Soils are vital to terrestrial life, yet fundamental knowledge gaps remain regarding quantification of soil biogeochemical processes; soil structural properties; soil resource value; the structure, role, and dynamics of soil biotas; and the evolution of soils under human activities. The transdisciplinary nature of these gaps requires a new generation of soil models. The International Soil Modeling Consortium (ISMC) aims to integrate and advance soil systems modeling, data gathering, and observational capabilities.
Last November, ISMC held its second biannual international conference at Wageningen University. More than 140 participants from 22 countries exchanged research perspectives through talks followed by panel discussions involving the audience and through posters. Since its founding in 2016, ISMC has established agreements and collaborations with international institutions and groups, including the International Union of Soil Sciences, and the consortium has hosted workshops at meetings, including those for AGU and the European Geosciences Union.
The conference identified three major challenges and opportunities:
First, most current soil and land surface models do not consider the dynamic nature of soil properties. Key soil properties are thus assumed to be constant in space and time, which is counter to observations. The impact of these assumptions on land surface–atmosphere exchanges and global climate simulations needs to be quantified. Adequate representations of space-time-dependent parameterizations of soil properties are urgently needed, and researchers must account for the impact of land use on soil properties.
Second, more research is needed on soil thermal conductivities; the impacts of climate change on soils, particularly in cold regions; and an adequate estimation of global soil carbon stocks, which are still highly uncertain. Highly resolved spatial and temporal data on soil properties are especially lacking in northern cold regions. More attention in these regions is needed to understand the role of river migration in landscape formation under climate change. Attention is also needed to quantify freeze-thaw cycling (cryoturbation) and the incomplete freezing of soil at depths (talik formation), which has particular implications for the high carbon storage and release during future climate change scenarios.
Third, highly resolved spatial soil data (e.g., International Soil Reference and Information Centre SoilGrids) and pedotransfer functions that convert basic soil properties into hydraulic properties are becoming increasingly available and vital in global climate and land surface models. Moreover, existing and newly launched satellite platforms provide unique global coverage of data that may be used as input to soil models. Approaches to reduce uncertainties in these properties are urgently needed.
The naturally high heterogeneity of soils, a focus on resource-intensive, economically important agricultural soils, and a geographic gross domestic product–driven data availability gradient create biases in data and methodological developments. Participants were encouraged to undertake action to leverage data at the global scale through a bottom-up approach, such as demonstrated in previous publications on infiltration data and soil water retention.
Participants also acknowledged the need to reconcile satellite measurements with the output of soil models. The conference encouraged ISMC members to further compare soil model platforms, expand the soil metadata platform, and enhance model capabilities that connect the dynamic nature of soils.
—Martine van der Ploeg ([email protected]) and Coleen Carranza, Soil Physics and Land Management Group, Wageningen University & Research, Netherlands; and Roland Baatz, IBG-3: Agrosphere, Forschungszentrum Jülich GmbH, Germany