Chemical composition of soil organic matter and potential enzyme activity in the topsoil along a moisture gradient in the High Arctic (Svalbard)

Geoderma ◽  
2020 ◽  
Vol 368 ◽  
pp. 114304 ◽  
Author(s):  
Ekaterina Pushkareva ◽  
Kai-Uwe Eckhardt ◽  
Vivien Hotter ◽  
Aline Frossard ◽  
Peter Leinweber ◽  
...  
Keyword(s):  
Organic Matter ◽  
Enzyme Activity ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
High Arctic ◽  
Moisture Gradient ◽  
Potential Enzyme Activity

Chemical composition of cover crops and soil organic matter pools in no‐tillage systems in the Cerrado

2021 ◽  
Author(s):  
Arminda Moreira de Carvalho ◽  
Luana Ramos Passos Ribeiro ◽  
Robélio Leandro Marchão ◽  
Alexsandra Duarte de Oliveira ◽  
Karina Pulrolnik ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Cover Crops ◽  
No Tillage ◽  
Tillage Systems

Effects of climate change on soil organic matter chemical composition and carbon content in different physical fractions

2021 ◽  
Author(s):  
Moritz Mohrlok ◽  
Victoria Martin ◽  
Alberto Canarini ◽  
Wolfgang Wanek ◽  
Michael Bahn ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Soil C ◽  
Size Classes ◽  
Soil Fractions ◽  
Total Soil ◽  
C And N ◽  
Amp Clay

<p>Soil organic matter (SOM) is composed of many pools with different properties (e.g. turnover times) which are generally used in biogeochemical models to predict carbon (C) dynamics. Physical fractionation methods are applied to isolate soil fractions that correspond to these pools. This allows the characterisation of chemical composition and C content of these fractions. There is still a lack of knowledge on how these individual fractions are affected by different climate change drivers, and therefore the fate of SOM remains elusive. We sampled soils from a multifactorial climate change experiment in a managed grassland in Austria four years after starting the experiment to investigate the response of SOM in physical soil fractions to temperature (eT: ambient and elevated by +3°C), atmospheric CO<sub>2</sub>-concentration (eCO<sub>2</sub>: ambient and elevated by +300 ppm) and to a future climate treatment (eT x eCO<sub>2</sub>: +3°C and + 300 ppm). A combination of slaking and wet sieving was used to obtain three size classes: macro-aggregates (maA, > 250 µm), micro-aggregates (miA, 63 µm – 250 µm) and free silt & clay (sc, < 63 µm). In both maA and miA, four different physical OM fractions were then isolated by density fractionation (using sodium polytungstate of ρ = 1.6 g*cm<sup>-3</sup>, ultrasonication and sieving): Free POM (fPOM), intra-aggregate POM (iPOM), silt & clay associated OM (SCaOM) and sand-associated OM (SaOM). We measured C and N contents and isotopic composition by EA-IRMS in all fractions and size classes and used a Pyrolysis-GC/MS approach to assess their chemical composition. For eCO<sub>2</sub> and eT x eCO<sub>2 </sub>plots, an isotope mixing-model was used to calculate the proportion of recent C derived from the elevated CO<sub>2 </sub>treatment. Total soil C and N did not significantly change with treatments.  eCO<sub>2</sub> decreased the relative proportion of maA-mineral-associated C and increased C in fPOM and iPOM. About 20% of bulk soil C was represented by the recent C derived from the CO<sub>2</sub> fumigation treatment. This significantly differed between size classes and density fractions (p < 0.001), which indicates inherent differences in OM age and turnover. Warming reduced the amount of new C incorporated into size classes. We found that each size class and fraction possessed a unique chemical fingerprint, but this was not significantly changed by the treatments. Overall, our results show that while climate change effects on total soil C were not significant after 4 years, soil fractions showed specific effects. Chemical composition differed significantly between size classes and fractions but was unaffected by simulated climate change. This highlights the importance to separate SOM into differing pools, while including changes to the molecular composition might not be necessary for improving model predictions.    </p>

scholarly journals Composition changes of eroded carbon at different spatial scales in a tropical watershed suggest enrichment of degraded material during transport

