ABSTRACT The demand for spatially and temporally exhaustive information on soil organic carbon (SOC) is growing exponentially. This is because many national, continental, and global initiatives strongly rely on such information, including soil health monitoring, sustainable land use, climate change mitigation, land degradation neutrality, and maintenance of ecosystem services. The objective of this study is to introduce HU‐SoilCarbonGrids ( https://husoilcarbongrids.hu/ ), which aims to meet diverse demands and provide reliable and comprehensive information on spatiotemporal SOC changes across Hungary. It relies on geographically and temporally referenced SOC stock observations ( n = 9385, collected every 3 years at 1048 monitoring sites) derived from the Hungarian Soil Information and Monitoring System, a large set of static and dynamic environmental covariates serving as proxies for the soil‐forming factors, and advanced digital soil mapping techniques to predict annually the space–time variability of SOC stock at a resolution of 100 m between 1992 and 2023 across the country, with the associated prediction uncertainty. In the case of dynamic covariates, their long‐term effects on SOC stock were also investigated and considered using various weighting functions. Based on the compiled map series, which provides a unique and reliable representation of SOC changes across Hungary, it was found that SOC stock has fluctuated at the country scale. Additionally, a net decreasing trend in SOC was obtained over the 32‐year long period at the country level. It was also demonstrated that SOC stocks show diverging trends across permanent land use types, with forests increasing, wetlands gradually declining, and croplands and grasslands fluctuating. Although the current version of HU‐SoilCarbonGrids meets diverse needs for dynamic SOC information, we are committed to improving it and releasing updated versions to support national and international initiatives, such as SOC conservation, soil health monitoring, sustainable land use and climate change mitigation.
Szatmári et al. (Thu,) studied this question.