Microbial necromass as a source for soil organic matter formation - implications for soil processes

2020 ◽  
Author(s):  
Anja Miltner ◽  
Tiantian Zheng ◽  
Chao Liang ◽  
Matthias Kästner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Surface Properties ◽  
Soil Microorganisms ◽  
Plant Litter ◽  
Plant Residues ◽  
Elemental Stoichiometry ◽  
Stress Changes ◽  
Cell Envelopes

<p>The vital role of soil microorganisms as catalysts for soil organic matter (SOM) formation has long been recognised. Plant residues are now considered to be transformed by soil microorganisms who use the plant litter as a carbon source for microbial biomass formation. How much carbon is retained as microbial biomass during transformation of plant material, critically depends on substrate availability, carbon use efficiency of the microorganisms, and maximum microbial growth. In addition, microorganisms presumably recycle biomass building blocks from plant or microbial material to avoid energy expenditure for biomass synthesis. After cell death, a part of the microbial necromass is cycling through the microbial food web; the other part is stabilised in soil (Miltner et al., 2012). Potential stabilisation mechanisms are similar to those for SOM in general, with organo-mineral interactions, in particular encapsulation and physical isolation, being important mechanisms. Independent of which pathway the plant-derived carbon goes, SOM constitutes a continuum of plant and microbial necromass at various stages of decay. The contribution of microbial necromass to the topsoil organic matter pool has recently been estimated to range from 30 to 60% (Liang et al., 2019). Such high contributions of microbial necromass have a number of important implications for understanding SOM transformation and sequestration processes. Most obviously, the chemical identity of the organic material changes. For example, while retaining a substantial part of the carbon, the elemental stoichiometry changes substantially. Some microbial necromass materials are rather long-lasting in soil. In general, cell envelope residues have a higher stability than bulk biomass carbon. Proteins have also been shown to be rather persistent in soil, presumably due to conformational changes and the spatial arrangement of microbial necromass material, e.g. fragments of cell envelopes presumably pile up in multiple layers and the material forms clusters of macromolecular size. Residual electron-shuttle biomolecules (e.g. oxidoreductases, Fe-S-cluster, quinoid complexes of respiratory chains) may persist and retain some activity and thus contribute to redox reactions in soil. In addition, the necromass is expected to cover soil particle surfaces and thus determine the surface properties of these particles. In particular, these materials contribute to the water storage potential. They affect water retention and nutrient diffusion as well as microbial motility. Adaption of microbes to water stress changes their cell surface properties and molecular composition and thus may determine overall soil wettability. Knowledge on the contribution of microbial necromass to SOM would thus be essential for modelling SOM formation and optimising soil management practices for maintaining soil functions.</p><p> </p><p>References:</p><p>Miltner A, Bombach P, Schmidt-Brücken B, Kästner M (2012) SOM genesis: Microbial biomass as a significant source. Biogeochemistry 111: 41-55.</p><p>Liang C, Amelung W, Lehmann J, Kästner M (2019) Quantitative assessment of microbial necromass contribution to soil organic matter. Global Change Biology 25: 3578-3590.</p>

scholarly journals Soil properties and not inputs control carbon : nitrogen : phosphorus ratios in cropped soils in the long term

SOIL ◽  
2016 ◽  
Vol 2 (1) ◽  
pp. 83-99 ◽  
Author(s):  
Emmanuel Frossard ◽  
Nina Buchmann ◽  
Else K. Bünemann ◽  
Delwende I. Kiba ◽  
François Lompo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Soil Properties ◽  
Nutrient Concentrations ◽  
Nutrient Ratios ◽  
Plant Residues ◽  
Wagga Wagga ◽  
Positive Correlation

