Importance of charred organic matter in Black Chernozem soils of Saskatchewan

2001 ◽  
Vol 81 (3) ◽  
pp. 285-297 ◽  
Author(s):  
E V Ponomarenko ◽  
D W Anderson
Keyword(s):  
Organic Matter ◽  
High Energy ◽  
Humus Formation ◽  
Organic C ◽  
Particle Size Fractions ◽  
Chernozem Soils ◽  
And Storage ◽  
Uv Oxidation ◽  
Products Of Incomplete Combustion ◽  
C Nmr

A combination of both conventional and novel techniques, such as micromorphology, scanning electron microscopy, and high energy ultraviolet photo-oxidation, have been applied to estimate the proportion of charred organic C in Black Chernozem soils in Saskatchewan. Char was represented by products of incomplete combustion of both arboreal and herbaceous vegetation. Char was found in all particle size fractions of A horizons of Black soils. Char was represented by a variety of forms, from fresh and angular, to rounded and clay-coated particles in the silt fraction. It is likely that the surface area and ability to adsorb clay vary with the size and nature of char particles. Sand-sized char includes particles with various surface properties and adsorptive ability. Generally, younger and lighter char with hydrophobic properties appears to be in the clay-sized fractions, whereas the silt contains heavier char particles coated with clay or containing clay in pores. Ultrasound, used to disperse soils, may fracture larger particles to finer sizes. The proportion of organic C in soils and fractions that is resistant to UV-oxidation was as high as 60%, which, based on published guidelines, indicates a very substantial char component in Black soils. CPMAS 13C NMR spectra indicate a strong aromatic peak at 130 ppm, also consistent with the presence of char. Results indicate that char particles as fine as silt size are present in significant amounts in Black soils, suggesting that char is an important component, and indicating the need for a new concept of humus formation and storage in Black soils. Key words: Char, carbon flows, carbon pool, UV-oxidation, fire, soil organic matter

THE EXTRACTION OF ORGANIC MATTER FROM SELECTED SOILS AND PARTICLE SIZE FRACTIONS WITH 0.5 M NaOH AND 0.1 M Na4P2O7 SOLUTIONS

1989 ◽  
Vol 69 (2) ◽  
pp. 253-262 ◽  
Author(s):  
M. SCHNITZER ◽  
P. SCHUPPLI
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Humic Acids ◽  
Nmr Spectra ◽  
Attractive Alternative ◽  
Particle Size Fractions ◽  
Molecular Weights ◽  
Naoh Solution ◽  
C Nmr ◽  
Medium Silt

Organic matter (OM) in the Bainsville and Melfort soils, and in coarse clay and medium silt fractions separated from these soils, was extracted under N2 with 0.5 M NaOH and unadjusted 0.1 M Na4P2O7 solutions. pH ranges of the soils and fractions in contact for 24 h with 0.5 M NaOH and 0.1 M Na4P2O7 solutions extended from 12.2 to 12.6 and 9.0 to 9.4, respectively. Slightly greater proportions of the soil-carbon were extracted by 0.5 M NaOH than by 0.1 M Na4P2O7 solution. The differences, however, did not appear to be significant and may vary from soil to soil. The efficiency of extraction and the characteristics of the extracted materials were assessed on humic acids (HAs), which were isolated from the extracts. From the Bainsville soil and fractions, 0.1 M Na4P2O7 solution extracted more high-molecular weight and more deeply colored HAs than did 0.5 M NaOH solution. But HAs extracted from the Melfort soil and fractions had similar molecular weights and colours. 13C NMR spectra showed that HAs extracted by 0.1 M Na4P2O7 solution tended to be more aromatic than HAs extracted by 0.5 M NaOH solution. Well defined solid-state 13C NMR spectra of HAs, containing up to 69.0% ash, could be recorded. Unadjusted 0.1 M Na4P2O7 solution under N2 was found to be an attractive alternative to 0.5 M NaOH solution as an extractant for soil OM. Key words: Humic acids, E4:E6 ratios, IR spectra, 13C NMR spectra, aromaticity

scholarly journals Long term trends in fertility of soils under continuous cultivation and cereal cropping in southern Queensland. III. Distribution and kinetics of soil organic carbon in particle size fractions

Soil Research ◽  
1986 ◽  
Vol 24 (2) ◽  
pp. 293 ◽  
Author(s):  
RC Dalal ◽  
RJ Mayer
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Size Fraction ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Clay Size Fraction ◽  
Sand Size

