Soil organic carbon stabilization mechanisms and temperature sensitivity in old terraced soils

Abstract. Being the most common human-created landforms, terrace construction has resulted in an extensive perturbation of land surface. However, our mechanistic understanding soil organic carbon (SOC) (de-)stabilization mechanisms and persistence SOC stored terraced soils is far from complete. Here we explored factors controlling stability temperature sensitivity (Q10) abandoned prehistoric agricultural NE England using fractionation temperature-sensitive incubation combined with burial-age measurements. Results showed that although buried contained 1.7 times more unprotected (i.e., coarse particulate carbon) than non-terraced at comparable depths, a significantly lower potential respiration was observed relative to control (non-terraced) profile. This suggests burial former topsoil due terracing provided mechanism for stabilizing SOC. Furthermore, shift fraction composition C towards mineral-protected increasing age. clear processed recalcitrant age also contributes soils. Temperature incubations revealed dominant controls on Q10 depend At relatively younger ages burial, reduction substrate availability mineral protection aging attenuates intrinsic decomposition. as becomes older, stocks deep horizons are characterized by higher sensitivity, potentially resulting poor quality C:N ratio). In conclusion, study site stabilized result during construction. The depth–age patterns differ those seen soils, this implications when assessing effects climate warming abandonment terrestrial cycle.