Soil organic carbon stocks are systematically overestimated by misuse of the parameters bulk density and rock fragment content
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 50, 38116 Braunschweig, Germany
Abstract. Estimation of soil organic carbon (SOC) stocks requires estimates of the carbon content, bulk density, rock fragment content and depth of a respective soil layer. However, different application of these parameters could introduce a considerable bias. Here, we explain why three out of four frequently applied methods overestimate SOC stocks. In soils rich in rock fragments (> 30 vol. %), SOC stocks could be overestimated by more than 100 %, as revealed by using German Agricultural Soil Inventory data. Due to relatively low rock fragments content, the mean systematic overestimation for German agricultural soils was 2.1–10.1 % for three different commonly used equations. The equation ensemble as re-formulated here might help to unify SOC stock determination and avoid overestimation in future studies.