Abstract. Stoichiometric approaches have been applied to understand the relationship between soil organic matter dynamics and biological nutrient transformations. However, very few studies have explicitly considered the effects of agricultural management practices on the soil C : N : P ratio. The aim of this study was to assess how different input types and rates would affect the C : N : P molar ratios of bulk soil, organic matter and microbial biomass in cropped soils in the long term. Thus, we analysed the C, N, and P inputs and budgets as well as soil properties in three long-term experiments established on different soil types: the Saria soil fertility trial (Burkina Faso), the Wagga Wagga rotation/stubble management/soil preparation trial (Australia), and the DOK (bio-Dynamic, bio-Organic, and “Konventionell”) cropping system trial (Switzerland). In each of these trials, there was a large range of C, N, and P inputs which had a strong impact on element concentrations in soils. However, although C : N : P ratios of the inputs were highly variable, they had only weak effects on soil C : N : P ratios. At Saria, a positive correlation was found between the N : P ratio of inputs and microbial biomass, while no relation was observed between the nutrient ratios of inputs and soil organic matter. At Wagga Wagga, the C : P ratio of inputs was significantly correlated to total soil C : P, N : P, and C : N ratios, but had no impact on the elemental composition of microbial biomass. In the DOK trial, a positive correlation was found between the C budget and the C to organic P ratio in soils, while the nutrient ratios of inputs were not related to those in the microbial biomass. We argue that these responses are due to differences in soil properties among sites. At Saria, the soil is dominated by quartz and some kaolinite, has a coarse texture, a fragile structure, and a low nutrient content. Thus, microorganisms feed on inputs (plant residues, manure). In contrast, the soil at Wagga Wagga contains illite and haematite, is richer in clay and nutrients, and has a stable structure. Thus, organic matter is protected from mineralization and can therefore accumulate, allowing microorganisms to feed on soil nutrients and to keep a constant C : N : P ratio. The DOK soil represents an intermediate situation, with high nutrient concentrations, but a rather fragile soil structure, where organic matter does not accumulate. We conclude that the study of C, N, and P ratios is important to understand the functioning of cropped soils in the long term, but that it must be coupled with a precise assessment of element inputs and budgets in the system and a good understanding of the ability of soils to stabilize C, N, and P compounds.

scholarly journals Potential of the soil microbial biomass C to tolerate and degrade persistent organic pollutants

2008 ◽  
Vol 3 (No. 1) ◽  
pp. 12-20 ◽  
Author(s):  
G. Mühlbachová
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Contaminated Soil ◽  
Soil Microorganisms ◽  
Soil Microbial Biomass ◽  
Microbial Biomass C ◽  
Microbial Activities ◽  
Soil Microbial Biomass C ◽  
Soil Microbial

A 12-day incubation experiment with the addition of glucose to soils contaminated with persistent organic pollutants (POPs) was carried out in order to estimate the potential microbial activities and the potential of the soil microbial biomass C to degrade 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (DDT), polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAHs). The microbial activities were affected in different ways depending on the type of pollutant. The soil organic matter also played an important role. The microbial activities were affected particularly by high concentrations of PAHs in the soils. Soil microorganisms in the PAHs contaminated soil used the added glucose to a lesser extent than in the non-contaminated soil, which in the contaminated soil resulted in a higher microbial biomass content during the first day of incubation. DDT, DDD and DDE, and PCB affected the soil microbial activities differently and, in comparison with control soils, decreased the microbial biomass C during the incubation. The increased microbial activities led to a significant decrease of PAH up to 44.6% in the soil long-term contaminated with PAHs, and up to 14% in the control soil after 12 days of incubation. No decrease of PAHs concentrations was observed in the soil which was previously amended with sewage sludges containing PAHs and had more organic matter from the sewage sludges. DDT and its derivates DDD and DDE decreased by about 10%, whereas the PCB contents were not affected at all by microbial activities. Studies on the microbial degradation of POPs could be useful for the development of methods focused on the remediation of the contaminated sites. An increase of soil microbial activities caused by addition of organic substrates can contribute to the degradation of pollutants in some soils. However, in situ biodegradation may be limited because of a complex set of environmental conditions, particularly of the soil organic matter. The degradability and availability of POPs for the soil microorganisms has to be estimated individually for each contaminated site.

