The potential of diffuse reflectance spectroscopy for the determination of carbon inventories in soils.

Investigations have shown that near- and mid-infrared reflectance spectroscopy can accurately determine organic-C in soil. Efforts have also demonstrated that both can differentiate between organic and inorganic-C in soils, but the mid-infrared produces more accurate calibrations. Nevertheless, the greatest benefit would come with in situ determinations where factors such as particle size, sample heterogeneity and moisture can be important. While the variations in large (> 20 mesh) particle size can adversely effect calibration accuracy, efforts have demonstrated that the scanning of larger amounts of sample can overcome this, but the effects of moisture have not been fully explored. While under in situ conditions C distribution and sample heterogeneity are a problem for any analytical method, the rapid analysis possible with spectroscopic techniques will allow many more samples to be analyzed. In conclusion, near- and mid-infrared spectroscopy have great potential for providing the C values needed for C sequestration studies.