Dichromate‐oxidizable and total organic carbon contents of representative soils of the major soil areas of Louisiana

Abstract

Dichromate‐oxidizable and total organic carbon in soils from the major mineral soil areas in Louisiana were measured. The objective was to determine if it is possible to use one correction factor for calculating total from dichromate‐oxidizable carbon for all mineral soil areas in the state or if separate correction factors are needed for each soil area. The recovery of total organic carbon from 179 soil samples from all mineral soil areas using the dichromate oxidation with no external heating (Walkley‐Black) method ranged from 46 to 87 % with a mean of 71 % and a c.v. of 9.8%. An average correction factor of 1.41 for calculating total from dichromate‐oxidizable organic carbon can be used for all mineral soil areas in Louisiana. However, this correction factor will be inaccurate for many individual soils. Although small but significant differences among the recoveries of total organic carbon from some of the different soil areas were observed, the differences are not large enough to warrant using separate correction factors for each soil area, since there is more variation within a soil area than between soil areas.