Soil analysis revealed a strong trend towards increasing total C content of soil, but only minor increases in oxidisable
organic C (by Walkley-Black method) were detected.
Contribution of oxidisable
organic carbon fractions to total organic carbon in plots subjected to different treatments over 10 years of rice cultivation.
frac2]), constituting ~47% of TOC, are the most easily oxidisable
fractions comprising mainly fungal hyphae, decaying young organic matter, polysaccharides, and other microbial products, the so-called light fraction (Janzen 1987).
The FTIR results from the incubated soils generally indicate the presence of readily oxidisable
carbon forms in Kimbe soils; peaks in the 1190 cmregion indicate polysaccharides and stretching peaks from OH (Grube et al.
The values of all of the three pools of organic C (OC), that is, very labile, Walkley-Black oxidisable
(WBOC) and total OC (TOC), followed the trend Inceptisols > Entisols > Alfisols.
He discussed the possibility of using the dichromate method without correction as a measure of the amount of readily oxidisable
OC in the soil; he increased the size of the glassware to improve titration endpoint determination used for the reaction (and therefore reduced the recovery of TOC because of reduced heat of reaction); and he discussed ambient temperature for its effect on recovery, the importance of the hydrogen ion concentration as the driver of the redox reaction (showing the relationship) and the importance of the concentration of potassium dichromate in terms of the amount of carbon in the sample that can be oxidised.
2006) that extracts watersoluble + exchangeable, reducible (Fe or Mn oxide-bound), and oxidisable
(organic and sulfide-bound) fractions.
Concentrations of total oxidisable
C in each soil extract were determined using a Total Organic Carbon Analyser (TOC-5000A: Shimadzu).
09; base saturation, 100% (exchangeable bases x 100/CEC); oxidisable
organic matter content, 17.
Of the 21 soil quality parameters considered for study, easily oxidisable
42 pre-washed in DDI water) were frozen at -20[degrees]C until analysed for total oxidisable
C (Shimadzu Model 5050).
15]N abundance in the biogenic and physicogenic aggregates; and determined C levels in oxidisable
fractions, particle-size fractions and humic fractions of SOM in biogenic and physicogenic aggregates.