scholarly journals Drying and rewetting conditions differentially affect the mineralization of fresh plant litter and extant soil organic matter

2018 ◽  
Vol 124 ◽  
pp. 81-89 ◽  
Author(s):  
Luis Lopez-Sangil ◽  
Iain P. Hartley ◽  
Pere Rovira ◽  
Pere Casals ◽  
Emma J. Sayer
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Plant Litter ◽  
Fresh Plant ◽  
Drying And Rewetting

scholarly journals Integrating plant litter quality, soil organic matter stabilization, and the carbon saturation concept

2015 ◽  
Vol 21 (9) ◽  
pp. 3200-3209 ◽  
Author(s):  
Michael J. Castellano ◽  
Kevin E. Mueller ◽  
Daniel C. Olk ◽  
John E. Sawyer ◽  
Johan Six
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Litter Quality ◽  
Plant Litter ◽  
Carbon Saturation ◽  
Organic Matter Stabilization

Rate of recycling of sulfur from urine, feces and litter applied to the soil surface

Soil Research ◽  
1994 ◽  
Vol 32 (3) ◽  
pp. 543 ◽  
Author(s):  
GJ Blair ◽  
AR Till ◽  
C Boswell
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Surface ◽  
Plant Litter ◽  
Test Plant ◽  
Soil P ◽  
S Uptake ◽  
Organic Matter Pool ◽  
Preferential Uptake ◽  
Soil Organic Matter Pool

The recycling of S from plant litter, dung and urine is an important process for supplying S for pastures. A pot experiment was conducted where 35S-labelled litter (25% white clover/38% ryegrass/21% weed) and S-35-labelled urine and faeces collected from sheep fed the same herbage as was used as litter was surface applied to pots and the fate of the applied S was followed for 100 days with ryegrass as the test plant. In camp soil, 45% of the S applied in urine was taken up by ryegrass plants within 12 days of application. In non-camp soil, the uptake of urine-S was about 20% over the same period. Cumulative uptake of 35S from urine in camp soil was subsequently restricted, with a maximum of 60% eventually measured in plants after 100 days. Mean rates of release of S (0-37 days) from litter and faeces was respectively 16.2 and 4.5 mg g-1 day-1. The calculated half-times from S in the two materials were respectively 43 and 154 days under controlled environmental conditions with adequate moisture. Litter S followed organic matter (OM) decomposition, but faecal S release was initially more rapid than faecal OM decomposition. There was little S release from faeces after day 25. Rather, S was immobilized in faeces during the 25-100 day period. The decomposition of litter and faeces was divided into an initial rapid process during which soluble S and more labile S was released, followed by a slower process involving the release of S from tissues more resistant to mineralization. The uptake of 35S from labelled materials was initially more rapid than would be expected for total S released from the added litter and faeces and the 35Suptake effect was short-lived relative to the continued effect of added material on total S uptake. The preferential uptake of 35S from the surface-applied material appears to be due to limited root development at the early stages of the experiment. Movement of 35S into the soil organic matter pool was very rapid; 58.4% of urine S was in the soil organic matter fraction in the non-camp soil by day 6. The amount of applied S in the organic matter equilibrated at about day 75. The accumulation of applied S from the materials added was greater than that recorded in previously reported studies for inorganic sulfate (e.g. about 50%). Soil P and S status had little effect on rates of release of S. from the applied materials, however, the effect of the camp and non-camp soil on total S recycling was markedly different as a result of the different amounts of plant growth and thus S uptake in the two soils. The decomposition of litter indicated peak rates of S release at two specific times over the 100 days and indicated successional changes in micro-organism activity. With faeces, the experiment was not continued for sufficiently long to show micro-organism effects.

scholarly journals The Use of Radiocarbon to Measure the Effects of Earthworms On Soil Development

Radiocarbon ◽  
1980 ◽  
Vol 22 (3) ◽  
pp. 892-896 ◽  
Author(s):  
J D Stout ◽  
K M Goh
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Profile ◽  
Mineral Soil ◽  
Soil Development ◽  
Plant Debris ◽  
Grassland Soils ◽  
Fresh Plant

