ANALYSIS OF CARBON IN CALCAREOUS SOILS USING A 2 TEMPERATURE DRY COMBUSTION INFRARED INSTRUMENTAL PROCEDURE

There is increasing interest in the role that soil carbon storage plays in buffering against changes in atmospheric carbon dioxide levels and, hence, in quantifying shifts in soil carbon content as a function of changing land use. Such a task involves the analysis of numerous soil samples. The methods presently available for soil carbon analysis are costly in both time and materials, particularly where the need to differentiate between organic and inorganic carbon forms requires lengthy acid pretreatment of the samples. We have successfully adapted a procedure for sequential two-temperature measurement of organic and inorganic carbon in soils by dry combustion infrared instrumental analysis. Several soils representing three soil orders, with organic C contents from < 1 to > 4% and inorganic C from < 1 to > 9%, were used in method development. Results correlate highly with accepted methods. The procedure offers a greater than 10-fold reduction in time required for sample preparation, analysis, and data acquisition.