scholarly journals Labile fractions of soil organic matter, their quantity and quality

2009 ◽  
Vol 55 (No. 6) ◽  
pp. 245-251 ◽  
Author(s):  
L. Kolář ◽  
S. Kužel ◽  
J. Horáček ◽  
V. Čechová ◽  
J. Borová-Batt ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Rate Constant ◽  
Chemical Oxidation ◽  
Particle Size Fractions ◽  
Labile Fraction ◽  
Humus Profile ◽  
Forms Of Carbon ◽  
Favorable Conditions

The objective of the present paper is to contribute to the evaluation of quantity and quality of non-humified part of soil organic matter (SOM). In samples of soil organic matter from the humus profile of Šumava forest soils and forest meadows, taxonomically designated as mor and moder forms, the fractions of labile soil carbon C<sub>cws</sub>, C<sub>hws</sub>, C<sub>PM</sub> and fraction of stable carbon represented by carbon of humus acids C<sub>HA</sub> and C<sub>FA</sub> were determined. Organic matter of samples was fractionated according to the degrees of hydrolyzability by two different methods in particle-size fractions of 2.00–0.25 mm and < 0.25 mm. The quality of labile fraction C<sub>hws</sub> was expressed on the basis of reaction kinetics as the rate constant of biochemical oxidation K<sub>bio</sub> and rate constant of chemical oxidation K<sub>chem</sub> of the first order reaction from a reduction in the concentration of C-compounds. The highest values of labile forms of carbon were determined in samples with the least favorable conditions for transformation processes of SOM, and these samples also had the highest content of labile forms in hydrolyses by both methods and the most labile fractions at the same time. The degree of SOM humification was strictly indirectly proportional to the lability of SOM and its hydrolyzability. The quality of labile fraction C<sub>hws</sub> can be expressed by both K<sub>bio</sub> and K<sub>chem</sub> while the sensitivity of K<sub>bio</sub> is higher but the reproducibility of K<sub>chem</sub> is better. K<sub>bio</sub> corresponds with the degree of SOM transformation, K<sub>chem</sub> with the proportion of C<sub>PM</sub> in total C<sub>ox</sub>.

Conversion of Brazilian savannah to agricultural land affects quantity and quality of labile soil organic matter

Geoderma ◽  
2022 ◽  
Vol 406 ◽  
pp. 115509
Author(s):  
Rafael S. Santos ◽  
Martin Wiesmeier ◽  
Dener M.S. Oliveira ◽  
Jorge L. Locatelli ◽  
Matheus S.C. Barreto ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Agricultural Land ◽  
Brazilian Savannah ◽  
Labile Soil Organic Matter

scholarly journals Biomass of Coarse Woody Debris Following Fire and Clearcutting in Lodgepole Pine Forests

1997 ◽  
Vol 21 ◽  
pp. 33-35
Author(s):  
Dennis Knight ◽  
Daniel Tinker
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Coarse Woody Debris ◽  
Significant Contribution ◽  
Woody Debris ◽  
Mineral Soil ◽  
Primary Source ◽  
Timber Harvesting ◽  
Micro Organisms

In forest ecosystems, the decomposition of coarse woody debris, woody roots, twigs, leaves and micro-organisms is a primary source of mineral soil organic matter. Primary productivity, the accumulation of nutrients, and other important ecosystem processes are largely dependent on the mineral soil organic matter that has developed during hundreds or thousands of years. Large quantities of coarse woody debris are typically produced following natural disturbances such as fires, pest/pathogen outbreaks, and windstorms, and make a significant contribution to the formation of soil organic matter (SOM). In contrast, timber harvesting often removes much of the coarse woody debris (CWD), which could result in a decrease in the quantity and a change in the quality of mineral soil organic matter.

scholarly journals Thermal fractionation of soil organic matter produces fine-scale distributions of SOM age

2021 ◽  
Author(s):  
Shane Stoner ◽  
Carlos Sierra ◽  
Marion Schrumpf ◽  
Sebastian Dötterl ◽  
Susan Trumbore
Keyword(s):  
Thermal Stability ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Chemical Oxidation ◽  
Fine Scale ◽  
Mineral Association ◽  
Density Fractions ◽  
Chemical Complexity ◽  
Wide Range ◽  
Carbon Release