Δ14C and δ13C values for organic matter in forest and grassland soils, in the presence or absence of earthworms, indicate that it should be possible to quantify the effects of earthworms on soil organic matter by this means. Without earthworms, both in forest and grassland soils, plant debris tends to accumulate on the surface of the mineral soil and little organic matter is incorporated into or is translocated down the soil profile. Where earthworms are present, there is much more marked incorporation of fresh plant debris in the mineral soil. This is shown especially by the pulse of ‘bomb’ carbon and also by the δ13C values.

scholarly journals Organic sediment formed during inundation of a degraded fen grassland emits large fluxes of CH<sub>4</sub> and CO<sub>2</sub>

2011 ◽  
Vol 8 (6) ◽  
pp. 1539-1550 ◽  
Author(s):  
M. Hahn-Schöfl ◽  
D. Zak ◽  
M. Minke ◽  
J. Gelbrecht ◽  
J. Augustin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Plant Litter ◽  
Electron Acceptors ◽  
Sediment Layer ◽  
Organic Substrates ◽  
Peat Layer ◽  
Ch4 Production ◽  
Fresh Plant ◽  
Fresh Organic Matter ◽  
Organic Sediment

Abstract. Peatland restoration by inundation of drained areas can alter local greenhouse gas emissions as CO2 and CH4. Factors that can influence these emissions include the quality and amount of substrates available for anaerobic degradation processes and the sources and availability of electron acceptors. In order to learn about possible sources of high CO2 and CH4. emissions from a rewetted degraded fen grassland, we performed incubation experiments that tested the effects of fresh plant litter in the flooded peats on pore water chemistry and CO2 and CH4. production and emission. The position in the soil profile of the pre-existing drained peat substrate affected initial rates of anaerobic CO2 production subsequent to flooding, with the uppermost peat layer producing the greatest specific rates of CO2 evolution. CH4 production rates depended on the availability of electron acceptors and was significant only when sulfate concentrations were reduced in the pore waters. Very high specific rates of both CO2 (maximum of 412 mg C d−1 kg−1 C) and CH4 production (788 mg C d−1 kg−1 C) were observed in a new sediment layer that accumulated over the 2.5 years since the site was flooded. This new sediment layer was characterized by overall low C content, but represented a mixture of sand and relatively easily decomposable plant litter from reed canary grass killed by flooding. Samples that excluded this new sediment layer but included intact roots remaining from flooded grasses had specific rates of CO2 (max. 28 mg C d−1 kg−1 C) and CH4 (max. 34 mg C d−1 kg−1 C) production that were 10–20 times lower than for the new sediment layer and were comparable to those of a newly flooded upper peat layer. Lowest rates of anaerobic CO2 and CH4 production (range of 4–8 mg C d−1 kg−1 C and <1 mg C d−1 kg−1 C) were observed when all fresh organic matter sources (plant litter and roots) were excluded. In conclusion, the presence of fresh organic substrates such as plant and root litter originating from plants killed by inundation has a high potential for CH4 production, whereas peat without any fresh plant-derived material is relatively inert. Significant anaerobic CO2 and CH4 production in peat only occurs when some labile organic matter is available, e.g. from remaining roots or root exudates.

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.

Soil fauna affects the optical properties in alkaline solutions extracted (humic acid-like) from forest litters during different phenological periods

2019 ◽  
Vol 99 (2) ◽  
pp. 195-207 ◽  
Author(s):  
Yu Tan ◽  
Wanqin Yang ◽  
Xiangyin Ni ◽  
Bo Tan ◽  
Kai Yue ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Humic Acid ◽  
Carbon Sequestration ◽  
Soil Organic Matter ◽  
Soil Fauna ◽  
Plant Litter ◽  
Alkaline Solutions ◽  
Richness Index

