Organic carbon content and turnover time in relation to pedogenic iron and aluminum in four temperate forest soils sampled in 2007

Dataset · Fri Dec 31 23:00:00 EST 2021

DOI:https://doi.org/10.15485/1898051· OSTI ID:1898051

Porras, Rachel ^[1]; Hicks Pries, Caitlin ^[2]; McFarlane, Karis ^[3]

---

1. Lawrence Berkeley National Laboratory; Lawrence Berkeley National Laboratory
2. Dartmouth College
3. Lawrence Livermore National Laboratory

Soil organic carbon (SOC) can be stabilized via association with iron (Fe) and aluminum (Al) minerals. Fe and Al can be strong predictors of SOC storage and turnover in soils with relatively high extractable metals content and moderately acidic to circumneutral pH. Here we test whether pedogenic Fe and Al influence SOC content and turnover in soils with low Fe and Al content and acidic pH. In soils from four sites spanning three soil orders, we quantified the amount of Fe and Al in operationally-defined poorly crystalline and organically-complexed phases using selective chemical dissolution applied to the soil fraction containing mineral-associated carbon. We evaluated the correlations of Fe and Al concentrations, mean annual precipitation (MAP), mean annual temperature (MAT), and pH with SOC content and 14C-based turnover times. We found that poorly crystalline Fe and Al content predicted SOC turnover times (p < 0.0001) consistent with findings of previous studies, while organically-complexed Fe and Al content was a better predictor of SOC concentration (p < 0.0001). Greater site-level MAP (p < 0.0001) and colder site-level MAT (p < 0.0001) were correlated with longer SOC turnover times but were not correlated with SOC content. Our results suggest that poorly crystalline Fe and Al effectively slow the turnover of SOC in these acidic soils, even when their combined content in the soil is less than 2% by mass. However, in the strongly acidic Spodosol, organo-metal complexes tended to be less stable resulting in a more actively cycling mineral-associated SOC pool. We characterized mineralogy and carbon content in soils from four forested sites in the eastern deciduous forest zone that span three soil orders. Using selective chemical dissolution applied to the soil fraction containing mineral-associated carbon, we quantified the amount of Fe and Al in operationally-defined poorly crystalline and organically-complexed phases, and correlated these with previously published SOC content and 14C-based turnover times (McFarlane et al. 2013). This dataset comprises site characterization undertaken in 2007 (.png) and subsequent soil analyses (.csv containing C, Fe, Al, 14C-derived TurnoverTime) concluded in 2010.

• Research Organization: Environmental System Science Data Infrastructure for a Virtual Ecosystem; Belowground Biogeochemistry Scientific Focus Area
• Sponsoring Organization: U.S. DOE > Office of Science > Biological and Environmental Research (BER)
• OSTI ID: 1898051
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
EARTH SCIENCE &gt; LAND SURFACE &gt; SOILS
EARTH SCIENCE &gt; LAND SURFACE &gt; SOILS &gt; CARBON
EARTH SCIENCE &gt; LAND SURFACE &gt; SOILS &gt; ORGANIC MATTER
EARTH SCIENCE &gt; LAND SURFACE &gt; SOILS &gt; SOIL CHEMISTRY
EARTH SCIENCE &gt; LAND SURFACE &gt; SOILS &gt; SOIL MOISTURE/WATER CONTENT
EARTH SCIENCE &gt; LAND SURFACE &gt; SOILS &gt; SOIL PH
EARTH SCIENCE &gt; LAND SURFACE &gt; SOILS &gt; SOIL TEMPERATURE