Hidden carbon stored in deep soils (#journal)

The hidden organic carbon in deep mineral soils 

Current estimates of soil organic carbon (SOC) are based on surficial measurements to depths of 0.3 to 1 m. But many of the world’s soils greatly exceed 1 m depth. This paper provides the first detailed analysis of these previously unreported stores of SOC. Soils from five sites in south-western Australia were analysed for SOC. These soils ranged between 5 and 38 m depth to bedrock.  Mean SOC for each of the five locations varied from 21.8–37.5 kg C m⁻², two to five times greater than from sampling to a depth of just 0.5 m.

This finding may have major implications for estimates of global carbon storage and modelling of the impacts of climate change. The paper demonstrates the need for a reassessment of the current shallow soil sampling depths for assessing carbon stocks and a revision of global SOC estimates.