The formation of soil organic matter via humification of plant litter is important for long-term carbon sequestration in forests; however, whether soil fauna affects litter humification is unclear. In this study, we quantified the effects of soil fauna on the optical properties (i.e., ΔlogK and E4/E6) of the alkaline-extracted humic acid-like solutions of four foliar litters by removing soil fauna via litterbags with different mesh sizes in two subtropical evergreen broad-leaved forests. Litterbags were collected at the leaf falling, budding, expanding, maturation, and senescence stages from November 2013 to October 2015 to assess whether the effects of soil fauna on litter humification vary in different plant phenology periods. The results showed that soil fauna significantly reduced the ΔlogK and E4/E6 values in the leaf expanding stage of oak litter and in the leaf falling stage of camphor and fir litters. The richness index of soil fauna explained 21%, 55%, 19%, and 45% of the variations in the E4/E6 values for oak, fir, camphor, and pine litters, respectively. The effects of litter water content on these optical properties were greater than that of temperature. These results indicated that soil fauna plays a key role in litter humification in the leaf expanding and falling stages and are potentially involved in soil carbon sequestration in these subtropical forests.

Radiocarbon incubations of archived soils: insights into drying/rewetting effects and constraining soil C models

2020 ◽  
Author(s):  
Jeffrey Beem Miller ◽  
Marion Schrumpf ◽  
Georg Guggenberger ◽  
Susan Trumbore
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Additional Time ◽  
Acceptable Error ◽  
Soil C ◽  
Drying And Rewetting ◽  
Duration Of Storage ◽  
Before And After ◽  
The Difference ◽  
And Storage

&lt;p&gt;Radiocarbon measurements of heterotrophically respired C (&amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt;) in laboratory soil incubations provide information about the age and source of microbially-available soil organic matter. However, due to the influence of &amp;#8220;bomb&amp;#8221; radiocarbon (from nuclear weapons testing in the mid-20&lt;sup&gt;th&lt;/sup&gt; century), measurements of &lt;sup&gt;14&lt;/sup&gt;C at a single time point can yield multiple solutions when modeling soil C cycling rates. Measuring &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt; on archived soils would provide additional time points to assess which solution is appropriate. We had two hypotheses regarding the effect of archiving on &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt;: 1) long-term storage does not affect &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt;, and 2) drying and rewetting effects on &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2 &lt;/sub&gt;are limited to CO&lt;sub&gt;2&lt;/sub&gt; released immediately following rewetting, without significant effects on CO&lt;sub&gt;2&lt;/sub&gt; released after respiration rates equilibrate.&lt;/p&gt;&lt;p&gt;To address the first hypothesis, sample splits of soils collected at nine grassland and 21 forest sites (n=30) between 2004 and 2011 (for which &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt; had been previously measured) were incubated again in 2018 after undergoing air-drying and storage. The difference in &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt; measured before and after archiving was significant (p &lt; 0.05); however, in line with our hypothesis, the number of years archived was not a significant predictor of the difference in a regression analysis.&lt;/p&gt;&lt;p&gt;To test the second hypothesis we first collected and analyzed &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt; following the &amp;#8220;pre-incubation&amp;#8221; period, i.e. the period immediately following rewetting, as well as after the equilibrium respiration period for the subset of samples (six grassland, six forest) for which we had data on the original pre-incubation period. In this subset we observed different responses in forest versus grassland soils in the equilibrium respiration period: &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2&lt;/sub&gt; decreased from the original value by 12.7 (&amp;#177;4.5) per mille in forests (p = 0.08), but increased by 22.2 (&amp;#177;6.7) per mille in grasslands (p &lt; 0.05) (errors are twice the standard error of the mean difference). In contrast to our second hypothesis the &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C of the CO&lt;sub&gt;2&lt;/sub&gt; released immediately following rewetting was not significantly different from the &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C of the CO&lt;sub&gt;2&lt;/sub&gt; respired under equilibrium respiration conditions, despite the much higher rate of respiration following rewetting. A final incubation experiment comparing freshly collected soils that were dried but not archived was conducted to distinguish conclusively between rewetting and storage effects, but we are still awaiting the data.&lt;/p&gt;&lt;p&gt;In conclusion, the drying/rewetting effect appears to drive the differences between &amp;#8710;&lt;sup&gt;14&lt;/sup&gt;C-CO&lt;sub&gt;2 &lt;/sub&gt;measured in incubations before and after archiving, rather than duration of storage. The radiocarbon incubation technique for archived samples is promising: the 12 to 22 per mille differences observed are not insignificant, but in many cases should be within the range of acceptable error in a modeling context. The wider implication of our results is that drying and rewetting soils appears to mobilize a different pool of soil organic matter than would otherwise be available to microbes, an effect that persists throughout an incubation and affects grassland and forest soils differently. This effect applies to radiocarbon incubations in general and warrants further investigation.&lt;/p&gt;

