Dithionite-Citrate-Bicarbonate-Extractable Organic Matter in Particle-Size Fractions of a Haplaquoll

1995 ◽  
Vol 59 (4) ◽  
pp. 1019-1027 ◽  
Author(s):  
H.-R. Schulten ◽  
P. Leinweber
Soil Research ◽  
1986 ◽  
Vol 24 (2) ◽  
pp. 293 ◽  
Author(s):  
RC Dalal ◽  
RJ Mayer

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.


1990 ◽  
Vol 70 (3) ◽  
pp. 395-402 ◽  
Author(s):  
J. ELUSTONDO ◽  
M. R. LAVERDIÈRE ◽  
D. A. ANGERS ◽  
A. N'DAYEGAMIYE

Water-stable aggregation and organic matter associated with particle-size fractions were compared for seven pairs of soils that were either under meadow or continuous corn cropping for more than 5 yr. Soils that have remained under meadow contained 25 and 29% more carbon and nitrogen than those under continuous corn. Carbon contents of the sand- and silt-size fractions were also 61 and 15% higher, respectively, under meadow than under continuous corn. The cropping system had no significant effect on the carbon and nitrogen contents of the clay-size fractions. The amount of water-stable aggregates (> 1 mm) was on average 34% higher in soils under meadow than in soils under corn cropping. Significant correlations were found between water-stable aggregates and total C (r = 0.77) and C in sand-size fraction (r = 0.79). The results also indicate that the beneficial effect of meadow over continuous corn on soil aggregation increases as soil clay content increases. Key words: Aggregation, organic matter, particle-size fractions, corn, meadow


Geoderma ◽  
2016 ◽  
Vol 264 ◽  
pp. 171-178 ◽  
Author(s):  
Oihane Fernández-Ugalde ◽  
Pierre Barré ◽  
Iñigo Virto ◽  
Fabien Hubert ◽  
Daniel Billiou ◽  
...  

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