Nitrogen cycling in brigalow clay soils under pasture and cropping

Soil Research ◽  
1997 ◽  
Vol 35 (6) ◽  
pp. 1323 ◽  
Author(s):  
F. A. Robertson ◽  
R. J. K. Myers ◽  
P. G. Saffigna
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Plant Uptake ◽  
Significant Proportion ◽  
Clay Soils ◽  
Plant Residues ◽  
Panicum Maximum ◽  
N Availability ◽  
Soil Inorganic

Clay soils previously under native brigalow (Acacia harpophylla) forest are highly productive under annual cropping in central and southern Queensland. Grass pastures sown on these soils are initially productive, but deteriorate after several years because of N-stress (rundown). The aim of this work was to compare the patterns of N cycling in these pasture and cropping systems, in order to understand the rundown of the pastures. A small pulse of 15N-labelled ammonium sulfate was applied in the field to sites cropped with sorghum (Sorghum bicolor) and under green panic (Panicum maximum var. trichoglume) pasture, and its movement through the soil and plant pools was followed over 2 growing seasons. There were large differences in the cycling of 15N in the cropping and pasture systems. Under sorghum, 60% of the applied 15N was immobilised by microorganisms after 4 days, after which it was re-mineralised. Plant uptake and stabilisation in soil organic matter and clay were relatively slow. The first sorghum crop assimilated 14% of the applied 15N. During the second season, most of the 15N was stabilised in soil organic matter and clay (maximum 42%). A significant proportion of the 15N remained in the soil inorganic pool over the 2 seasons. Under green panic, 82% of the 15N left the soil inorganic pool within 4 days and entered the microbial biomass, soil organic matter, and the plant. Uptake and re-release of 15N were most rapid in the microbial biomass (maximum uptake 34% of applied after 4 days). Microbial immobilisation and re-mineralisation were, however, slower under green panic than under sorghum. The pasture plant accumulated 32% of the applied 15N, two-thirds of which was re-released in the second season. Stabilised N represented up to 62% of the applied 15N, and was consistently greater under green panic than under sorghum. After 2 seasons, 15N was released from the stabilised N pool in both systems, at approximately the same rate as it had been stabilised. At the end of the experiment, 40% of the applied 15N was unaccounted for in the pasture system, and 66% in the crop system. The reduced N availability in the pasture system was attributed to immobilisation of N in soil organic matter and clay, plant material, and, to a lesser extent, soil microbial biomass. This immobilisation resulted from the large accumulation of carbonaceous plant residues.

Influences of Biochar Aging Processes by Eco-Environmental Conditions

2013 ◽  
Vol 790 ◽  
pp. 467-470 ◽  
Author(s):  
Lu Lu Kong ◽  
Qi Xing Zhou
Keyword(s):  
Organic Matter ◽  
High Temperature ◽  
Soil Organic Matter ◽  
Surface Properties ◽  
Influencing Factors ◽  
Contaminated Soil ◽  
Environmental Conditions ◽  
Soil Microorganisms ◽  
Functional Material ◽  
Soil Components

Biochar is receiving increasing attention as a promising functional material in contaminated soil remediation. However, aging processes of biochar can usually take place and affect its remediation function, because surface properties of biochar are expected to change through a variety of biotic and abiotic processes. In this review, some important influencing factors of biochar aging processes were discussed, including temperature, and soil-physical, soil-chemical and soil-biological components. It pointed out that biochar aging processes may be promoted by high temperature, protected by soil components, particularly soil organic matter (SOM), and interactions with soil microorganisms. To further prolong application of biochar in nature, biochar aging can be mitigated by its influencing factors.