Distribution of soil organic carbon in sand-, silt- and clay-size fractions during cultivation for periods ranging from 20 to 70 years was studied in six major soils used for cereal cropping in southern Queensland. Particle-size fractions were obtained by dispersion in water using cation exchange resin, sieving and sedimentation. In the soils' virgin state no single particle-size fraction was found to be consistently enriched as compared to the whole soil in organic C in all six soils, although the largest proportion (48%) of organic C was in the clay-size fraction; silt and sand-size fractions contained remaining organic C in equal amounts. Upon cultivation, the amounts of organic C declined from all particle-size fractions in most soils, although the loss rates differed considerably among different fractions and from the whole soil. The proportion of the sand-size fraction declined rapidly (from 26% to 12% overall), whereas that of the clay-size fraction increased from 48% to 61% overall. The proportion of silt-size organic C was least affected by cultivation in most soils. It was inferred, therefore, that the sand-size organic matter is rapidly lost from soil, through mineralization as well as disintegration into silt-size and clay-size fractions, and that the clay fraction provides protection for the soil organic matter against microbial and enzymic degradation.

ATTEMPTS TO IMPROVE SOLID STATE 13C NMR SPECTRA OF WHOLE MINERAL SOILS

1988 ◽  
Vol 68 (3) ◽  
pp. 593-602 ◽  
Author(s):  
M. A. ARSHAD ◽  
J. A. RIPMEESTER ◽  
M. SCHNITZER
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Solid State ◽  
Nmr Spectra ◽  
Important Indicator ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Mineral Soils ◽  
C Nmr

This study describes a number of different preparation techniques for recording solid state 13C NMR spectra of whole mineral soils. Removal of paramagnetic Fe3+ improves the quality of 13C NMR spectra of whole soils and of particle size fractions. The C:Fe ratio appears to be an important indicator for obtaining satisfactory 13C NMR spectra of whole soils and fractions separated from them. If the C:Fe ratio is >> 1, the quality of the spectrum will be good; if the ratio is > 1, a reasonable spectrum will be obtained, but if the ratio is < 1, the spectrum will be poor. Organic-matter-rich soil and particle size fractions separated by a flotation technique produce well-defined 13C NMR spectra, typical of humic materials. Reduction of C-enriched fractions with sodium dithionite and stannous chloride improves the spectral resolution. The data presented herein show that satisfactory solid state 13C NMR spectra can be run on untreated soil particle size fractions, non-magnetic portions of whole soils, and fractions enriched in soil organic matter by flotation, especially after chemical reduction. Key words: 13C NMR spectroscopy, paramagnetic mineral separation

scholarly journals Thickening and Storage of Sewage Sludge Contribute to the Degradation of LAS and EOX and the Humification of Organic Matter

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 933
Author(s):  
Ali Khakbaz ◽  
Daniele Goi ◽  
Carlo Bravo ◽  
Marco Contin
Keyword(s):  
Organic Matter ◽  
Sewage Sludge ◽  
Humic Substances ◽  
Municipal Wastewater ◽  
Biological Activities ◽  
Land Application ◽  
Organic Matter Quality ◽  
Organic C ◽  
And Storage

Land application of sewage sludge on agricultural soils can be sustainable only if pollutant contents and organic matter quality meet the requirements imposed by minimization of environmental risks. This study investigated the degradation of linear alkylbenzene sulfonates (LAS) and extractable organic halogens (EOX) and the formation of humic substances (HS) during the thickening and storage phases of sewage sludge treatment. Changes in spectroscopic properties (UV-Vis, FT-IR, and excitation-emission matrix (EEM) fluorescence) of HS were also evaluated to assess the occurrence of biological activities during these curing phases of sewage sludge (SS). Humic acids (HA), fulvic acids (FA), EOX, and LAS were extracted from sewage sludge sampled from four municipal wastewater treatment plants of different size and treatment sequence, before and after 90 days of aerobic or anaerobic storage. During storage, the loss of organic C in the SS ranged from almost null to 31%. No significant changes of FA were registered, whereas HA increased in almost all samples, up to 30%. The amount of humic substances synthesized during storage correlated with the percentage of C lost. Spectroscopic changes of FA and HA showed an increase in their aromaticity, with a corresponding decrease in the aliphatic contribution. These changes show the improved agronomical quality of SS. LAS decreased during storage up to 30%, surprisingly more under anaerobic than aerobic conditions, whereas EOX decreased significantly in all samples, even up to 81%. In conclusion, although storage may be normally considered not influencing the quality of SS, their organic matter quality improved and contamination decreased during 90 days of storage, whatever the conditions of oxygen availability applied.

