The global mineralogical capacity of soils to store carbon

Dr Katerina Georgiou1,2, Dr Wenting Feng3, Dr Jennifer Harden1, Dr Rose Abramoff4, Dr William Riley2, Dr Rob Jackson1, Dr Margaret Torn2,5

1Earth System Science, Stanford University, , United States, 2Lawrence Berkeley National Laboratory, , United States, 3Agricultural Resources & Regional Planning, Chinese Academy of Agricultural Sciences, , China, 4Laboratoire des Sciences du Climat et de l’Environnement, , France, 5Energy & Resources Group, University of California at Berkeley, , United States

Soil – the largest terrestrial pool of actively-cycling carbon – has the potential to sequester vast amounts of carbon globally. Chemical- and physical-associations of organic matter with mineral surfaces are known to play a critical role in this storage and preservation. However, the maximum capacity of soils to store carbon globally, and the role of mineralogy in driving this limit and its spatial variation, is still unknown. Here we present a comprehensive analysis of mineral-associated carbon and auxiliary variables from sites that span diverse biomes and soil types. We find that soil mineralogical properties dictate the maximum capacity of soils to stabilize organic matter associated with minerals, and that this mineral-associated organic matter accounts for the majority of carbon and nitrogen in soil organic matter. Explicit representations of mineral-organic associations are still lacking in Earth system models, and our findings are essential for informing and parameterizing model formulations at global scales. Our results suggest that most soils contain substantially less carbon than their mineral-associated carbon capacity (i.e., they are below carbon saturation), and that this is particularly evident in deeper soils and in poorly-managed and degraded lands. We calculate the mineralogical limit of low- and high-activity mineral soils to stabilize carbon, and use these empirically-derived limits to estimate the global potential for soil minerals to stabilize carbon. This estimate, and the underlying spatial distribution, provides crucial insights and motivation for targeted soil management and conservation efforts. Increasing soil carbon storage through restoration is a promising avenue for mitigating global emissions with lasting co-benefits.


Biography: Katerina Georgiou is a USDA Postdoctoral Fellow in the Dept. of Earth System Science at Stanford University. She received a Ph.D. from UC Berkeley and Lawrence Berkeley National Lab as a NSF and DOE Graduate Fellow.

SOIL ORGANIC MATTER

7th International Symposium
Soil Organic Matter

6 – 11 October 2019

Hilton Adelaide

Adelaide, South Australia

Australia

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