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

&lt;p&gt;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.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;Miltner A, Bombach P, Schmidt-Br&amp;#252;cken B, K&amp;#228;stner M (2012) SOM genesis: Microbial biomass as a significant source. Biogeochemistry 111: 41-55.&lt;/p&gt;&lt;p&gt;Liang C, Amelung W, Lehmann J, K&amp;#228;stner M (2019) Quantitative assessment of microbial necromass contribution to soil organic matter. Global Change Biology 25: 3578-3590.&lt;/p&gt;

Progress in soil organic matter research

2007 ◽  
Vol 31 (2) ◽  
pp. 131-154 ◽  
Author(s):  
Vineet Yadav ◽  
George Malanson
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Litter Decomposition ◽  
Soil Aggregates ◽  
Plant Litter ◽  
Monitoring Methods ◽  
Plant Litter Decomposition ◽  
Research Themes ◽  
Climatic Scenarios ◽  
Decomposition Models

Retention and sequestration of soil organic matter is extremely important for the maintenance of soil structure, agricultural productivity and carbon sequestration. Research in soil organic matter has advanced on many fronts in the last half century. During this time understanding of the factors governing plant litter decomposition has increased considerably resulting in the formulation of process and organism-based models. Remote sensing has been shown to be useful for quickly monitoring stocks of soil organic carbon in the topsoil although much remains to be done to establish its efficacy. Fluxes of soil organic matter in the changing climatic scenarios have been studied though outcomes remain debatable. In this paper an attempt is made to present these various aspects of soil organic matter cohesively. The focus is mainly on litter decomposition, models and monitoring methods, role of soil aggregates and erosion, impact of climate change on long-term dynamics of soil organic matter and impending research themes needing further attention.

scholarly journals 315 Formation, persistence, and function of soil organic matter: how recent scientific advances apply in agroecosystems

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 51-52
Author(s):  
Jocelyn M Lavallee ◽  
Francesca Cotrufo
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Management Practices ◽  
Agricultural Soils ◽  
Effective Means ◽  
Plant Litter ◽  
Paradigm Shifts ◽  
The Usa ◽  
And Function

Abstract Soil organic matter is fundamental to healthy and productive soils and building it is an effective means by which to draw down atmospheric greenhouse gas concentrations with added co-benefits. Scientific understanding of soil organic matter dynamics is constantly evolving, and the past decade has seen major advances and paradigm shifts. Soil organic matter creation from decaying plant litter is now thought to occur under two separate pathways, yielding two functionally different types: predominantly plant-derived, unprotected particulate organic matter (POM) and predominantly microbially-derived, mineral-associated organic matter (MAOM). The idea of naturally-occurring humic substances in soils has been largely abandoned, and long-term soil organic matter persistence is now understood to be driven mainly by mineral association. We will present the research behind these paradigm shifts, and show how considering POM and MAOM separately is key to understanding the mechanisms driving carbon accrual and persistence in soil, and therefore to guiding policy and management for soil carbon sequestration. We will present drivers of POM and MAOM contents, from individual fields to continents, including their capacity for sequestration and saturation in agricultural soils of the USA, and their responses to common management practices in agroecosystems.

Sign in / Sign up

Export Citation Format

Share Document