Turnover of soil organic matter and storage of corn residue carbon estimated from natural 13C abundance

1995 ◽  
Vol 75 (2) ◽  
pp. 161-167 ◽  
Author(s):  
E. G. Gregorich ◽  
C. M. Monreal ◽  
B. H. Ellert
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Soil ◽  
Half Life ◽  
Light Fraction ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Corn Residue

Total organic C and natural C abundance were measured in a forest soil and a soil under corn (Zea mays L.) to assess management-induced changes in the quantity and initial source of organic matter. The total mass of organic C in the cultivated soil was 19% lower than in the forest soil. It was estimated that after 25 yr of continuous corn, 100 Mg C ha−1 was returned to the soil as residues, of which only 23 Mg ha−1 remained in the soil; 88% of the remaining corn-derived C (C4-derived C) was in the plow layer. About 30% of the soil organic C in the plow layer (0–27 cm) was derived from corn. Assuming first order kinetics, the half-life of C3-derived C in the 0- to 15-cm layer was 13 yr. The half-life of C3-derived C in the 0- to 30-cm layer, which included organic C below the plow layer, was 24 yr. Mineralization of the light fraction (LF) was faster than that of organic matter associated with particle-size fractions. More than 70% of the LF had turned over since the start of corn cropping, and 45% of organic matter in the sand fraction comprised corn residue. The half-life of C3-derived C in the LF was 8 yr. The mineralization of C from native organic matter associated with the coarse silt fraction was the slowest of all particle-size fractions. Key words: Soil organic matter, carbon storage, natural 13C abundance, light fraction, particle-size fractions, mineralization

scholarly journals Nature of organic carbon and nitrogen in physically protected organic matter of some Australian soils as revealed by solid-state 13C and 15N NMR spectroscopy

Soil Research ◽  
2000 ◽  
Vol 38 (1) ◽  
pp. 113 ◽  
Author(s):  
H. Knicker ◽  
J. O. Skjemstad
Keyword(s):  
Organic Matter ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Bulk Sample ◽  
High Energy ◽  
15N Nmr ◽  
Particle Size Fractions ◽  
Carbon And Nitrogen ◽  
Photo Oxidation ◽  
15N Nmr Spectroscopy

The <53-□m particle-size fractions of 5 different Australian soils were subjected to high energy ultraviolet (UV) photo-oxidation for a period of 2 h in order to remove most of the physically unprotected organic material. Solid-state 13C and 15N nuclear magnetic resonance (NMR) spectroscopy was applied for characterising the chemical nature of the remaining organic fraction. The 13C NMR spectroscopic comparison of the residues after UV photo-oxidation and the untreated bulk soils revealed a considerable increase in condensed aromatic structures in the residues for 4 of the 5 soils. This behaviour was recently shown to be typical for char-containing soils. In the sample where no char was detectable by NMR spectroscopy, the physically protected carbon consisted of functional groups similar to those observed for the organic matter of the bulk sample, although their relative proportions were altered. The solid-state 15N NMR spectrum from this sample revealed that some peptide structures were able to resist UV photo-oxidation, probably physically protected within the core of microaggregates. Heterocyclic aromatic nitrogen was not detected in this spectrum, but pyrrolic nitrogen was found to comprise a major fraction of the residues after photo-oxidation of the <53-□m fractions of the char- containing soils. Acid hydrolysis of these samples confirmed that some peptide-like material was still present. The identification of a considerable amount of aromatic carbon and nitrogen, assignable to charred material in 4 of the 5 investigated soils, supports previous observations that char largely comprises the inert or passive organic matter pool of many Australian soils. The influence of such material on the carbon and nitrogen dynamics in such soils, however, requires further research.

Possible role of aluminum in stabilizing organic matter in particle size fractions of Chernozemic and solonetizic soils

2002 ◽  
Vol 82 (2) ◽  
pp. 265-268 ◽  
Author(s):  
D. Curtin
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Specific Surface ◽  
Clay Fraction ◽  
Organic Matter Content ◽  
Ultrasonic Dispersion ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Organic Matter Stabilization

Although phyllosilicate clays, with their large surface areas, are often considered to play the leading role in stabilizing soil organic matter against microbial attack, several studies have suggested recently that oxides of Al and Fe may stabilize organic matter in some soils. The distribution of organic C and oxides in clay (< 0.2 and 0.2–2 mm) and silt fractions (2–5, 5–20, and 20–50 mm) of four Saskatchewan soils (organic C ranged from 21 to 46 g kg-1) was examined to differentiate the contributions of oxides and specific surface to organic matter retention. Carbon concentrations in the particle size fractions (separated following ultrasonic dispersion of the soils) tended to be highest in the fine silt and coarse clay fractions, not in the fine clay as would be expected if specific surface was the sole factor governing organic matter content. When data for the four soils were pooled there was a strong relationship between organic C (y) in the size fractions and Al (x) extracted by dithionite-citrate-bicarbonate [y = 33.9 x0,5 - 7.3; R2 = 0.90***], suggesting a role for A1 in determining the C storage capacity of the size fractions. The C: A1 ratio increased from an average of 12:1 in clay-sized material to 28:1 in coarse silt. Because it had less A1 per unit mass of C, organic matter in the silt separates may be more weakly bonded to mineral material than is clay-associated organic matter. This may imply that organic matter bound to silt is less stable, and thus susceptible to mineralization, than is organic matter residing in the clay fraction. Key words: Organic matter stabilization, particle size separates, extractable A1 and Fe

