{"type": "FeatureCollection", "features": [{"id": "10.1016/j.soilbio.2021.108466", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:16:14Z", "type": "Journal Article", "created": "2021-11-03", "title": "Improved global-scale predictions of soil carbon stocks with Millennial Version 2", "description": "Abstract Soil carbon (C) models are used to predict C sequestration responses to climate and land use change. Yet, the soil models embedded in Earth system models typically do not represent processes that reflect our current understanding of soil C cycling, such as microbial decomposition, mineral association, and aggregation. Rather, they rely on conceptual pools with turnover times that are fit to bulk C stocks and/or fluxes. As measurements of soil fractions become increasingly available, it is necessary for soil C models to represent these measurable quantities so that model processes can be evaluated more accurately. Here we present Version 2 (V2) of the Millennial model, a soil model developed to simulate C pools that can be measured by extraction or fractionation, including particulate organic C, mineral-associated organic C, aggregate C, microbial biomass, and low molecular weight C. Model processes have been updated to reflect the current understanding of mineral-association, temperature sensitivity and reaction kinetics, and different model structures were tested within an open-source framework. We evaluated the ability of Millennial V2 to simulate total soil organic C (SOC), as well as the mineral-associated and particulate fractions, using three independent data sets of soil fractionation measurements spanning a range of climate and geochemistry in Australia (N\u00a0=\u00a0495), Europe (N\u00a0=\u00a0175), and across the globe (N\u00a0=\u00a0659). When using all the data together (N\u00a0=\u00a01329), the Millennial V2 model predicted SOC (RMSE\u00a0=\u00a03.3\u00a0kg\u00a0C m\u22122, AIC\u00a0=\u00a0675, R i n 2 \u00a0=\u00a00.31, R o u t 2 \u00a0=\u00a00.26) better than the widely-used first-order decomposition model Century (RMSE\u00a0=\u00a03.4\u00a0kg\u00a0C m\u22122, AIC\u00a0=\u00a0696, R i n 2 \u00a0=\u00a00.21, R o u t 2 \u00a0=\u00a00.18) across sites, despite the fact that Millennial V2 has an increase in process complexity and number of parameters compared to Century. Millennial V2 also reproduced the observed fraction of C in MAOM and larger particle size fractions for most latitudes and biomes, and allows for a more detailed understanding of the pools and processes that affect model performance. It is important to note that this study evaluates the spatial variation in C stock only, and that the temporal dynamics of Millennial V2 remain to be tested. The Millennial V2 model updates the conceptual Century model pools and processes and represents our current understanding of the roles that microbial activity, mineral association and aggregation play in soil C sequestration.", "keywords": ["2. Zero hunger", "[SDU.OCEAN]Sciences of the Universe [physics]/Ocean", "550", "Mineral association", "Atmosphere", "Soil organic carbon stocks", "[SDU.OCEAN] Sciences of the Universe [physics]/Ocean", " Atmosphere", "15. Life on land", "551", "Microbial decomposition", "01 natural sciences", "[SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces", " environment", "13. Climate action", "Soil carbon modeling", "[SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces", "environment", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1016/j.soilbio.2021.108466"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Soil%20Biology%20and%20Biochemistry", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.soilbio.2021.108466", "name": "item", "description": "10.1016/j.soilbio.2021.108466", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.soilbio.2021.108466"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2022-01-01T00:00:00Z"}}, {"id": "10.1029/2020jg006119", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:16:41Z", "type": "Journal Article", "created": "2021-08-28", "title": "Impacts of Drying and Rewetting on the Radiocarbon Signature of Respired CO2 and Implications for Incubating Archived Soils", "description": "Abstract

