Effect of Sedimentation on Soil Organic Carbon Content and δ13C Values After 7 Years of Burial

Abstract

Assessing the effect of rapid sedimentation on the relative storage value/stability of soil organic carbon (SOC) and discrimination of carbon isotope values (δ13C) is needed for improving the use of buried soils as paleoclimatic indicators. In the spring of 2005, plots were established on a Teller fine sandy loam (fine-loamy, mixed, active, thermic, Udic Argiustoll) located in central Oklahoma. The experiment consisted of three treatments of simulated burial (8, 16, 24 cm in depth) by a fine sandy loam deposit and a control (no burial, 0-cm depth). The buried A-horizons were evaluated for changes in SOC and δ13C values after 7 years. All buried horizons significantly decreased in SOC compared with the control at the 0- to 5-cm depth. The control (unburied) averaged 1.60% SOC, whereas the buried horizons averaged 0.83% SOC (a 48% decrease). Differences in δ13C values were observed between the control, buried, and newly formed soil surface (^A-horizon). The δ13C values for buried A-horizons were greater than the control, whereas those for the newly formed soil surface were less than the control. Burial causing discontinuation of organic matter additions resulted in significant reductions in SOC and the alteration of δ13C values during a relatively short period through the loss of easily oxidizable soil organic matter.