ULTRASONIC DISPERSION OF AGGREGATES: DISTRIBUTION OF ORGANIC MATTER IN SIZE FRACTIONS

1988 ◽  
Vol 68 (2) ◽  
pp. 395-403 ◽  
Author(s):  
R. G. KACHANOSKI ◽  
R. P. VORONEY ◽  
E. G. GREGORICH
Keyword(s):  
Organic Matter ◽  
Energy Levels ◽  
Physical Method ◽  
Ultrasonic Energy ◽  
Ultrasonic Dispersion ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Continuous Corn ◽  
Sand Size

Aggregates (1–2 mm) from a soil under continuous corn management were subjected to a mild shaking treatment and ultrasonic energy levels ranging from 100 to 1500 J mL−1 water to determine the degree of aggregate disruption and dispersion. More clay- and fewer sand-size particles were recovered with greater amounts of applied energy indicating greater aggregate disruption and dispersion with higher energy levels. Most of the breakdown of sand-size aggregates occurred between energy levels of 300 and 500 J mL−1. Ultrasonic energy levels of 500 J mL−1 or greater were more effective than using 20% hydrogen peroxide plus 16 h of shaking in dispersing sand-size microaggregates. Surface area measurements of the clay indicated no severe fragmentation or alteration of primary particles had occurred. With increased applied ultrasonic energy and more complete dispersion, the amount of organic C recovered increased in the clay- and decreased in the sand-size fractions. At complete dispersion, there was no evidence of redistribution of organic matter by ultrasonification and the sand-, silt- and clay-size fractions contained 5, 30 and 60% of the soil organic C. Results of this study suggest that ultrasonic dispersion techniques can be used as a physical method to separate microaggregates from soil and thereby study the nature of organic matter within them. Key words: Ultrasonic dispersion methodology, aggregates, organic matter distribution, particle size fractions

Changes in chemical nature of soil organic carbon in Vertisols under wheat in south-eastern Queensland

Soil Research ◽  
2001 ◽  
Vol 39 (2) ◽  
pp. 343 ◽  
Author(s):  
J. O. Skjemstad ◽  
R. C. Dalal ◽  
L. J. Janik ◽  
J. A. McGowan
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Plant Material ◽  
Turnover Rate ◽  
High Energy ◽  
Resistant Plant ◽  
Microbial Decomposition ◽  
Organic C ◽  
The Impact ◽  
C Nmr

The impact of cropping and cultivation (up to 50 years) on the nature and pool structure of organic C in two different soil types was investigated using a combination of physical and chemical fractionations and solid-state 13 C NMR spectroscopy. NMR spectroscopy revealed that aryl C contributed significantly to the organic C in the Waco soil (Pellustert) but not in the Langlands-Logie soil (Chromustert). The aryl C content of both soils was largely preserved despite the significant decrease in total organic C, following cultivation, although other organic forms appeared to rapidly decline at similar rates to one another. High energy UV photo-oxidation along with solid-state 13 C NMR spectroscopy demonstrated that the aryl C was mainly charcoal (char) in the <53 mm fraction of the soils which appeared to be highly resistant to microbial decomposition. Char C content of the Waco soil remained near 6.0 g C/kg soil and near 2.0 g C/kg soil for the Langlands-Logie soil. This char was evident to a depth of at least 30 cm in both soils. Fractionation yielded 4 organic C fractions: particulate organic C, humic C, char C, and physically protected C. By equating these fractions to the resistant plant material (particulate organic C), humic pool (humic C), and inert pool (char C) of the RothC soil C turnover model and comparing a number of simulations with measured fractions, we showed that the inert pool equated well with the measured char C. The measured particulate organic C fraction was of an appropriate size to represent the resistant plant material pool of the model but appeared to have a much slower turnover rate. Similarly, the measured humic pool was of a similar size to that required by the model but was more labile (faster turnover rate) than that used in the RothC model. This may be due to a combination of the labile proteinaceous nature of this pool and its lower than expected protection by physical association with the smectitic clay matrix.

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