Recovery rate of organic C in organic matter fractions of Grantsburg soils

Imtiaz Hussain, Kenneth R. Olson

Research output: Contribution to journalArticlepeer-review


Walkley-Black method is a simple and rapid method for organic carbon analysis. Because of incomplete oxidation of organic carbon (C), the recovery of organic C is low with this method. Assuming the 77% recovery of organic C with Walkley-Black method, the results are corrected with a correction factor of 1.30. The objective of this study is to determine the soil organic C recovery rate and appropriate correction factor for Walkley-Black (wet combustion) method for tilled soils in southern Illinois. Soil samples were collected in 1995 and 1996 from a trial established in southern Illinois on a moderately well drained, Grantsburg (fine-silty, mixed, mesic Oxyaquic Fragiudalf) soil. Organic C contents with the Leco analyzer (dry combustion) were significantly higher as compared to the Walkley-Black method in different tillage systems (no-till, chisel plow and moldboard plow), soil organic matter fractions (whole soil and mineral fraction) and soil depths (0-5 and 515 cm). The recovery percentage of organic C was lower than the assumed percentage with the Walkley-Black method. No significant differences in organic C recovery percentage were found due to differences in tillage systems and depths, whereas the recovery percentage was lower in mineral fraction as compared to the whole soil. The lower organic C recovery percentage was due to the more stable organic C compounds in the mineral fraction. On the basis of these findings, correction factors of 1.35 and 1.41 are proposed for whole soil and mineral organic C analysis with Walkley-Black method, respectively for tilled Grantsburg and other similar soils in southern Illinois.

Original languageEnglish (US)
Pages (from-to)995-1001
Number of pages7
JournalCommunications in Soil Science and Plant Analysis
Issue number7-8
StatePublished - 2000

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science


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