Eric Lund, Colin Christy, and Giyoung Kweon. Veris Technologies, 601 N. Broadway, Salina, KS 67401-2017
Existing soil carbon levels (and rates of sequestration) often vary significantly within a field. Detecting minute rates of carbon change against a background of variability is difficult, since carbon levels can vary by 1-2% within a few meters, and the rate of carbon change over a 10 year period is typically less than .5%. This measurement problem results in a large amount of uncertainty in the levels of carbon actually sequestered. That uncertainty leads to skepticism as to effectiveness of soil carbon sequestration methods, and is a cause of significant discounts in carbon credit trading. Soil measurements using near-infrared spectroscopy (NIR) have been shown to relate closely to soil carbon levels, and a mobile NIR shank system has been developed for rapid field-scale mapping of the horizontal carbon variations within a field. These maps, coupled with lab-analyzed calibration samples, along with targeted NIR probing for characterizing the vertical variations in carbon, demonstrate an important step in reducing the uncertainty of soil carbon sequestration measurements.