&lt;p&gt;Soil organic matter (SOM) is a complex collection of organic molecules of varying origin, structure, chemical activity, and mineral association. A wide array of laboratory methods exists to separate SOM based on qualitative, biological, chemical, and physical characteristics. However, all present conceptual and logistical limitations, including the requirement of a substantial amount soil material.&lt;/p&gt;&lt;p&gt;An newly applied alternative method of fractionation relies on a conceptual analogue between biochemical stability in soil and thermal stability, e.g. more persistent SOM will require higher temperatures (greater energy inputs) to decompose than less persistent SOM. This accounts for both chemical complexity and mineral association as main factors in determining SOM persistence.&lt;/p&gt;&lt;p&gt;In this method, carbon is released by heating SOM to 900&amp;#176;C at a constant rate. The peaks of carbon release are grouped into activation energy pools, CO&lt;sub&gt;2 &lt;/sub&gt;is collected, and analyzed for &lt;sup&gt;13&lt;/sup&gt;C and &lt;sup&gt;14&lt;/sup&gt;C. We seek to describe in finer detail the distribution of soil radiocarbon by adding another fractionation step following a different paradigm of SOM stability, and explore mineralogical effects on SOM quality and stability using thermal analysis, radiocarbon, and gas chromatography.&lt;/p&gt;&lt;p&gt;Here, we analyzed bulk soil and soil fractions derived from density separation and chemical oxidation, as well as mineral horizons dominated by diverse mineralogies. Density fractions contained a wide range of radiocarbon activities and that young SOM is stabilized across multiple fractions, likely due to organomineral complexation. Initial results showed that soil minerals with limited stabilization potential released C at lower temperatures than those with diverse stabilization mechanisms. High-temperature sub-fractions contained the oldest carbon across fractions and minerals, thus supporting the assumption that thermal stability can be used as a limited analogue for stability in soil. We present a fine-scale distribution of radiocarbon in SOM and discuss the potential of this method for comparison with other fractionation techniques.&lt;/p&gt;

Quality of Soil Organic Matter Under Crop Rotations and Continuous Cultures

2013 ◽  
pp. 251-259
Author(s):  
B. P. Boincean ◽  
L. I. Bulat ◽  
M. A. Bugaciuc ◽  
M. Cebotari ◽  
V. V. Cuzeac
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Crop Rotations ◽  
Continuous Cultures

scholarly journals Effect of Different Doses of Nutrients on Changes of Soil Organic Matter in Rendzic Leptosol

2012 ◽  
Vol 58 (4) ◽  
pp. 131-137
Author(s):  
Vladimír Šimanský ◽  
Erika Tobiašová
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Samples ◽  
Water Soluble ◽  
Hot Water ◽  
Fertilizer Treatment ◽  
Content Increase ◽  
Npk Fertilizer ◽  
Different Doses

Abstract The effect of different doses of NPK fertilizer on the changes in quantity and quality of soil organic matter (SOM) in Rendzic Leptosol was evaluated. Soil samples were taken from three treatments of different fertilization: (1) control - without fertilization, (2) NPK 1 - doses of NPK fertilizer in 1st degree intensity for vine, and (3) NPK 3 - doses of NPK fertilizer in 3rd degree intensity for vine in the vineyard. Soil samples were collected in years 2008-2011 during the spring. The higher dose of NPK fertilizer (3rd degree intensity of vineyards fertilization) was responsible for the higher content of labile carbon (by 21% in 0-0.3 m and by 11% as average of the two depths 0-0.3 m and 0.3-0.6 m). However, by application of a higher dose of NPK (1.39%) in comparison to no fertilizer treatment (1.35%) or NPK 1 (1.35%) the tendency of total organic carbon content increase and hot-water soluble carbon decrease were determined. Fertilization had a negative effect on SOM stability. Intensity of fertilization affected the changes in quantity and quality of SOM; therefore it is very important to pay attention to the quantity and quality of organic matter in productive vineyards.

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