Application of the Oxidizable Carbon Ratio Dating Procedure and Its Implications for Pedogenic Research
The oxidizable carbon ratio (OCR), expressed as the ratio of total C by loss-on-ignition to readily oxidizable C by wet oxidation, challenges the presumed biological stability of carbonized organic matter. Previous studies demonstrate that charcoal is biologically recycled at a slow, but measurable rate, and that the rate of biochemical degradation of the carbonized organic matter varies within the specific physical and environ-mental contexts of the sample. The OCR-dating procedure determines an age for the C sample by use of a systems formula designed to account for the biological influences of O2, moisture, temperature, C concentration and the media's (soil) reactivity. These variables are measured by soil texture and depth below the soil surface, the site-specific mean annual temperature and rainfall, percentage of total C, and the soil pH. Residual influences on this system are included through a statistically derived constant. Using data from locations in North America and East Africa, a strong correlation [r = 0.98, standard error (SE) = 0.03] is demonstrated between the age estimates obtained by the OCR-dating procedure and 14C radiocarbon age estimates. Outliers define how river inundation and poor sample preparations adversely affect the results. This procedure is expanded to measuring the OCR of relatively stable residual organic matter, and to date the age of buried soil horizons. The OCR-dating procedure accounts for the interdependent dynamics of climate, biota, parent material, and time, providing an empirical test of Jenny's model for pedogenesis.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 1995. . Copyright © 1995 by the Soil Science Society of America, Inc., 5585 Guilford Rd., Madison, WI 53711 USA