showed a significant reduction of particle size at ≥50 J mL−1 by an average factor of 1.37±0.16 and a concurrent reduction of recovery rates by an average of 21.7±10.7 % when being extracted. Our results imply that increasing ultrasonication causes increasing retention of POM within the sedimenting phase, leading to a misinterpretation of certain POM fractions as more strongly bound oPOM or part of the mineral-associated organic matter (MOM). This could, for example, lead to a false estimation of physical stabilization. In contrast, neither fresh nor weathered polyethylene (PE), polyethylene terephthalate (PET) and polybutylene adipate terephthalate (PBAT) microplastics showed a reduction of particle size or the recovery rate after application of ultrasound. We conclude that ultrasonication applied to soils has no impact on microplastic size distribution and thus provides a valuable tool for the assessment of microplastics in soils and soil aggregates.

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