Carbon Determination System for Whole Soil Cores

Abstract

A new dry-combustion system, the soil carbon bench (SCB), has been developed to enable carbon determination for whole soil cores and larger quantities (300–600 g) of composited soil material. A principle driving aim of the work was to lower the analytical errors that arise due to carbon heterogeneity in large soil aliquots, an important consideration during measurement of soil carbon (C) stocks. The method employs pure oxygen to oxidize and transfer combustion products to the detection system but also incorporates oxidized copper (CuO) catalyst to complete the conversion. The system configuration and gas used have facilitated collection of C responses in near real time without interference from excess oxygen or water. Soil processing requirements are minimal and involve breaking up and drying the soil core to remove free water prior to analysis. It has been tested on soil carbon matrix of known composition and on field soils. The results have been very encouraging by providing reliable and reproducible calibration and test soil data. The next phase of work is planned to evaluate the SCB in conjunction with various soil sampling designs.

Keywords:

• Carbon sequestration
• global change
• high temperature combustion
• soil carbon stocks
• soil testing methodology
• total organic carbon