Radiocarbon Evidence for Contrasting Soil Carbon Dynamics in a Andisol and Non-Andisol Pasture Soil Comparison
Year: 2010
Type: article
Abstract: In 1959, Athol Rafter began a substantial pro-gramme of monitoring the flow of 14 C produced by atmospheric thermonuclear tests through New Zea-land’s atmosphere, biosphere and soil. A database of over ~400 soil radiocarbon measurements spanning 50 years has now been compiled. A key comparison within the dataset is described here, providing quanti-fi cation of the differences in soil C dynamics between Andisols and non-Andisols. We use 14 C to quantify soil carbon turnover parameters in deforested dairy pastures under similar climate in the Tokomaru silt loam (non-Andisol) versus the Egmont black loam (Andisol), originally sampled in 1962, 1965 and 1969. After adding surface soils sampled to a similar depth in 2008, we use a 2-box model to calculate that the residence time of stabilized soil C in the Toko-maru soils is ~9 years compared to ~17 years for the Egmont soils. This difference represents nearly a dou-bling of soil C residence time, and roughly explains the doubling of the soil C stock. With three measure-ments in the 1960s, and an assumption of a 1000 year residence time for passive soil C in the surface layer, the data is of sufficient resolution to estimate that passive soil C comprises 15% of the soil C pool in Tokomaru soils versus 27% in Egmont soils. The Tokomaru/Egmont comparison is necessarily illustra-tive since neither site was replicated extensively, but does provide globally unique data. The comparison supports evidence that C dynamics does differ in Andisols versus non-Andisols, as a result of both the mineral allophane and Al complexation.
Authors: W. T. Baisden, Roger L. Parfitt, Craig Ross
Institution: Crown Research Institutes
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W97468207