A Billion Tons of Unaccounted for Carbon in the Southeastern United States

Abstract

Because Earth's soil contains more carbon than the atmosphere and all terrestrial vegetation combined, forecasting and managing the global carbon cycle in the face of natural and anthropogenic change requires accurate representations of this carbon. Here from regional geomorphic and soil databases, we characterize the mass, distribution, and cycling of previously unaccounted for soil carbon across the southeastern U.S. Coastal Plain, referred to as “deep‐podzolized carbon.” We show that geomorphologic‐hydrologic interactions stabilize approximately 1.1 × 10−9 t of deep‐podzolized carbon (equivalent to roughly 18% of the soil organic carbon stored across the entire region from 0–30 cm), and that this potentially ancient carbon is predictably distributed coincident with Pleistocene marine transgressions. We not only redefine soil carbon storage in the region but we also introduce the Earth Sciences to a massive organic carbon pool that interacts with landscape evolution and hydrology, has essentially never been studied, and is ripe for interdisciplinary research.

Large, old pools of carbon and microbial communities are present deep in soils under a temperate planted forest

“…Previous research has identified large stores of unaccounted C stocks located in subsoils (Balesdent et al, 2018;Gonzalez et al, 2018;Ross et al, 2020). Our research identified that within Puruki Forest, 35% of total SOC stocks were allocated to soils deeper than 30 cm.…”