The radiocarbon signature of respired CO2 (\uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2) measured in laboratory soil incubations integrates contributions from soil carbon pools with a wide range of ages, making it a powerful model constraint. Incubating archived soils enriched by \uffe2\uff80\uff9cbomb\uffe2\uff80\uff90C\uffe2\uff80\uff9d from mid\uffe2\uff80\uff9020th century nuclear weapons testing would be even more powerful as it would enable us to trace this pulse over time. However, air\uffe2\uff80\uff90drying and subsequent rewetting of archived soils, as well as storage duration, may alter the relative contribution to respiration from soil carbon pools with different cycling rates. We designed three experiments to assess air\uffe2\uff80\uff90drying and rewetting effects on \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 with constant storage duration (Experiment 1), without storage (Experiment 2), and with variable storage duration (Experiment 3). We found that air\uffe2\uff80\uff90drying and rewetting led to small but significant (\uffce\uffb1\uffc2\uffa0<\uffc2\uffa00.05) shifts in \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 relative to undried controls in all experiments, with grassland soils responding more strongly than forest soils. Storage duration (4\uffe2\uff80\uff9314\uffc2\uffa0y) did not have a substantial effect. Mean differences (95% CIs) for experiments 1, 2, and 3 were: 23.3\uffe2\uff80\uffb0 (\uffc2\uffb16.6), 19.6\uffe2\uff80\uffb0 (\uffc2\uffb110.3), and 29.3\uffe2\uff80\uffb0 (\uffc2\uffb129.1) for grassland soils, versus \uffe2\uff88\uff9211.6\uffe2\uff80\uffb0 (\uffc2\uffb14.1), 12.7\uffe2\uff80\uffb0 (\uffc2\uffb18.5), and \uffe2\uff88\uff9224.2\uffe2\uff80\uffb0 (\uffc2\uffb113.2) for forest soils. Our results indicate that air\uffe2\uff80\uff90drying and rewetting soils mobilizes a slightly older pool of carbon that would otherwise be inaccessible to microbes, an effect that persists throughout the incubation. However, as the bias in \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 from air\uffe2\uff80\uff90drying and rewetting is small, measuring \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 in incubations of archived soils appears to be a promising technique for constraining soil carbon models.The radiocarbon signature of respired CO2 (\uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2) measured in laboratory soil incubations integrates contributions from soil carbon pools with a wide range of ages, making it a powerful model constraint. Incubating archived soils enriched by \uffe2\uff80\uff9cbomb\uffe2\uff80\uff90C\uffe2\uff80\uff9d from mid\uffe2\uff80\uff9020th century nuclear weapons testing would be even more powerful as it would enable us to trace this pulse over time. However, air\uffe2\uff80\uff90drying and subsequent rewetting of archived soils, as well as storage duration, may alter the relative contribution to respiration from soil carbon pools with different cycling rates. We designed three experiments to assess air\uffe2\uff80\uff90drying and rewetting effects on \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 with constant storage duration (Experiment 1), without storage (Experiment 2), and with variable storage duration (Experiment 3). We found that air\uffe2\uff80\uff90drying and rewetting led to small but significant (\uffce\uffb1\uffc2\uffa0<\uffc2\uffa00.05) shifts in \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 relative to undried controls in all experiments, with grassland soils responding more strongly than forest soils. Storage duration (4\uffe2\uff80\uff9314\uffc2\uffa0y) did not have a substantial effect. Mean differences (95% CIs) for experiments 1, 2, and 3 were: 23.3\uffe2\uff80\uffb0 (\uffc2\uffb16.6), 19.6\uffe2\uff80\uffb0 (\uffc2\uffb110.3), and 29.3\uffe2\uff80\uffb0 (\uffc2\uffb129.1) for grassland soils, versus \uffe2\uff88\uff9211.6\uffe2\uff80\uffb0 (\uffc2\uffb14.1), 12.7\uffe2\uff80\uffb0 (\uffc2\uffb18.5), and \uffe2\uff88\uff9224.2\uffe2\uff80\uffb0 (\uffc2\uffb113.2) for forest soils. Our results indicate that air\uffe2\uff80\uff90drying and rewetting soils mobilizes a slightly older pool of carbon that would otherwise be inaccessible to microbes, an effect that persists throughout the incubation. However, as the bias in \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 from air\uffe2\uff80\uff90drying and rewetting is small, measuring \uffe2\uff88\uff8614C\uffe2\uff80\uff90CO2 in incubations of archived soils appears to be a promising technique for constraining soil carbon models.