2014 ◽  
Vol 11 (12) ◽  
pp. 3299-3305 ◽  
Author(s):  
C. Rumpel ◽  
V. Chaplot ◽  
P. Ciais ◽  
A. Chabbi ◽  
B. Bouahom ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Isotope Composition ◽  
Spatial Scales ◽  
Suspended Sediments ◽  
Resonance Spectroscopy ◽  
Vertical Decomposition ◽  
Degraded Material ◽  
Soil Units

Abstract. In order to assess whether eroded carbon is a net source or sink of atmospheric CO2, characterisation of the chemical composition and residence time of eroded organic matter (EOM) at the landscape level is needed. This information is crucial to evaluate (1) how fast EOM can be decomposed by soil microbes during its lateral transport and (2) its impact at deposition sites. This study considers a continuum of scales to measure the composition of EOM across a steep hillslope landscape of the Mekong basin with intense erosion. We sampled suspended sediments eroded during rainfall events from runoff plots (1 and 2.5 m2) and the outlets of four nested watersheds (0.6 × 104 to 1 × 107 m2). Here we show that changes in the chemical composition of EOM (measured by nuclear magnetic resonance spectroscopy) and in its 13C and 15N isotope composition from plot scale through to landscape scale provide consistent evidence for enrichment of more decomposed EOM across distances of 10 km. Between individual soil units (1 m2) to a small watershed (107 m2), the observed 28% decrease of the C/N ratio, the enrichment of 13C and 15N isotopes as well as O-alkyl C in EOM is of similar magnitude as changes recorded with depth in soil profiles due to soil organic matter "vertical" decomposition. Radiocarbon measurements indicated ageing of EOM from the plot to the watershed scale. Therefore transport of EOM may lead to enrichment of stabilised soil organic matter compounds, eventually being subject to export from the watershed.

Evaluating biodegradability of soil organic matter by its thermal stability and chemical composition

2015 ◽  
Vol 91 ◽  
pp. 182-191 ◽  
Author(s):  
E.G. Gregorich ◽  
A.W. Gillespie ◽  
M.H. Beare ◽  
D. Curtin ◽  
H. Sanei ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter

Soil Enzyme Activities of Wetland in Liangzi Lake

2014 ◽  
Vol 700 ◽  
pp. 235-238
Author(s):  
Han Feng Xiong
Keyword(s):  
Organic Matter ◽  
Enzyme Activity ◽  
Soil Organic Matter ◽  
Phosphatase Activity ◽  
Urease Activity ◽  
Soil Enzyme ◽  
Soil Enzyme Activity ◽  
Wetland Soil ◽  
Positive Correlation ◽  
Change Trend

Soil enzyme activity is closely related to ecosystem course and function.Tendency and intensity of different biochemical course carried on in the soil was reflected by enzyme activity. This paper deals with the soil enzyme activity, content of organic matter, N,P 'and the relation of the enzyme activity with soil organic matter, N,P in soil of Liangzi Lake wetland by soil samples analyzed. The results shows that in the wetland soil,the urease activity is 0.397-0.652 mg/g ;the phosphatase activity is phenol6.52-11.53 mg/g; The activity of Cellulase in the soil is 0.397 - 0.652 mg/g. The change trend of Cellulase and phosphatase activity throughout the year is summer > autumn > winter > spring. The change trend of urinary enzyme throughout the year is summer > spring > autumn > winter. There is notably positive correlation between the urease activity and soil available nitrogen. There is notably positive corelation between the phosphatase activity and soil available P in the paddy field.There is notably positive correlation between the Cellulase activity and soil organic matter.

Sign in / Sign up

Export Citation Format

Share Document