The association of organic matter (OM) with minerals in soils that leads to the stabilization of OM has been linked to specific surface area (SSA) and mineralogy. This study investigated the mineral properties and OM stabilization in 12 surface tropical soil samples. The results showed that stable carbon (stable C) was primarily preserved in silt and clay fractions. The clay fraction was mainly composed of kaolinite, with minor amounts of hematite. The SSA was highly correlated with both crystalline and poorly crystalline Fe oxides and clay content, but there was low correlation with stable and labile carbon. The correlation between SSA and Fe oxides was stronger with crystalline than with poorly crystalline minerals and clay. In general, the SSA of soils increased after removal of organic carbon. However, some samples, especially in the clay fraction, showed a decrease in SSA after removal of organic carbon because of the effect of coating or precipitation of OM on the weakly crystalline Fe oxides.
1Department of Soil Science, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand.
2Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware, USA.
Address for correspondence: Dr. Irb Kheoruenromne, Department of Soil Science, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand. E-mail: firstname.lastname@example.org
Financial Disclosure/Conflicts of Interest: The authors report no conflicts of interest.
Received March 19, 2013.
Accepted for publication July 11, 2013.