Biochemistry of plant litter types drives differentiation into particulate and mineral-associated soil organic matter and determines the magnitude of priming effect

2020 ◽  
Author(s):  
Luís Fernando Januário Almeida ◽  
Luis Carlos Colocho Hurtarte ◽  
Pedro Paulo Teixeira ◽  
Thiago M. Inagaki ◽  
Ivan Francisco de Souza ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Incubation Period ◽  
Biochemical Composition ◽  
Priming Effect ◽  
Plant Litter ◽  
Plant Residue ◽  
Control Treatment ◽  
Plant Residues ◽  
Similar Amount

<p>Soil organic matter (SOM) originates predominantly from above and belowground OM inputs derived from plants. Although the formation of SOM is well studied, it still remains unclear how the biochemical composition of litter affects the formation of new SOM as well as the degradation of “native” SOM. In the present study we aimed to disentangle the effect of plant litter composition on C transference from different plant tissues into specific SOM fractions and to determine the magnitude of priming effect on native SOC caused by litter amendments. To this end, we individually incubated <sup>13</sup>C enriched Eucalyptus spp. major litter types (bark, leaves, twigs and roots) in soil (0–20 cm) of a sandy-clay loam (Haplic Ferralsol - Brazil). Additionally, a soil sample without plant residue addition was incubated as a control. The samples were incubated at 80% of their water-holding capacity at 25 ºC for 200 days. Soil respiration was assessed along the incubation period through headspace gas sampling and <sup>13</sup>C/<sup>12</sup>C–CO<sub>2</sub> analysis in a cavity ring-down spectrometer. After the incubation, soil subsamples were physically fractionated using a combined density-particle size separation method. The total C and the δ <sup>13</sup>C of each soil organic matter fraction were measured and the litter-C contribution for each SOM fraction was assessed using a two-end member isotope mixing model. The molecular composition of the incubated plant material and SOM fractions were determined by solid-state <sup>13</sup>C-CPMAS-NMR spectroscopy. Interestingly, we found no significant differences for total SOM contents among the different treatments. Conversely, incubation without litter amendment (control treatment) resulted in lower total SOM contents, indicating mineralization of “native” SOM along the incubation period. The partitioning of litter-derived C into SOM fractions indicated that leaves litter were preferentially transferred to mineral associated organic matter (MAOM), while roots contributed more to particulate organic matter (POM). Cumulative C-CO<sub>2</sub> evolution from the treatments over the incubation period increased in the following order: twigs > leaves > bark > roots > controls. Incubation with twigs, bark and roots significantly increased “native” SOM respiration, while the treatment with leaves addition did not differ from the control. When tracing the source of “native” SOM-derived CO<sub>2</sub>, we observed a similar amount of C being respired from MAOM, regardless the treatment, while incubation with twigs, bark and roots resulted in higher respiration of “native” SOM-derived C from POM. Our data demonstrates that the biochemical composition of plant litter determines the fate of newly formed organic matter (MAOM or POM) and controls the degradation of “native” SOM. Therefore, plant residues enriched in more easily degradable compounds (leaves) are preferentially transferred to MAOM and causes less native SOC priming. On the other hand, plant residues enriched in structural compounds (twigs, bark and roots), are preferentially respired or allocated into the POM, also resulting in higher priming effect intensity.</p>

scholarly journals Nitrogen Immobilisation and Microbial Biomass Build-Up Induced by Miscanthus x giganteus L. Based Fertilisers

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1386
Author(s):  
Michael Stotter ◽  
Florian Wichern ◽  
Ralf Pude ◽  
Martin Hamer
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Triticum Aestivum L ◽  
Microbial Biomass C ◽  
Microbial Biomass N ◽  
Miscanthus X Giganteus ◽  
Organic Fertilisers ◽  
Biomass N ◽  
Set Up

Cultivation of Miscanthus x giganteus L. (Mis) with annual harvest of biomass could provide an additional C source for farmers. To test the potential of Mis-C for immobilizing inorganic N from slurry or manure and as a C source for soil organic matter build-up in comparison to wheat (Triticum aestivum L.) straw (WS), a greenhouse experiment was performed. Pot experiments with ryegrass (Lolium perenne L.) were set up to investigate the N dynamics of two organic fertilisers based on Mis at Campus Klein-Altendorf, Germany. The two fertilisers, a mixture of cattle slurry and Mis as well as cattle manure from Mis-bedding material resulted in a slightly higher N immobilisation. Especially at the 1st and 2nd harvest, they were partly significantly different compared with the WS treatments. The fertilisers based on Mis resulted in a slightly higher microbial biomass C and microbial biomass N and thus can be identified as an additional C source to prevent nitrogen losses and for the build-up of soil organic matter (SOM) in the long-term.

