Does phyllosilicate mineralogy explain organic matter stabilization in different particle-size fractions in a 19-year C3/C4 chronosequence in a temperate Cambisol?

Geoderma ◽  
2016 ◽  
Vol 264 ◽  
pp. 171-178 ◽  
Author(s):  
Oihane Fernández-Ugalde ◽  
Pierre Barré ◽  
Iñigo Virto ◽  
Fabien Hubert ◽  
Daniel Billiou ◽  
...  
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Organic Matter Stabilization

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

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.

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