Direct Determination of Organic Carbon by Dry Combustion in Soils with Carbonates

Philadelphia

2006

Sonderdruck

0010-3624

12250S

202781

In acid soils, where organic carbon (C) corresponds to total C, direct determination of organic C by dry combustion is possible, whereas in soils with carbonates also a separate measurement of inorganic C is required. In this case, direct quantification of organic C can be accomplished by the Walkley‐Black method, which is time‐consuming and involves greatly polluting by‐products. Hence, a method able to determine directly organic C by dry combustion is strongly needed for soils with carbonates. This study proposes such a method, after it was found to be highly reliable in calcareous soils of a Mediterranean island. The correction factor to use in the Walkley‐Black method to account for nonrecoverable C was calculated. It does not show any overall relationship with the contents of either organic C or inorganic C, and for all land uses examined in the island, it is not significantly different from the commonly suggested value 1.30.Keywords: Calcareous soils, soil organic carbon (SOC), soil inorganic carbon (SIC), Walkley‐Black method, correction factor (CF)Schlüsselwörter: Kalkhaltige Böden, organischer Kohlenstoff im Boden (SOC), anorganischer Kohlenstoff im Boden (SIC), Walkley-Black-Methode, Korrekturfaktor (CF)