scholarly journals ORGANIC CARBON DYNAMICS IN GRASSLAND SOILS. 1. BACKGROUND INFORMATION AND COMPUTER SIMULATION

1981 ◽  
Vol 61 (2) ◽  
pp. 185-201 ◽  
Author(s):  
J. A. VAN VEEN ◽  
E. A. PAUL
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Experimental Studies ◽  
Decay Rates ◽  
Background Information ◽  
Plant Residues ◽  
Decomposition Rates ◽  
Straw Decomposition ◽  
Soil Biomass ◽  
The World

The decomposition rates of 14C-labelled plant residues in different parts of the world were characterized and mathematically simulated. The easily decomposable materials, cellulose and hemicellulose, were described as being decomposed directly by the soil biomass; the lignin fraction of aboveground residues and the resistant portion of the roots entered a decomposable native soil organic matter. Here it could be decomposed by the soil biomass or react with other soil constituents in the formation of more recalcitrant soil organic matter. The transformation rates were considered to be independent of biomass size (first–order). Data from 14C plant residue incorporation studies which yielded net decomposition rates of added materials and from carbon dating of the recalcitrant soil organic matter were transformed to gross decomposition rate constants for three soil depths. The model adequately described soil organic matter transformations under native grassland and the effect of cultivation on organic matter levels. Correction for microbial growth and moisture and temperature variations showed that the rate of wheat straw decomposition, based on a full year in the field in southern Saskatchewan, was 0.05 that under optimal laboratory conditions. The relative decay rates for plant residues during the summer months of the North American Great Plains was 0.1 times that of the laboratory. Comparison with data from other parts of the world showed an annual relative rate of 0.12 for straw decomposition in England, whereas gross decomposition rates in Nigeria were 0.5 those of laboratory rates. Both the decomposable and recalcitrant organic matter were found to be affected by the extent of physical protection within the soil. The extent of protection was simulated and compared to data from experimental studies on the persistence of 14C-labelled amino acids in soil. The extent of protection influenced the steady-state levels of soil carbon upon cultivation more than did the original decomposition rates of the plant residues.

Assimilation of CO2 by soil microorganisms and transformation into soil organic matter

2004 ◽  
Vol 35 (9) ◽  
pp. 1015-1024 ◽  
Author(s):  
Anja Miltner ◽  
Hans-Hermann Richnow ◽  
Frank-Dieter Kopinke ◽  
Matthias Kästner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Microorganisms

Soil microbial biomass—Interpretation and consideration for soil monitoring

Soil Research ◽  
2011 ◽  
Vol 49 (4) ◽  
pp. 287 ◽  
Author(s):  
V. Gonzalez-Quiñones ◽  
E. A. Stockdale ◽  
N. C. Banning ◽  
F. C. Hoyle ◽  
Y. Sawada ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Biomass ◽  
Soil Microorganisms ◽  
Soil Microbial Biomass ◽  
Biological Function ◽  
Anthropogenic Change ◽  
Soil Monitoring ◽  
Soil Microbial ◽  
Quality Assessments ◽  
The Impact

Since 1970, measurement of the soil microbial biomass (SMB) has been widely adopted as a relatively simple means of assessing the impact of environmental and anthropogenic change on soil microorganisms. The SMB is living and dynamic, and its activity is responsible for the regulation of organic matter transformations and associated energy and nutrient cycling in soil. At a gross level, an increase in SMB is considered beneficial, while a decline in SMB may be considered detrimental if this leads to a decline in biological function. However, absolute SMB values are more difficult to interpret. Target or reference values of SMB are needed for soil quality assessments and to allow ameliorative action to be taken at an appropriate time. However, critical values have not yet been successfully identified for SMB. This paper provides a conceptual framework which outlines how SMB values could be interpreted and measured, with examples provided within an Australian context.

Sign in / Sign up

Export Citation Format

Share Document