A Novel Method for Measurement of Carbon on Whole Soil Cores

Abstract

Dry combustion is a reliable method of determining soil C but like all methods has been challenged by the required scale. Several methods for measuring soil carbon stocks have been promoted in recent years as a way of dealing with the current soil C data crisis but techniques such as spectroscopy depend on standardisation by dry combustion. A new robust approach has been developed where the contents of whole soil cores are analysed by dry combustion to yield C data for full depth intervals. The system has a configuration which is based on extracting all C from a 50 cm long soil plug. The method relies on direct quantitative detection and minimising any interference from water. Apart from pre-drying to remove excess moisture, the flow-on benefits have been reduced time and associated costs in soil processing. The advantage is that this methodology captures the natural variability in all dimensions and can directly produce results on a volumetric (kg/m³) or gravimetric basis (g/kg). Determinations on cores have been reproduced within 0.1 % C (mass basis) which is the level of sensitivity required. The technique, which can be deployed on cores set out according to an appropriate sampling design, facilitates fast and cost effective determination of soil C stocks to support mapping, modeling and management.